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SubjectRe: [PATCH] Increase number of dynamic inodes in procfs (2.6.5)
Andrew Morton wrote:
> Nathan Lynch <nathanl@austin.ibm.com> wrote:
>
>>On some larger ppc64 configurations /proc/device-tree is exhausting
>> procfs' dynamic (non-pid) inode range (16K). This patch makes the
>> dynamic inode range 0xf0000000-0xffffffff
>>and changes the inode number
>> allocator to use a growable linked list of bitmaps.
>
> This open-codes a simple version of lib/idr.c. Please use lib/idr.c
> instead. There's an example in fs/super.c

Ok, thanks for the tip. Is this better?

Nathan
diff -pru linux-2.6.5-mm4/fs/proc/generic.c linux-2.6.5-mm4.new/fs/proc/generic.c
--- linux-2.6.5-mm4/fs/proc/generic.c 2004-04-14 20:32:34.000000000 -0500
+++ linux-2.6.5-mm4.new/fs/proc/generic.c 2004-04-14 20:34:57.000000000 -0500
@@ -15,6 +15,8 @@
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/smp_lock.h>
+#include <linux/init.h>
+#include <linux/idr.h>
#include <asm/uaccess.h>
#include <asm/bitops.h>

@@ -275,24 +277,51 @@ static int xlate_proc_name(const char *n
return 0;
}

-static unsigned long proc_alloc_map[(PROC_NDYNAMIC + BITS_PER_LONG - 1) / BITS_PER_LONG];
+static struct idr proc_inum_idr;
+static spinlock_t proc_inum_lock = SPIN_LOCK_UNLOCKED; /* protects the above */

-spinlock_t proc_alloc_map_lock = SPIN_LOCK_UNLOCKED;
+#define PROC_DYNAMIC_FIRST 0xF0000000UL

-static int make_inode_number(void)
+void __init init_proc_inum_idr(void)
{
- int i;
- spin_lock(&proc_alloc_map_lock);
- i = find_first_zero_bit(proc_alloc_map, PROC_NDYNAMIC);
- if (i < 0 || i >= PROC_NDYNAMIC) {
- i = -1;
- goto out;
- }
- set_bit(i, proc_alloc_map);
- i += PROC_DYNAMIC_FIRST;
-out:
- spin_unlock(&proc_alloc_map_lock);
- return i;
+ idr_init(&proc_inum_idr);
+}
+
+/*
+ * Return an inode number between PROC_DYNAMIC_FIRST and
+ * 0xffffffff, or zero on failure.
+ */
+static unsigned int get_inode_number(void)
+{
+ unsigned int i, inum = 0;
+
+retry:
+ if (0 == idr_pre_get(&proc_inum_idr, GFP_KERNEL))
+ return 0;
+
+ spin_lock(&proc_inum_lock);
+ i = idr_get_new(&proc_inum_idr, NULL);
+ spin_unlock(&proc_inum_lock);
+
+ if (i == -1)
+ goto retry;
+
+ inum = (i & MAX_ID_MASK) + PROC_DYNAMIC_FIRST;
+
+ /* inum will never be more than 0xf0ffffff, so no check
+ * for overflow.
+ */
+
+ return inum;
+}
+
+static void release_inode_number(unsigned int inum)
+{
+ int id = (inum - PROC_DYNAMIC_FIRST) | ~MAX_ID_MASK;
+
+ spin_lock(&proc_inum_lock);
+ idr_remove(&proc_inum_idr, id);
+ spin_unlock(&proc_inum_lock);
}

static int
@@ -346,7 +375,7 @@ struct dentry *proc_lookup(struct inode
if (de->namelen != dentry->d_name.len)
continue;
if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
- int ino = de->low_ino;
+ unsigned int ino = de->low_ino;
error = -EINVAL;
inode = proc_get_inode(dir->i_sb, ino, de);
break;
@@ -452,10 +481,10 @@ static struct inode_operations proc_dir_

