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Commit b8399dee authored by Josef Bacik's avatar Josef Bacik
Browse files

Btrfs: do not do fast caching if we are allocating blocks for tree_root 



Since the fast caching uses normal tree locking, we can possibly deadlock if we
get to the caching via a btrfs_search_slot() on the tree_root.  So just check to
see if the root we are on is the tree root, and just don't do the fast caching.

Reported-by: default avatarSage Weil <sage@newdream.net>
Signed-off-by: default avatarJosef Bacik <josef@redhat.com>
parent 2b20982e

fs/btrfs/extent-tree.c

+12 −6
Original line number Diff line number Diff line
@@ -429,6 +429,7 @@ static int caching_kthread(void *data) 


static int cache_block_group(struct btrfs_block_group_cache *cache,

			     struct btrfs_trans_handle *trans,

			     struct btrfs_root *root,

			     int load_cache_only)

{

	struct btrfs_fs_info *fs_info = cache->fs_info;
@@ -442,9 +443,12 @@ static int cache_block_group(struct btrfs_block_group_cache *cache, 


	/*

	 * We can't do the read from on-disk cache during a commit since we need

	 * to have the normal tree locking.

	 * to have the normal tree locking.  Also if we are currently trying to

	 * allocate blocks for the tree root we can't do the fast caching since

	 * we likely hold important locks.

	 */

	if (!trans->transaction->in_commit) {

	if (!trans->transaction->in_commit &&

	    (root && root != root->fs_info->tree_root)) {

		spin_lock(&cache->lock);

		if (cache->cached != BTRFS_CACHE_NO) {

			spin_unlock(&cache->lock);
@@ -4083,7 +4087,7 @@ static int update_block_group(struct btrfs_trans_handle *trans, 
		 * space back to the block group, otherwise we will leak space.

		 */

		if (!alloc && cache->cached == BTRFS_CACHE_NO)

			cache_block_group(cache, trans, 1);

			cache_block_group(cache, trans, NULL, 1);



		byte_in_group = bytenr - cache->key.objectid;

		WARN_ON(byte_in_group > cache->key.offset);
@@ -4937,7 +4941,8 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans, 
		if (unlikely(block_group->cached == BTRFS_CACHE_NO)) {

			u64 free_percent;



			ret = cache_block_group(block_group, trans, 1);

			ret = cache_block_group(block_group, trans,

						orig_root, 1);

			if (block_group->cached == BTRFS_CACHE_FINISHED)

				goto have_block_group;
@@ -4961,7 +4966,8 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans, 
			if (loop > LOOP_CACHING_NOWAIT ||

			    (loop > LOOP_FIND_IDEAL &&

			     atomic_read(&space_info->caching_threads) < 2)) {

				ret = cache_block_group(block_group, trans, 0);

				ret = cache_block_group(block_group, trans,

							orig_root, 0);

				BUG_ON(ret);

			}

			found_uncached_bg = true;
@@ -5518,7 +5524,7 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans, 
	u64 num_bytes = ins->offset;



	block_group = btrfs_lookup_block_group(root->fs_info, ins->objectid);

	cache_block_group(block_group, trans, 0);

	cache_block_group(block_group, trans, NULL, 0);

	caching_ctl = get_caching_control(block_group);



	if (!caching_ctl) {