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, 13 insertions, 6 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index ba3968571024..869864ddcc29 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -866,7 +866,8 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
         u64 devid;
         int ret = 0;
 
-        mutex_lock(&root->fs_info->fs_mutex);
+        mutex_lock(&root->fs_info->alloc_mutex);
+        mutex_lock(&root->fs_info->chunk_mutex);
         mutex_lock(&uuid_mutex);
 
         all_avail = root->fs_info->avail_data_alloc_bits |
@@ -984,7 +985,8 @@ error_close:
                 close_bdev_excl(bdev);
 out:
         mutex_unlock(&uuid_mutex);
-        mutex_unlock(&root->fs_info->fs_mutex);
+        mutex_unlock(&root->fs_info->chunk_mutex);
+        mutex_unlock(&root->fs_info->alloc_mutex);
         return ret;
 }
 
@@ -1003,7 +1005,10 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         if (!bdev) {
                 return -EIO;
         }
-        mutex_lock(&root->fs_info->fs_mutex);
+
+        mutex_lock(&root->fs_info->alloc_mutex);
+        mutex_lock(&root->fs_info->chunk_mutex);
+
         trans = btrfs_start_transaction(root, 1);
         devices = &root->fs_info->fs_devices->devices;
         list_for_each(cur, devices) {
@@ -1057,7 +1062,9 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         root->fs_info->fs_devices->open_devices++;
 out:
         btrfs_end_transaction(trans, root);
-        mutex_unlock(&root->fs_info->fs_mutex);
+        mutex_unlock(&root->fs_info->chunk_mutex);
+        mutex_unlock(&root->fs_info->alloc_mutex);
+
         return ret;
 
 out_close_bdev:
@@ -1297,9 +1304,10 @@ int btrfs_balance(struct btrfs_root *dev_root)
         struct btrfs_key found_key;
 
 
+        BUG(); /* FIXME, needs locking */
+
         dev_root = dev_root->fs_info->dev_root;
 
-        mutex_lock(&dev_root->fs_info->fs_mutex);
         /* step one make some room on all the devices */
         list_for_each(cur, devices) {
                 device = list_entry(cur, struct btrfs_device, dev_list);
@@ -1368,7 +1376,6 @@ int btrfs_balance(struct btrfs_root *dev_root)
         ret = 0;
 error:
         btrfs_free_path(path);
-        mutex_unlock(&dev_root->fs_info->fs_mutex);
         return ret;
 }