path: root/fs/locks.c
diff options
authorLinus Torvalds <torvalds@linux-foundation.org>2010-10-27 12:38:12 -0400
committerArnd Bergmann <arnd@arndb.de>2010-10-27 22:06:17 +0200
commitf7347ce4ee7c65415f84be915c018473e7076f31 (patch)
tree613ce14f088ad00bdbc77cdfb686a40a4851180f /fs/locks.c
parentc5b1f0d92c36851aca09ac6c7c0c4f9690ac14f3 (diff)
fasync: re-organize fasync entry insertion to allow it under a spinlock
You currently cannot use "fasync_helper()" in an atomic environment to insert a new fasync entry, because it will need to allocate the new "struct fasync_struct". Yet fcntl_setlease() wants to call this under lock_flocks(), which is in the process of being converted from the BKL to a spinlock. In order to fix this, this abstracts out the actual fasync list insertion and the fasync allocations into functions of their own, and teaches fs/locks.c to pre-allocate the fasync_struct entry. That way the actual list insertion can happen while holding the required spinlock. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bfields@redhat.com: rebase on top of my changes to Arnd's patch] Tested-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'fs/locks.c')
1 files changed, 17 insertions, 1 deletions
diff --git a/fs/locks.c b/fs/locks.c
index 0391d2ff5a4e..85fd9ce1abae 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1505,6 +1505,7 @@ EXPORT_SYMBOL_GPL(vfs_setlease);
int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
struct file_lock *fl;
+ struct fasync_struct *new;
struct inode *inode = filp->f_path.dentry->d_inode;
int error;
@@ -1512,12 +1513,25 @@ int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
if (IS_ERR(fl))
return PTR_ERR(fl);
+ new = fasync_alloc();
+ if (!new) {
+ locks_free_lock(fl);
+ return -ENOMEM;
+ }
error = __vfs_setlease(filp, arg, &fl);
if (error || arg == F_UNLCK)
goto out_unlock;
- error = fasync_helper(fd, filp, 1, &fl->fl_fasync);
+ /*
+ * fasync_insert_entry() returns the old entry if any.
+ * If there was no old entry, then it used 'new' and
+ * inserted it into the fasync list. Clear new so that
+ * we don't release it here.
+ */
+ if (!fasync_insert_entry(fd, filp, &fl->fl_fasync, new))
+ new = NULL;
if (error < 0) {
/* remove lease just inserted by setlease */
fl->fl_type = F_UNLCK | F_INPROGRESS;
@@ -1529,6 +1543,8 @@ int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
+ if (new)
+ fasync_free(new);
return error;

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