[PATCH V4 01/12] kernfs: use idr instead of ida to manage inode number

Shaohua Li
2017-06-28T16:34:23Z

From: Shaohua Li <shli@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.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Shaohua Li <shli@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 db5900aaa..8ad7a17 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;
@@ -875,13 +882,13 @@ 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);

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 a9b11b8..5f5d602 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -163,7 +163,7 @@ 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