kernfs: implement kernfs_root->supers list
Currently, there's no way to find out which super_blocks are
associated with a given kernfs_root. Let's implement it - the planned
inotify extension to kernfs_notify() needs it.
Make kernfs_super_info point back to the super_block and chain it at
kernfs_root->supers.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 78f3403..43aa979 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -711,6 +711,7 @@
return ERR_PTR(-ENOMEM);
ida_init(&root->ino_ida);
+ INIT_LIST_HEAD(&root->supers);
kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO,
KERNFS_DIR);
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 8be13b2..dc84a3e 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -49,6 +49,8 @@
* mount.c
*/
struct kernfs_super_info {
+ struct super_block *sb;
+
/*
* The root associated with this super_block. Each super_block is
* identified by the root and ns it's associated with.
@@ -62,6 +64,9 @@
* an array and compare kernfs_node tag against every entry.
*/
const void *ns;
+
+ /* anchored at kernfs_root->supers, protected by kernfs_mutex */
+ struct list_head node;
};
#define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info))
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 6a5f04a..f25a7c0 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -68,6 +68,7 @@
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 = SYSFS_MAGIC;
@@ -166,12 +167,18 @@
*new_sb_created = !sb->s_root;
if (!sb->s_root) {
+ struct kernfs_super_info *info = kernfs_info(sb);
+
error = kernfs_fill_super(sb);
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);
@@ -190,6 +197,10 @@
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.
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index b0122dc..589318b 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -144,6 +144,10 @@
/* private fields, do not use outside kernfs proper */
struct ida ino_ida;
struct kernfs_syscall_ops *syscall_ops;
+
+ /* list of kernfs_super_info of this root, protected by kernfs_mutex */
+ struct list_head supers;
+
wait_queue_head_t deactivate_waitq;
};
