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authorJosef Bacik <josef@redhat.com>2012-04-12 16:03:57 -0400
committerChris Mason <chris.mason@oracle.com>2012-04-12 20:54:01 -0400
commitd53ba47484ed6245e640ee4bfe9d21e9bfc15765 (patch)
tree12bcb989f0e210f25770a72441eb8b947fd2fad3
parent4edc2ca388d62abffe38149f6ac00e749ea721c5 (diff)
Btrfs: use commit root when loading free space cache
A user reported that booting his box up with btrfs root on 3.4 was way slower than on 3.3 because I removed the ideal caching code. It turns out that we don't load the free space cache if we're in a commit for deadlock reasons, but since we're reading the cache and it hasn't changed yet we are safe reading the inode and free space item from the commit root, so do that and remove all of the deadlock checks so we don't unnecessarily skip loading the free space cache. The user reported this fixed the slowness. Thanks, Tested-by: Calvin Walton <calvin.walton@kepstin.ca> Signed-off-by: Josef Bacik <josef@redhat.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
-rw-r--r--fs/btrfs/extent-tree.c4
-rw-r--r--fs/btrfs/free-space-cache.c9
2 files changed, 3 insertions, 10 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a2134d8141c..2b35f8d14bb 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -529,9 +529,7 @@ static int cache_block_group(struct btrfs_block_group_cache *cache,
* allocate blocks for the tree root we can't do the fast caching since
* we likely hold important locks.
*/
- if (trans && (!trans->transaction->in_commit) &&
- (root && root != root->fs_info->tree_root) &&
- btrfs_test_opt(root, SPACE_CACHE)) {
+ if (fs_info->mount_opt & BTRFS_MOUNT_SPACE_CACHE) {
ret = load_free_space_cache(fs_info, cache);
spin_lock(&cache->lock);
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 054707ed579..baaa518baaf 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -748,13 +748,6 @@ int load_free_space_cache(struct btrfs_fs_info *fs_info,
u64 used = btrfs_block_group_used(&block_group->item);
/*
- * If we're unmounting then just return, since this does a search on the
- * normal root and not the commit root and we could deadlock.
- */
- if (btrfs_fs_closing(fs_info))
- return 0;
-
- /*
* If this block group has been marked to be cleared for one reason or
* another then we can't trust the on disk cache, so just return.
*/
@@ -768,6 +761,8 @@ int load_free_space_cache(struct btrfs_fs_info *fs_info,
path = btrfs_alloc_path();
if (!path)
return 0;
+ path->search_commit_root = 1;
+ path->skip_locking = 1;
inode = lookup_free_space_inode(root, block_group, path);
if (IS_ERR(inode)) {