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authorLinus Torvalds <torvalds@linux-foundation.org>2014-10-26 11:19:18 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-10-26 11:19:18 -0700
commitd1e14f1d63eb15ebe97d1a8544ddc143486b0204 (patch)
treea73e7c751f23835483f1e8029d04547192611975
parent2cc91884b6b3f7328680b8ea7563016d3aee3d19 (diff)
parentdb6ec212b53abc29a5bb6ac8c810010fc28d5191 (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs updates from Al Viro: "overlayfs merge + leak fix for d_splice_alias() failure exits" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: overlayfs: embed middle into overlay_readdir_data overlayfs: embed root into overlay_readdir_data overlayfs: make ovl_cache_entry->name an array instead of pointer overlayfs: don't hold ->i_mutex over opening the real directory fix inode leaks on d_splice_alias() failure exits fs: limit filesystem stacking depth overlay: overlay filesystem documentation overlayfs: implement show_options overlayfs: add statfs support overlay filesystem shmem: support RENAME_WHITEOUT ext4: support RENAME_WHITEOUT vfs: add RENAME_WHITEOUT vfs: add whiteout support vfs: export check_sticky() vfs: introduce clone_private_mount() vfs: export __inode_permission() to modules vfs: export do_splice_direct() to modules vfs: add i_op->dentry_open()
-rw-r--r--Documentation/filesystems/Locking2
-rw-r--r--Documentation/filesystems/overlayfs.txt198
-rw-r--r--Documentation/filesystems/vfs.txt7
-rw-r--r--MAINTAINERS7
-rw-r--r--fs/Kconfig1
-rw-r--r--fs/Makefile1
-rw-r--r--fs/btrfs/ioctl.c20
-rw-r--r--fs/dcache.c2
-rw-r--r--fs/ecryptfs/main.c7
-rw-r--r--fs/ext4/namei.c95
-rw-r--r--fs/internal.h7
-rw-r--r--fs/namei.c41
-rw-r--r--fs/namespace.c27
-rw-r--r--fs/open.c23
-rw-r--r--fs/overlayfs/Kconfig10
-rw-r--r--fs/overlayfs/Makefile7
-rw-r--r--fs/overlayfs/copy_up.c414
-rw-r--r--fs/overlayfs/dir.c921
-rw-r--r--fs/overlayfs/inode.c425
-rw-r--r--fs/overlayfs/overlayfs.h191
-rw-r--r--fs/overlayfs/readdir.c590
-rw-r--r--fs/overlayfs/super.c796
-rw-r--r--fs/splice.c1
-rw-r--r--include/linux/fs.h39
-rw-r--r--include/linux/mount.h3
-rw-r--r--include/uapi/linux/fs.h1
-rw-r--r--mm/shmem.c36
27 files changed, 3814 insertions, 58 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 94d93b1f8b53..b30753cbf431 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -67,6 +67,7 @@ prototypes:
struct file *, unsigned open_flag,
umode_t create_mode, int *opened);
int (*tmpfile) (struct inode *, struct dentry *, umode_t);
+ int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
locking rules:
all may block
@@ -96,6 +97,7 @@ fiemap: no
update_time: no
atomic_open: yes
tmpfile: no
+dentry_open: no
Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on
victim.
diff --git a/Documentation/filesystems/overlayfs.txt b/Documentation/filesystems/overlayfs.txt
new file mode 100644
index 000000000000..530850a72735
--- /dev/null
+++ b/Documentation/filesystems/overlayfs.txt
@@ -0,0 +1,198 @@
+Written by: Neil Brown <neilb@suse.de>
+
+Overlay Filesystem
+==================
+
+This document describes a prototype for a new approach to providing
+overlay-filesystem functionality in Linux (sometimes referred to as
+union-filesystems). An overlay-filesystem tries to present a
+filesystem which is the result over overlaying one filesystem on top
+of the other.
+
+The result will inevitably fail to look exactly like a normal
+filesystem for various technical reasons. The expectation is that
+many use cases will be able to ignore these differences.
+
+This approach is 'hybrid' because the objects that appear in the
+filesystem do not all appear to belong to that filesystem. In many
+cases an object accessed in the union will be indistinguishable
+from accessing the corresponding object from the original filesystem.
+This is most obvious from the 'st_dev' field returned by stat(2).
+
+While directories will report an st_dev from the overlay-filesystem,
+all non-directory objects will report an st_dev from the lower or
+upper filesystem that is providing the object. Similarly st_ino will
+only be unique when combined with st_dev, and both of these can change
+over the lifetime of a non-directory object. Many applications and
+tools ignore these values and will not be affected.
+
+Upper and Lower
+---------------
+
+An overlay filesystem combines two filesystems - an 'upper' filesystem
+and a 'lower' filesystem. When a name exists in both filesystems, the
+object in the 'upper' filesystem is visible while the object in the
+'lower' filesystem is either hidden or, in the case of directories,
+merged with the 'upper' object.
+
+It would be more correct to refer to an upper and lower 'directory
+tree' rather than 'filesystem' as it is quite possible for both
+directory trees to be in the same filesystem and there is no
+requirement that the root of a filesystem be given for either upper or
+lower.
+
+The lower filesystem can be any filesystem supported by Linux and does
+not need to be writable. The lower filesystem can even be another
+overlayfs. The upper filesystem will normally be writable and if it
+is it must support the creation of trusted.* extended attributes, and
+must provide valid d_type in readdir responses, so NFS is not suitable.
+
+A read-only overlay of two read-only filesystems may use any
+filesystem type.
+
+Directories
+-----------
+
+Overlaying mainly involves directories. If a given name appears in both
+upper and lower filesystems and refers to a non-directory in either,
+then the lower object is hidden - the name refers only to the upper
+object.
+
+Where both upper and lower objects are directories, a merged directory
+is formed.
+
+At mount time, the two directories given as mount options "lowerdir" and
+"upperdir" are combined into a merged directory:
+
+ mount -t overlayfs overlayfs -olowerdir=/lower,upperdir=/upper,\
+workdir=/work /merged
+
+The "workdir" needs to be an empty directory on the same filesystem
+as upperdir.
+
+Then whenever a lookup is requested in such a merged directory, the
+lookup is performed in each actual directory and the combined result
+is cached in the dentry belonging to the overlay filesystem. If both
+actual lookups find directories, both are stored and a merged
+directory is created, otherwise only one is stored: the upper if it
+exists, else the lower.
+
+Only the lists of names from directories are merged. Other content
+such as metadata and extended attributes are reported for the upper
+directory only. These attributes of the lower directory are hidden.
+
+whiteouts and opaque directories
+--------------------------------
+
+In order to support rm and rmdir without changing the lower
+filesystem, an overlay filesystem needs to record in the upper filesystem
+that files have been removed. This is done using whiteouts and opaque
+directories (non-directories are always opaque).
+
+A whiteout is created as a character device with 0/0 device number.
+When a whiteout is found in the upper level of a merged directory, any
+matching name in the lower level is ignored, and the whiteout itself
+is also hidden.
+
+A directory is made opaque by setting the xattr "trusted.overlay.opaque"
+to "y". Where the upper filesystem contains an opaque directory, any
+directory in the lower filesystem with the same name is ignored.
+
+readdir
+-------
+
+When a 'readdir' request is made on a merged directory, the upper and
+lower directories are each read and the name lists merged in the
+obvious way (upper is read first, then lower - entries that already
+exist are not re-added). This merged name list is cached in the
+'struct file' and so remains as long as the file is kept open. If the
+directory is opened and read by two processes at the same time, they
+will each have separate caches. A seekdir to the start of the
+directory (offset 0) followed by a readdir will cause the cache to be
+discarded and rebuilt.
+
+This means that changes to the merged directory do not appear while a
+directory is being read. This is unlikely to be noticed by many
+programs.
+
+seek offsets are assigned sequentially when the directories are read.
+Thus if
+ - read part of a directory
+ - remember an offset, and close the directory
+ - re-open the directory some time later
+ - seek to the remembered offset
+
+there may be little correlation between the old and new locations in
+the list of filenames, particularly if anything has changed in the
+directory.
+
+Readdir on directories that are not merged is simply handled by the
+underlying directory (upper or lower).
+
+
+Non-directories
+---------------
+
+Objects that are not directories (files, symlinks, device-special
+files etc.) are presented either from the upper or lower filesystem as
+appropriate. When a file in the lower filesystem is accessed in a way
+the requires write-access, such as opening for write access, changing
+some metadata etc., the file is first copied from the lower filesystem
+to the upper filesystem (copy_up). Note that creating a hard-link
+also requires copy_up, though of course creation of a symlink does
+not.
+
+The copy_up may turn out to be unnecessary, for example if the file is
+opened for read-write but the data is not modified.
+
+The copy_up process first makes sure that the containing directory
+exists in the upper filesystem - creating it and any parents as
+necessary. It then creates the object with the same metadata (owner,
+mode, mtime, symlink-target etc.) and then if the object is a file, the
+data is copied from the lower to the upper filesystem. Finally any
+extended attributes are copied up.
+
+Once the copy_up is complete, the overlay filesystem simply
+provides direct access to the newly created file in the upper
+filesystem - future operations on the file are barely noticed by the
+overlay filesystem (though an operation on the name of the file such as
+rename or unlink will of course be noticed and handled).
+
+
+Non-standard behavior
+---------------------
+
+The copy_up operation essentially creates a new, identical file and
+moves it over to the old name. The new file may be on a different
+filesystem, so both st_dev and st_ino of the file may change.
+
+Any open files referring to this inode will access the old data and
+metadata. Similarly any file locks obtained before copy_up will not
+apply to the copied up file.
+
+On a file opened with O_RDONLY fchmod(2), fchown(2), futimesat(2) and
+fsetxattr(2) will fail with EROFS.
+
+If a file with multiple hard links is copied up, then this will
+"break" the link. Changes will not be propagated to other names
+referring to the same inode.
+
+Symlinks in /proc/PID/ and /proc/PID/fd which point to a non-directory
+object in overlayfs will not contain valid absolute paths, only
+relative paths leading up to the filesystem's root. This will be
+fixed in the future.
+
+Some operations are not atomic, for example a crash during copy_up or
+rename will leave the filesystem in an inconsistent state. This will
+be addressed in the future.
+
+Changes to underlying filesystems
+---------------------------------
+
+Offline changes, when the overlay is not mounted, are allowed to either
+the upper or the lower trees.
+
+Changes to the underlying filesystems while part of a mounted overlay
+filesystem are not allowed. If the underlying filesystem is changed,
+the behavior of the overlay is undefined, though it will not result in
+a crash or deadlock.
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index fceff7c00a3c..20bf204426ca 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -364,6 +364,7 @@ struct inode_operations {
int (*atomic_open)(struct inode *, struct dentry *, struct file *,
unsigned open_flag, umode_t create_mode, int *opened);
int (*tmpfile) (struct inode *, struct dentry *, umode_t);
+ int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
};
Again, all methods are called without any locks being held, unless
@@ -696,6 +697,12 @@ struct address_space_operations {
but instead uses bmap to find out where the blocks in the file
are and uses those addresses directly.
+ dentry_open: *WARNING: probably going away soon, do not use!* This is an
+ alternative to f_op->open(), the difference is that this method may open
+ a file not necessarily originating from the same filesystem as the one
+ i_op->open() was called on. It may be useful for stacking filesystems
+ which want to allow native I/O directly on underlying files.
+
invalidatepage: If a page has PagePrivate set, then invalidatepage
will be called when part or all of the page is to be removed
diff --git a/MAINTAINERS b/MAINTAINERS
index 0484f2c526f0..ec25b0e1e745 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6840,6 +6840,13 @@ F: drivers/scsi/osd/
F: include/scsi/osd_*
F: fs/exofs/
+OVERLAYFS FILESYSTEM
+M: Miklos Szeredi <miklos@szeredi.hu>
+L: linux-fsdevel@vger.kernel.org
+S: Supported
+F: fs/overlayfs/*
+F: Documentation/filesystems/overlayfs.txt
+
P54 WIRELESS DRIVER
M: Christian Lamparter <chunkeey@googlemail.com>
L: linux-wireless@vger.kernel.org
diff --git a/fs/Kconfig b/fs/Kconfig
index db5dc1598716..664991afe0c0 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -67,6 +67,7 @@ source "fs/quota/Kconfig"
source "fs/autofs4/Kconfig"
source "fs/fuse/Kconfig"
+source "fs/overlayfs/Kconfig"
menu "Caches"
diff --git a/fs/Makefile b/fs/Makefile
index 90c88529892b..34a1b9dea6dd 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -104,6 +104,7 @@ obj-$(CONFIG_QNX6FS_FS) += qnx6/
obj-$(CONFIG_AUTOFS4_FS) += autofs4/
obj-$(CONFIG_ADFS_FS) += adfs/
obj-$(CONFIG_FUSE_FS) += fuse/
+obj-$(CONFIG_OVERLAYFS_FS) += overlayfs/
obj-$(CONFIG_UDF_FS) += udf/
obj-$(CONFIG_SUN_OPENPROMFS) += openpromfs/
obj-$(CONFIG_OMFS_FS) += omfs/
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 8d2b76e29d3b..4399f0c3a4ce 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -765,23 +765,6 @@ out:
return ret;
}
-/* copy of check_sticky in fs/namei.c()
-* It's inline, so penalty for filesystems that don't use sticky bit is
-* minimal.
-*/
-static inline int btrfs_check_sticky(struct inode *dir, struct inode *inode)
-{
- kuid_t fsuid = current_fsuid();
-
- if (!(dir->i_mode & S_ISVTX))
- return 0;
- if (uid_eq(inode->i_uid, fsuid))
- return 0;
- if (uid_eq(dir->i_uid, fsuid))
- return 0;
- return !capable(CAP_FOWNER);
-}
-
/* copy of may_delete in fs/namei.c()
* Check whether we can remove a link victim from directory dir, check
* whether the type of victim is right.
@@ -817,8 +800,7 @@ static int btrfs_may_delete(struct inode *dir, struct dentry *victim, int isdir)
return error;
if (IS_APPEND(dir))
return -EPERM;
- if (btrfs_check_sticky(dir, victim->d_inode)||
- IS_APPEND(victim->d_inode)||
+ if (check_sticky(dir, victim->d_inode) || IS_APPEND(victim->d_inode) ||
IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
return -EPERM;
if (isdir) {
diff --git a/fs/dcache.c b/fs/dcache.c
index d5a23fd0da90..3ffef7f4e5cd 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2673,11 +2673,13 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
if (!IS_ROOT(new)) {
spin_unlock(&inode->i_lock);
dput(new);
+ iput(inode);
return ERR_PTR(-EIO);
}
if (d_ancestor(new, dentry)) {
spin_unlock(&inode->i_lock);
dput(new);
+ iput(inode);
return ERR_PTR(-EIO);
}
write_seqlock(&rename_lock);
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index 1b119d3bf924..c4cd1fd86cc2 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -566,6 +566,13 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags
s->s_maxbytes = path.dentry->d_sb->s_maxbytes;
s->s_blocksize = path.dentry->d_sb->s_blocksize;
s->s_magic = ECRYPTFS_SUPER_MAGIC;
+ s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1;
+
+ rc = -EINVAL;
+ if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
+ pr_err("eCryptfs: maximum fs stacking depth exceeded\n");
+ goto out_free;
+ }
inode = ecryptfs_get_inode(path.dentry->d_inode, s);
rc = PTR_ERR(inode);
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index adb559de23c1..123798c5ac31 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3148,6 +3148,39 @@ static void ext4_update_dir_count(handle_t *handle, struct ext4_renament *ent)
}
}
+static struct inode *ext4_whiteout_for_rename(struct ext4_renament *ent,
+ int credits, handle_t **h)
+{
+ struct inode *wh;
+ handle_t *handle;
+ int retries = 0;
+
+ /*
+ * for inode block, sb block, group summaries,
+ * and inode bitmap
+ */
+ credits += (EXT4_MAXQUOTAS_TRANS_BLOCKS(ent->dir->i_sb) +
+ EXT4_XATTR_TRANS_BLOCKS + 4);
+retry:
+ wh = ext4_new_inode_start_handle(ent->dir, S_IFCHR | WHITEOUT_MODE,
+ &ent->dentry->d_name, 0, NULL,
+ EXT4_HT_DIR, credits);
+
+ handle = ext4_journal_current_handle();
+ if (IS_ERR(wh)) {
+ if (handle)
+ ext4_journal_stop(handle);
+ if (PTR_ERR(wh) == -ENOSPC &&
+ ext4_should_retry_alloc(ent->dir->i_sb, &retries))
+ goto retry;
+ } else {
+ *h = handle;
+ init_special_inode(wh, wh->i_mode, WHITEOUT_DEV);
+ wh->i_op = &ext4_special_inode_operations;
+ }
+ return wh;
+}
+
/*
* Anybody can rename anything with this: the permission checks are left to the
* higher-level routines.
