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, 8 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index fe40bdd984ff..f638803549e0 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -724,6 +724,7 @@ static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
 
         INIT_LIST_HEAD(&root->dirty_list);
         spin_lock_init(&root->node_lock);
+        mutex_init(&root->objectid_mutex);
         memset(&root->root_key, 0, sizeof(root->root_key));
         memset(&root->root_item, 0, sizeof(root->root_item));
         memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
@@ -1146,6 +1147,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         INIT_LIST_HEAD(&fs_info->space_info);
         btrfs_mapping_init(&fs_info->mapping_tree);
         atomic_set(&fs_info->nr_async_submits, 0);
+        atomic_set(&fs_info->throttles, 0);
         fs_info->sb = sb;
         fs_info->max_extent = (u64)-1;
         fs_info->max_inline = 8192 * 1024;
@@ -1199,7 +1201,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         mapping_set_gfp_mask(fs_info->btree_inode->i_mapping, GFP_NOFS);
 
         mutex_init(&fs_info->trans_mutex);
-        mutex_init(&fs_info->fs_mutex);
+        mutex_init(&fs_info->drop_mutex);
         mutex_init(&fs_info->alloc_mutex);
         mutex_init(&fs_info->chunk_mutex);
 
@@ -1278,8 +1280,6 @@ struct btrfs_root *open_ctree(struct super_block *sb,
                 goto fail_sb_buffer;
         }
 
-        mutex_lock(&fs_info->fs_mutex);
-
         mutex_lock(&fs_info->chunk_mutex);
         ret = btrfs_read_sys_array(tree_root);
         mutex_unlock(&fs_info->chunk_mutex);
@@ -1342,7 +1342,6 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         fs_info->metadata_alloc_profile = (u64)-1;
         fs_info->system_alloc_profile = fs_info->metadata_alloc_profile;
 
-        mutex_unlock(&fs_info->fs_mutex);
         return tree_root;
 
 fail_extent_root:
@@ -1350,7 +1349,6 @@ fail_extent_root:
 fail_tree_root:
         free_extent_buffer(tree_root->node);
 fail_sys_array:
-        mutex_unlock(&fs_info->fs_mutex);
 fail_sb_buffer:
         extent_io_tree_empty_lru(&BTRFS_I(fs_info->btree_inode)->io_tree);
         btrfs_stop_workers(&fs_info->workers);
@@ -1562,8 +1560,9 @@ int close_ctree(struct btrfs_root *root)
         struct btrfs_fs_info *fs_info = root->fs_info;
 
         fs_info->closing = 1;
+        smp_mb();
+
         btrfs_transaction_flush_work(root);
-        mutex_lock(&fs_info->fs_mutex);
         btrfs_defrag_dirty_roots(root->fs_info);
         trans = btrfs_start_transaction(root, 1);
         ret = btrfs_commit_transaction(trans, root);
@@ -1574,7 +1573,6 @@ int close_ctree(struct btrfs_root *root)
         BUG_ON(ret);
 
         write_ctree_super(NULL, root);
-        mutex_unlock(&fs_info->fs_mutex);
 
         btrfs_transaction_flush_work(root);
 
@@ -1679,7 +1677,8 @@ void btrfs_throttle(struct btrfs_root *root)
         struct backing_dev_info *bdi;
 
         bdi = &root->fs_info->bdi;
-        if (root->fs_info->throttles && bdi_write_congested(bdi)) {
+        if (atomic_read(&root->fs_info->throttles) &&
+            bdi_write_congested(bdi)) {
 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,18)
                 congestion_wait(WRITE, HZ/20);
 #else