diff options
Diffstat (limited to 'fs/kernfs/mount.c')
| -rw-r--r-- | fs/kernfs/mount.c | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index 95dcd1d558bb..f973ae9b05f1 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -68,6 +68,7 @@ static int kernfs_fill_super(struct super_block *sb, unsigned long magic) struct inode *inode; struct dentry *root; + info->sb = sb; sb->s_blocksize = PAGE_CACHE_SIZE; sb->s_blocksize_bits = PAGE_CACHE_SHIFT; sb->s_magic = magic; @@ -167,12 +168,18 @@ struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags, *new_sb_created = !sb->s_root; if (!sb->s_root) { + struct kernfs_super_info *info = kernfs_info(sb); + error = kernfs_fill_super(sb, magic); if (error) { deactivate_locked_super(sb); return ERR_PTR(error); } sb->s_flags |= MS_ACTIVE; + + mutex_lock(&kernfs_mutex); + list_add(&info->node, &root->supers); + mutex_unlock(&kernfs_mutex); } return dget(sb->s_root); @@ -191,6 +198,10 @@ void kernfs_kill_sb(struct super_block *sb) struct kernfs_super_info *info = kernfs_info(sb); struct kernfs_node *root_kn = sb->s_root->d_fsdata; + mutex_lock(&kernfs_mutex); + list_del(&info->node); + mutex_unlock(&kernfs_mutex); + /* * Remove the superblock from fs_supers/s_instances * so we can't find it, before freeing kernfs_super_info. @@ -200,6 +211,36 @@ void kernfs_kill_sb(struct super_block *sb) kernfs_put(root_kn); } +/** + * kernfs_pin_sb: try to pin the superblock associated with a kernfs_root + * @kernfs_root: the kernfs_root in question + * @ns: the namespace tag + * + * Pin the superblock so the superblock won't be destroyed in subsequent + * operations. This can be used to block ->kill_sb() which may be useful + * for kernfs users which dynamically manage superblocks. + * + * Returns NULL if there's no superblock associated to this kernfs_root, or + * -EINVAL if the superblock is being freed. + */ +struct super_block *kernfs_pin_sb(struct kernfs_root *root, const void *ns) +{ + struct kernfs_super_info *info; + struct super_block *sb = NULL; + + mutex_lock(&kernfs_mutex); + list_for_each_entry(info, &root->supers, node) { + if (info->ns == ns) { + sb = info->sb; + if (!atomic_inc_not_zero(&info->sb->s_active)) + sb = ERR_PTR(-EINVAL); + break; + } + } + mutex_unlock(&kernfs_mutex); + return sb; +} + void __init kernfs_init(void) { kernfs_node_cache = kmem_cache_create("kernfs_node_cache", |