nilfs2: simplify life cycle management of nilfs object

This stops pre-allocating nilfs object in nilfs_get_sb routine, and
stops managing its life cycle by reference counting.

nilfs_find_or_create_nilfs() function, nilfs->ns_mount_mutex,
nilfs_objects list, and the reference counter will be removed through
the simplification.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

1 files changed, 22 insertions, 45 deletions

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 2e58e7c629b5..5893cb27c909 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -356,7 +356,7 @@ static void nilfs_put_super(struct super_block *sb)
                 up_write(&nilfs->ns_sem);
         }
 
-        put_nilfs(sbi->s_nilfs);
+        destroy_nilfs(nilfs);
         sbi->s_super = NULL;
         sb->s_fs_info = NULL;
         kfree(sbi);
@@ -836,15 +836,14 @@ static int nilfs_try_to_shrink_tree(struct dentry *root_dentry)
  * @sb: super_block
  * @data: mount options
  * @silent: silent mode flag
- * @nilfs: the_nilfs struct
  *
  * This function is called exclusively by nilfs->ns_mount_mutex.
  * So, the recovery process is protected from other simultaneous mounts.
  */
 static int
-nilfs_fill_super(struct super_block *sb, void *data, int silent,
-                 struct the_nilfs *nilfs)
+nilfs_fill_super(struct super_block *sb, void *data, int silent)
 {
+        struct the_nilfs *nilfs;
         struct nilfs_sb_info *sbi;
         struct nilfs_root *fsroot;
         __u64 cno;
@@ -855,14 +854,18 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
                 return -ENOMEM;
 
         sb->s_fs_info = sbi;
+        sbi->s_super = sb;
 
-        get_nilfs(nilfs);
+        nilfs = alloc_nilfs(sb->s_bdev);
+        if (!nilfs) {
+                err = -ENOMEM;
+                goto failed_sbi;
+        }
         sbi->s_nilfs = nilfs;
-        sbi->s_super = sb;
 
         err = init_nilfs(nilfs, sbi, (char *)data);
         if (err)
-                goto failed_sbi;
+                goto failed_nilfs;
 
         spin_lock_init(&sbi->s_inode_lock);
         INIT_LIST_HEAD(&sbi->s_dirty_files);
@@ -885,14 +888,14 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
 
         err = load_nilfs(nilfs, sbi);
         if (err)
-                goto failed_sbi;
+                goto failed_nilfs;
 
         cno = nilfs_last_cno(nilfs);
         err = nilfs_attach_checkpoint(sbi, cno, true, &fsroot);
         if (err) {
                 printk(KERN_ERR "NILFS: error loading last checkpoint "
                        "(checkpoint number=%llu).\n", (unsigned long long)cno);
-                goto failed_sbi;
+                goto failed_nilfs;
         }
 
         if (!(sb->s_flags & MS_RDONLY)) {
@@ -921,8 +924,10 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
  failed_checkpoint:
         nilfs_put_root(fsroot);
 
+ failed_nilfs:
+        destroy_nilfs(nilfs);
+
  failed_sbi:
-        put_nilfs(nilfs);
         sb->s_fs_info = NULL;
         kfree(sbi);
         return err;
@@ -1077,7 +1082,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
         struct nilfs_super_data sd;
         struct super_block *s;
         fmode_t mode = FMODE_READ;
-        struct the_nilfs *nilfs;
         struct dentry *root_dentry;
         int err, s_new = false;
 
@@ -1095,18 +1099,10 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
                 goto failed;
         }
 
-        nilfs = find_or_create_nilfs(sd.bdev);
-        if (!nilfs) {
-                err = -ENOMEM;
-                goto failed;
-        }
-
-        mutex_lock(&nilfs->ns_mount_mutex);
-
         s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, sd.bdev);
         if (IS_ERR(s)) {
                 err = PTR_ERR(s);
-                goto failed_unlock;
+                goto failed;
         }
 
         if (!s->s_root) {
@@ -1120,10 +1116,9 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
                 strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id));
                 sb_set_blocksize(s, block_size(sd.bdev));
 
-                err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0,
-                                       nilfs);
+                err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
                 if (err)
-                        goto cancel_new;
+                        goto failed_super;
 
                 s->s_flags |= MS_ACTIVE;
         } else if (!sd.cno) {
@@ -1153,17 +1148,12 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
 
         if (sd.cno) {
                 err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);
-                if (err) {
-                        if (s_new)
-                                goto cancel_new;
+                if (err)
                         goto failed_super;
-                }
         } else {
                 root_dentry = dget(s->s_root);
         }
 
-        mutex_unlock(&nilfs->ns_mount_mutex);
-        put_nilfs(nilfs);
         if (!s_new)
                 close_bdev_exclusive(sd.bdev, mode);
 
@@ -1173,23 +1163,10 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
 
  failed_super:
         deactivate_locked_super(s);
- failed_unlock:
-        mutex_unlock(&nilfs->ns_mount_mutex);
-        put_nilfs(nilfs);
- failed:
-        close_bdev_exclusive(sd.bdev, mode);
-        return err;
 
- cancel_new:
-        /* Abandoning the newly allocated superblock */
-        mutex_unlock(&nilfs->ns_mount_mutex);
-        put_nilfs(nilfs);
-        deactivate_locked_super(s);
-        /*
-         * This deactivate_locked_super() invokes close_bdev_exclusive().
-         * We must finish all post-cleaning before this call;
-         * put_nilfs() needs the block device.
-         */
+ failed:
+        if (!s_new)
+                close_bdev_exclusive(sd.bdev, mode);
         return err;
 }