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btrfs: do not shorten unpin len for caching block groups 

commit 9076dbd5ee upstream.

While fixing up our ->last_byte_to_unpin locking I noticed that we will
shorten len based on ->last_byte_to_unpin if we're caching when we're
adding back the free space.  This is correct for the free space, as we
cannot unpin more than ->last_byte_to_unpin, however we use len to
adjust the ->bytes_pinned counters and such, which need to track the
actual pinned usage.  This could result in
WARN_ON(space_info->bytes_pinned) triggering at unmount time.

Fix this by using a local variable for the amount to add to free space
cache, and leave len untouched in this case.

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Josef Bacik 2020-10-23 09:58:04 -04:00 committed by Greg Kroah-Hartman
parent af7414836d
commit 1d11ed122f
1 changed files with 4 additions and 4 deletions
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8
fs/btrfs/extent-tree.c
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@ -2838,10 +2838,10 @@ static int unpin_extent_range(struct btrfs_fs_info *fs_info,
len = cache->key.objectid + cache->key.offset - start;
len = min(len, end + 1 - start);
if (start < cache->last_byte_to_unpin) {
len = min(len, cache->last_byte_to_unpin - start);
if (return_free_space)
btrfs_add_free_space(cache, start, len);
if (start < cache->last_byte_to_unpin && return_free_space) {
u64 add_len = min(len, cache->last_byte_to_unpin - start);
btrfs_add_free_space(cache, start, add_len);
}
start += len;