[PATCH review 14/16] proc: Generalize proc inode allocation

Eric W. Biederman
2012-11-19T15:17:07Z

Generalize the proc inode allocation so that it can be
used without having to having to create a proc_dir_entry.

This will allow namespace file descriptors to remain light
weight entitities but still have the same inode number
when the backing namespace is the same.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
fs/proc/generic.c | 26 +++++++++++++-------------
include/linux/proc_fs.h | 10 ++++++++++
2 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 0d80cef..7b3ae3c 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -350,14 +350,14 @@ static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
* Return an inode number between PROC_DYNAMIC_FIRST and
* 0xffffffff, or zero on failure.
*/
-static unsigned int get_inode_number(void)
+int proc_alloc_inum(unsigned int *inum)
{
unsigned int i;
int error;

retry:
- if (ida_pre_get(&proc_inum_ida, GFP_KERNEL) == 0)
- return 0;
+ if (!ida_pre_get(&proc_inum_ida, GFP_KERNEL))
+ return -ENOMEM;

spin_lock(&proc_inum_lock);
error = ida_get_new(&proc_inum_ida, &i);
@@ -365,18 +365,19 @@ retry:
if (error == -EAGAIN)
goto retry;
else if (error)
- return 0;
+ return error;

if (i > UINT_MAX - PROC_DYNAMIC_FIRST) {
spin_lock(&proc_inum_lock);
ida_remove(&proc_inum_ida, i);
spin_unlock(&proc_inum_lock);
- return 0;
+ return -ENOSPC;
}
- return PROC_DYNAMIC_FIRST + i;
+ *inum = PROC_DYNAMIC_FIRST + i;
+ return 0;
}

-static void release_inode_number(unsigned int inum)
+void proc_free_inum(unsigned int inum)
{
spin_lock(&proc_inum_lock);
ida_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
@@ -554,13 +555,12 @@ static const struct inode_operations proc_dir_inode_operations = {

static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp)
{
- unsigned int i;
struct proc_dir_entry *tmp;
+ int ret;

- i = get_inode_number();
- if (i == 0)
- return -EAGAIN;
- dp->low_ino = i;
+ ret = proc_alloc_inum(&dp->low_ino);
+ if (ret)
+ return ret;

if (S_ISDIR(dp->mode)) {
if (dp->proc_iops == NULL) {
@@ -764,7 +764,7 @@ EXPORT_SYMBOL(proc_create_data);

static void free_proc_entry(struct proc_dir_entry *de)
{
- release_inode_number(de->low_ino);
+ proc_free_inum(de->low_ino);

if (S_ISLNK(de->mode))
kfree(de->data);
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 3144781..bf1d000 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -176,6 +176,8 @@ extern struct proc_dir_entry *proc_net_mkdir(struct net *net, const char *name,
extern struct file *proc_ns_fget(int fd);
extern bool proc_ns_inode(struct inode *inode);

+extern int proc_alloc_inum(unsigned int *pino);
+extern void proc_free_inum(unsigned int inum);
#else

#define proc_net_fops_create(net, name, mode, fops) ({ (void)(mode), NULL; })
@@ -235,6 +237,14 @@ static inline bool proc_ns_inode(struct inode *inode)
return false;
}

+static inline int proc_alloc_inum(unsigned int *inum)
+{
+ *inum = 1;
+ return 0;
+}
+static inline void proc_free_inum(unsigned int inum)
+{
+}
#endif /* CONFIG_PROC_FS */

#if !defined(CONFIG_PROC_KCORE)
--
1.7.5.4