[PATCH 23/61] sysfs: allocate inode number using ida

Greg Kroah-Hartman
2007-07-11T23:43:29Z

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>
---
fs/sysfs/dir.c | 45 ++++++++++++++++++++++++++++++++++++---------
1 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 2544aae..f09626c 100644
--- 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);
--
1.5.2.2