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 extern void free_proc_entry(struct proc_dir_entry *);
  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         struct task_struct *tsk;
  62
  63         /* Let go of any associated process */
  64         tsk = PROC_I(inode)->task;
  65         if (tsk)
  66                 put_task_struct(tsk);
  67
  68         /* Let go of any associated proc directory entry */
  69         de = PROC_I(inode)->pde;
  70         if (de) {
  71                 if (de->owner)
  72                         module_put(de->owner);
  73                 de_put(de);
  74         }
  75         clear_inode(inode);
  76 }
  77
  78 struct vfsmount *proc_mnt;
  79
  80 static void proc_read_inode(struct inode * inode)
  81 {
  82         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  83 }
  84
  85 static kmem_cache_t * proc_inode_cachep;
  86
  87 static struct inode *proc_alloc_inode(struct super_block *sb)
  88 {
  89         struct proc_inode *ei;
  90         struct inode *inode;
  91
  92         ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, SLAB_KERNEL);
  93         if (!ei)
  94                 return NULL;
  95         ei->task = NULL;
  96         ei->type = 0;
  97         ei->op.proc_get_link = NULL;
  98         ei->pde = NULL;
  99         inode = &ei->vfs_inode;
 100         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 101         return inode;
 102 }
 103
 104 static void proc_destroy_inode(struct inode *inode)
 105 {
 106         kmem_cache_free(proc_inode_cachep, PROC_I(inode));
 107 }
 108
 109 static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
 110 {
 111         struct proc_inode *ei = (struct proc_inode *) foo;
 112
 113         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 114             SLAB_CTOR_CONSTRUCTOR)
 115                 inode_init_once(&ei->vfs_inode);
 116 }
 117
 118 int __init proc_init_inodecache(void)
 119 {
 120         proc_inode_cachep = kmem_cache_create("proc_inode_cache",
 121                                              sizeof(struct proc_inode),
 122                                              0, SLAB_RECLAIM_ACCOUNT,
 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         inode = iget(sb, ino);
 158         if (!inode)
 159                 goto out_fail;
 160
 161         PROC_I(inode)->pde = de;
 162         if (de) {
 163                 if (de->mode) {
 164                         inode->i_mode = de->mode;
 165                         inode->i_uid = de->uid;
 166                         inode->i_gid = de->gid;
 167                 }
 168                 if (de->size)
 169                         inode->i_size = de->size;
 170                 if (de->nlink)
 171                         inode->i_nlink = de->nlink;
 172                 if (!try_module_get(de->owner))
 173                         goto out_fail;
 174                 if (de->proc_iops)
 175                         inode->i_op = de->proc_iops;
 176                 if (de->proc_fops)
 177                         inode->i_fop = de->proc_fops;
 178         }
 179
 180 out:
 181         return inode;
 182
 183 out_fail:
 184         de_put(de);
 185         goto out;
 186 }
 187
 188 int proc_fill_super(struct super_block *s, void *data, int silent)
 189 {
 190         struct inode * root_inode;
 191
 192         s->s_flags |= MS_NODIRATIME;
 193         s->s_blocksize = 1024;
 194         s->s_blocksize_bits = 10;
 195         s->s_magic = PROC_SUPER_MAGIC;
 196         s->s_op = &proc_sops;
 197         s->s_time_gran = 1;
 198
 199         root_inode = proc_get_inode(s, PROC_ROOT_INO, &proc_root);
 200         if (!root_inode)
 201                 goto out_no_root;
 202         /*
 203          * Fixup the root inode's nlink value
 204          */
 205         root_inode->i_nlink += nr_processes();
 206         root_inode->i_uid = 0;
 207         root_inode->i_gid = 0;
 208         s->s_root = d_alloc_root(root_inode);
 209         if (!s->s_root)
 210                 goto out_no_root;
 211         return 0;
 212
 213 out_no_root:
 214         printk("proc_read_super: get root inode failed\n");
 215         iput(root_inode);
 216         return -ENOMEM;
 217 }
 218 MODULE_LICENSE("GPL");