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Btrfs: ensure deletion from pinned_chunks list is protected 

The call to remove_extent_mapping() actually deletes the extent map
from the list it's included in - fs_info->pinned_chunks - and that
list is protected by the chunk mutex. Therefore make that call
while holding the chunk mutex and remove the redundant list delete
call because it's a noop.

This fixes an overlook of the patch titled
"Btrfs: fix race between fs trimming and block group remove/allocation"
following the same obvervation from the patch titled
"Btrfs: fix unprotected deletion from pending_chunks list".

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Filipe Manana 2014-12-04 15:31:01 +00:00 committed by Chris Mason
parent 9627aeee3e
commit a1e7e16ed3
1 changed files with 5 additions and 3 deletions
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8
fs/btrfs/free-space-cache.c
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@ -3185,16 +3185,18 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
spin_unlock(&block_group->lock);
lock_chunks(block_group->fs_info->chunk_root);
em_tree = &block_group->fs_info->mapping_tree.map_tree;
write_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, block_group->key.objectid,
1);
BUG_ON(!em); /* logic error, can't happen */
/*
* remove_extent_mapping() will delete us from the pinned_chunks
* list, which is protected by the chunk mutex.
*/
remove_extent_mapping(em_tree, em);
write_unlock(&em_tree->lock);
lock_chunks(block_group->fs_info->chunk_root);
list_del_init(&em->list);
unlock_chunks(block_group->fs_info->chunk_root);
/* once for us and once for the tree */