This is a note to let you know that I've just added the patch titled
Btrfs: fix racy system chunk allocation when setting block group ro
to the 4.0-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-fix-racy-system-chunk-allocation-when-setting-block-group-ro.patch
and it can be found in the queue-4.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From a96295965b600f2dc6ad661c4803c86e87db3d7b Mon Sep 17 00:00:00 2001
From: Filipe Manana <[email protected]>
Date: Mon, 18 May 2015 19:11:40 +0100
Subject: Btrfs: fix racy system chunk allocation when setting block group ro
From: Filipe Manana <[email protected]>
commit a96295965b600f2dc6ad661c4803c86e87db3d7b upstream.
If while setting a block group read-only we end up allocating a system
chunk, through check_system_chunk(), we were not doing it while holding
the chunk mutex which is a problem if a concurrent chunk allocation is
happening, through do_chunk_alloc(), as it means both block groups can
end up using the same logical addresses and physical regions in the
device(s). So make sure we hold the chunk mutex.
Fixes: 2f0810880f08 ("btrfs: delete chunk allocation attemp when
setting block group ro")
Signed-off-by: Filipe Manana <[email protected]>
Signed-off-by: Chris Mason <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/btrfs/extent-tree.c | 2 ++
fs/btrfs/volumes.c | 1 +
2 files changed, 3 insertions(+)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -8548,7 +8548,9 @@ int btrfs_set_block_group_ro(struct btrf
out:
if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) {
alloc_flags = update_block_group_flags(root, cache->flags);
+ lock_chunks(root->fs_info->chunk_root);
check_system_chunk(trans, root, alloc_flags);
+ unlock_chunks(root->fs_info->chunk_root);
}
btrfs_end_transaction(trans, root);
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4626,6 +4626,7 @@ int btrfs_alloc_chunk(struct btrfs_trans
{
u64 chunk_offset;
+ ASSERT(mutex_is_locked(&extent_root->fs_info->chunk_mutex));
chunk_offset = find_next_chunk(extent_root->fs_info);
return __btrfs_alloc_chunk(trans, extent_root, chunk_offset, type);
}
Patches currently in stable-queue which might be from [email protected] are
queue-4.0/btrfs-fix-racy-system-chunk-allocation-when-setting-block-group-ro.patch
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