path: root/include/linux
diff options
authorAl Viro <viro@zeniv.linux.org.uk>2014-02-09 15:18:09 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2014-02-09 15:18:09 -0500
commitd311d79de305f1ada47cadd672e6ed1b28a949eb (patch)
treeed5fe40264a27e1d8cc4410352585dfb34af50d8 /include/linux
parent38dbfb59d1175ef458d006556061adeaa8751b72 (diff)
fix O_SYNC|O_APPEND syncing the wrong range on write()
It actually goes back to 2004 ([PATCH] Concurrent O_SYNC write support) when sync_page_range() had been introduced; generic_file_write{,v}() correctly synced pos_after_write - written .. pos_after_write - 1 but generic_file_aio_write() synced pos_before_write .. pos_before_write + written - 1 instead. Which is not the same thing with O_APPEND, obviously. A couple of years later correct variant had been killed off when everything switched to use of generic_file_aio_write(). All users of generic_file_aio_write() are affected, and the same bug has been copied into other instances of ->aio_write(). The fix is trivial; the only subtle point is that generic_write_sync() ought to be inlined to avoid calculations useless for the majority of calls. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'include/linux')
1 files changed, 7 insertions, 1 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 09f553c59813..75ff961be051 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2273,7 +2273,13 @@ extern int filemap_fdatawrite_range(struct address_space *mapping,
extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
int datasync);
extern int vfs_fsync(struct file *file, int datasync);
-extern int generic_write_sync(struct file *file, loff_t pos, loff_t count);
+static inline int generic_write_sync(struct file *file, loff_t pos, loff_t count)
+ if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
+ return 0;
+ return vfs_fsync_range(file, pos, pos + count - 1,
+ (file->f_flags & __O_SYNC) ? 0 : 1);
extern void emergency_sync(void);
extern void emergency_remount(void);

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