Permalink
Browse files

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>
  • Loading branch information...
1 parent 38dbfb5 commit d311d79de305f1ada47cadd672e6ed1b28a949eb Al Viro committed Feb 9, 2014
Showing with 14 additions and 25 deletions.
  1. +2 −2 fs/cifs/file.c
  2. +1 −1 fs/ext4/file.c
  3. +1 −1 fs/ntfs/file.c
  4. +0 −17 fs/sync.c
  5. +1 −1 fs/xfs/xfs_file.c
  6. +7 −1 include/linux/fs.h
  7. +2 −2 mm/filemap.c
View
4 fs/cifs/file.c
@@ -2559,8 +2559,8 @@ cifs_writev(struct kiocb *iocb, const struct iovec *iov,
if (rc > 0) {
ssize_t err;
- err = generic_write_sync(file, pos, rc);
- if (err < 0 && rc > 0)
+ err = generic_write_sync(file, iocb->ki_pos - rc, rc);
+ if (err < 0)
rc = err;
}
View
2 fs/ext4/file.c
@@ -152,7 +152,7 @@ ext4_file_dio_write(struct kiocb *iocb, const struct iovec *iov,
if (ret > 0) {
ssize_t err;
- err = generic_write_sync(file, pos, ret);
+ err = generic_write_sync(file, iocb->ki_pos - ret, ret);
if (err < 0 && ret > 0)
ret = err;
}
View
2 fs/ntfs/file.c
@@ -2134,7 +2134,7 @@ static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos);
mutex_unlock(&inode->i_mutex);
if (ret > 0) {
- int err = generic_write_sync(file, pos, ret);
+ int err = generic_write_sync(file, iocb->ki_pos - ret, ret);
if (err < 0)
ret = err;
}
View
17 fs/sync.c
@@ -222,23 +222,6 @@ SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
return do_fsync(fd, 1);
}
-/**
- * generic_write_sync - perform syncing after a write if file / inode is sync
- * @file: file to which the write happened
- * @pos: offset where the write started
- * @count: length of the write
- *
- * This is just a simple wrapper about our general syncing function.
- */
-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);
-}
-EXPORT_SYMBOL(generic_write_sync);
-
/*
* sys_sync_file_range() permits finely controlled syncing over a segment of
* a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
View
2 fs/xfs/xfs_file.c
@@ -799,7 +799,7 @@ xfs_file_aio_write(
XFS_STATS_ADD(xs_write_bytes, ret);
/* Handle various SYNC-type writes */
- err = generic_write_sync(file, pos, ret);
+ err = generic_write_sync(file, iocb->ki_pos - ret, ret);
if (err < 0)
ret = err;
}
View
8 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);
#ifdef CONFIG_BLOCK
View
4 mm/filemap.c
@@ -2553,8 +2553,8 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
if (ret > 0) {
ssize_t err;
- err = generic_write_sync(file, pos, ret);
- if (err < 0 && ret > 0)
+ err = generic_write_sync(file, iocb->ki_pos - ret, ret);
+ if (err < 0)
ret = err;
}
return ret;

0 comments on commit d311d79

Please sign in to comment.