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

- i = make_inode_number();
- if (i < 0)
+ i = get_inode_number();
+ if (i == 0)
return -EAGAIN;
dp->low_ino = i;
dp->next = dir->subdir;
@@ -621,11 +650,13 @@ struct proc_dir_entry *create_proc_entry

void free_proc_entry(struct proc_dir_entry *de)
{
- int ino = de->low_ino;
+ unsigned int ino = de->low_ino;

- if (ino < PROC_DYNAMIC_FIRST ||
- ino >= PROC_DYNAMIC_FIRST+PROC_NDYNAMIC)
+ if (ino < PROC_DYNAMIC_FIRST)
return;
+
+ release_inode_number(ino);
+
if (S_ISLNK(de->mode) && de->data)
kfree(de->data);
kfree(de);
@@ -653,8 +684,6 @@ void remove_proc_entry(const char *name,
de->next = NULL;
if (S_ISDIR(de->mode))
parent->nlink--;
- clear_bit(de->low_ino - PROC_DYNAMIC_FIRST,
- proc_alloc_map);
proc_kill_inodes(de);
de->nlink = 0;
WARN_ON(de->subdir);
diff -pru linux-2.6.5-mm4/fs/proc/inode-alloc.txt linux-2.6.5-mm4.new/fs/proc/inode-alloc.txt
--- linux-2.6.5-mm4/fs/proc/inode-alloc.txt 2004-01-09 00:59:26.000000000 -0600
+++ linux-2.6.5-mm4.new/fs/proc/inode-alloc.txt 2004-04-14 20:34:57.000000000 -0500
@@ -4,9 +4,10 @@ Current inode allocations in the proc-fs
00000001-00000fff static entries (goners)
001 root-ino

- 00001000-00001fff dynamic entries
+ 00001000-00001fff unused
0001xxxx-7fffxxxx pid-dir entries for pid 1-7fff
- 80000000-ffffffff unused
+ 80000000-efffffff unused
+ f0000000-ffffffff dynamic entries

Goal:
a) once we'll split the thing into several virtual filesystems we
diff -pru linux-2.6.5-mm4/fs/proc/inode.c linux-2.6.5-mm4.new/fs/proc/inode.c
--- linux-2.6.5-mm4/fs/proc/inode.c 2004-04-14 20:32:34.000000000 -0500
+++ linux-2.6.5-mm4.new/fs/proc/inode.c 2004-04-14 20:34:57.000000000 -0500
@@ -181,7 +181,7 @@ static int parse_options(char *options,u
return 1;
}

-struct inode * proc_get_inode(struct super_block * sb, int ino,
+struct inode * proc_get_inode(struct super_block * sb, unsigned int ino,
struct proc_dir_entry * de)
{
struct inode * inode;
diff -pru linux-2.6.5-mm4/include/linux/proc_fs.h linux-2.6.5-mm4.new/include/linux/proc_fs.h
--- linux-2.6.5-mm4/include/linux/proc_fs.h 2004-04-14 20:32:35.000000000 -0500
+++ linux-2.6.5-mm4.new/include/linux/proc_fs.h 2004-04-14 20:34:57.000000000 -0500
@@ -26,9 +26,6 @@ enum {

/* Finally, the dynamically allocatable proc entries are reserved: */

-#define PROC_DYNAMIC_FIRST 4096
-#define PROC_NDYNAMIC 16384
-
#define PROC_SUPER_MAGIC 0x9fa0

/*
@@ -53,7 +50,7 @@ typedef int (write_proc_t)(struct file *
typedef int (get_info_t)(char *, char **, off_t, int);

struct proc_dir_entry {
- unsigned short low_ino;
+ unsigned int low_ino;
unsigned short namelen;
const char *name;
mode_t mode;
@@ -102,7 +99,7 @@ extern void remove_proc_entry(const char

extern struct vfsmount *proc_mnt;
extern int proc_fill_super(struct super_block *,void *,int);
-extern struct inode * proc_get_inode(struct super_block *, int, struct proc_dir_entry *);
+extern struct inode * proc_get_inode(struct super_block *, unsigned int, struct proc_dir_entry *);

extern int proc_match(int, const char *,struct proc_dir_entry *);
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