@@ -3157,7 +3190,8 @@ static void ext4_update_dir_count(handle_t *handle, struct ext4_renament *ent)
* This comes from rename(const char *oldpath, const char *newpath)
*/
static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
- struct inode *new_dir, struct dentry *new_dentry)
+ struct inode *new_dir, struct dentry *new_dentry,
+ unsigned int flags)
{
handle_t *handle = NULL;
struct ext4_renament old = {
@@ -3172,6 +3206,9 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
};
int force_reread;
int retval;
+ struct inode *whiteout = NULL;
+ int credits;
+ u8 old_file_type;
dquot_initialize(old.dir);
dquot_initialize(new.dir);
@@ -3210,11 +3247,17 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
if (new.inode && !test_opt(new.dir->i_sb, NO_AUTO_DA_ALLOC))
ext4_alloc_da_blocks(old.inode);
- handle = ext4_journal_start(old.dir, EXT4_HT_DIR,
- (2 * EXT4_DATA_TRANS_BLOCKS(old.dir->i_sb) +
- EXT4_INDEX_EXTRA_TRANS_BLOCKS + 2));
- if (IS_ERR(handle))
- return PTR_ERR(handle);
+ credits = (2 * EXT4_DATA_TRANS_BLOCKS(old.dir->i_sb) +
+ EXT4_INDEX_EXTRA_TRANS_BLOCKS + 2);
+ if (!(flags & RENAME_WHITEOUT)) {
+ handle = ext4_journal_start(old.dir, EXT4_HT_DIR, credits);
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+ } else {
+ whiteout = ext4_whiteout_for_rename(&old, credits, &handle);
+ if (IS_ERR(whiteout))
+ return PTR_ERR(whiteout);
+ }
if (IS_DIRSYNC(old.dir) || IS_DIRSYNC(new.dir))
ext4_handle_sync(handle);
@@ -3242,13 +3285,26 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
*/
force_reread = (new.dir->i_ino == old.dir->i_ino &&
ext4_test_inode_flag(new.dir, EXT4_INODE_INLINE_DATA));
+
+ old_file_type = old.de->file_type;
+ if (whiteout) {
+ /*
+ * Do this before adding a new entry, so the old entry is sure
+ * to be still pointing to the valid old entry.
+ */
+ retval = ext4_setent(handle, &old, whiteout->i_ino,
+ EXT4_FT_CHRDEV);
+ if (retval)
+ goto end_rename;
+ ext4_mark_inode_dirty(handle, whiteout);
+ }
if (!new.bh) {
retval = ext4_add_entry(handle, new.dentry, old.inode);
if (retval)
goto end_rename;
} else {
retval = ext4_setent(handle, &new,
- old.inode->i_ino, old.de->file_type);
+ old.inode->i_ino, old_file_type);
if (retval)
goto end_rename;
}
@@ -3263,10 +3319,12 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
old.inode->i_ctime = ext4_current_time(old.inode);
ext4_mark_inode_dirty(handle, old.inode);
- /*
- * ok, that's it
- */
- ext4_rename_delete(handle, &old, force_reread);
+ if (!whiteout) {
+ /*
+ * ok, that's it
+ */
+ ext4_rename_delete(handle, &old, force_reread);
+ }
if (new.inode) {
ext4_dec_count(handle, new.inode);
@@ -3302,6 +3360,12 @@ end_rename:
brelse(old.dir_bh);
brelse(old.bh);
brelse(new.bh);
+ if (whiteout) {
+ if (retval)
+ drop_nlink(whiteout);
+ unlock_new_inode(whiteout);
+ iput(whiteout);
+ }
if (handle)
ext4_journal_stop(handle);
return retval;
@@ -3434,18 +3498,15 @@ static int ext4_rename2(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags)
{
- if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
+ if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
return -EINVAL;
if (flags & RENAME_EXCHANGE) {
return ext4_cross_rename(old_dir, old_dentry,
new_dir, new_dentry);
}
- /*
- * Existence checking was done by the VFS, otherwise "RENAME_NOREPLACE"
- * is equivalent to regular rename.
- */
- return ext4_rename(old_dir, old_dentry, new_dir, new_dentry);
+
+ return ext4_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
}
/*
diff --git a/fs/internal.h b/fs/internal.h
index 9477f8f6aefc..757ba2abf21e 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -47,7 +47,6 @@ extern void __init chrdev_init(void);
/*
* namei.c
*/
-extern int __inode_permission(struct inode *, int);
extern int user_path_mountpoint_at(int, const char __user *, unsigned int, struct path *);
extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
const char *, unsigned int, struct path *);
@@ -139,12 +138,6 @@ extern long prune_dcache_sb(struct super_block *sb, unsigned long nr_to_scan,
extern int rw_verify_area(int, struct file *, const loff_t *, size_t);
/*
- * splice.c
- */
-extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
- loff_t *opos, size_t len, unsigned int flags);
-
-/*
* pipe.c
*/
extern const struct file_operations pipefifo_fops;
diff --git a/fs/namei.c b/fs/namei.c
index 43927d14db67..42df664e95e5 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -416,6 +416,7 @@ int __inode_permission(struct inode *inode, int mask)
return security_inode_permission(inode, mask);
}
+EXPORT_SYMBOL(__inode_permission);
/**
* sb_permission - Check superblock-level permissions
@@ -2383,22 +2384,17 @@ kern_path_mountpoint(int dfd, const char *name, struct path *path,
}
EXPORT_SYMBOL(kern_path_mountpoint);
-/*
- * It's inline, so penalty for filesystems that don't use sticky bit is
- * minimal.
- */
-static inline int check_sticky(struct inode *dir, struct inode *inode)
+int __check_sticky(struct inode *dir, struct inode *inode)
{
kuid_t fsuid = current_fsuid();
- if (!(dir->i_mode & S_ISVTX))
- return 0;
if (uid_eq(inode->i_uid, fsuid))
return 0;
if (uid_eq(dir->i_uid, fsuid))
return 0;
return !capable_wrt_inode_uidgid(inode, CAP_FOWNER);
}
+EXPORT_SYMBOL(__check_sticky);
/*
* Check whether we can remove a link victim from directory dir, check
@@ -3064,9 +3060,12 @@ finish_open_created:
error = may_open(&nd->path, acc_mode, open_flag);
if (error)
goto out;
- file->f_path.mnt = nd->path.mnt;
- error = finish_open(file, nd->path.dentry, NULL, opened);
- if (error) {
+
+ BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
+ error = vfs_open(&nd->path, file, current_cred());
+ if (!error) {
+ *opened |= FILE_OPENED;
+ } else {
if (error == -EOPENSTALE)
goto stale_open;
goto out;
@@ -4210,12 +4209,16 @@ SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname,
bool should_retry = false;
int error;
- if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
+ if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
return -EINVAL;
- if ((flags & RENAME_NOREPLACE) && (flags & RENAME_EXCHANGE))
+ if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) &&
+ (flags & RENAME_EXCHANGE))
return -EINVAL;
+ if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD))
+ return -EPERM;
+
retry:
from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags);
if (IS_ERR(from)) {
@@ -4347,6 +4350,20 @@ SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newna
return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
}
+int vfs_whiteout(struct inode *dir, struct dentry *dentry)
+{
+ int error = may_create(dir, dentry);
+ if (error)
+ return error;
+
+ if (!dir->i_op->mknod)
+ return -EPERM;
+
+ return dir->i_op->mknod(dir, dentry,
+ S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
+}
+EXPORT_SYMBOL(vfs_whiteout);
+
int readlink_copy(char __user *buffer, int buflen, const char *link)
{
int len = PTR_ERR(link);
diff --git a/fs/namespace.c b/fs/namespace.c
index fbba8b17330d..5b66b2b3624d 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1686,6 +1686,33 @@ void drop_collected_mounts(struct vfsmount *mnt)
namespace_unlock();
}
+/**
+ * clone_private_mount - create a private clone of a path
+ *
+ * This creates a new vfsmount, which will be the clone of @path. The new will
+ * not be attached anywhere in the namespace and will be private (i.e. changes
+ * to the originating mount won't be propagated into this).
+ *
+ * Release with mntput().
+ */
+struct vfsmount *clone_private_mount(struct path *path)
+{
+ struct mount *old_mnt = real_mount(path->mnt);
+ struct mount *new_mnt;
+
+ if (IS_MNT_UNBINDABLE(old_mnt))
+ return ERR_PTR(-EINVAL);
+
+ down_read(&namespace_sem);
+ new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE);
+ up_read(&namespace_sem);
+ if (IS_ERR(new_mnt))
+ return ERR_CAST(new_mnt);
+
+ return &new_mnt->mnt;
+}
+EXPORT_SYMBOL_GPL(clone_private_mount);
+
int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
struct vfsmount *root)
{
diff --git a/fs/open.c b/fs/open.c
index d6fd3acde134..de92c13b58be 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -823,8 +823,7 @@ struct file *dentry_open(const struct path *path, int flags,
f = get_empty_filp();
if (!IS_ERR(f)) {
f->f_flags = flags;
- f->f_path = *path;
- error = do_dentry_open(f, NULL, cred);
+ error = vfs_open(path, f, cred);
if (!error) {
/* from now on we need fput() to dispose of f */
error = open_check_o_direct(f);
@@ -841,6 +840,26 @@ struct file *dentry_open(const struct path *path, int flags,
}
EXPORT_SYMBOL(dentry_open);
+/**
+ * vfs_open - open the file at the given path
+ * @path: path to open
+ * @filp: newly allocated file with f_flag initialized
+ * @cred: credentials to use
+ */
+int vfs_open(const struct path *path, struct file *filp,
+ const struct cred *cred)
+{
+ struct inode *inode = path->dentry->d_inode;
+
+ if (inode->i_op->dentry_open)
+ return inode->i_op->dentry_open(path->dentry, filp, cred);
+ else {
+ filp->f_path = *path;
+ return do_dentry_open(filp, NULL, cred);
+ }
+}
+EXPORT_SYMBOL(vfs_open);
+
static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
{
int lookup_flags = 0;
diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig
new file mode 100644
index 000000000000..e60125976873
--- /dev/null
+++ b/fs/overlayfs/Kconfig
@@ -0,0 +1,10 @@
+config OVERLAYFS_FS
+ tristate "Overlay filesystem support"
+ help
+ An overlay filesystem combines two filesystems - an 'upper' filesystem
+ and a 'lower' filesystem. When a name exists in both filesystems, the
+ object in the 'upper' filesystem is visible while the object in the
+ 'lower' filesystem is either hidden or, in the case of directories,
+ merged with the 'upper' object.
+
+ For more information see Documentation/filesystems/overlayfs.txt
diff --git a/fs/overlayfs/Makefile b/fs/overlayfs/Makefile
new file mode 100644
index 000000000000..8f91889480d0
--- /dev/null
+++ b/fs/overlayfs/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for the overlay filesystem.
+#
+
+obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o
+
+overlayfs-objs := super.o inode.o dir.o readdir.o copy_up.o
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
new file mode 100644
index 000000000000..ea10a8719107
--- /dev/null
+++ b/fs/overlayfs/copy_up.c
@@ -0,0 +1,414 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/splice.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+#include <linux/uaccess.h>
+#include <linux/sched.h>
+#include <linux/namei.h>
+#include "overlayfs.h"
+
+#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
+
+int ovl_copy_xattr(struct dentry *old, struct dentry *new)
+{
+ ssize_t list_size, size;
+ char *buf, *name, *value;
+ int error;
+
+ if (!old->d_inode->i_op->getxattr ||
+ !new->d_inode->i_op->getxattr)
+ return 0;
+
+ list_size = vfs_listxattr(old, NULL, 0);
+ if (list_size <= 0) {
+ if (list_size == -EOPNOTSUPP)
+ return 0;
+ return list_size;
+ }
+
+ buf = kzalloc(list_size, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ error = -ENOMEM;
+ value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL);
+ if (!value)
+ goto out;
+
+ list_size = vfs_listxattr(old, buf, list_size);
+ if (list_size <= 0) {
+ error = list_size;
+ goto out_free_value;
+ }
+
+ for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
+ size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX);
+ if (size <= 0) {
+ error = size;
+ goto out_free_value;
+ }
+ error = vfs_setxattr(new, name, value, size, 0);
+ if (error)
+ goto out_free_value;
+ }
+
+out_free_value:
+ kfree(value);
+out:
+ kfree(buf);
+ return error;
+}
+
+static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
+{
+ struct file *old_file;
+ struct file *new_file;
+ loff_t old_pos = 0;
+ loff_t new_pos = 0;
+ int error = 0;
+
+ if (len == 0)
+ return 0;
+
+ old_file = ovl_path_open(old, O_RDONLY);
+ if (IS_ERR(old_file))
+ return PTR_ERR(old_file);
+
+ new_file = ovl_path_open(new, O_WRONLY);
+ if (IS_ERR(new_file)) {
+ error = PTR_ERR(new_file);
+ goto out_fput;
+ }
+
+ /* FIXME: copy up sparse files efficiently */
+ while (len) {
+ size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
+ long bytes;
+
+ if (len < this_len)
+ this_len = len;
+
+ if (signal_pending_state(TASK_KILLABLE, current)) {
+ error = -EINTR;
+ break;
+ }
+
+ bytes = do_splice_direct(old_file, &old_pos,
+ new_file, &new_pos,
+ this_len, SPLICE_F_MOVE);
+ if (bytes <= 0) {
+ error = bytes;
+ break;
+ }
+ WARN_ON(old_pos != new_pos);
+
+ len -= bytes;
+ }
+
+ fput(new_file);
+out_fput:
+ fput(old_file);
+ return error;
+}
+
+static char *ovl_read_symlink(struct dentry *realdentry)
+{
+ int res;
+ char *buf;
+ struct inode *inode = realdentry->d_inode;
+ mm_segment_t old_fs;
+
+ res = -EINVAL;
+ if (!inode->i_op->readlink)
+ goto err;
+
+ res = -ENOMEM;
+ buf = (char *) __get_free_page(GFP_KERNEL);
+ if (!buf)
+ goto err;
+
+ old_fs = get_fs();
+ set_fs(get_ds());
+ /* The cast to a user pointer is valid due to the set_fs() */
+ res = inode->i_op->readlink(realdentry,
+ (char __user *)buf, PAGE_SIZE - 1);
+ set_fs(old_fs);
+ if (res < 0) {
+ free_page((unsigned long) buf);
+ goto err;
+ }
+ buf[res] = '\0';
+
+ return buf;
+
+err:
+ return ERR_PTR(res);
+}
+
+static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
+{
+ struct iattr attr = {
+ .ia_valid =
+ ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
+ .ia_atime = stat->atime,
+ .ia_mtime = stat->mtime,
+ };
+
+ return notify_change(upperdentry, &attr, NULL);
+}
+
+int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
+{
+ int err = 0;
+
+ if (!S_ISLNK(stat->mode)) {
+ struct iattr attr = {
+ .ia_valid = ATTR_MODE,
+ .ia_mode = stat->mode,
+ };
+ err = notify_change(upperdentry, &attr, NULL);
+ }
+ if (!err) {
+ struct iattr attr = {
+ .ia_valid = ATTR_UID | ATTR_GID,
+ .ia_uid = stat->uid,
+ .ia_gid = stat->gid,
+ };
+ err = notify_change(upperdentry, &attr, NULL);
+ }
+ if (!err)
+ ovl_set_timestamps(upperdentry, stat);
+
+ return err;
+
+}
+
+static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
+ struct dentry *dentry, struct path *lowerpath,
+ struct kstat *stat, struct iattr *attr,
+ const char *link)
+{
+ struct inode *wdir = workdir->d_inode;
+ struct inode *udir = upperdir->d_inode;
+ struct dentry *newdentry = NULL;
+ struct dentry *upper = NULL;
+ umode_t mode = stat->mode;
+ int err;
+
+ newdentry = ovl_lookup_temp(workdir, dentry);
+ err = PTR_ERR(newdentry);
+ if (IS_ERR(newdentry))
+ goto out;
+
+ upper = lookup_one_len(dentry->d_name.name, upperdir,
+ dentry->d_name.len);
+ err = PTR_ERR(upper);
+ if (IS_ERR(upper))
+ goto out1;
+
+ /* Can't properly set mode on creation because of the umask */
+ stat->mode &= S_IFMT;
+ err = ovl_create_real(wdir, newdentry, stat, link, NULL, true);
+ stat->mode = mode;
+ if (err)
+ goto out2;
+
+ if (S_ISREG(stat->mode)) {
+ struct path upperpath;
+ ovl_path_upper(dentry, &upperpath);
+ BUG_ON(upperpath.dentry != NULL);
+ upperpath.dentry = newdentry;
+
+ err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
+ if (err)
+ goto out_cleanup;
+ }
+
+ err = ovl_copy_xattr(lowerpath->dentry, newdentry);
+ if (err)
+ goto out_cleanup;
+
+ mutex_lock(&newdentry->d_inode->i_mutex);
+ err = ovl_set_attr(newdentry, stat);
+ if (!err && attr)
+ err = notify_change(newdentry, attr, NULL);
+ mutex_unlock(&newdentry->d_inode->i_mutex);
+ if (err)
+ goto out_cleanup;
+
+ err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
+ if (err)
+ goto out_cleanup;
+
+ ovl_dentry_update(dentry, newdentry);
+ newdentry = NULL;
+
+ /*
+ * Non-directores become opaque when copied up.
