Hello,
There is a lockdep warning that pops up complaining about grabbing the
block_group->alloc_mutex while holding the fs_info->pinned_mutex. This is
because in cache_block_group we grabe the pinned_mutex while holding the
alloc_mutex. This patch fixes this particular complaint by adding a cache_mutex
that will be held when caching the block group and no other time. This will
keep the lockdep warning from happening, and is a little cleaner. I also added
a test to see if the block group is cached before calling cache_block_group in
find_free_extent to keep us from checking the block group needlessly, since
really you are only going to need to call cache_block_group once, and every time
after that you will be fine. Thank you,
Signed-off-by: Josef Bacik <jbacik@xxxxxxxxxx>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index abb2733..8d9c2b4 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -561,6 +561,7 @@ struct btrfs_block_group_cache {
struct btrfs_block_group_item item;
spinlock_t lock;
struct mutex alloc_mutex;
+ struct mutex cache_mutex;
u64 pinned;
u64 reserved;
u64 flags;
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 155c8dc..59690f8 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -158,8 +158,8 @@ static int add_new_free_space(struct btrfs_block_group_cache *block_group,
start = extent_end + 1;
} else if (extent_start > start && extent_start < end) {
size = extent_start - start;
- ret = btrfs_add_free_space_lock(block_group, start,
- size);
+ ret = btrfs_add_free_space(block_group, start,
+ size);
BUG_ON(ret);
start = extent_end + 1;
} else {
@@ -169,7 +169,7 @@ static int add_new_free_space(struct btrfs_block_group_cache *block_group,
if (start < end) {
size = end - start;
- ret = btrfs_add_free_space_lock(block_group, start, size);
+ ret = btrfs_add_free_space(block_group, start, size);
BUG_ON(ret);
}
mutex_unlock(&info->pinned_mutex);
@@ -2247,17 +2247,20 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans,
* should never happen
*/
WARN_ON(!block_group);
+
+ if (unlikely(!block_group->cached)) {
+ mutex_lock(&block_group->cache_mutex);
+ ret = cache_block_group(root, block_group);
+ mutex_unlock(&block_group->cache_mutex);
+ if (ret)
+ break;
+ }
+
mutex_lock(&block_group->alloc_mutex);
if (unlikely(!block_group_bits(block_group, data)))
goto new_group;
- ret = cache_block_group(root, block_group);
- if (ret) {
- mutex_unlock(&block_group->alloc_mutex);
- break;
- }
-
- if (block_group->ro)
+ if (unlikely(block_group->ro))
goto new_group;
free_space = btrfs_find_free_space(block_group, search_start,
@@ -2630,12 +2633,12 @@ int btrfs_alloc_logged_extent(struct btrfs_trans_handle *trans,
struct btrfs_block_group_cache *block_group;
block_group = btrfs_lookup_block_group(root->fs_info, ins->objectid);
- mutex_lock(&block_group->alloc_mutex);
+ mutex_lock(&block_group->cache_mutex);
cache_block_group(root, block_group);
+ mutex_unlock(&block_group->cache_mutex);
- ret = btrfs_remove_free_space_lock(block_group, ins->objectid,
- ins->offset);
- mutex_unlock(&block_group->alloc_mutex);
+ ret = btrfs_remove_free_space(block_group, ins->objectid,
+ ins->offset);
BUG_ON(ret);
ret = __btrfs_alloc_reserved_extent(trans, root, parent, root_objectid,
ref_generation, owner, ins);
@@ -5156,6 +5159,7 @@ int btrfs_read_block_groups(struct btrfs_root *root)
spin_lock_init(&cache->lock);
mutex_init(&cache->alloc_mutex);
+ mutex_init(&cache->cache_mutex);
INIT_LIST_HEAD(&cache->list);
read_extent_buffer(leaf, &cache->item,
btrfs_item_ptr_offset(leaf, path->slots[0]),
@@ -5207,6 +5211,7 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
cache->key.offset = size;
spin_lock_init(&cache->lock);
mutex_init(&cache->alloc_mutex);
+ mutex_init(&cache->cache_mutex);
INIT_LIST_HEAD(&cache->list);
btrfs_set_key_type(&cache->key, BTRFS_BLOCK_GROUP_ITEM_KEY);
--
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