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 #include <linux/capability.h>
  15 #include <linux/errno.h>
  16 #include <asm/semaphore.h>
  17 #include "sysfs.h"
  18
  19 extern struct super_block * sysfs_sb;
  20
  21 static const struct address_space_operations sysfs_aops = {
  22         .readpage       = simple_readpage,
  23         .prepare_write  = simple_prepare_write,
  24         .commit_write   = simple_commit_write
  25 };
  26
  27 static struct backing_dev_info sysfs_backing_dev_info = {
  28         .ra_pages       = 0,    /* No readahead */
  29         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
  30 };
  31
  32 static const struct inode_operations sysfs_inode_operations ={
  33         .setattr        = sysfs_setattr,
  34 };
  35
  36 void sysfs_delete_inode(struct inode *inode)
  37 {
  38         /* Free the shadowed directory inode operations */
  39         if (sysfs_is_shadowed_inode(inode)) {
  40                 kfree(inode->i_op);
  41                 inode->i_op = NULL;
  42         }
  43         return generic_delete_inode(inode);
  44 }
  45
  46 int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
  47 {
  48         struct inode * inode = dentry->d_inode;
  49         struct sysfs_dirent * sd = dentry->d_fsdata;
  50         struct iattr * sd_iattr;
  51         unsigned int ia_valid = iattr->ia_valid;
  52         int error;
  53
  54         if (!sd)
  55                 return -EINVAL;
  56
  57         sd_iattr = sd->s_iattr;
  58
  59         error = inode_change_ok(inode, iattr);
  60         if (error)
  61                 return error;
  62
  63         error = inode_setattr(inode, iattr);
  64         if (error)
  65                 return error;
  66
  67         if (!sd_iattr) {
  68                 /* setting attributes for the first time, allocate now */
  69                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  70                 if (!sd_iattr)
  71                         return -ENOMEM;
  72                 /* assign default attributes */
  73                 sd_iattr->ia_mode = sd->s_mode;
  74                 sd_iattr->ia_uid = 0;
  75                 sd_iattr->ia_gid = 0;
  76                 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  77                 sd->s_iattr = sd_iattr;
  78         }
  79
  80         /* attributes were changed atleast once in past */
  81
  82         if (ia_valid & ATTR_UID)
  83                 sd_iattr->ia_uid = iattr->ia_uid;
  84         if (ia_valid & ATTR_GID)
  85                 sd_iattr->ia_gid = iattr->ia_gid;
  86         if (ia_valid & ATTR_ATIME)
  87                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
  88                                                 inode->i_sb->s_time_gran);
  89         if (ia_valid & ATTR_MTIME)
  90                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
  91                                                 inode->i_sb->s_time_gran);
  92         if (ia_valid & ATTR_CTIME)
  93                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
  94                                                 inode->i_sb->s_time_gran);
  95         if (ia_valid & ATTR_MODE) {
  96                 umode_t mode = iattr->ia_mode;
  97
  98                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  99                         mode &= ~S_ISGID;
 100                 sd_iattr->ia_mode = sd->s_mode = mode;
 101         }
 102
 103         return error;
 104 }
 105
 106 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
 107 {
 108         inode->i_mode = mode;
 109         inode->i_uid = 0;
 110         inode->i_gid = 0;
 111         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 112 }
 113
 114 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
 115 {
 116         inode->i_mode = iattr->ia_mode;
 117         inode->i_uid = iattr->ia_uid;
 118         inode->i_gid = iattr->ia_gid;
 119         inode->i_atime = iattr->ia_atime;
 120         inode->i_mtime = iattr->ia_mtime;
 121         inode->i_ctime = iattr->ia_ctime;
 122 }
 123
 124
 125 /*
 126  * sysfs has a different i_mutex lock order behavior for i_mutex than other
 127  * filesystems; sysfs i_mutex is called in many places with subsystem locks
 128  * held. At the same time, many of the VFS locking rules do not apply to
 129  * sysfs at all (cross directory rename for example). To untangle this mess
 130  * (which gives false positives in lockdep), we're giving sysfs inodes their
 131  * own class for i_mutex.
