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proc: Generalize proc inode allocation 

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.

Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2011-06-17 13:33:20 -07:00
parent 4f326c0064
commit 33d6dce607
2 changed files with 23 additions and 13 deletions
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26
fs/proc/generic.c
View File

@ -350,14 +350,14 @@ static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
* Return an inode number between PROC_DYNAMIC_FIRST and * Return an inode number between PROC_DYNAMIC_FIRST and
* 0xffffffff, or zero on failure. * 0xffffffff, or zero on failure.
*/ */
static unsigned int get_inode_number(void) int proc_alloc_inum(unsigned int *inum)
{ {
unsigned int i; unsigned int i;
int error; int error;
retry: retry:
if (ida_pre_get(&proc_inum_ida, GFP_KERNEL) == 0) if (!ida_pre_get(&proc_inum_ida, GFP_KERNEL))
return 0; return -ENOMEM;
spin_lock(&proc_inum_lock); spin_lock(&proc_inum_lock);
error = ida_get_new(&proc_inum_ida, &i); error = ida_get_new(&proc_inum_ida, &i);
@ -365,18 +365,19 @@ retry:
if (error == -EAGAIN) if (error == -EAGAIN)
goto retry; goto retry;
else if (error) else if (error)
return 0; return error;
if (i > UINT_MAX - PROC_DYNAMIC_FIRST) { if (i > UINT_MAX - PROC_DYNAMIC_FIRST) {
spin_lock(&proc_inum_lock); spin_lock(&proc_inum_lock);
ida_remove(&proc_inum_ida, i); ida_remove(&proc_inum_ida, i);
spin_unlock(&proc_inum_lock); 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); spin_lock(&proc_inum_lock);
ida_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST); 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) static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp)
{ {
unsigned int i;
struct proc_dir_entry *tmp; struct proc_dir_entry *tmp;
int ret;
i = get_inode_number(); ret = proc_alloc_inum(&dp->low_ino);
if (i == 0) if (ret)
return -EAGAIN; return ret;
dp->low_ino = i;
if (S_ISDIR(dp->mode)) { if (S_ISDIR(dp->mode)) {
if (dp->proc_iops == NULL) { if (dp->proc_iops == NULL) {
@ -764,7 +764,7 @@ EXPORT_SYMBOL(proc_create_data);
static void free_proc_entry(struct proc_dir_entry *de) 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)) if (S_ISLNK(de->mode))
kfree(de->data); kfree(de->data);

10
include/linux/proc_fs.h
View File

@ -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 struct file *proc_ns_fget(int fd);
extern bool proc_ns_inode(struct inode *inode); 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 #else
#define proc_net_fops_create(net, name, mode, fops) ({ (void)(mode), NULL; }) #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; 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 */ #endif /* CONFIG_PROC_FS */
#if !defined(CONFIG_PROC_KCORE) #if !defined(CONFIG_PROC_KCORE)