fs/proc/inode.c

   1 /*
   2  *  linux/fs/proc/inode.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/time.h>
   8 #include <linux/proc_fs.h>
   9 #include <linux/kernel.h>
  10 #include <linux/mm.h>
  11 #include <linux/string.h>
  12 #include <linux/stat.h>
  13 #include <linux/file.h>
  14 #include <linux/limits.h>
  15 #include <linux/init.h>
  16 #include <linux/module.h>
  17 #include <linux/smp_lock.h>
  18
  19 #include <asm/system.h>
  20 #include <asm/uaccess.h>
  21
  22 #include "internal.h"
  23
  24 static inline struct proc_dir_entry * de_get(struct proc_dir_entry *de)
  25 {
  26         if (de)
  27                 atomic_inc(&de->count);
  28         return de;
  29 }
  30
  31 /*
  32  * Decrements the use count and checks for deferred deletion.
  33  */
  34 static void de_put(struct proc_dir_entry *de)
  35 {
  36         if (de) {
  37                 lock_kernel();
  38                 if (!atomic_read(&de->count)) {
  39                         printk("de_put: entry %s already free!\n", de->name);
  40                         unlock_kernel();
  41                         return;
  42                 }
  43
  44                 if (atomic_dec_and_test(&de->count)) {
  45                         if (de->deleted) {
  46                                 printk("de_put: deferred delete of %s\n",
  47                                         de->name);
  48                                 free_proc_entry(de);
  49                         }
  50                 }
  51                 unlock_kernel();
  52         }
  53 }
  54
  55 /*
  56  * Decrement the use count of the proc_dir_entry.
  57  */
  58 static void proc_delete_inode(struct inode *inode)
  59 {
  60         struct proc_dir_entry *de;
  61
  62         truncate_inode_pages(&inode->i_data, 0);
  63
  64         /* Stop tracking associated processes */
  65         put_pid(PROC_I(inode)->pid);
  66
  67         /* Let go of any associated proc directory entry */
  68         de = PROC_I(inode)->pde;
  69         if (de) {
  70                 if (de->owner)
  71                         module_put(de->owner);
  72                 de_put(de);
  73         }
  74         clear_inode(inode);
  75 }
  76
  77 struct vfsmount *proc_mnt;
  78
  79 static void proc_read_inode(struct inode * inode)
  80 {
  81         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  82 }
  83
  84 static struct kmem_cache * proc_inode_cachep;
  85
  86 static struct inode *proc_alloc_inode(struct super_block *sb)
  87 {
  88         struct proc_inode *ei;
  89         struct inode *inode;
  90
  91         ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
  92         if (!ei)
  93                 return NULL;
  94         ei->pid = NULL;
  95         ei->fd = 0;
  96         ei->op.proc_get_link = NULL;
  97         ei->pde = NULL;
  98         inode = &ei->vfs_inode;
  99         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 100         return inode;
 101 }
 102
 103 static void proc_destroy_inode(struct inode *inode)
 104 {
 105         kmem_cache_free(proc_inode_cachep, PROC_I(inode));
 106 }
 107
 108 static void init_once(void * foo, struct kmem_cache * cachep, unsigned long flags)
 109 {
 110         struct proc_inode *ei = (struct proc_inode *) foo;
 111
 112         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 113             SLAB_CTOR_CONSTRUCTOR)
 114                 inode_init_once(&ei->vfs_inode);
 115 }
 116
 117 int __init proc_init_inodecache(void)
 118 {
 119         proc_inode_cachep = kmem_cache_create("proc_inode_cache",
 120                                              sizeof(struct proc_inode),
 121                                              0, (SLAB_RECLAIM_ACCOUNT|
 122                                                 SLAB_MEM_SPREAD),
 123                                              init_once, NULL);
 124         if (proc_inode_cachep == NULL)
 125                 return -ENOMEM;
 126         return 0;
 127 }
 128
 129 static int proc_remount(struct super_block *sb, int *flags, char *data)
 130 {
 131         *flags |= MS_NODIRATIME;
 132         return 0;
 133 }
 134
 135 static struct super_operations proc_sops = {
 136         .alloc_inode    = proc_alloc_inode,
 137         .destroy_inode  = proc_destroy_inode,
 138         .read_inode     = proc_read_inode,
 139         .drop_inode     = generic_delete_inode,
 140         .delete_inode   = proc_delete_inode,
 141         .statfs         = simple_statfs,
 142         .remount_fs     = proc_remount,
 143 };
 144
 145 struct inode *proc_get_inode(struct super_block *sb, unsigned int ino,
 146                                 struct proc_dir_entry *de)
 147 {
 148         struct inode * inode;
 149
 150         /*
 151          * Increment the use count so the dir entry can't disappear.
 152          */
 153         de_get(de);
 154
 155         WARN_ON(de && de->deleted);
 156
 157         if (de != NULL && !try_module_get(de->owner))
 158                 goto out_mod;
 159
 160         inode = iget(sb, ino);
 161         if (!inode)
 162                 goto out_ino;
 163
 164         PROC_I(inode)->pde = de;
 165         if (de) {
 166                 if (de->mode) {
 167                         inode->i_mode = de->mode;
 168                         inode->i_uid = de->uid;
 169                         inode->i_gid = de->gid;
 170                 }
 171                 if (de->size)
 172                         inode->i_size = de->size;
 173                 if (de->nlink)
 174                         inode->i_nlink = de->nlink;
 175                 if (de->proc_iops)
 176                         inode->i_op = de->proc_iops;
 177                 if (de->proc_fops)
 178                         inode->i_fop = de->proc_fops;
 179         }
 180
 181         return inode;
 182
 183 out_ino:
 184         if (de != NULL)
 185                 module_put(de->owner);
 186 out_mod:
 187         de_put(de);
 188         return NULL;
 189 }
 190
 191 int proc_fill_super(struct super_block *s, void *data, int silent)
 192 {
 193         struct inode * root_inode;
 194
 195         s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
 196         s->s_blocksize = 1024;
 197         s->s_blocksize_bits = 10;
 198         s->s_magic = PROC_SUPER_MAGIC;
 199         s->s_op = &proc_sops;
 200         s->s_time_gran = 1;
 201
 202         root_inode = proc_get_inode(s, PROC_ROOT_INO, &proc_root);
 203         if (!root_inode)
 204                 goto out_no_root;
 205         root_inode->i_uid = 0;
 206         root_inode->i_gid = 0;
 207         s->s_root = d_alloc_root(root_inode);
 208         if (!s->s_root)
 209                 goto out_no_root;
 210         return 0;
 211
 212 out_no_root:
 213         printk("proc_read_super: get root inode failed\n");
 214         iput(root_inode);
 215         return -ENOMEM;
 216 }
 217 MODULE_LICENSE("GPL");