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, 6 insertions, 18 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 3fbf74e93dba..6002eb64daf9 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -63,7 +63,6 @@ static noinline int create_subvol(struct btrfs_root *root, char *name,
         u64 new_dirid = BTRFS_FIRST_FREE_OBJECTID;
         unsigned long nr = 1;
 
-        mutex_lock(&root->fs_info->fs_mutex);
         ret = btrfs_check_free_space(root, 1, 0);
         if (ret)
                 goto fail_commit;
@@ -164,7 +163,6 @@ fail:
         if (err && !ret)
                 ret = err;
 fail_commit:
-        mutex_unlock(&root->fs_info->fs_mutex);
         btrfs_btree_balance_dirty(root, nr);
         btrfs_throttle(root);
         return ret;
@@ -181,7 +179,6 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
         if (!root->ref_cows)
                 return -EINVAL;
 
-        mutex_lock(&root->fs_info->fs_mutex);
         ret = btrfs_check_free_space(root, 1, 0);
         if (ret)
                 goto fail_unlock;
@@ -208,7 +205,6 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
         err = btrfs_commit_transaction(trans, root);
 
 fail_unlock:
-        mutex_unlock(&root->fs_info->fs_mutex);
         btrfs_btree_balance_dirty(root, nr);
         btrfs_throttle(root);
         return ret;
@@ -228,9 +224,7 @@ int btrfs_defrag_file(struct file *file)
         unsigned long i;
         int ret;
 
-        mutex_lock(&root->fs_info->fs_mutex);
         ret = btrfs_check_free_space(root, inode->i_size, 0);
-        mutex_unlock(&root->fs_info->fs_mutex);
         if (ret)
                 return -ENOSPC;
 
@@ -315,7 +309,8 @@ static int btrfs_ioctl_resize(struct btrfs_root *root, void __user *arg)
                 goto out;
         }
 
-        mutex_lock(&root->fs_info->fs_mutex);
+        mutex_lock(&root->fs_info->alloc_mutex);
+        mutex_lock(&root->fs_info->chunk_mutex);
         sizestr = vol_args->name;
         devstr = strchr(sizestr, ':');
         if (devstr) {
@@ -385,7 +380,8 @@ static int btrfs_ioctl_resize(struct btrfs_root *root, void __user *arg)
         }
 
 out_unlock:
-        mutex_unlock(&root->fs_info->fs_mutex);
+        mutex_lock(&root->fs_info->alloc_mutex);
+        mutex_lock(&root->fs_info->chunk_mutex);
 out:
         kfree(vol_args);
         return ret;
@@ -428,11 +424,9 @@ static noinline int btrfs_ioctl_snap_create(struct btrfs_root *root,
         }
 
         root_dirid = root->fs_info->sb->s_root->d_inode->i_ino,
-        mutex_lock(&root->fs_info->fs_mutex);
         di = btrfs_lookup_dir_item(NULL, root->fs_info->tree_root,
                             path, root_dirid,
                             vol_args->name, namelen, 0);
-        mutex_unlock(&root->fs_info->fs_mutex);
         btrfs_free_path(path);
 
         if (di && !IS_ERR(di)) {
@@ -445,10 +439,12 @@ static noinline int btrfs_ioctl_snap_create(struct btrfs_root *root,
                 goto out;
         }
 
+        mutex_lock(&root->fs_info->drop_mutex);
         if (root == root->fs_info->tree_root)
                 ret = create_subvol(root, vol_args->name, namelen);
         else
                 ret = create_snapshot(root, vol_args->name, namelen);
+        mutex_unlock(&root->fs_info->drop_mutex);
 out:
         kfree(vol_args);
         return ret;
@@ -461,10 +457,8 @@ static int btrfs_ioctl_defrag(struct file *file)
 
         switch (inode->i_mode & S_IFMT) {
         case S_IFDIR:
-                mutex_lock(&root->fs_info->fs_mutex);
                 btrfs_defrag_root(root, 0);
                 btrfs_defrag_root(root->fs_info->extent_root, 0);
-                mutex_unlock(&root->fs_info->fs_mutex);
                 break;
         case S_IFREG:
                 btrfs_defrag_file(file);
@@ -588,7 +582,6 @@ long btrfs_ioctl_clone(struct file *file, unsigned long src_fd)
                 unlock_extent(&BTRFS_I(src)->io_tree, 0, (u64)-1, GFP_NOFS);
         }
 
-        mutex_lock(&root->fs_info->fs_mutex);
         trans = btrfs_start_transaction(root, 0);
         path = btrfs_alloc_path();
         if (!path) {
@@ -685,7 +678,6 @@ out:
         unlock_extent(&BTRFS_I(src)->io_tree, 0, (u64)-1, GFP_NOFS);
 
         btrfs_end_transaction(trans, root);
-        mutex_unlock(&root->fs_info->fs_mutex);
 
 out_unlock:
         mutex_unlock(&src->i_mutex);
@@ -711,7 +703,6 @@ long btrfs_ioctl_trans_start(struct file *file)
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
-        mutex_lock(&root->fs_info->fs_mutex);
         if (file->private_data) {
                 ret = -EINPROGRESS;
                 goto out;
@@ -723,7 +714,6 @@ long btrfs_ioctl_trans_start(struct file *file)
                 ret = -ENOMEM;
         /*printk(KERN_INFO "btrfs_ioctl_trans_start on %p\n", file);*/
 out:
-        mutex_unlock(&root->fs_info->fs_mutex);
         return ret;
 }
 
@@ -740,7 +730,6 @@ long btrfs_ioctl_trans_end(struct file *file)
         struct btrfs_trans_handle *trans;
         int ret = 0;
 
-        mutex_lock(&root->fs_info->fs_mutex);
         trans = file->private_data;
         if (!trans) {
                 ret = -EINVAL;
@@ -749,7 +738,6 @@ long btrfs_ioctl_trans_end(struct file *file)
         btrfs_end_transaction(trans, root);
         file->private_data = 0;
 out:
-        mutex_unlock(&root->fs_info->fs_mutex);
         return ret;
 }