+ */
+ if (!S_ISDIR(stat->mode))
+ ovl_dentry_set_opaque(dentry, true);
+out2:
+ dput(upper);
+out1:
+ dput(newdentry);
+out:
+ return err;
+
+out_cleanup:
+ ovl_cleanup(wdir, newdentry);
+ goto out;
+}
+
+/*
+ * Copy up a single dentry
+ *
+ * Directory renames only allowed on "pure upper" (already created on
+ * upper filesystem, never copied up). Directories which are on lower or
+ * are merged may not be renamed. For these -EXDEV is returned and
+ * userspace has to deal with it. This means, when copying up a
+ * directory we can rely on it and ancestors being stable.
+ *
+ * Non-directory renames start with copy up of source if necessary. The
+ * actual rename will only proceed once the copy up was successful. Copy
+ * up uses upper parent i_mutex for exclusion. Since rename can change
+ * d_parent it is possible that the copy up will lock the old parent. At
+ * that point the file will have already been copied up anyway.
+ */
+int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
+ struct path *lowerpath, struct kstat *stat,
+ struct iattr *attr)
+{
+ struct dentry *workdir = ovl_workdir(dentry);
+ int err;
+ struct kstat pstat;
+ struct path parentpath;
+ struct dentry *upperdir;
+ struct dentry *upperdentry;
+ const struct cred *old_cred;
+ struct cred *override_cred;
+ char *link = NULL;
+
+ ovl_path_upper(parent, &parentpath);
+ upperdir = parentpath.dentry;
+
+ err = vfs_getattr(&parentpath, &pstat);
+ if (err)
+ return err;
+
+ if (S_ISLNK(stat->mode)) {
+ link = ovl_read_symlink(lowerpath->dentry);
+ if (IS_ERR(link))
+ return PTR_ERR(link);
+ }
+
+ err = -ENOMEM;
+ override_cred = prepare_creds();
+ if (!override_cred)
+ goto out_free_link;
+
+ override_cred->fsuid = stat->uid;
+ override_cred->fsgid = stat->gid;
+ /*
+ * CAP_SYS_ADMIN for copying up extended attributes
+ * CAP_DAC_OVERRIDE for create
+ * CAP_FOWNER for chmod, timestamp update
+ * CAP_FSETID for chmod
+ * CAP_CHOWN for chown
+ * CAP_MKNOD for mknod
+ */
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
+ cap_raise(override_cred->cap_effective, CAP_FOWNER);
+ cap_raise(override_cred->cap_effective, CAP_FSETID);
+ cap_raise(override_cred->cap_effective, CAP_CHOWN);
+ cap_raise(override_cred->cap_effective, CAP_MKNOD);
+ old_cred = override_creds(override_cred);
+
+ err = -EIO;
+ if (lock_rename(workdir, upperdir) != NULL) {
+ pr_err("overlayfs: failed to lock workdir+upperdir\n");
+ goto out_unlock;
+ }
+ upperdentry = ovl_dentry_upper(dentry);
+ if (upperdentry) {
+ unlock_rename(workdir, upperdir);
+ err = 0;
+ /* Raced with another copy-up? Do the setattr here */
+ if (attr) {
+ mutex_lock(&upperdentry->d_inode->i_mutex);
+ err = notify_change(upperdentry, attr, NULL);
+ mutex_unlock(&upperdentry->d_inode->i_mutex);
+ }
+ goto out_put_cred;
+ }
+
+ err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
+ stat, attr, link);
+ if (!err) {
+ /* Restore timestamps on parent (best effort) */
+ ovl_set_timestamps(upperdir, &pstat);
+ }
+out_unlock:
+ unlock_rename(workdir, upperdir);
+out_put_cred:
+ revert_creds(old_cred);
+ put_cred(override_cred);
+
+out_free_link:
+ if (link)
+ free_page((unsigned long) link);
+
+ return err;
+}
+
+int ovl_copy_up(struct dentry *dentry)
+{
+ int err;
+
+ err = 0;
+ while (!err) {
+ struct dentry *next;
+ struct dentry *parent;
+ struct path lowerpath;
+ struct kstat stat;
+ enum ovl_path_type type = ovl_path_type(dentry);
+
+ if (type != OVL_PATH_LOWER)
+ break;
+
+ next = dget(dentry);
+ /* find the topmost dentry not yet copied up */
+ for (;;) {
+ parent = dget_parent(next);
+
+ type = ovl_path_type(parent);
+ if (type != OVL_PATH_LOWER)
+ break;
+
+ dput(next);
+ next = parent;
+ }
+
+ ovl_path_lower(next, &lowerpath);
+ err = vfs_getattr(&lowerpath, &stat);
+ if (!err)
+ err = ovl_copy_up_one(parent, next, &lowerpath, &stat, NULL);
+
+ dput(parent);
+ dput(next);
+ }
+
+ return err;
+}
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
new file mode 100644
index 000000000000..15cd91ad9940
--- /dev/null
+++ b/fs/overlayfs/dir.c
@@ -0,0 +1,921 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+#include <linux/cred.h>
+#include "overlayfs.h"
+
+void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
+{
+ int err;
+
+ dget(wdentry);
+ if (S_ISDIR(wdentry->d_inode->i_mode))
+ err = ovl_do_rmdir(wdir, wdentry);
+ else
+ err = ovl_do_unlink(wdir, wdentry);
+ dput(wdentry);
+
+ if (err) {
+ pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
+ wdentry, err);
+ }
+}
+
+struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry)
+{
+ struct dentry *temp;
+ char name[20];
+
+ snprintf(name, sizeof(name), "#%lx", (unsigned long) dentry);
+
+ temp = lookup_one_len(name, workdir, strlen(name));
+ if (!IS_ERR(temp) && temp->d_inode) {
+ pr_err("overlayfs: workdir/%s already exists\n", name);
+ dput(temp);
+ temp = ERR_PTR(-EIO);
+ }
+
+ return temp;
+}
+
+/* caller holds i_mutex on workdir */
+static struct dentry *ovl_whiteout(struct dentry *workdir,
+ struct dentry *dentry)
+{
+ int err;
+ struct dentry *whiteout;
+ struct inode *wdir = workdir->d_inode;
+
+ whiteout = ovl_lookup_temp(workdir, dentry);
+ if (IS_ERR(whiteout))
+ return whiteout;
+
+ err = ovl_do_whiteout(wdir, whiteout);
+ if (err) {
+ dput(whiteout);
+ whiteout = ERR_PTR(err);
+ }
+
+ return whiteout;
+}
+
+int ovl_create_real(struct inode *dir, struct dentry *newdentry,
+ struct kstat *stat, const char *link,
+ struct dentry *hardlink, bool debug)
+{
+ int err;
+
+ if (newdentry->d_inode)
+ return -ESTALE;
+
+ if (hardlink) {
+ err = ovl_do_link(hardlink, dir, newdentry, debug);
+ } else {
+ switch (stat->mode & S_IFMT) {
+ case S_IFREG:
+ err = ovl_do_create(dir, newdentry, stat->mode, debug);
+ break;
+
+ case S_IFDIR:
+ err = ovl_do_mkdir(dir, newdentry, stat->mode, debug);
+ break;
+
+ case S_IFCHR:
+ case S_IFBLK:
+ case S_IFIFO:
+ case S_IFSOCK:
+ err = ovl_do_mknod(dir, newdentry,
+ stat->mode, stat->rdev, debug);
+ break;
+
+ case S_IFLNK:
+ err = ovl_do_symlink(dir, newdentry, link, debug);
+ break;
+
+ default:
+ err = -EPERM;
+ }
+ }
+ if (!err && WARN_ON(!newdentry->d_inode)) {
+ /*
+ * Not quite sure if non-instantiated dentry is legal or not.
+ * VFS doesn't seem to care so check and warn here.
+ */
+ err = -ENOENT;
+ }
+ return err;
+}
+
+static int ovl_set_opaque(struct dentry *upperdentry)
+{
+ return ovl_do_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0);
+}
+
+static void ovl_remove_opaque(struct dentry *upperdentry)
+{
+ int err;
+
+ err = ovl_do_removexattr(upperdentry, ovl_opaque_xattr);
+ if (err) {
+ pr_warn("overlayfs: failed to remove opaque from '%s' (%i)\n",
+ upperdentry->d_name.name, err);
+ }
+}
+
+static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
+ struct kstat *stat)
+{
+ int err;
+ enum ovl_path_type type;
+ struct path realpath;
+
+ type = ovl_path_real(dentry, &realpath);
+ err = vfs_getattr(&realpath, stat);
+ if (err)
+ return err;
+
+ stat->dev = dentry->d_sb->s_dev;
+ stat->ino = dentry->d_inode->i_ino;
+
+ /*
+ * It's probably not worth it to count subdirs to get the
+ * correct link count. nlink=1 seems to pacify 'find' and
+ * other utilities.
