[PATCH 02/11] kernfs: use idr instead of ida to manage inode number

[Shaohua Li]

From: Shaohua Li <s...@fb.com>

kernfs uses ida to manage inode number. The problem is we can't get
kernfs_node from inode number with ida. Switching to use idr, next patch
will add an API to get kernfs_node from inode number.

Signed-off-by: Shaohua Li <s...@fb.com>
---
 fs/kernfs/dir.c        | 17 ++++++++++++-----
 include/linux/kernfs.h |  2 +-
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 09d093e..8e8545a 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -21,6 +21,7 @@
 DEFINE_MUTEX(kernfs_mutex);
 static DEFINE_SPINLOCK(kernfs_rename_lock);    /* kn->parent and ->name */
 static char kernfs_pr_cont_buf[PATH_MAX];      /* protected by rename_lock */
+static DEFINE_SPINLOCK(kernfs_idr_lock);       /* root->ino_idr */
 
 #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb)
 
@@ -533,7 +534,9 @@ void kernfs_put(struct kernfs_node *kn)
                simple_xattrs_free(&kn->iattr->xattrs);
        }
        kfree(kn->iattr);
-       ida_simple_remove(&root->ino_ida, kn->ino);
+       spin_lock(&kernfs_idr_lock);
+       idr_remove(&root->ino_idr, kn->ino);
+       spin_unlock(&kernfs_idr_lock);
        kmem_cache_free(kernfs_node_cache, kn);
 
        kn = parent;
@@ -542,7 +545,7 @@ void kernfs_put(struct kernfs_node *kn)
                        goto repeat;
        } else {
                /* just released the root kn, free @root too */
-               ida_destroy(&root->ino_ida);
+               idr_destroy(&root->ino_idr);
                kfree(root);
        }
 }
@@ -630,7 +633,11 @@ static struct kernfs_node *__kernfs_new_node(struct 
kernfs_root *root,
        if (!kn)
                goto err_out1;
 
-       ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL);
+       idr_preload(GFP_KERNEL);
+       spin_lock(&kernfs_idr_lock);
+       ret = idr_alloc(&root->ino_idr, kn, 1, 0, GFP_ATOMIC);
+       spin_unlock(&kernfs_idr_lock);
+       idr_preload_end();
        if (ret < 0)
                goto err_out2;
        kn->ino = ret;
@@ -876,14 +883,14 @@ struct kernfs_root *kernfs_create_root(struct 
kernfs_syscall_ops *scops,
        if (!root)
                return ERR_PTR(-ENOMEM);
 
-       ida_init(&root->ino_ida);
+       idr_init(&root->ino_idr);
        INIT_LIST_HEAD(&root->supers);
        atomic_set(&root->next_generation, 0);
 
        kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO,
                               KERNFS_DIR);
        if (!kn) {
-               ida_destroy(&root->ino_ida);
+               idr_destroy(&root->ino_idr);
                kfree(root);
                return ERR_PTR(-ENOMEM);
        }
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index c5f0fa7..61668d1 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -164,7 +164,7 @@ struct kernfs_root {
        unsigned int            flags;  /* KERNFS_ROOT_* flags */
 
        /* private fields, do not use outside kernfs proper */
-       struct ida              ino_ida;
+       struct idr              ino_idr;
        struct kernfs_syscall_ops *syscall_ops;
 
        /* list of kernfs_super_info of this root, protected by kernfs_mutex */
-- 
2.9.3