fs/sysfs/inode.c

   1 /*
   2  * inode.c - basic inode and dentry operations.
   3  *
   4  * sysfs is Copyright (c) 2001-3 Patrick Mochel
   5  *
   6  * Please see Documentation/filesystems/sysfs.txt for more information.
   7  */
   8
   9 #undef DEBUG
  10
  11 #include <linux/pagemap.h>
  12 #include <linux/namei.h>
  13 #include <linux/backing-dev.h>
  14 extern struct super_block * sysfs_sb;
  15
  16 static struct address_space_operations sysfs_aops = {
  17         .readpage       = simple_readpage,
  18         .prepare_write  = simple_prepare_write,
  19         .commit_write   = simple_commit_write
  20 };
  21
  22 static struct backing_dev_info sysfs_backing_dev_info = {
  23         .ra_pages       = 0,    /* No readahead */
  24         .memory_backed  = 1,    /* Does not contribute to dirty memory */
  25 };
  26
  27 struct inode * sysfs_new_inode(mode_t mode)
  28 {
  29         struct inode * inode = new_inode(sysfs_sb);
  30         if (inode) {
  31                 inode->i_mode = mode;
  32                 inode->i_uid = current->fsuid;
  33                 inode->i_gid = current->fsgid;
  34                 inode->i_blksize = PAGE_CACHE_SIZE;
  35                 inode->i_blocks = 0;
  36                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  37                 inode->i_mapping->a_ops = &sysfs_aops;
  38                 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
  39         }
  40         return inode;
  41 }
  42
  43 int sysfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
  44 {
  45         int error = 0;
  46         struct inode * inode = NULL;
  47         if (dentry) {
  48                 if (!dentry->d_inode) {
  49                         if ((inode = sysfs_new_inode(mode))) {
  50                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
  51                                         struct inode *p_inode = dentry->d_parent->d_inode;
  52                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
  53                                 }
  54                                 goto Proceed;
  55                         }
  56                         else
  57                                 error = -ENOMEM;
  58                 } else
  59                         error = -EEXIST;
  60         } else
  61                 error = -ENOENT;
  62         goto Done;
  63
  64  Proceed:
  65         if (init)
  66                 error = init(inode);
  67         if (!error) {
  68                 d_instantiate(dentry, inode);
  69                 dget(dentry); /* Extra count - pin the dentry in core */
  70         } else
  71                 iput(inode);
  72  Done:
  73         return error;
  74 }
  75
  76 int sysfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
  77 {
  78         return sysfs_create(dentry, mode, NULL);
  79 }
  80
  81 struct dentry * sysfs_get_dentry(struct dentry * parent, const char * name)
  82 {
  83         struct qstr qstr;
  84
  85         qstr.name = name;
  86         qstr.len = strlen(name);
  87         qstr.hash = full_name_hash(name,qstr.len);
  88         return lookup_hash(&qstr,parent);
  89 }
  90
  91 void sysfs_hash_and_remove(struct dentry * dir, const char * name)
  92 {
  93         struct dentry * victim;
  94
  95         down(&dir->d_inode->i_sem);
  96         victim = sysfs_get_dentry(dir,name);
  97         if (!IS_ERR(victim)) {
  98                 /* make sure dentry is really there */
  99                 if (victim->d_inode &&
 100                     (victim->d_parent->d_inode == dir->d_inode)) {
 101                         pr_debug("sysfs: Removing %s (%d)\n", victim->d_name.name,
 102                                  atomic_read(&victim->d_count));
 103
 104                         d_drop(victim);
 105                         /* release the target kobject in case of
 106                          * a symlink
 107                          */
 108                         if (S_ISLNK(victim->d_inode->i_mode))
 109                                 kobject_put(victim->d_fsdata);
 110                         simple_unlink(dir->d_inode,victim);
 111                 }
 112                 /*
 113                  * Drop reference from sysfs_get_dentry() above.
 114                  */
 115                 dput(victim);
 116         }
 117         up(&dir->d_inode->i_sem);
 118 }
 119
 120