+ */
+ if (type == OVL_PATH_MERGE)
+ stat->nlink = 1;
+
+ return 0;
+}
+
+static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
+ struct kstat *stat, const char *link,
+ struct dentry *hardlink)
+{
+ struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
+ struct inode *udir = upperdir->d_inode;
+ struct dentry *newdentry;
+ int err;
+
+ mutex_lock_nested(&udir->i_mutex, I_MUTEX_PARENT);
+ newdentry = lookup_one_len(dentry->d_name.name, upperdir,
+ dentry->d_name.len);
+ err = PTR_ERR(newdentry);
+ if (IS_ERR(newdentry))
+ goto out_unlock;
+ err = ovl_create_real(udir, newdentry, stat, link, hardlink, false);
+ if (err)
+ goto out_dput;
+
+ ovl_dentry_version_inc(dentry->d_parent);
+ ovl_dentry_update(dentry, newdentry);
+ ovl_copyattr(newdentry->d_inode, inode);
+ d_instantiate(dentry, inode);
+ newdentry = NULL;
+out_dput:
+ dput(newdentry);
+out_unlock:
+ mutex_unlock(&udir->i_mutex);
+ return err;
+}
+
+static int ovl_lock_rename_workdir(struct dentry *workdir,
+ struct dentry *upperdir)
+{
+ /* Workdir should not be the same as upperdir */
+ if (workdir == upperdir)
+ goto err;
+
+ /* Workdir should not be subdir of upperdir and vice versa */
+ if (lock_rename(workdir, upperdir) != NULL)
+ goto err_unlock;
+
+ return 0;
+
+err_unlock:
+ unlock_rename(workdir, upperdir);
+err:
+ pr_err("overlayfs: failed to lock workdir+upperdir\n");
+ return -EIO;
+}
+
+static struct dentry *ovl_clear_empty(struct dentry *dentry,
+ struct list_head *list)
+{
+ struct dentry *workdir = ovl_workdir(dentry);
+ struct inode *wdir = workdir->d_inode;
+ struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
+ struct inode *udir = upperdir->d_inode;
+ struct path upperpath;
+ struct dentry *upper;
+ struct dentry *opaquedir;
+ struct kstat stat;
+ int err;
+
+ err = ovl_lock_rename_workdir(workdir, upperdir);
+ if (err)
+ goto out;
+
+ ovl_path_upper(dentry, &upperpath);
+ err = vfs_getattr(&upperpath, &stat);
+ if (err)
+ goto out_unlock;
+
+ err = -ESTALE;
+ if (!S_ISDIR(stat.mode))
+ goto out_unlock;
+ upper = upperpath.dentry;
+ if (upper->d_parent->d_inode != udir)
+ goto out_unlock;
+
+ opaquedir = ovl_lookup_temp(workdir, dentry);
+ err = PTR_ERR(opaquedir);
+ if (IS_ERR(opaquedir))
+ goto out_unlock;
+
+ err = ovl_create_real(wdir, opaquedir, &stat, NULL, NULL, true);
+ if (err)
+ goto out_dput;
+
+ err = ovl_copy_xattr(upper, opaquedir);
+ if (err)
+ goto out_cleanup;
+
+ err = ovl_set_opaque(opaquedir);
+ if (err)
+ goto out_cleanup;
+
+ mutex_lock(&opaquedir->d_inode->i_mutex);
+ err = ovl_set_attr(opaquedir, &stat);
+ mutex_unlock(&opaquedir->d_inode->i_mutex);
+ if (err)
+ goto out_cleanup;
+
+ err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
+ if (err)
+ goto out_cleanup;
+
+ ovl_cleanup_whiteouts(upper, list);
+ ovl_cleanup(wdir, upper);
+ unlock_rename(workdir, upperdir);
+
+ /* dentry's upper doesn't match now, get rid of it */
+ d_drop(dentry);
+
+ return opaquedir;
+
+out_cleanup:
+ ovl_cleanup(wdir, opaquedir);
+out_dput:
+ dput(opaquedir);
+out_unlock:
+ unlock_rename(workdir, upperdir);
+out:
+ return ERR_PTR(err);
+}
+
+static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry,
+ enum ovl_path_type type)
+{
+ int err;
+ struct dentry *ret = NULL;
+ LIST_HEAD(list);
+
+ err = ovl_check_empty_dir(dentry, &list);
+ if (err)
+ ret = ERR_PTR(err);
+ else if (type == OVL_PATH_MERGE)
+ ret = ovl_clear_empty(dentry, &list);
+
+ ovl_cache_free(&list);
+
+ return ret;
+}
+
+static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
+ struct kstat *stat, const char *link,
+ struct dentry *hardlink)
+{
+ struct dentry *workdir = ovl_workdir(dentry);
+ struct inode *wdir = workdir->d_inode;
+ struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
+ struct inode *udir = upperdir->d_inode;
+ struct dentry *upper;
+ struct dentry *newdentry;
+ int err;
+
+ err = ovl_lock_rename_workdir(workdir, upperdir);
+ if (err)
+ goto out;
+
+ newdentry = ovl_lookup_temp(workdir, dentry);
+ err = PTR_ERR(newdentry);
+ if (IS_ERR(newdentry))
+ goto out_unlock;
+
+ upper = lookup_one_len(dentry->d_name.name, upperdir,
+ dentry->d_name.len);
+ err = PTR_ERR(upper);
+ if (IS_ERR(upper))
+ goto out_dput;
+
+ err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
+ if (err)
+ goto out_dput2;
+
+ if (S_ISDIR(stat->mode)) {
+ err = ovl_set_opaque(newdentry);
+ if (err)
+ goto out_cleanup;
+
+ err = ovl_do_rename(wdir, newdentry, udir, upper,
+ RENAME_EXCHANGE);
+ if (err)
+ goto out_cleanup;
+
+ ovl_cleanup(wdir, upper);
+ } else {
+ err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
+ if (err)
+ goto out_cleanup;
+ }
+ ovl_dentry_version_inc(dentry->d_parent);
+ ovl_dentry_update(dentry, newdentry);
+ ovl_copyattr(newdentry->d_inode, inode);
+ d_instantiate(dentry, inode);
+ newdentry = NULL;
+out_dput2:
+ dput(upper);
+out_dput:
+ dput(newdentry);
+out_unlock:
+ unlock_rename(workdir, upperdir);
+out:
+ return err;
+
+out_cleanup:
+ ovl_cleanup(wdir, newdentry);
+ goto out_dput2;
+}
+
+static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev,
+ const char *link, struct dentry *hardlink)
+{
+ int err;
+ struct inode *inode;
+ struct kstat stat = {
+ .mode = mode,
+ .rdev = rdev,
+ };
+
+ err = -ENOMEM;
+ inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
+ if (!inode)
+ goto out;
+
+ err = ovl_copy_up(dentry->d_parent);
+ if (err)
+ goto out_iput;
+
+ if (!ovl_dentry_is_opaque(dentry)) {
+ err = ovl_create_upper(dentry, inode, &stat, link, hardlink);
+ } else {
+ const struct cred *old_cred;
+ struct cred *override_cred;
+
+ err = -ENOMEM;
+ override_cred = prepare_creds();
+ if (!override_cred)
+ goto out_iput;
+
+ /*
+ * CAP_SYS_ADMIN for setting opaque xattr
+ * CAP_DAC_OVERRIDE for create in workdir, rename
+ * CAP_FOWNER for removing whiteout from sticky dir
+ */
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
+ cap_raise(override_cred->cap_effective, CAP_FOWNER);
+ old_cred = override_creds(override_cred);
+
+ err = ovl_create_over_whiteout(dentry, inode, &stat, link,
+ hardlink);
+
+ revert_creds(old_cred);
+ put_cred(override_cred);
+ }
+
+ if (!err)
+ inode = NULL;
+out_iput:
+ iput(inode);
+out:
+ return err;
+}
+
+static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
+ const char *link)
+{
+ int err;
+
+ err = ovl_want_write(dentry);
+ if (!err) {
+ err = ovl_create_or_link(dentry, mode, rdev, link, NULL);
+ ovl_drop_write(dentry);
+ }
+
+ return err;
+}
+
+static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
+ bool excl)
+{
+ return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
+}
+
+static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+ return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
+}
+
+static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
+ dev_t rdev)
+{
+ /* Don't allow creation of "whiteout" on overlay */
+ if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
+ return -EPERM;
+
+ return ovl_create_object(dentry, mode, rdev, NULL);
+}
+
+static int ovl_symlink(struct inode *dir, struct dentry *dentry,
+ const char *link)
+{
+ return ovl_create_object(dentry, S_IFLNK, 0, link);
+}
+
+static int ovl_link(struct dentry *old, struct inode *newdir,
+ struct dentry *new)
+{
+ int err;
+ struct dentry *upper;
+
+ err = ovl_want_write(old);
+ if (err)
+ goto out;
+
+ err = ovl_copy_up(old);
+ if (err)
+ goto out_drop_write;
+
+ upper = ovl_dentry_upper(old);
+ err = ovl_create_or_link(new, upper->d_inode->i_mode, 0, NULL, upper);
+
+out_drop_write:
+ ovl_drop_write(old);
+out:
+ return err;
+}
+
+static int ovl_remove_and_whiteout(struct dentry *dentry,
+ enum ovl_path_type type, bool is_dir)
+{
+ struct dentry *workdir = ovl_workdir(dentry);
+ struct inode *wdir = workdir->d_inode;
+ struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
+ struct inode *udir = upperdir->d_inode;
+ struct dentry *whiteout;
+ struct dentry *upper;
+ struct dentry *opaquedir = NULL;
+ int err;
+
+ if (is_dir) {
+ opaquedir = ovl_check_empty_and_clear(dentry, type);
+ err = PTR_ERR(opaquedir);
+ if (IS_ERR(opaquedir))
+ goto out;
+ }
+
+ err = ovl_lock_rename_workdir(workdir, upperdir);
+ if (err)
+ goto out_dput;
+
+ whiteout = ovl_whiteout(workdir, dentry);
+ err = PTR_ERR(whiteout);
+ if (IS_ERR(whiteout))
+ goto out_unlock;
+
+ if (type == OVL_PATH_LOWER) {
+ upper = lookup_one_len(dentry->d_name.name, upperdir,
+ dentry->d_name.len);
+ err = PTR_ERR(upper);
+ if (IS_ERR(upper))
+ goto kill_whiteout;
+
+ err = ovl_do_rename(wdir, whiteout, udir, upper, 0);
+ dput(upper);
+ if (err)
+ goto kill_whiteout;
+ } else {
+ int flags = 0;
+
+ upper = ovl_dentry_upper(dentry);
+ if (opaquedir)
+ upper = opaquedir;
+ err = -ESTALE;
+ if (upper->d_parent != upperdir)
+ goto kill_whiteout;
+
+ if (is_dir)
+ flags |= RENAME_EXCHANGE;
+
+ err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
+ if (err)
+ goto kill_whiteout;
+
+ if (is_dir)
+ ovl_cleanup(wdir, upper);
+ }
+ ovl_dentry_version_inc(dentry->d_parent);
+out_d_drop:
+ d_drop(dentry);
+ dput(whiteout);
+out_unlock:
+ unlock_rename(workdir, upperdir);
+out_dput:
+ dput(opaquedir);
+out:
+ return err;
+
+kill_whiteout:
+ ovl_cleanup(wdir, whiteout);
+ goto out_d_drop;
+}
+
+static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
+{
+ struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
+ struct inode *dir = upperdir->d_inode;
+ struct dentry *upper = ovl_dentry_upper(dentry);
+ int err;
+
+ mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
+ err = -ESTALE;
+ if (upper->d_parent == upperdir) {
+ /* Don't let d_delete() think it can reset d_inode */
+ dget(upper);
+ if (is_dir)
+ err = vfs_rmdir(dir, upper);
+ else
+ err = vfs_unlink(dir, upper, NULL);
+ dput(upper);
+ ovl_dentry_version_inc(dentry->d_parent);
+ }
+
+ /*
+ * Keeping this dentry hashed would mean having to release
+ * upperpath/lowerpath, which could only be done if we are the
+ * sole user of this dentry. Too tricky... Just unhash for
+ * now.
+ */
+ d_drop(dentry);
+ mutex_unlock(&dir->i_mutex);
+
+ return err;
+}
+
+static inline int ovl_check_sticky(struct dentry *dentry)
+{
+ struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
+ struct inode *inode = ovl_dentry_real(dentry)->d_inode;
+
+ if (check_sticky(dir, inode))
+ return -EPERM;
+
+ return 0;
+}
+
+static int ovl_do_remove(struct dentry *dentry, bool is_dir)
+{
+ enum ovl_path_type type;
+ int err;
+
+ err = ovl_check_sticky(dentry);
+ if (err)
+ goto out;
+
+ err = ovl_want_write(dentry);
+ if (err)
+ goto out;
+
+ err = ovl_copy_up(dentry->d_parent);
+ if (err)
+ goto out_drop_write;
+
+ type = ovl_path_type(dentry);
+ if (type == OVL_PATH_PURE_UPPER) {
+ err = ovl_remove_upper(dentry, is_dir);
+ } else {
+ const struct cred *old_cred;
+ struct cred *override_cred;
+
+ err = -ENOMEM;
+ override_cred = prepare_creds();
+ if (!override_cred)
+ goto out_drop_write;
+
+ /*
+ * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir
+ * CAP_DAC_OVERRIDE for create in workdir, rename
+ * CAP_FOWNER for removing whiteout from sticky dir
+ * CAP_FSETID for chmod of opaque dir
+ * CAP_CHOWN for chown of opaque dir
+ */
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
+ cap_raise(override_cred->cap_effective, CAP_FOWNER);
+ cap_raise(override_cred->cap_effective, CAP_FSETID);
+ cap_raise(override_cred->cap_effective, CAP_CHOWN);
+ old_cred = override_creds(override_cred);
+
+ err = ovl_remove_and_whiteout(dentry, type, is_dir);
+
+ revert_creds(old_cred);
+ put_cred(override_cred);
+ }
+out_drop_write:
+ ovl_drop_write(dentry);
+out:
+ return err;
+}
+
+static int ovl_unlink(struct inode *dir, struct dentry *dentry)
+{
+ return ovl_do_remove(dentry, false);
+}
+
+static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ return ovl_do_remove(dentry, true);
+}
+
+static int ovl_rename2(struct inode *olddir, struct dentry *old,
+ struct inode *newdir, struct dentry *new,
+ unsigned int flags)
+{
+ int err;
+ enum ovl_path_type old_type;
+ enum ovl_path_type new_type;
+ struct dentry *old_upperdir;
+ struct dentry *new_upperdir;
+ struct dentry *olddentry;
+ struct dentry *newdentry;
+ struct dentry *trap;
+ bool old_opaque;
+ bool new_opaque;
+ bool new_create = false;
+ bool cleanup_whiteout = false;
+ bool overwrite = !(flags & RENAME_EXCHANGE);
+ bool is_dir = S_ISDIR(old->d_inode->i_mode);
+ bool new_is_dir = false;
+ struct dentry *opaquedir = NULL;
+ const struct cred *old_cred = NULL;
+ struct cred *override_cred = NULL;
+
+ err = -EINVAL;
+ if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
+ goto out;
+
+ flags &= ~RENAME_NOREPLACE;
+
+ err = ovl_check_sticky(old);
+ if (err)
+ goto out;
+
+ /* Don't copy up directory trees */
+ old_type = ovl_path_type(old);
+ err = -EXDEV;
+ if ((old_type == OVL_PATH_LOWER || old_type == OVL_PATH_MERGE) && is_dir)
+ goto out;
+
+ if (new->d_inode) {
+ err = ovl_check_sticky(new);
+ if (err)
+ goto out;
+
+ if (S_ISDIR(new->d_inode->i_mode))
+ new_is_dir = true;
+
+ new_type = ovl_path_type(new);
+ err = -EXDEV;
+ if (!overwrite && (new_type == OVL_PATH_LOWER || new_type == OVL_PATH_MERGE) && new_is_dir)
+ goto out;
+
+ err = 0;
+ if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) {
+ if (ovl_dentry_lower(old)->d_inode ==
+ ovl_dentry_lower(new)->d_inode)
+ goto out;
+ }
+ if (new_type != OVL_PATH_LOWER && old_type != OVL_PATH_LOWER) {
+ if (ovl_dentry_upper(old)->d_inode ==
+ ovl_dentry_upper(new)->d_inode)
+ goto out;
+ }
+ } else {
+ if (ovl_dentry_is_opaque(new))
+ new_type = OVL_PATH_UPPER;
+ else
+ new_type = OVL_PATH_PURE_UPPER;
+ }
+
+ err = ovl_want_write(old);
+ if (err)
+ goto out;
+
+ err = ovl_copy_up(old);
+ if (err)
+ goto out_drop_write;
+
+ err = ovl_copy_up(new->d_parent);
+ if (err)
+ goto out_drop_write;
+ if (!overwrite) {
+ err = ovl_copy_up(new);
+ if (err)
+ goto out_drop_write;
+ }
+
+ old_opaque = old_type != OVL_PATH_PURE_UPPER;
+ new_opaque = new_type != OVL_PATH_PURE_UPPER;
+
+ if (old_opaque || new_opaque) {
+ err = -ENOMEM;
+ override_cred = prepare_creds();
+ if (!override_cred)
+ goto out_drop_write;
+
+ /*
+ * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir
+ * CAP_DAC_OVERRIDE for create in workdir
+ * CAP_FOWNER for removing whiteout from sticky dir
+ * CAP_FSETID for chmod of opaque dir
+ * CAP_CHOWN for chown of opaque dir
+ */
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
+ cap_raise(override_cred->cap_effective, CAP_FOWNER);
+ cap_raise(override_cred->cap_effective, CAP_FSETID);
+ cap_raise(override_cred->cap_effective, CAP_CHOWN);
+ old_cred = override_creds(override_cred);
+ }
+
+ if (overwrite && (new_type == OVL_PATH_LOWER || new_type == OVL_PATH_MERGE) && new_is_dir) {
+ opaquedir = ovl_check_empty_and_clear(new, new_type);
+ err = PTR_ERR(opaquedir);
+ if (IS_ERR(opaquedir)) {
+ opaquedir = NULL;
+ goto out_revert_creds;
+ }
+ }
+
+ if (overwrite) {
+ if (old_opaque) {
+ if (new->d_inode || !new_opaque) {
+ /* Whiteout source */
+ flags |= RENAME_WHITEOUT;
+ } else {
+ /* Switch whiteouts */
+ flags |= RENAME_EXCHANGE;
+ }
+ } else if (is_dir && !new->d_inode && new_opaque) {
+ flags |= RENAME_EXCHANGE;
+ cleanup_whiteout = true;
+ }
+ }
+
+ old_upperdir = ovl_dentry_upper(old->d_parent);
+ new_upperdir = ovl_dentry_upper(new->d_parent);
+
+ trap = lock_rename(new_upperdir, old_upperdir);
+
+ olddentry = ovl_dentry_upper(old);
+ newdentry = ovl_dentry_upper(new);
+ if (newdentry) {
+ if (opaquedir) {
+ newdentry = opaquedir;
+ opaquedir = NULL;
+ } else {
+ dget(newdentry);
+ }
+ } else {
+ new_create = true;
+ newdentry = lookup_one_len(new->d_name.name, new_upperdir,
+ new->d_name.len);
+ err = PTR_ERR(newdentry);
+ if (IS_ERR(newdentry))
+ goto out_unlock;
+ }
+
+ err = -ESTALE;
+ if (olddentry->d_parent != old_upperdir)
+ goto out_dput;
+ if (newdentry->d_parent != new_upperdir)
+ goto out_dput;
+ if (olddentry == trap)
+ goto out_dput;
+ if (newdentry == trap)
+ goto out_dput;
+
+ if (is_dir && !old_opaque && new_opaque) {
+ err = ovl_set_opaque(olddentry);
+ if (err)
+ goto out_dput;
+ }
+ if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
+ err = ovl_set_opaque(newdentry);
+ if (err)
+ goto out_dput;
+ }
+
+ if (old_opaque || new_opaque) {
+ err = ovl_do_rename(old_upperdir->d_inode, olddentry,
+ new_upperdir->d_inode, newdentry,
+ flags);
+ } else {
+ /* No debug for the plain case */
+ BUG_ON(flags & ~RENAME_EXCHANGE);
+ err = vfs_rename(old_upperdir->d_inode, olddentry,
+ new_upperdir->d_inode, newdentry,
+ NULL, flags);
+ }
+
+ if (err) {
+ if (is_dir && !old_opaque && new_opaque)
+ ovl_remove_opaque(olddentry);
+ if (!overwrite && new_is_dir && old_opaque && !new_opaque)
+ ovl_remove_opaque(newdentry);
+ goto out_dput;
+ }
+
+ if (is_dir && old_opaque && !new_opaque)
+ ovl_remove_opaque(olddentry);
+ if (!overwrite && new_is_dir && !old_opaque && new_opaque)
+ ovl_remove_opaque(newdentry);
+
+ if (old_opaque != new_opaque) {
+ ovl_dentry_set_opaque(old, new_opaque);
+ if (!overwrite)
+ ovl_dentry_set_opaque(new, old_opaque);
+ }
+
+ if (cleanup_whiteout)
+ ovl_cleanup(old_upperdir->d_inode, newdentry);
+
+ ovl_dentry_version_inc(old->d_parent);
+ ovl_dentry_version_inc(new->d_parent);
+
+out_dput:
+ dput(newdentry);
+out_unlock:
+ unlock_rename(new_upperdir, old_upperdir);
+out_revert_creds:
+ if (old_opaque || new_opaque) {
+ revert_creds(old_cred);
+ put_cred(override_cred);
+ }
+out_drop_write:
+ ovl_drop_write(old);
+out:
+ dput(opaquedir);
+ return err;
+}
+
+const struct inode_operations ovl_dir_inode_operations = {
+ .lookup = ovl_lookup,
+ .mkdir = ovl_mkdir,
+ .symlink = ovl_symlink,
+ .unlink = ovl_unlink,
+ .rmdir = ovl_rmdir,
+ .rename2 = ovl_rename2,
+ .link = ovl_link,
+ .setattr = ovl_setattr,
+ .create = ovl_create,
+ .mknod = ovl_mknod,
+ .permission = ovl_permission,
+ .getattr = ovl_dir_getattr,
+ .setxattr = ovl_setxattr,
+ .getxattr = ovl_getxattr,
+ .listxattr = ovl_listxattr,
+ .removexattr = ovl_removexattr,
+};
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
new file mode 100644
index 000000000000..af2d18c9fcee
--- /dev/null
+++ b/fs/overlayfs/inode.c
@@ -0,0 +1,425 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/xattr.h>
+#include "overlayfs.h"
+
+static int ovl_copy_up_last(struct dentry *dentry, struct iattr *attr,
+ bool no_data)
+{
+ int err;
+ struct dentry *parent;
+ struct kstat stat;
+ struct path lowerpath;
+
+ parent = dget_parent(dentry);
+ err = ovl_copy_up(parent);
+ if (err)
+ goto out_dput_parent;
+
+ ovl_path_lower(dentry, &lowerpath);
+ err = vfs_getattr(&lowerpath, &stat);
+ if (err)
+ goto out_dput_parent;
+
+ if (no_data)
+ stat.size = 0;
+
+ err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat, attr);
+
+out_dput_parent:
+ dput(parent);
+ return err;
+}
+
+int ovl_setattr(struct dentry *dentry, struct iattr *attr)
+{
+ int err;
+ struct dentry *upperdentry;
+
+ err = ovl_want_write(dentry);
+ if (err)
+ goto out;
+
+ upperdentry = ovl_dentry_upper(dentry);
+ if (upperdentry) {
+ mutex_lock(&upperdentry->d_inode->i_mutex);
+ err = notify_change(upperdentry, attr, NULL);
+ mutex_unlock(&upperdentry->d_inode->i_mutex);
+ } else {
+ err = ovl_copy_up_last(dentry, attr, false);
+ }
+ ovl_drop_write(dentry);
+out:
+ return err;
+}
+
+static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry,
+ struct kstat *stat)
+{
+ struct path realpath;
+
+ ovl_path_real(dentry, &realpath);
+ return vfs_getattr(&realpath, stat);
+}
+
+int ovl_permission(struct inode *inode, int mask)
+{
+ struct ovl_entry *oe;
+ struct dentry *alias = NULL;
+ struct inode *realinode;
+ struct dentry *realdentry;
+ bool is_upper;
+ int err;
+
+ if (S_ISDIR(inode->i_mode)) {
+ oe = inode->i_private;
+ } else if (mask & MAY_NOT_BLOCK) {
+ return -ECHILD;
+ } else {
+ /*
+ * For non-directories find an alias and get the info
+ * from there.
