This is a note to let you know that I've just added the patch titled
Btrfs: do not move em to modified list when unpinning
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
btrfs-do-not-move-em-to-modified-list-when-unpinning.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a28046956c71985046474283fa3bcd256915fb72 Mon Sep 17 00:00:00 2001
From: Josef Bacik <jbacik@xxxxxx>
Date: Fri, 14 Nov 2014 16:16:30 -0500
Subject: Btrfs: do not move em to modified list when unpinning
From: Josef Bacik <jbacik@xxxxxx>
commit a28046956c71985046474283fa3bcd256915fb72 upstream.
We use the modified list to keep track of which extents have been modified so we
know which ones are candidates for logging at fsync() time. Newly modified
extents are added to the list at modification time, around the same time the
ordered extent is created. We do this so that we don't have to wait for ordered
extents to complete before we know what we need to log. The problem is when
something like this happens
log extent 0-4k on inode 1
copy csum for 0-4k from ordered extent into log
sync log
commit transaction
log some other extent on inode 1
ordered extent for 0-4k completes and adds itself onto modified list again
log changed extents
see ordered extent for 0-4k has already been logged
at this point we assume the csum has been copied
sync log
crash
On replay we will see the extent 0-4k in the log, drop the original 0-4k extent
which is the same one that we are replaying which also drops the csum, and then
we won't find the csum in the log for that bytenr. This of course causes us to
have errors about not having csums for certain ranges of our inode. So remove
the modified list manipulation in unpin_extent_cache, any modified extents
should have been added well before now, and we don't want them re-logged. This
fixes my test that I could reliably reproduce this problem with. Thanks,
Signed-off-by: Josef Bacik <jbacik@xxxxxx>
Signed-off-by: Chris Mason <clm@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/extent_map.c | 2 --
1 file changed, 2 deletions(-)
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -287,8 +287,6 @@ int unpin_extent_cache(struct extent_map
if (!em)
goto out;
- if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))
- list_move(&em->list, &tree->modified_extents);
em->generation = gen;
clear_bit(EXTENT_FLAG_PINNED, &em->flags);
em->mod_start = em->start;
Patches currently in stable-queue which might be from jbacik@xxxxxx are
queue-3.18/btrfs-make-sure-logged-extents-complete-in-the-current-transaction-v3.patch
queue-3.18/btrfs-do-not-move-em-to-modified-list-when-unpinning.patch
queue-3.18/btrfs-make-sure-we-wait-on-logged-extents-when-fsycning-two-subvols.patch
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