fs/proc/inode.c

   1 /*
   2  *  linux/fs/proc/inode.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/sched.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/locks.h>
  15 #include <linux/limits.h>
  16 #define __NO_VERSION__
  17 #include <linux/module.h>
  18 #include <linux/smp_lock.h>
  19
  20 #include <asm/system.h>
  21 #include <asm/uaccess.h>
  22
  23 extern void free_proc_entry(struct proc_dir_entry *);
  24
  25 struct proc_dir_entry * de_get(struct proc_dir_entry *de)
  26 {
  27         if (de)
  28                 atomic_inc(&de->count);
  29         return de;
  30 }
  31
  32 /*
  33  * Decrements the use count and checks for deferred deletion.
  34  */
  35 void de_put(struct proc_dir_entry *de)
  36 {
  37         if (de) {
  38                 lock_kernel();
  39                 if (!atomic_read(&de->count)) {
  40                         printk("de_put: entry %s already free!\n", de->name);
  41                         unlock_kernel();
  42                         return;
  43                 }
  44
  45                 if (atomic_dec_and_test(&de->count)) {
  46                         if (de->deleted) {
  47                                 printk("de_put: deferred delete of %s\n",
  48                                         de->name);
  49                                 free_proc_entry(de);
  50                         }
  51                 }
  52                 unlock_kernel();
  53         }
  54 }
  55
  56 /*
  57  * Decrement the use count of the proc_dir_entry.
  58  */
  59 static void proc_delete_inode(struct inode *inode)
  60 {
  61         struct proc_dir_entry *de = inode->u.generic_ip;
  62
  63         inode->i_state = I_CLEAR;
  64
  65         if (PROC_INODE_PROPER(inode)) {
  66                 proc_pid_delete_inode(inode);
  67                 return;
  68         }
  69         if (de) {
  70                 if (de->owner)
  71                         __MOD_DEC_USE_COUNT(de->owner);
  72                 de_put(de);
  73         }
  74 }
  75
  76 struct vfsmount *proc_mnt;
  77
  78 static void proc_read_inode(struct inode * inode)
  79 {
  80         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  81 }
  82
  83 static int proc_statfs(struct super_block *sb, struct statfs *buf)
  84 {
  85         buf->f_type = PROC_SUPER_MAGIC;
  86         buf->f_bsize = PAGE_SIZE/sizeof(long);
  87         buf->f_bfree = 0;
  88         buf->f_bavail = 0;
  89         buf->f_ffree = 0;
  90         buf->f_namelen = NAME_MAX;
  91         return 0;
  92 }
  93
  94 static struct super_operations proc_sops = {
  95         read_inode:     proc_read_inode,
  96         put_inode:      force_delete,
  97         delete_inode:   proc_delete_inode,
  98         statfs:         proc_statfs,
  99 };
 100
 101
 102 static int parse_options(char *options,uid_t *uid,gid_t *gid)
 103 {
 104         char *this_char,*value;
 105
 106         *uid = current->uid;
 107         *gid = current->gid;
 108         if (!options) return 1;
 109         for (this_char = strtok(options,","); this_char; this_char = strtok(NULL,",")) {
 110                 if ((value = strchr(this_char,'=')) != NULL)
 111                         *value++ = 0;
 112                 if (!strcmp(this_char,"uid")) {
 113                         if (!value || !*value)
 114                                 return 0;
 115                         *uid = simple_strtoul(value,&value,0);
 116                         if (*value)
 117                                 return 0;
 118                 }
 119                 else if (!strcmp(this_char,"gid")) {
 120                         if (!value || !*value)
 121                                 return 0;
 122                         *gid = simple_strtoul(value,&value,0);
 123                         if (*value)
 124                                 return 0;
 125                 }
 126                 else return 1;
 127         }
 128         return 1;
 129 }
 130
 131 struct inode * proc_get_inode(struct super_block * sb, int ino,
 132                                 struct proc_dir_entry * de)
 133 {
 134         struct inode * inode;
 135
 136         /*
 137          * Increment the use count so the dir entry can't disappear.
 138          */
 139         de_get(de);
 140 #if 1
 141 /* shouldn't ever happen */
 142 if (de && de->deleted)
 143 printk("proc_iget: using deleted entry %s, count=%d\n", de->name, atomic_read(&de->count));
 144 #endif
 145
 146         inode = iget(sb, ino);
 147         if (!inode)
 148                 goto out_fail;
 149
 150         inode->u.generic_ip = (void *) de;
 151         if (de) {
 152                 if (de->mode) {
 153                         inode->i_mode = de->mode;
 154                         inode->i_uid = de->uid;
 155                         inode->i_gid = de->gid;
 156                 }
 157                 if (de->size)
 158                         inode->i_size = de->size;
 159                 if (de->nlink)
 160                         inode->i_nlink = de->nlink;
 161                 if (de->owner)
 162                         __MOD_INC_USE_COUNT(de->owner);
 163                 if (S_ISBLK(de->mode)||S_ISCHR(de->mode)||S_ISFIFO(de->mode))
 164                         init_special_inode(inode,de->mode,kdev_t_to_nr(de->rdev));
 165                 else {
 166                         if (de->proc_iops)
 167                                 inode->i_op = de->proc_iops;
 168                         if (de->proc_fops)
 169                                 inode->i_fop = de->proc_fops;
 170                 }
 171         }
 172
 173 out:
 174         return inode;
 175
 176 out_fail:
 177         de_put(de);
 178         goto out;
 179 }
 180
 181 struct super_block *proc_read_super(struct super_block *s,void *data,
 182                                     int silent)
 183 {
 184         struct inode * root_inode;
 185         struct task_struct *p;
 186
 187         s->s_blocksize = 1024;
 188         s->s_blocksize_bits = 10;
 189         s->s_magic = PROC_SUPER_MAGIC;
 190         s->s_op = &proc_sops;
 191         root_inode = proc_get_inode(s, PROC_ROOT_INO, &proc_root);
 192         if (!root_inode)
 193                 goto out_no_root;
 194         /*
 195          * Fixup the root inode's nlink value
 196          */
 197         read_lock(&tasklist_lock);
 198         for_each_task(p) if (p->pid) root_inode->i_nlink++;
 199         read_unlock(&tasklist_lock);
 200         s->s_root = d_alloc_root(root_inode);
 201         if (!s->s_root)
 202                 goto out_no_root;
 203         parse_options(data, &root_inode->i_uid, &root_inode->i_gid);
 204         return s;
 205
 206 out_no_root:
 207         printk("proc_read_super: get root inode failed\n");
 208         iput(root_inode);
 209         return NULL;
 210 }