+ */
+ alias = d_find_any_alias(inode);
+ if (WARN_ON(!alias))
+ return -ENOENT;
+
+ oe = alias->d_fsdata;
+ }
+
+ realdentry = ovl_entry_real(oe, &is_upper);
+
+ /* Careful in RCU walk mode */
+ realinode = ACCESS_ONCE(realdentry->d_inode);
+ if (!realinode) {
+ WARN_ON(!(mask & MAY_NOT_BLOCK));
+ err = -ENOENT;
+ goto out_dput;
+ }
+
+ if (mask & MAY_WRITE) {
+ umode_t mode = realinode->i_mode;
+
+ /*
+ * Writes will always be redirected to upper layer, so
+ * ignore lower layer being read-only.
+ *
+ * If the overlay itself is read-only then proceed
+ * with the permission check, don't return EROFS.
+ * This will only happen if this is the lower layer of
+ * another overlayfs.
+ *
+ * If upper fs becomes read-only after the overlay was
+ * constructed return EROFS to prevent modification of
+ * upper layer.
+ */
+ err = -EROFS;
+ if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) &&
+ (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
+ goto out_dput;
+ }
+
+ err = __inode_permission(realinode, mask);
+out_dput:
+ dput(alias);
+ return err;
+}
+
+
+struct ovl_link_data {
+ struct dentry *realdentry;
+ void *cookie;
+};
+
+static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ void *ret;
+ struct dentry *realdentry;
+ struct inode *realinode;
+
+ realdentry = ovl_dentry_real(dentry);
+ realinode = realdentry->d_inode;
+
+ if (WARN_ON(!realinode->i_op->follow_link))
+ return ERR_PTR(-EPERM);
+
+ ret = realinode->i_op->follow_link(realdentry, nd);
+ if (IS_ERR(ret))
+ return ret;
+
+ if (realinode->i_op->put_link) {
+ struct ovl_link_data *data;
+
+ data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL);
+ if (!data) {
+ realinode->i_op->put_link(realdentry, nd, ret);
+ return ERR_PTR(-ENOMEM);
+ }
+ data->realdentry = realdentry;
+ data->cookie = ret;
+
+ return data;
+ } else {
+ return NULL;
+ }
+}
+
+static void ovl_put_link(struct dentry *dentry, struct nameidata *nd, void *c)
+{
+ struct inode *realinode;
+ struct ovl_link_data *data = c;
+
+ if (!data)
+ return;
+
+ realinode = data->realdentry->d_inode;
+ realinode->i_op->put_link(data->realdentry, nd, data->cookie);
+ kfree(data);
+}
+
+static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
+{
+ struct path realpath;
+ struct inode *realinode;
+
+ ovl_path_real(dentry, &realpath);
+ realinode = realpath.dentry->d_inode;
+
+ if (!realinode->i_op->readlink)
+ return -EINVAL;
+
+ touch_atime(&realpath);
+
+ return realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
+}
+
+
+static bool ovl_is_private_xattr(const char *name)
+{
+ return strncmp(name, "trusted.overlay.", 14) == 0;
+}
+
+int ovl_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ int err;
+ struct dentry *upperdentry;
+
+ err = ovl_want_write(dentry);
+ if (err)
+ goto out;
+
+ err = -EPERM;
+ if (ovl_is_private_xattr(name))
+ goto out_drop_write;
+
+ err = ovl_copy_up(dentry);
+ if (err)
+ goto out_drop_write;
+
+ upperdentry = ovl_dentry_upper(dentry);
+ err = vfs_setxattr(upperdentry, name, value, size, flags);
+
+out_drop_write:
+ ovl_drop_write(dentry);
+out:
+ return err;
+}
+
+ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
+ void *value, size_t size)
+{
+ if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE &&
+ ovl_is_private_xattr(name))
+ return -ENODATA;
+
+ return vfs_getxattr(ovl_dentry_real(dentry), name, value, size);
+}
+
+ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
+{
+ ssize_t res;
+ int off;
+
+ res = vfs_listxattr(ovl_dentry_real(dentry), list, size);
+ if (res <= 0 || size == 0)
+ return res;
+
+ if (ovl_path_type(dentry->d_parent) != OVL_PATH_MERGE)
+ return res;
+
+ /* filter out private xattrs */
+ for (off = 0; off < res;) {
+ char *s = list + off;
+ size_t slen = strlen(s) + 1;
+
+ BUG_ON(off + slen > res);
+
+ if (ovl_is_private_xattr(s)) {
+ res -= slen;
+ memmove(s, s + slen, res - off);
+ } else {
+ off += slen;
+ }
+ }
+
+ return res;
+}
+
+int ovl_removexattr(struct dentry *dentry, const char *name)
+{
+ int err;
+ struct path realpath;
+ enum ovl_path_type type;
+
+ err = ovl_want_write(dentry);
+ if (err)
+ goto out;
+
+ if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE &&
+ ovl_is_private_xattr(name))
+ goto out_drop_write;
+
+ type = ovl_path_real(dentry, &realpath);
+ if (type == OVL_PATH_LOWER) {
+ err = vfs_getxattr(realpath.dentry, name, NULL, 0);
+ if (err < 0)
+ goto out_drop_write;
+
+ err = ovl_copy_up(dentry);
+ if (err)
+ goto out_drop_write;
+
+ ovl_path_upper(dentry, &realpath);
+ }
+
+ err = vfs_removexattr(realpath.dentry, name);
+out_drop_write:
+ ovl_drop_write(dentry);
+out:
+ return err;
+}
+
+static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
+ struct dentry *realdentry)
+{
+ if (type != OVL_PATH_LOWER)
+ return false;
+
+ if (special_file(realdentry->d_inode->i_mode))
+ return false;
+
+ if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
+ return false;
+
+ return true;
+}
+
+static int ovl_dentry_open(struct dentry *dentry, struct file *file,
+ const struct cred *cred)
+{
+ int err;
+ struct path realpath;
+ enum ovl_path_type type;
+ bool want_write = false;
+
+ type = ovl_path_real(dentry, &realpath);
+ if (ovl_open_need_copy_up(file->f_flags, type, realpath.dentry)) {
+ want_write = true;
+ err = ovl_want_write(dentry);
+ if (err)
+ goto out;
+
+ if (file->f_flags & O_TRUNC)
+ err = ovl_copy_up_last(dentry, NULL, true);
+ else
+ err = ovl_copy_up(dentry);
+ if (err)
+ goto out_drop_write;
+
+ ovl_path_upper(dentry, &realpath);
+ }
+
+ err = vfs_open(&realpath, file, cred);
+out_drop_write:
+ if (want_write)
+ ovl_drop_write(dentry);
+out:
+ return err;
+}
+
+static const struct inode_operations ovl_file_inode_operations = {
+ .setattr = ovl_setattr,
+ .permission = ovl_permission,
+ .getattr = ovl_getattr,
+ .setxattr = ovl_setxattr,
+ .getxattr = ovl_getxattr,
+ .listxattr = ovl_listxattr,
+ .removexattr = ovl_removexattr,
+ .dentry_open = ovl_dentry_open,
+};
+
+static const struct inode_operations ovl_symlink_inode_operations = {
+ .setattr = ovl_setattr,
+ .follow_link = ovl_follow_link,
+ .put_link = ovl_put_link,
+ .readlink = ovl_readlink,
+ .getattr = ovl_getattr,
+ .setxattr = ovl_setxattr,
+ .getxattr = ovl_getxattr,
+ .listxattr = ovl_listxattr,
+ .removexattr = ovl_removexattr,
+};
+
+struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
+ struct ovl_entry *oe)
+{
+ struct inode *inode;
+
+ inode = new_inode(sb);
+ if (!inode)
+ return NULL;
+
+ mode &= S_IFMT;
+
+ inode->i_ino = get_next_ino();
+ inode->i_mode = mode;
+ inode->i_flags |= S_NOATIME | S_NOCMTIME;
+
+ switch (mode) {
+ case S_IFDIR:
+ inode->i_private = oe;
+ inode->i_op = &ovl_dir_inode_operations;
+ inode->i_fop = &ovl_dir_operations;
+ break;
+
+ case S_IFLNK:
+ inode->i_op = &ovl_symlink_inode_operations;
+ break;
+
+ case S_IFREG:
+ case S_IFSOCK:
+ case S_IFBLK:
+ case S_IFCHR:
+ case S_IFIFO:
+ inode->i_op = &ovl_file_inode_operations;
+ break;
+
+ default:
+ WARN(1, "illegal file type: %i\n", mode);
+ iput(inode);
+ inode = NULL;
+ }
+
+ return inode;
+
+}
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
new file mode 100644
index 000000000000..814bed33dd07
--- /dev/null
+++ b/fs/overlayfs/overlayfs.h
@@ -0,0 +1,191 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+
+struct ovl_entry;
+
+enum ovl_path_type {
+ OVL_PATH_PURE_UPPER,
+ OVL_PATH_UPPER,
+ OVL_PATH_MERGE,
+ OVL_PATH_LOWER,
+};
+
+extern const char *ovl_opaque_xattr;
+
+static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ int err = vfs_rmdir(dir, dentry);
+ pr_debug("rmdir(%pd2) = %i\n", dentry, err);
+ return err;
+}
+
+static inline int ovl_do_unlink(struct inode *dir, struct dentry *dentry)
+{
+ int err = vfs_unlink(dir, dentry, NULL);
+ pr_debug("unlink(%pd2) = %i\n", dentry, err);
+ return err;
+}
+
+static inline int ovl_do_link(struct dentry *old_dentry, struct inode *dir,
+ struct dentry *new_dentry, bool debug)
+{
+ int err = vfs_link(old_dentry, dir, new_dentry, NULL);
+ if (debug) {
+ pr_debug("link(%pd2, %pd2) = %i\n",
+ old_dentry, new_dentry, err);
+ }
+ return err;
+}
+
+static inline int ovl_do_create(struct inode *dir, struct dentry *dentry,
+ umode_t mode, bool debug)
+{
+ int err = vfs_create(dir, dentry, mode, true);
+ if (debug)
+ pr_debug("create(%pd2, 0%o) = %i\n", dentry, mode, err);
+ return err;
+}
+
+static inline int ovl_do_mkdir(struct inode *dir, struct dentry *dentry,
+ umode_t mode, bool debug)
+{
+ int err = vfs_mkdir(dir, dentry, mode);
+ if (debug)
+ pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, err);
+ return err;
+}
+
+static inline int ovl_do_mknod(struct inode *dir, struct dentry *dentry,
+ umode_t mode, dev_t dev, bool debug)
+{
+ int err = vfs_mknod(dir, dentry, mode, dev);
+ if (debug) {
+ pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n",
+ dentry, mode, dev, err);
+ }
+ return err;
+}
+
+static inline int ovl_do_symlink(struct inode *dir, struct dentry *dentry,
+ const char *oldname, bool debug)
+{
+ int err = vfs_symlink(dir, dentry, oldname);
+ if (debug)
+ pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
+ return err;
+}
+
+static inline int ovl_do_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ int err = vfs_setxattr(dentry, name, value, size, flags);
+ pr_debug("setxattr(%pd2, \"%s\", \"%*s\", 0x%x) = %i\n",
+ dentry, name, (int) size, (char *) value, flags, err);
+ return err;
+}
+
+static inline int ovl_do_removexattr(struct dentry *dentry, const char *name)
+{
+ int err = vfs_removexattr(dentry, name);
+ pr_debug("removexattr(%pd2, \"%s\") = %i\n", dentry, name, err);
+ return err;
+}
+
+static inline int ovl_do_rename(struct inode *olddir, struct dentry *olddentry,
+ struct inode *newdir, struct dentry *newdentry,
+ unsigned int flags)
+{
+ int err;
+
+ pr_debug("rename2(%pd2, %pd2, 0x%x)\n",
+ olddentry, newdentry, flags);
+
+ err = vfs_rename(olddir, olddentry, newdir, newdentry, NULL, flags);
+
+ if (err) {
+ pr_debug("...rename2(%pd2, %pd2, ...) = %i\n",
+ olddentry, newdentry, err);
+ }
+ return err;
+}
+
+static inline int ovl_do_whiteout(struct inode *dir, struct dentry *dentry)
+{
+ int err = vfs_whiteout(dir, dentry);
+ pr_debug("whiteout(%pd2) = %i\n", dentry, err);
+ return err;
+}
+
+enum ovl_path_type ovl_path_type(struct dentry *dentry);
+u64 ovl_dentry_version_get(struct dentry *dentry);
+void ovl_dentry_version_inc(struct dentry *dentry);
+void ovl_path_upper(struct dentry *dentry, struct path *path);
+void ovl_path_lower(struct dentry *dentry, struct path *path);
+enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
+struct dentry *ovl_dentry_upper(struct dentry *dentry);
+struct dentry *ovl_dentry_lower(struct dentry *dentry);
+struct dentry *ovl_dentry_real(struct dentry *dentry);
+struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper);
+struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry);
+void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache);
+struct dentry *ovl_workdir(struct dentry *dentry);
+int ovl_want_write(struct dentry *dentry);
+void ovl_drop_write(struct dentry *dentry);
+bool ovl_dentry_is_opaque(struct dentry *dentry);
+void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque);
+bool ovl_is_whiteout(struct dentry *dentry);
+void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry);
+struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
+ unsigned int flags);
+struct file *ovl_path_open(struct path *path, int flags);
+
+struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry,
+ struct kstat *stat, const char *link);
+
+/* readdir.c */
+extern const struct file_operations ovl_dir_operations;
+int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list);
+void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list);
+void ovl_cache_free(struct list_head *list);
+
+/* inode.c */
+int ovl_setattr(struct dentry *dentry, struct iattr *attr);
+int ovl_permission(struct inode *inode, int mask);
+int ovl_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags);
+ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
+ void *value, size_t size);
+ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
+int ovl_removexattr(struct dentry *dentry, const char *name);
+
+struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
+ struct ovl_entry *oe);
+static inline void ovl_copyattr(struct inode *from, struct inode *to)
+{
+ to->i_uid = from->i_uid;
+ to->i_gid = from->i_gid;
+}
+
+/* dir.c */
+extern const struct inode_operations ovl_dir_inode_operations;
+struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry);