 132  */
 133 static struct lock_class_key sysfs_inode_imutex_key;
 134
 135 struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd)
 136 {
 137         struct inode * inode = new_inode(sysfs_sb);
 138         if (inode) {
 139                 inode->i_blocks = 0;
 140                 inode->i_mapping->a_ops = &sysfs_aops;
 141                 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
 142                 inode->i_op = &sysfs_inode_operations;
 143                 lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
 144
 145                 if (sd->s_iattr) {
 146                         /* sysfs_dirent has non-default attributes
 147                          * get them for the new inode from persistent copy
 148                          * in sysfs_dirent
 149                          */
 150                         set_inode_attr(inode, sd->s_iattr);
 151                 } else
 152                         set_default_inode_attr(inode, mode);
 153         }
 154         return inode;
 155 }
 156
 157 int sysfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
 158 {
 159         int error = 0;
 160         struct inode * inode = NULL;
 161         if (dentry) {
 162                 if (!dentry->d_inode) {
 163                         struct sysfs_dirent * sd = dentry->d_fsdata;
 164                         if ((inode = sysfs_new_inode(mode, sd))) {
 165                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
 166                                         struct inode *p_inode = dentry->d_parent->d_inode;
 167                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 168                                 }
 169                                 goto Proceed;
 170                         }
 171                         else
 172                                 error = -ENOMEM;
 173                 } else
 174                         error = -EEXIST;
 175         } else
 176                 error = -ENOENT;
 177         goto Done;
 178
 179  Proceed:
 180         if (init)
 181                 error = init(inode);
 182         if (!error) {
 183                 d_instantiate(dentry, inode);
 184                 if (S_ISDIR(mode))
 185                         dget(dentry);  /* pin only directory dentry in core */
 186         } else
 187                 iput(inode);
 188  Done:
 189         return error;
 190 }
 191
 192 /*
 193  * Get the name for corresponding element represented by the given sysfs_dirent
 194  */
 195 const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
 196 {
 197         struct attribute * attr;
 198         struct bin_attribute * bin_attr;
 199         struct sysfs_symlink  * sl;
 200
 201         BUG_ON(!sd || !sd->s_element);
 202
 203         switch (sd->s_type) {
 204                 case SYSFS_DIR:
 205                         /* Always have a dentry so use that */
 206                         return sd->s_dentry->d_name.name;
 207
 208                 case SYSFS_KOBJ_ATTR:
 209                         attr = sd->s_element;
 210                         return attr->name;
 211
 212                 case SYSFS_KOBJ_BIN_ATTR:
 213                         bin_attr = sd->s_element;
 214                         return bin_attr->attr.name;
 215
 216                 case SYSFS_KOBJ_LINK:
 217                         sl = sd->s_element;
 218                         return sl->link_name;
 219         }
 220         return NULL;
 221 }
 222
 223 static inline void orphan_all_buffers(struct inode *node)
 224 {
 225         struct sysfs_buffer_collection *set = node->i_private;
 226         struct sysfs_buffer *buf;
 227
 228         mutex_lock_nested(&node->i_mutex, I_MUTEX_CHILD);
 229         if (node->i_private) {
 230                 list_for_each_entry(buf, &set->associates, associates) {
 231                         down(&buf->sem);
 232                         buf->orphaned = 1;
 233                         up(&buf->sem);
 234                 }
 235         }
 236         mutex_unlock(&node->i_mutex);
 237 }
 238
 239
 240 /*
 241  * Unhashes the dentry corresponding to given sysfs_dirent
 242  * Called with parent inode's i_mutex held.
 243  */
 244 void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
 245 {
 246         struct dentry * dentry = sd->s_dentry;
 247         struct inode *inode;
 248
 249         if (dentry) {
 250                 spin_lock(&dcache_lock);
 251                 spin_lock(&dentry->d_lock);
 252                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
 253                         inode = dentry->d_inode;
 254                         spin_lock(&inode->i_lock);
 255                         __iget(inode);
 256                         spin_unlock(&inode->i_lock);
 257                         dget_locked(dentry);
 258                         __d_drop(dentry);
 259                         spin_unlock(&dentry->d_lock);
 260                         spin_unlock(&dcache_lock);
 261                         simple_unlink(parent->d_inode, dentry);
 262                         orphan_all_buffers(inode);
 263                         iput(inode);
 264                 } else {
 265                         spin_unlock(&dentry->d_lock);
 266                         spin_unlock(&dcache_lock);
 267                 }
 268         }
 269 }
 270
 271 int sysfs_hash_and_remove(struct dentry * dir, const char * name)
 272 {
 273         struct sysfs_dirent * sd;
 274         struct sysfs_dirent * parent_sd;
 275         int found = 0;
 276
 277         if (!dir)
 278                 return -ENOENT;
 279
 280         if (dir->d_inode == NULL)
 281                 /* no inode means this hasn't been made visible yet */
 282                 return -ENOENT;
 283
 284         parent_sd = dir->d_fsdata;
 285         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 286         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 287                 if (!sd->s_element)
 288                         continue;
 289                 if (!strcmp(sysfs_get_name(sd), name)) {
 290                         list_del_init(&sd->s_sibling);
 291                         sysfs_drop_dentry(sd, dir);
 292                         sysfs_put(sd);
 293                         found = 1;
 294                         break;
 295                 }
 296         }
 297         mutex_unlock(&dir->d_inode->i_mutex);
 298
 299         return found ? 0 : -ENOENT;
 300 }