sysfs: allocate inode number using ida

sysfs used simple incrementing allocator which is not guaranteed to be
unique.  This patch makes sysfs use ida to give each sd a unique and
packed inode number.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 2544aae6f583cba953af45caed46c622adeb775c..f09626cc568aafe39b4e0c7b5aefdff855fe9297 100644 (file)
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -9,12 +9,42 @@
 #include <linux/module.h>
 #include <linux/kobject.h>
 #include <linux/namei.h>
+#include <linux/idr.h>
 #include <asm/semaphore.h>
 #include "sysfs.h"
 
 DECLARE_RWSEM(sysfs_rename_sem);
 spinlock_t sysfs_lock = SPIN_LOCK_UNLOCKED;
 
+static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
+static DEFINE_IDA(sysfs_ino_ida);
+
+int sysfs_alloc_ino(ino_t *pino)
+{
+       int ino, rc;
+
+ retry:
+       spin_lock(&sysfs_ino_lock);
+       rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
+       spin_unlock(&sysfs_ino_lock);
+
+       if (rc == -EAGAIN) {
+               if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
+                       goto retry;
+               rc = -ENOMEM;
+       }
+
+       *pino = ino;
+       return rc;
+}
+
+static void sysfs_free_ino(ino_t ino)
+{
+       spin_lock(&sysfs_ino_lock);
+       ida_remove(&sysfs_ino_ida, ino);
+       spin_unlock(&sysfs_ino_lock);
+}
+
 void release_sysfs_dirent(struct sysfs_dirent * sd)
 {
        if (sd->s_type & SYSFS_KOBJ_LINK) {
@@ -24,6 +54,7 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
                kfree(sl);
        }
        kfree(sd->s_iattr);
+       sysfs_free_ino(sd->s_ino);
        kmem_cache_free(sysfs_dir_cachep, sd);
 }
 
@@ -54,14 +85,6 @@ static struct dentry_operations sysfs_dentry_ops = {
        .d_iput         = sysfs_d_iput,
 };
 
-static unsigned int sysfs_inode_counter;
-ino_t sysfs_get_inum(void)
-{
-       if (unlikely(sysfs_inode_counter < 3))
-               sysfs_inode_counter = 3;
-       return sysfs_inode_counter++;
-}
-
 /*
  * Allocates a new sysfs_dirent and links it to the parent sysfs_dirent
  */
@@ -73,7 +96,11 @@ static struct sysfs_dirent * __sysfs_new_dirent(void * element)
        if (!sd)
                return NULL;
 
-       sd->s_ino = sysfs_get_inum();
+       if (sysfs_alloc_ino(&sd->s_ino)) {
+               kmem_cache_free(sysfs_dir_cachep, sd);
+               return NULL;
+       }
+
        atomic_set(&sd->s_count, 1);
        atomic_set(&sd->s_event, 1);
        INIT_LIST_HEAD(&sd->s_children);