+int ovl_create_real(struct inode *dir, struct dentry *newdentry,
+ struct kstat *stat, const char *link,
+ struct dentry *hardlink, bool debug);
+void ovl_cleanup(struct inode *dir, struct dentry *dentry);
+
+/* copy_up.c */
+int ovl_copy_up(struct dentry *dentry);
+int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
+ struct path *lowerpath, struct kstat *stat,
+ struct iattr *attr);
+int ovl_copy_xattr(struct dentry *old, struct dentry *new);
+int ovl_set_attr(struct dentry *upper, struct kstat *stat);
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
new file mode 100644
index 000000000000..910553f37aca
--- /dev/null
+++ b/fs/overlayfs/readdir.c
@@ -0,0 +1,590 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/namei.h>
+#include <linux/file.h>
+#include <linux/xattr.h>
+#include <linux/rbtree.h>
+#include <linux/security.h>
+#include <linux/cred.h>
+#include "overlayfs.h"
+
+struct ovl_cache_entry {
+ unsigned int len;
+ unsigned int type;
+ u64 ino;
+ bool is_whiteout;
+ struct list_head l_node;
+ struct rb_node node;
+ char name[];
+};
+
+struct ovl_dir_cache {
+ long refcount;
+ u64 version;
+ struct list_head entries;
+};
+
+struct ovl_readdir_data {
+ struct dir_context ctx;
+ bool is_merge;
+ struct rb_root root;
+ struct list_head *list;
+ struct list_head middle;
+ int count;
+ int err;
+};
+
+struct ovl_dir_file {
+ bool is_real;
+ bool is_upper;
+ struct ovl_dir_cache *cache;
+ struct ovl_cache_entry cursor;
+ struct file *realfile;
+ struct file *upperfile;
+};
+
+static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n)
+{
+ return container_of(n, struct ovl_cache_entry, node);
+}
+
+static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
+ const char *name, int len)
+{
+ struct rb_node *node = root->rb_node;
+ int cmp;
+
+ while (node) {
+ struct ovl_cache_entry *p = ovl_cache_entry_from_node(node);
+
+ cmp = strncmp(name, p->name, len);
+ if (cmp > 0)
+ node = p->node.rb_right;
+ else if (cmp < 0 || len < p->len)
+ node = p->node.rb_left;
+ else
+ return p;
+ }
+
+ return NULL;
+}
+
+static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len,
+ u64 ino, unsigned int d_type)
+{
+ struct ovl_cache_entry *p;
+ size_t size = offsetof(struct ovl_cache_entry, name[len + 1]);
+
+ p = kmalloc(size, GFP_KERNEL);
+ if (p) {
+ memcpy(p->name, name, len);
+ p->name[len] = '\0';
+ p->len = len;
+ p->type = d_type;
+ p->ino = ino;
+ p->is_whiteout = false;
+ }
+
+ return p;
+}
+
+static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
+ const char *name, int len, u64 ino,
+ unsigned int d_type)
+{
+ struct rb_node **newp = &rdd->root.rb_node;
+ struct rb_node *parent = NULL;
+ struct ovl_cache_entry *p;
+
+ while (*newp) {
+ int cmp;
+ struct ovl_cache_entry *tmp;
+
+ parent = *newp;
+ tmp = ovl_cache_entry_from_node(*newp);
+ cmp = strncmp(name, tmp->name, len);
+ if (cmp > 0)
+ newp = &tmp->node.rb_right;
+ else if (cmp < 0 || len < tmp->len)
+ newp = &tmp->node.rb_left;
+ else
+ return 0;
+ }
+
+ p = ovl_cache_entry_new(name, len, ino, d_type);
+ if (p == NULL)
+ return -ENOMEM;
+
+ list_add_tail(&p->l_node, rdd->list);
+ rb_link_node(&p->node, parent, newp);
+ rb_insert_color(&p->node, &rdd->root);
+
+ return 0;
+}
+
+static int ovl_fill_lower(struct ovl_readdir_data *rdd,
+ const char *name, int namelen,
+ loff_t offset, u64 ino, unsigned int d_type)
+{
+ struct ovl_cache_entry *p;
+
+ p = ovl_cache_entry_find(&rdd->root, name, namelen);
+ if (p) {
+ list_move_tail(&p->l_node, &rdd->middle);
+ } else {
+ p = ovl_cache_entry_new(name, namelen, ino, d_type);
+ if (p == NULL)
+ rdd->err = -ENOMEM;
+ else
+ list_add_tail(&p->l_node, &rdd->middle);
+ }
+
+ return rdd->err;
+}
+
+void ovl_cache_free(struct list_head *list)
+{
+ struct ovl_cache_entry *p;
+ struct ovl_cache_entry *n;
+
+ list_for_each_entry_safe(p, n, list, l_node)
+ kfree(p);
+
+ INIT_LIST_HEAD(list);
+}
+
+static void ovl_cache_put(struct ovl_dir_file *od, struct dentry *dentry)
+{
+ struct ovl_dir_cache *cache = od->cache;
+
+ list_del(&od->cursor.l_node);
+ WARN_ON(cache->refcount <= 0);
+ cache->refcount--;
+ if (!cache->refcount) {
+ if (ovl_dir_cache(dentry) == cache)
+ ovl_set_dir_cache(dentry, NULL);
+
+ ovl_cache_free(&cache->entries);
+ kfree(cache);
+ }
+}
+
+static int ovl_fill_merge(void *buf, const char *name, int namelen,
+ loff_t offset, u64 ino, unsigned int d_type)
+{
+ struct ovl_readdir_data *rdd = buf;
+
+ rdd->count++;
+ if (!rdd->is_merge)
+ return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
+ else
+ return ovl_fill_lower(rdd, name, namelen, offset, ino, d_type);
+}
+
+static inline int ovl_dir_read(struct path *realpath,
+ struct ovl_readdir_data *rdd)
+{
+ struct file *realfile;
+ int err;
+
+ realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY);
+ if (IS_ERR(realfile))
+ return PTR_ERR(realfile);
+
+ rdd->ctx.pos = 0;
+ do {
+ rdd->count = 0;
+ rdd->err = 0;
+ err = iterate_dir(realfile, &rdd->ctx);
+ if (err >= 0)
+ err = rdd->err;
+ } while (!err && rdd->count);
+ fput(realfile);
+
+ return err;
+}
+
+static void ovl_dir_reset(struct file *file)
+{
+ struct ovl_dir_file *od = file->private_data;
+ struct ovl_dir_cache *cache = od->cache;
+ struct dentry *dentry = file->f_path.dentry;
+ enum ovl_path_type type = ovl_path_type(dentry);
+
+ if (cache && ovl_dentry_version_get(dentry) != cache->version) {
+ ovl_cache_put(od, dentry);
+ od->cache = NULL;
+ }
+ WARN_ON(!od->is_real && type != OVL_PATH_MERGE);
+ if (od->is_real && type == OVL_PATH_MERGE)
+ od->is_real = false;
+}
+
+static int ovl_dir_mark_whiteouts(struct dentry *dir,
+ struct ovl_readdir_data *rdd)
+{
+ struct ovl_cache_entry *p;
+ struct dentry *dentry;
+ const struct cred *old_cred;
+ struct cred *override_cred;
+
+ override_cred = prepare_creds();
+ if (!override_cred) {
+ ovl_cache_free(rdd->list);
+ return -ENOMEM;
+ }
+
+ /*
+ * CAP_DAC_OVERRIDE for lookup
+ */
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
+ old_cred = override_creds(override_cred);
+
+ mutex_lock(&dir->d_inode->i_mutex);
+ list_for_each_entry(p, rdd->list, l_node) {
+ if (!p->name)
+ continue;
+
+ if (p->type != DT_CHR)
+ continue;
+
+ dentry = lookup_one_len(p->name, dir, p->len);
+ if (IS_ERR(dentry))
+ continue;
+
+ p->is_whiteout = ovl_is_whiteout(dentry);
+ dput(dentry);
+ }
+ mutex_unlock(&dir->d_inode->i_mutex);
+
+ revert_creds(old_cred);
+ put_cred(override_cred);
+
+ return 0;
+}
+
+static inline int ovl_dir_read_merged(struct path *upperpath,
+ struct path *lowerpath,
+ struct list_head *list)
+{
+ int err;
+ struct ovl_readdir_data rdd = {
+ .ctx.actor = ovl_fill_merge,
+ .list = list,
+ .root = RB_ROOT,
+ .is_merge = false,
+ };
+
+ if (upperpath->dentry) {
+ err = ovl_dir_read(upperpath, &rdd);
+ if (err)
+ goto out;
+
+ if (lowerpath->dentry) {
+ err = ovl_dir_mark_whiteouts(upperpath->dentry, &rdd);
+ if (err)
+ goto out;
+ }
+ }
+ if (lowerpath->dentry) {
+ /*
+ * Insert lowerpath entries before upperpath ones, this allows
+ * offsets to be reasonably constant
+ */
+ list_add(&rdd.middle, rdd.list);
+ rdd.is_merge = true;
+ err = ovl_dir_read(lowerpath, &rdd);
+ list_del(&rdd.middle);
+ }
+out:
+ return err;
+
+}
+
+static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
+{
+ struct ovl_cache_entry *p;
+ loff_t off = 0;
+
+ list_for_each_entry(p, &od->cache->entries, l_node) {
+ if (!p->name)
+ continue;
+ if (off >= pos)
+ break;
+ off++;
+ }
+ list_move_tail(&od->cursor.l_node, &p->l_node);
+}
+
+static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
+{
+ int res;
+ struct path lowerpath;
+ struct path upperpath;
+ struct ovl_dir_cache *cache;
+
+ cache = ovl_dir_cache(dentry);
+ if (cache && ovl_dentry_version_get(dentry) == cache->version) {
+ cache->refcount++;
+ return cache;
+ }
+ ovl_set_dir_cache(dentry, NULL);
+
+ cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL);
+ if (!cache)
+ return ERR_PTR(-ENOMEM);
+
+ cache->refcount = 1;
+ INIT_LIST_HEAD(&cache->entries);
+
+ ovl_path_lower(dentry, &lowerpath);
+ ovl_path_upper(dentry, &upperpath);
+
+ res = ovl_dir_read_merged(&upperpath, &lowerpath, &cache->entries);
+ if (res) {
+ ovl_cache_free(&cache->entries);
+ kfree(cache);
+ return ERR_PTR(res);
+ }
+
+ cache->version = ovl_dentry_version_get(dentry);
+ ovl_set_dir_cache(dentry, cache);
+
+ return cache;
+}
+
+static int ovl_iterate(struct file *file, struct dir_context *ctx)
+{
+ struct ovl_dir_file *od = file->private_data;
+ struct dentry *dentry = file->f_path.dentry;
+
+ if (!ctx->pos)
+ ovl_dir_reset(file);
+
+ if (od->is_real)
+ return iterate_dir(od->realfile, ctx);
+
+ if (!od->cache) {
+ struct ovl_dir_cache *cache;
+
+ cache = ovl_cache_get(dentry);
+ if (IS_ERR(cache))
+ return PTR_ERR(cache);
+
+ od->cache = cache;
+ ovl_seek_cursor(od, ctx->pos);
+ }
+
+ while (od->cursor.l_node.next != &od->cache->entries) {
+ struct ovl_cache_entry *p;
+
+ p = list_entry(od->cursor.l_node.next, struct ovl_cache_entry, l_node);
+ /* Skip cursors */
+ if (p->name) {
+ if (!p->is_whiteout) {
+ if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
+ break;
+ }
+ ctx->pos++;
+ }
+ list_move(&od->cursor.l_node, &p->l_node);
+ }
+ return 0;
+}
+
+static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
+{
+ loff_t res;
+ struct ovl_dir_file *od = file->private_data;
+
+ mutex_lock(&file_inode(file)->i_mutex);
+ if (!file->f_pos)
+ ovl_dir_reset(file);
+
+ if (od->is_real) {
+ res = vfs_llseek(od->realfile, offset, origin);
+ file->f_pos = od->realfile->f_pos;
+ } else {
+ res = -EINVAL;
+
+ switch (origin) {
+ case SEEK_CUR:
+ offset += file->f_pos;
+ break;
+ case SEEK_SET:
+ break;
+ default:
+ goto out_unlock;
+ }
+ if (offset < 0)
+ goto out_unlock;
+
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ if (od->cache)
+ ovl_seek_cursor(od, offset);
+ }
+ res = offset;
+ }
+out_unlock:
+ mutex_unlock(&file_inode(file)->i_mutex);
+
+ return res;
+}
+
+static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
+ int datasync)
+{
+ struct ovl_dir_file *od = file->private_data;
+ struct dentry *dentry = file->f_path.dentry;
+ struct file *realfile = od->realfile;
+
+ /*
+ * Need to check if we started out being a lower dir, but got copied up
+ */
+ if (!od->is_upper && ovl_path_type(dentry) == OVL_PATH_MERGE) {
+ struct inode *inode = file_inode(file);
+
+ realfile = od->upperfile;
+ if (!realfile) {
+ struct path upperpath;
+
+ ovl_path_upper(dentry, &upperpath);
+ realfile = ovl_path_open(&upperpath, O_RDONLY);
+ mutex_lock(&inode->i_mutex);
+ if (!od->upperfile) {
+ if (IS_ERR(realfile)) {
+ mutex_unlock(&inode->i_mutex);
+ return PTR_ERR(realfile);
+ }
+ od->upperfile = realfile;
+ } else {
+ /* somebody has beaten us to it */
+ if (!IS_ERR(realfile))
+ fput(realfile);
+ realfile = od->upperfile;
+ }
+ mutex_unlock(&inode->i_mutex);
+ }
+ }
+
+ return vfs_fsync_range(realfile, start, end, datasync);
+}
+
+static int ovl_dir_release(struct inode *inode, struct file *file)
+{
+ struct ovl_dir_file *od = file->private_data;
+
+ if (od->cache) {
+ mutex_lock(&inode->i_mutex);
+ ovl_cache_put(od, file->f_path.dentry);
+ mutex_unlock(&inode->i_mutex);
+ }
+ fput(od->realfile);
+ if (od->upperfile)
+ fput(od->upperfile);
+ kfree(od);
+
+ return 0;
+}
+
+static int ovl_dir_open(struct inode *inode, struct file *file)
+{
+ struct path realpath;
+ struct file *realfile;
+ struct ovl_dir_file *od;
+ enum ovl_path_type type;
+
+ od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL);
+ if (!od)
+ return -ENOMEM;
+
+ type = ovl_path_real(file->f_path.dentry, &realpath);
+ realfile = ovl_path_open(&realpath, file->f_flags);
+ if (IS_ERR(realfile)) {
+ kfree(od);
+ return PTR_ERR(realfile);
+ }
+ INIT_LIST_HEAD(&od->cursor.l_node);
+ od->realfile = realfile;
+ od->is_real = (type != OVL_PATH_MERGE);
+ od->is_upper = (type != OVL_PATH_LOWER);
+ file->private_data = od;
+
+ return 0;
+}
+
+const struct file_operations ovl_dir_operations = {
+ .read = generic_read_dir,
+ .open = ovl_dir_open,
+ .iterate = ovl_iterate,
+ .llseek = ovl_dir_llseek,
+ .fsync = ovl_dir_fsync,
+ .release = ovl_dir_release,
+};
+
+int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
+{
+ int err;
+ struct path lowerpath;
+ struct path upperpath;
+ struct ovl_cache_entry *p;
+
+ ovl_path_upper(dentry, &upperpath);
+ ovl_path_lower(dentry, &lowerpath);
+
+ err = ovl_dir_read_merged(&upperpath, &lowerpath, list);
+ if (err)
+ return err;
+
+ err = 0;
+
+ list_for_each_entry(p, list, l_node) {
+ if (p->is_whiteout)
+ continue;
+
+ if (p->name[0] == '.') {
+ if (p->len == 1)
+ continue;
+ if (p->len == 2 && p->name[1] == '.')
