From 333db94cdde9e6dfdedab9290d04d812f83e0922 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 25 Jun 2008 16:01:30 -0400 Subject: [PATCH] Btrfs: Fix snapshot deletion to release the alloc_mutex much more often. This lowers the impact of snapshot deletion on the rest of the FS. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 2 +- fs/btrfs/disk-io.c | 2 ++ fs/btrfs/extent-tree.c | 28 ++++++++++++++++++++-------- 3 files changed, 23 insertions(+), 9 deletions(-) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index fd68601b60b1..5edbcc09b3cc 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1255,7 +1255,7 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root lowest_level = p->lowest_level; WARN_ON(lowest_level && ins_len); WARN_ON(p->nodes[0] != NULL); - WARN_ON(root == root->fs_info->extent_root && + WARN_ON(cow && root == root->fs_info->extent_root && !mutex_is_locked(&root->fs_info->alloc_mutex)); WARN_ON(root == root->fs_info->chunk_root && !mutex_is_locked(&root->fs_info->chunk_mutex)); diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index ffc363d2fb24..3cc480b83819 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1674,6 +1674,7 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf) void btrfs_throttle(struct btrfs_root *root) { +#if 0 struct backing_dev_info *bdi; bdi = &root->fs_info->bdi; @@ -1686,6 +1687,7 @@ void btrfs_throttle(struct btrfs_root *root) #endif } +#endif } void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 544fc3f2fe6c..6274f30031db 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -1223,8 +1223,8 @@ printk("space info full %Lu\n", flags); ret = btrfs_make_block_group(trans, extent_root, 0, flags, BTRFS_FIRST_CHUNK_TREE_OBJECTID, start, num_bytes); BUG_ON(ret); - mutex_unlock(&extent_root->fs_info->chunk_mutex); out: + mutex_unlock(&extent_root->fs_info->chunk_mutex); return 0; } @@ -2181,17 +2181,29 @@ static void noinline reada_walk_down(struct btrfs_root *root, continue; } } - mutex_unlock(&root->fs_info->alloc_mutex); ret = readahead_tree_block(root, bytenr, blocksize, btrfs_node_ptr_generation(node, i)); last = bytenr + blocksize; cond_resched(); - mutex_lock(&root->fs_info->alloc_mutex); if (ret) break; } } +/* + * we want to avoid as much random IO as we can with the alloc mutex + * held, so drop the lock and do the lookup, then do it again with the + * lock held. + */ +int drop_snap_lookup_refcount(struct btrfs_root *root, u64 start, u64 len, + u32 *refs) +{ + mutex_unlock(&root->fs_info->alloc_mutex); + lookup_extent_ref(NULL, root, start, len, refs); + mutex_lock(&root->fs_info->alloc_mutex); + return lookup_extent_ref(NULL, root, start, len, refs); +} + /* * helper function for drop_snapshot, this walks down the tree dropping ref * counts as it goes. @@ -2215,8 +2227,7 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans, WARN_ON(*level < 0); WARN_ON(*level >= BTRFS_MAX_LEVEL); - ret = lookup_extent_ref(trans, root, - path->nodes[*level]->start, + ret = drop_snap_lookup_refcount(root, path->nodes[*level]->start, path->nodes[*level]->len, &refs); BUG_ON(ret); if (refs > 1) @@ -2245,7 +2256,7 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans, ptr_gen = btrfs_node_ptr_generation(cur, path->slots[*level]); blocksize = btrfs_level_size(root, *level - 1); - ret = lookup_extent_ref(trans, root, bytenr, blocksize, &refs); + ret = drop_snap_lookup_refcount(root, bytenr, blocksize, &refs); BUG_ON(ret); if (refs != 1) { parent = path->nodes[*level]; @@ -2261,15 +2272,16 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans, next = btrfs_find_tree_block(root, bytenr, blocksize); if (!next || !btrfs_buffer_uptodate(next, ptr_gen)) { free_extent_buffer(next); + mutex_unlock(&root->fs_info->alloc_mutex); + reada_walk_down(root, cur, path->slots[*level]); - mutex_unlock(&root->fs_info->alloc_mutex); next = read_tree_block(root, bytenr, blocksize, ptr_gen); mutex_lock(&root->fs_info->alloc_mutex); /* we've dropped the lock, double check */ - ret = lookup_extent_ref(trans, root, bytenr, + ret = drop_snap_lookup_refcount(root, bytenr, blocksize, &refs); BUG_ON(ret); if (refs != 1) { -- 2.30.2