Commit d311d79d authored by Al Viro's avatar Al Viro
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: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 38dbfb59

fs/cifs/file.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

	}

fs/ext4/file.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

	}

fs/ntfs/file.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

	}

fs/sync.c

+0 −17
Original line number Diff line number Diff line
@@ -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

fs/xfs/xfs_file.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

	}

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