+ continue;
+ }
+ err = -ENOTEMPTY;
+ break;
+ }
+
+ return err;
+}
+
+void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list)
+{
+ struct ovl_cache_entry *p;
+
+ mutex_lock_nested(&upper->d_inode->i_mutex, I_MUTEX_PARENT);
+ list_for_each_entry(p, list, l_node) {
+ struct dentry *dentry;
+
+ if (!p->is_whiteout)
+ continue;
+
+ dentry = lookup_one_len(p->name, upper, p->len);
+ if (IS_ERR(dentry)) {
+ pr_err("overlayfs: lookup '%s/%.*s' failed (%i)\n",
+ upper->d_name.name, p->len, p->name,
+ (int) PTR_ERR(dentry));
+ continue;
+ }
+ ovl_cleanup(upper->d_inode, dentry);
+ dput(dentry);
+ }
+ mutex_unlock(&upper->d_inode->i_mutex);
+}
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
new file mode 100644
index 000000000000..08b704cebfc4
--- /dev/null
+++ b/fs/overlayfs/super.c
@@ -0,0 +1,796 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+#include <linux/mount.h>
+#include <linux/slab.h>
+#include <linux/parser.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/statfs.h>
+#include <linux/seq_file.h>
+#include "overlayfs.h"
+
+MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
+MODULE_DESCRIPTION("Overlay filesystem");
+MODULE_LICENSE("GPL");
+
+#define OVERLAYFS_SUPER_MAGIC 0x794c764f
+
+struct ovl_config {
+ char *lowerdir;
+ char *upperdir;
+ char *workdir;
+};
+
+/* private information held for overlayfs's superblock */
+struct ovl_fs {
+ struct vfsmount *upper_mnt;
+ struct vfsmount *lower_mnt;
+ struct dentry *workdir;
+ long lower_namelen;
+ /* pathnames of lower and upper dirs, for show_options */
+ struct ovl_config config;
+};
+
+struct ovl_dir_cache;
+
+/* private information held for every overlayfs dentry */
+struct ovl_entry {
+ struct dentry *__upperdentry;
+ struct dentry *lowerdentry;
+ struct ovl_dir_cache *cache;
+ union {
+ struct {
+ u64 version;
+ bool opaque;
+ };
+ struct rcu_head rcu;
+ };
+};
+
+const char *ovl_opaque_xattr = "trusted.overlay.opaque";
+
+
+enum ovl_path_type ovl_path_type(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ if (oe->__upperdentry) {
+ if (oe->lowerdentry) {
+ if (S_ISDIR(dentry->d_inode->i_mode))
+ return OVL_PATH_MERGE;
+ else
+ return OVL_PATH_UPPER;
+ } else {
+ if (oe->opaque)
+ return OVL_PATH_UPPER;
+ else
+ return OVL_PATH_PURE_UPPER;
+ }
+ } else {
+ return OVL_PATH_LOWER;
+ }
+}
+
+static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
+{
+ struct dentry *upperdentry = ACCESS_ONCE(oe->__upperdentry);
+ /*
+ * Make sure to order reads to upperdentry wrt ovl_dentry_update()
+ */
+ smp_read_barrier_depends();
+ return upperdentry;
+}
+
+void ovl_path_upper(struct dentry *dentry, struct path *path)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ path->mnt = ofs->upper_mnt;
+ path->dentry = ovl_upperdentry_dereference(oe);
+}
+
+enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
+{
+
+ enum ovl_path_type type = ovl_path_type(dentry);
+
+ if (type == OVL_PATH_LOWER)
+ ovl_path_lower(dentry, path);
+ else
+ ovl_path_upper(dentry, path);
+
+ return type;
+}
+
+struct dentry *ovl_dentry_upper(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ return ovl_upperdentry_dereference(oe);
+}
+
+struct dentry *ovl_dentry_lower(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ return oe->lowerdentry;
+}
+
+struct dentry *ovl_dentry_real(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ struct dentry *realdentry;
+
+ realdentry = ovl_upperdentry_dereference(oe);
+ if (!realdentry)
+ realdentry = oe->lowerdentry;
+
+ return realdentry;
+}
+
+struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper)
+{
+ struct dentry *realdentry;
+
+ realdentry = ovl_upperdentry_dereference(oe);
+ if (realdentry) {
+ *is_upper = true;
+ } else {
+ realdentry = oe->lowerdentry;
+ *is_upper = false;
+ }
+ return realdentry;
+}
+
+struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ return oe->cache;
+}
+
+void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ oe->cache = cache;
+}
+
+void ovl_path_lower(struct dentry *dentry, struct path *path)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ path->mnt = ofs->lower_mnt;
+ path->dentry = oe->lowerdentry;
+}
+
+int ovl_want_write(struct dentry *dentry)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ return mnt_want_write(ofs->upper_mnt);
+}
+
+void ovl_drop_write(struct dentry *dentry)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ mnt_drop_write(ofs->upper_mnt);
+}
+
+struct dentry *ovl_workdir(struct dentry *dentry)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ return ofs->workdir;
+}
+
+bool ovl_dentry_is_opaque(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ return oe->opaque;
+}
+
+void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ oe->opaque = opaque;
+}
+
+void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ WARN_ON(!mutex_is_locked(&upperdentry->d_parent->d_inode->i_mutex));
+ WARN_ON(oe->__upperdentry);
+ BUG_ON(!upperdentry->d_inode);
+ /*
+ * Make sure upperdentry is consistent before making it visible to
+ * ovl_upperdentry_dereference().
+ */
+ smp_wmb();
+ oe->__upperdentry = upperdentry;
+}
+
+void ovl_dentry_version_inc(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
+ oe->version++;
+}
+
+u64 ovl_dentry_version_get(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
+ return oe->version;
+}
+
+bool ovl_is_whiteout(struct dentry *dentry)
+{
+ struct inode *inode = dentry->d_inode;
+
+ return inode && IS_WHITEOUT(inode);
+}
+
+static bool ovl_is_opaquedir(struct dentry *dentry)
+{
+ int res;
+ char val;
+ struct inode *inode = dentry->d_inode;
+
+ if (!S_ISDIR(inode->i_mode) || !inode->i_op->getxattr)
+ return false;
+
+ res = inode->i_op->getxattr(dentry, ovl_opaque_xattr, &val, 1);
+ if (res == 1 && val == 'y')
+ return true;
+
+ return false;
+}
+
+static void ovl_dentry_release(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ if (oe) {
+ dput(oe->__upperdentry);
+ dput(oe->lowerdentry);
+ kfree_rcu(oe, rcu);
+ }
+}
+
+static const struct dentry_operations ovl_dentry_operations = {
+ .d_release = ovl_dentry_release,
+};
+
+static struct ovl_entry *ovl_alloc_entry(void)
+{
+ return kzalloc(sizeof(struct ovl_entry), GFP_KERNEL);
+}
+
+static inline struct dentry *ovl_lookup_real(struct dentry *dir,
+ struct qstr *name)
+{
+ struct dentry *dentry;
+
+ mutex_lock(&dir->d_inode->i_mutex);
+ dentry = lookup_one_len(name->name, dir, name->len);
+ mutex_unlock(&dir->d_inode->i_mutex);
+
+ if (IS_ERR(dentry)) {
+ if (PTR_ERR(dentry) == -ENOENT)
+ dentry = NULL;
+ } else if (!dentry->d_inode) {
+ dput(dentry);
+ dentry = NULL;
+ }
+ return dentry;
+}
+
+struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
+ unsigned int flags)
+{
+ struct ovl_entry *oe;
+ struct dentry *upperdir;
+ struct dentry *lowerdir;
+ struct dentry *upperdentry = NULL;
+ struct dentry *lowerdentry = NULL;
+ struct inode *inode = NULL;
+ int err;
+
+ err = -ENOMEM;
+ oe = ovl_alloc_entry();
+ if (!oe)
+ goto out;
+
+ upperdir = ovl_dentry_upper(dentry->d_parent);
+ lowerdir = ovl_dentry_lower(dentry->d_parent);
+
+ if (upperdir) {
+ upperdentry = ovl_lookup_real(upperdir, &dentry->d_name);
+ err = PTR_ERR(upperdentry);
+ if (IS_ERR(upperdentry))
+ goto out_put_dir;
+
+ if (lowerdir && upperdentry) {
+ if (ovl_is_whiteout(upperdentry)) {
+ dput(upperdentry);
+ upperdentry = NULL;
+ oe->opaque = true;
+ } else if (ovl_is_opaquedir(upperdentry)) {
+ oe->opaque = true;
+ }
+ }
+ }
+ if (lowerdir && !oe->opaque) {
+ lowerdentry = ovl_lookup_real(lowerdir, &dentry->d_name);
+ err = PTR_ERR(lowerdentry);
+ if (IS_ERR(lowerdentry))
+ goto out_dput_upper;
+ }
+
+ if (lowerdentry && upperdentry &&
+ (!S_ISDIR(upperdentry->d_inode->i_mode) ||
+ !S_ISDIR(lowerdentry->d_inode->i_mode))) {
+ dput(lowerdentry);
+ lowerdentry = NULL;
+ oe->opaque = true;
+ }
+
+ if (lowerdentry || upperdentry) {
+ struct dentry *realdentry;
+
+ realdentry = upperdentry ? upperdentry : lowerdentry;
+ err = -ENOMEM;
+ inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode,
+ oe);
+ if (!inode)
+ goto out_dput;
+ ovl_copyattr(realdentry->d_inode, inode);
+ }
+
+ oe->__upperdentry = upperdentry;
+ oe->lowerdentry = lowerdentry;
+
+ dentry->d_fsdata = oe;
+ d_add(dentry, inode);
+
+ return NULL;
+
+out_dput:
+ dput(lowerdentry);
+out_dput_upper:
+ dput(upperdentry);
+out_put_dir:
+ kfree(oe);
+out:
+ return ERR_PTR(err);
+}
+
+struct file *ovl_path_open(struct path *path, int flags)
+{
+ return dentry_open(path, flags, current_cred());
+}
+
+static void ovl_put_super(struct super_block *sb)
+{
+ struct ovl_fs *ufs = sb->s_fs_info;
+
+ dput(ufs->workdir);
+ mntput(ufs->upper_mnt);
+ mntput(ufs->lower_mnt);
+
+ kfree(ufs->config.lowerdir);
+ kfree(ufs->config.upperdir);
+ kfree(ufs->config.workdir);
+ kfree(ufs);
+}
+
+/**
+ * ovl_statfs
+ * @sb: The overlayfs super block
+ * @buf: The struct kstatfs to fill in with stats
+ *
+ * Get the filesystem statistics. As writes always target the upper layer
+ * filesystem pass the statfs to the same filesystem.
+ */
+static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct dentry *root_dentry = dentry->d_sb->s_root;
+ struct path path;
+ int err;
+
+ ovl_path_upper(root_dentry, &path);
+
+ err = vfs_statfs(&path, buf);
+ if (!err) {
+ buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen);
+ buf->f_type = OVERLAYFS_SUPER_MAGIC;
+ }
+
+ return err;
+}
+
+/**
+ * ovl_show_options
+ *
+ * Prints the mount options for a given superblock.
+ * Returns zero; does not fail.
