Btrfs: Replace the big fs_mutex with a collection of other locks

Extent alloctions are still protected by a large alloc_mutex.
Objectid allocations are covered by a objectid mutex
Other btree operations are protected by a lock on individual btree nodes

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 7 insertions, 11 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 7e40c516fe62..890b9e9d8e27 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1577,9 +1577,11 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                 }
 
                 /* block accounting for super block */
+                spin_lock_irq(&info->delalloc_lock);
                 super_used = btrfs_super_bytes_used(&info->super_copy);
                 btrfs_set_super_bytes_used(&info->super_copy,
                                            super_used - num_bytes);
+                spin_unlock_irq(&info->delalloc_lock);
 
                 /* block accounting for root item */
                 root_used = btrfs_root_used(&root->root_item);
@@ -1968,8 +1970,10 @@ again:
         }
 
         /* block accounting for super block */
+        spin_lock_irq(&info->delalloc_lock);
         super_used = btrfs_super_bytes_used(&info->super_copy);
         btrfs_set_super_bytes_used(&info->super_copy, super_used + num_bytes);
+        spin_unlock_irq(&info->delalloc_lock);
 
         /* block accounting for root item */
         root_used = btrfs_root_used(&root->root_item);
@@ -2172,12 +2176,12 @@ static void noinline reada_walk_down(struct btrfs_root *root,
                                 continue;
                         }
                 }
-                mutex_unlock(&root->fs_info->fs_mutex);
+                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->fs_mutex);
+                mutex_lock(&root->fs_info->alloc_mutex);
                 if (ret)
                         break;
         }
@@ -2254,11 +2258,9 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
                         free_extent_buffer(next);
                         reada_walk_down(root, cur, path->slots[*level]);
 
-                        mutex_unlock(&root->fs_info->fs_mutex);
                         mutex_unlock(&root->fs_info->alloc_mutex);
                         next = read_tree_block(root, bytenr, blocksize,
                                                ptr_gen);
-                        mutex_lock(&root->fs_info->fs_mutex);
                         mutex_lock(&root->fs_info->alloc_mutex);
 
                         /* we've dropped the lock, double check */
@@ -2381,6 +2383,7 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
         int orig_level;
         struct btrfs_root_item *root_item = &root->root_item;
 
+        WARN_ON(!mutex_is_locked(&root->fs_info->drop_mutex));
         path = btrfs_alloc_path();
         BUG_ON(!path);
 
@@ -2710,7 +2713,6 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
                     *last_file_root == ref_root)
                         goto out;
 
-                mutex_unlock(&extent_root->fs_info->fs_mutex);
                 inode = btrfs_iget_locked(extent_root->fs_info->sb,
                                           ref_objectid, found_root);
                 if (inode->i_state & I_NEW) {
@@ -2727,7 +2729,6 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
                  * the latest version of the tree root
                  */
                 if (is_bad_inode(inode)) {
-                        mutex_lock(&extent_root->fs_info->fs_mutex);
                         goto out;
                 }
                 *last_file_objectid = inode->i_ino;
@@ -2736,7 +2737,6 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
 
                 relocate_inode_pages(inode, ref_offset, extent_key->offset);
                 iput(inode);
-                mutex_lock(&extent_root->fs_info->fs_mutex);
         } else {
                 struct btrfs_trans_handle *trans;
                 struct extent_buffer *eb;
@@ -3033,9 +3033,7 @@ next:
 
                 if (progress && need_resched()) {
                         memcpy(&key, &found_key, sizeof(key));
-                        mutex_unlock(&root->fs_info->fs_mutex);
                         cond_resched();
-                        mutex_lock(&root->fs_info->fs_mutex);
                         btrfs_release_path(root, path);
                         btrfs_search_slot(NULL, root, &key, path, 0, 0);
                         progress = 0;
@@ -3068,9 +3066,7 @@ next:
                 trans = btrfs_start_transaction(tree_root, 1);
                 btrfs_commit_transaction(trans, tree_root);
 
-                mutex_unlock(&root->fs_info->fs_mutex);
                 btrfs_clean_old_snapshots(tree_root);
-                mutex_lock(&root->fs_info->fs_mutex);
 
                 trans = btrfs_start_transaction(tree_root, 1);
                 btrfs_commit_transaction(trans, tree_root);