Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 549054af authored by David Chinner's avatar David Chinner Committed by Tim Shimmin
Browse files

[XFS] Fix sub-block zeroing for buffered writes into unwritten extents. 



When writing less than a filesystem block of data into an unwritten extent
via buffered I/O, __xfs_get_blocks fails to set the buffer new flag. As a
result, the generic code will not zero either edge of the block resulting
in garbage being written to disk either side of the real data. Set the
buffer new state on bufferd writes to unwritten extents to ensure that
zeroing occurs.

SGI-PV: 960328
SGI-Modid: xfs-linux-melb:xfs-kern:28000a

Signed-off-by: default avatarDavid Chinner <dgc@sgi.com>
Signed-off-by: default avatarLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: default avatarTim Shimmin <tes@sgi.com>
parent 5478eead

fs/xfs/linux-2.6/xfs_aops.c

+9 −4
Original line number Diff line number Diff line
@@ -1283,13 +1283,18 @@ __xfs_get_blocks( 
	bh_result->b_bdev = iomap.iomap_target->bt_bdev;



	/*

	 * If we previously allocated a block out beyond eof and we are

	 * now coming back to use it then we will need to flag it as new

	 * even if it has a disk address.

	 * If we previously allocated a block out beyond eof and we are now

	 * coming back to use it then we will need to flag it as new even if it

	 * has a disk address.

	 *

	 * With sub-block writes into unwritten extents we also need to mark

	 * the buffer as new so that the unwritten parts of the buffer gets

	 * correctly zeroed.

	 */

	if (create &&

	    ((!buffer_mapped(bh_result) && !buffer_uptodate(bh_result)) ||

	     (offset >= i_size_read(inode)) || (iomap.iomap_flags & IOMAP_NEW)))

	     (offset >= i_size_read(inode)) ||

	     (iomap.iomap_flags & (IOMAP_NEW|IOMAP_UNWRITTEN))))

		set_buffer_new(bh_result);



	if (iomap.iomap_flags & IOMAP_DELAY) {