+ */
+static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
+{
+ struct super_block *sb = dentry->d_sb;
+ struct ovl_fs *ufs = sb->s_fs_info;
+
+ seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir);
+ seq_printf(m, ",upperdir=%s", ufs->config.upperdir);
+ seq_printf(m, ",workdir=%s", ufs->config.workdir);
+ return 0;
+}
+
+static const struct super_operations ovl_super_operations = {
+ .put_super = ovl_put_super,
+ .statfs = ovl_statfs,
+ .show_options = ovl_show_options,
+};
+
+enum {
+ OPT_LOWERDIR,
+ OPT_UPPERDIR,
+ OPT_WORKDIR,
+ OPT_ERR,
+};
+
+static const match_table_t ovl_tokens = {
+ {OPT_LOWERDIR, "lowerdir=%s"},
+ {OPT_UPPERDIR, "upperdir=%s"},
+ {OPT_WORKDIR, "workdir=%s"},
+ {OPT_ERR, NULL}
+};
+
+static int ovl_parse_opt(char *opt, struct ovl_config *config)
+{
+ char *p;
+
+ while ((p = strsep(&opt, ",")) != NULL) {
+ int token;
+ substring_t args[MAX_OPT_ARGS];
+
+ if (!*p)
+ continue;
+
+ token = match_token(p, ovl_tokens, args);
+ switch (token) {
+ case OPT_UPPERDIR:
+ kfree(config->upperdir);
+ config->upperdir = match_strdup(&args[0]);
+ if (!config->upperdir)
+ return -ENOMEM;
+ break;
+
+ case OPT_LOWERDIR:
+ kfree(config->lowerdir);
+ config->lowerdir = match_strdup(&args[0]);
+ if (!config->lowerdir)
+ return -ENOMEM;
+ break;
+
+ case OPT_WORKDIR:
+ kfree(config->workdir);
+ config->workdir = match_strdup(&args[0]);
+ if (!config->workdir)
+ return -ENOMEM;
+ break;
+
+ default:
+ return -EINVAL;
+ }
+ }
+ return 0;
+}
+
+#define OVL_WORKDIR_NAME "work"
+
+static struct dentry *ovl_workdir_create(struct vfsmount *mnt,
+ struct dentry *dentry)
+{
+ struct inode *dir = dentry->d_inode;
+ struct dentry *work;
+ int err;
+ bool retried = false;
+
+ err = mnt_want_write(mnt);
+ if (err)
+ return ERR_PTR(err);
+
+ mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
+retry:
+ work = lookup_one_len(OVL_WORKDIR_NAME, dentry,
+ strlen(OVL_WORKDIR_NAME));
+
+ if (!IS_ERR(work)) {
+ struct kstat stat = {
+ .mode = S_IFDIR | 0,
+ };
+
+ if (work->d_inode) {
+ err = -EEXIST;
+ if (retried)
+ goto out_dput;
+
+ retried = true;
+ ovl_cleanup(dir, work);
+ dput(work);
+ goto retry;
+ }
+
+ err = ovl_create_real(dir, work, &stat, NULL, NULL, true);
+ if (err)
+ goto out_dput;
+ }
+out_unlock:
+ mutex_unlock(&dir->i_mutex);
+ mnt_drop_write(mnt);
+
+ return work;
+
+out_dput:
+ dput(work);
+ work = ERR_PTR(err);
+ goto out_unlock;
+}
+
+static int ovl_mount_dir(const char *name, struct path *path)
+{
+ int err;
+
+ err = kern_path(name, LOOKUP_FOLLOW, path);
+ if (err) {
+ pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
+ err = -EINVAL;
+ }
+ return err;
+}
+
+static bool ovl_is_allowed_fs_type(struct dentry *root)
+{
+ const struct dentry_operations *dop = root->d_op;
+
+ /*
+ * We don't support:
+ * - automount filesystems
+ * - filesystems with revalidate (FIXME for lower layer)
+ * - filesystems with case insensitive names
+ */
+ if (dop &&
+ (dop->d_manage || dop->d_automount ||
+ dop->d_revalidate || dop->d_weak_revalidate ||
+ dop->d_compare || dop->d_hash)) {
+ return false;
+ }
+ return true;
+}
+
+/* Workdir should not be subdir of upperdir and vice versa */
+static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
+{
+ bool ok = false;
+
+ if (workdir != upperdir) {
+ ok = (lock_rename(workdir, upperdir) == NULL);
+ unlock_rename(workdir, upperdir);
+ }
+ return ok;
+}
+
+static int ovl_fill_super(struct super_block *sb, void *data, int silent)
+{
+ struct path lowerpath;
+ struct path upperpath;
+ struct path workpath;
+ struct inode *root_inode;
+ struct dentry *root_dentry;
+ struct ovl_entry *oe;
+ struct ovl_fs *ufs;
+ struct kstatfs statfs;
+ int err;
+
+ err = -ENOMEM;
+ ufs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
+ if (!ufs)
+ goto out;
+
+ err = ovl_parse_opt((char *) data, &ufs->config);
+ if (err)
+ goto out_free_config;
+
+ /* FIXME: workdir is not needed for a R/O mount */
+ err = -EINVAL;
+ if (!ufs->config.upperdir || !ufs->config.lowerdir ||
+ !ufs->config.workdir) {
+ pr_err("overlayfs: missing upperdir or lowerdir or workdir\n");
+ goto out_free_config;
+ }
+
+ err = -ENOMEM;
+ oe = ovl_alloc_entry();
+ if (oe == NULL)
+ goto out_free_config;
+
+ err = ovl_mount_dir(ufs->config.upperdir, &upperpath);
+ if (err)
+ goto out_free_oe;
+
+ err = ovl_mount_dir(ufs->config.lowerdir, &lowerpath);
+ if (err)
+ goto out_put_upperpath;
+
+ err = ovl_mount_dir(ufs->config.workdir, &workpath);
+ if (err)
+ goto out_put_lowerpath;
+
+ err = -EINVAL;
+ if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) ||
+ !S_ISDIR(lowerpath.dentry->d_inode->i_mode) ||
+ !S_ISDIR(workpath.dentry->d_inode->i_mode)) {
+ pr_err("overlayfs: upperdir or lowerdir or workdir not a directory\n");
+ goto out_put_workpath;
+ }
+
+ if (upperpath.mnt != workpath.mnt) {
+ pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
+ goto out_put_workpath;
+ }
+ if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
+ pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
+ goto out_put_workpath;
+ }
+
+ if (!ovl_is_allowed_fs_type(upperpath.dentry)) {
+ pr_err("overlayfs: filesystem of upperdir is not supported\n");
+ goto out_put_workpath;
+ }
+
+ if (!ovl_is_allowed_fs_type(lowerpath.dentry)) {
+ pr_err("overlayfs: filesystem of lowerdir is not supported\n");
+ goto out_put_workpath;
+ }
+
+ err = vfs_statfs(&lowerpath, &statfs);
+ if (err) {
+ pr_err("overlayfs: statfs failed on lowerpath\n");
+ goto out_put_workpath;
+ }
+ ufs->lower_namelen = statfs.f_namelen;
+
+ sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth,
+ lowerpath.mnt->mnt_sb->s_stack_depth) + 1;
+
+ err = -EINVAL;
+ if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
+ pr_err("overlayfs: maximum fs stacking depth exceeded\n");
+ goto out_put_workpath;
+ }
+
+ ufs->upper_mnt = clone_private_mount(&upperpath);
+ err = PTR_ERR(ufs->upper_mnt);
+ if (IS_ERR(ufs->upper_mnt)) {
+ pr_err("overlayfs: failed to clone upperpath\n");
+ goto out_put_workpath;
+ }
+
+ ufs->lower_mnt = clone_private_mount(&lowerpath);
+ err = PTR_ERR(ufs->lower_mnt);
+ if (IS_ERR(ufs->lower_mnt)) {
+ pr_err("overlayfs: failed to clone lowerpath\n");
+ goto out_put_upper_mnt;
+ }
+
+ ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry);
+ err = PTR_ERR(ufs->workdir);
+ if (IS_ERR(ufs->workdir)) {
+ pr_err("overlayfs: failed to create directory %s/%s\n",
+ ufs->config.workdir, OVL_WORKDIR_NAME);
+ goto out_put_lower_mnt;
+ }
+
+ /*
+ * Make lower_mnt R/O. That way fchmod/fchown on lower file
+ * will fail instead of modifying lower fs.
+ */
+ ufs->lower_mnt->mnt_flags |= MNT_READONLY;
+
+ /* If the upper fs is r/o, we mark overlayfs r/o too */
+ if (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)
+ sb->s_flags |= MS_RDONLY;
+
+ sb->s_d_op = &ovl_dentry_operations;
+
+ err = -ENOMEM;
+ root_inode = ovl_new_inode(sb, S_IFDIR, oe);
+ if (!root_inode)
+ goto out_put_workdir;
+
+ root_dentry = d_make_root(root_inode);
+ if (!root_dentry)
+ goto out_put_workdir;
+
+ mntput(upperpath.mnt);
+ mntput(lowerpath.mnt);
+ path_put(&workpath);
+
+ oe->__upperdentry = upperpath.dentry;
+ oe->lowerdentry = lowerpath.dentry;
+
+ root_dentry->d_fsdata = oe;
+
+ sb->s_magic = OVERLAYFS_SUPER_MAGIC;
+ sb->s_op = &ovl_super_operations;
+ sb->s_root = root_dentry;
+ sb->s_fs_info = ufs;
+
+ return 0;
+
+out_put_workdir:
+ dput(ufs->workdir);
+out_put_lower_mnt:
+ mntput(ufs->lower_mnt);
+out_put_upper_mnt:
+ mntput(ufs->upper_mnt);
+out_put_workpath:
+ path_put(&workpath);
+out_put_lowerpath:
+ path_put(&lowerpath);
+out_put_upperpath:
+ path_put(&upperpath);
+out_free_oe:
+ kfree(oe);
+out_free_config:
+ kfree(ufs->config.lowerdir);
+ kfree(ufs->config.upperdir);
+ kfree(ufs->config.workdir);
+ kfree(ufs);
+out:
+ return err;
+}
+
+static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *raw_data)
+{
+ return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
+}
+
+static struct file_system_type ovl_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "overlayfs",
+ .mount = ovl_mount,
+ .kill_sb = kill_anon_super,
+};
+MODULE_ALIAS_FS("overlayfs");
+
+static int __init ovl_init(void)
+{
+ return register_filesystem(&ovl_fs_type);
+}
+
+static void __exit ovl_exit(void)
+{
+ unregister_filesystem(&ovl_fs_type);
+}
+
+module_init(ovl_init);
+module_exit(ovl_exit);
diff --git a/fs/splice.c b/fs/splice.c
index f5cb9ba84510..75c6058eabf2 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1330,6 +1330,7 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
return ret;
}
+EXPORT_SYMBOL(do_splice_direct);
static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
struct pipe_inode_info *opipe,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a957d4366c24..4e41a4a331bb 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -223,6 +223,13 @@ typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
#define ATTR_TIMES_SET (1 << 16)
/*
+ * Whiteout is represented by a char device. The following constants define the
+ * mode and device number to use.
+ */
+#define WHITEOUT_MODE 0
+#define WHITEOUT_DEV 0
+
+/*
* This is the Inode Attributes structure, used for notify_change(). It
* uses the above definitions as flags, to know which values have changed.
* Also, in this manner, a Filesystem can look at only the values it cares
@@ -254,6 +261,12 @@ struct iattr {
*/
#include <linux/quota.h>
+/*
+ * Maximum number of layers of fs stack. Needs to be limited to
+ * prevent kernel stack overflow
+ */
+#define FILESYSTEM_MAX_STACK_DEPTH 2
+
/**
* enum positive_aop_returns - aop return codes with specific semantics
*
@@ -1266,6 +1279,11 @@ struct super_block {
struct list_lru s_dentry_lru ____cacheline_aligned_in_smp;
struct list_lru s_inode_lru ____cacheline_aligned_in_smp;
struct rcu_head rcu;
+
+ /*
+ * Indicates how deep in a filesystem stack this SB is
+ */
+ int s_stack_depth;
};
extern struct timespec current_fs_time(struct super_block *sb);
@@ -1398,6 +1416,7 @@ extern int vfs_link(struct dentry *, struct inode *, struct dentry *, struct ino
extern int vfs_rmdir(struct inode *, struct dentry *);
extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **, unsigned int);
+extern int vfs_whiteout(struct inode *, struct dentry *);
/*
* VFS dentry helper functions.
@@ -1528,6 +1547,9 @@ struct inode_operations {
umode_t create_mode, int *opened);
int (*tmpfile) (struct inode *, struct dentry *, umode_t);
int (*set_acl)(struct inode *, struct posix_acl *, int);
+
+ /* WARNING: probably going away soon, do not use! */
+ int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
} ____cacheline_aligned;
ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
@@ -1625,6 +1647,9 @@ struct super_operations {
#define IS_AUTOMOUNT(inode) ((inode)->i_flags & S_AUTOMOUNT)
#define IS_NOSEC(inode) ((inode)->i_flags & S_NOSEC)
+#define IS_WHITEOUT(inode) (S_ISCHR(inode->i_mode) && \
+ (inode)->i_rdev == WHITEOUT_DEV)
+
/*
* Inode state bits. Protected by inode->i_lock
*
@@ -2040,6 +2065,7 @@ extern struct file *file_open_name(struct filename *, int, umode_t);
extern struct file *filp_open(const char *, int, umode_t);
extern struct file *file_open_root(struct dentry *, struct vfsmount *,
const char *, int);
+extern int vfs_open(const struct path *, struct file *, const struct cred *);
extern struct file * dentry_open(const struct path *, int, const struct cred *);
extern int filp_close(struct file *, fl_owner_t id);
@@ -2253,7 +2279,9 @@ extern sector_t bmap(struct inode *, sector_t);
#endif
extern int notify_change(struct dentry *, struct iattr *, struct inode **);
extern int inode_permission(struct inode *, int);
+extern int __inode_permission(struct inode *, int);
extern int generic_permission(struct inode *, int);
+extern int __check_sticky(struct inode *dir, struct inode *inode);
static inline bool execute_ok(struct inode *inode)
{
@@ -2452,6 +2480,9 @@ extern ssize_t iter_file_splice_write(struct pipe_inode_info *,
struct file *, loff_t *, size_t, unsigned int);
extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
struct file *out, loff_t *, size_t len, unsigned int flags);
+extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
+ loff_t *opos, size_t len, unsigned int flags);
+
extern void
file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
@@ -2737,6 +2768,14 @@ static inline int is_sxid(umode_t mode)
return (mode & S_ISUID) || ((mode & S_ISGID) && (mode & S_IXGRP));
}
+static inline int check_sticky(struct inode *dir, struct inode *inode)
+{
+ if (!(dir->i_mode & S_ISVTX))
+ return 0;
+
+ return __check_sticky(dir, inode);
+}
+
static inline void inode_has_no_xattr(struct inode *inode)
{
if (!is_sxid(inode->i_mode) && (inode->i_sb->s_flags & MS_NOSEC))
diff --git a/include/linux/mount.h b/include/linux/mount.h
index 9262e4bf0cc3..c2c561dc0114 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -81,6 +81,9 @@ extern struct vfsmount *mntget(struct vfsmount *mnt);
extern struct vfsmount *mnt_clone_internal(struct path *path);
extern int __mnt_is_readonly(struct vfsmount *mnt);
+struct path;
+extern struct vfsmount *clone_private_mount(struct path *path);
+
struct file_system_type;
extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
int flags, const char *name,
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index ca1a11bb4443..3735fa0a6784 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -37,6 +37,7 @@
#define RENAME_NOREPLACE (1 << 0) /* Don't overwrite target */
#define RENAME_EXCHANGE (1 << 1) /* Exchange source and dest */
+#define RENAME_WHITEOUT (1 << 2) /* Whiteout source */
struct fstrim_range {
__u64 start;
diff --git a/mm/shmem.c b/mm/shmem.c
index cd6fc7590e54..185836ba53ef 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2345,6 +2345,32 @@ static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, stru
return 0;
}
+static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry)
+{
+ struct dentry *whiteout;
+ int error;
+
+ whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
+ if (!whiteout)
+ return -ENOMEM;
+
+ error = shmem_mknod(old_dir, whiteout,
+ S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
+ dput(whiteout);
+ if (error)
+ return error;
+
+ /*
+ * Cheat and hash the whiteout while the old dentry is still in
+ * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
+ *
+ * d_lookup() will consistently find one of them at this point,
+ * not sure which one, but that isn't even important.
+ */
+ d_rehash(whiteout);
+ return 0;
+}
+
/*
* The VFS layer already does all the dentry stuff for rename,
* we just have to decrement the usage count for the target if
@@ -2356,7 +2382,7 @@ static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struc
struct inode *inode = old_dentry->d_inode;
int they_are_dirs = S_ISDIR(inode->i_mode);
- if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
+ if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
return -EINVAL;
if (flags & RENAME_EXCHANGE)
@@ -2365,6 +2391,14 @@ static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struc
if (!simple_empty(new_dentry))
return -ENOTEMPTY;
+ if (flags & RENAME_WHITEOUT) {
+ int error;
+
+ error = shmem_whiteout(old_dir, old_dentry);
+ if (error)
+ return error;
+ }
+
if (new_dentry->d_inode) {
(void) shmem_unlink(new_dir, new_dentry);
if (they_are_dirs) {

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