fs/ubifs/misc.h

   1 /*
   2  * This file is part of UBIFS.
   3  *
   4  * Copyright (C) 2006-2008 Nokia Corporation
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published by
   8  * the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc., 51
  17  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18  *
  19  * Authors: Artem Bityutskiy (Битюцкий Артём)
  20  *          Adrian Hunter
  21  */
  22
  23 /*
  24  * This file contains miscellaneous helper functions.
  25  */
  26
  27 #ifndef __UBIFS_MISC_H__
  28 #define __UBIFS_MISC_H__
  29
  30 /**
  31  * ubifs_zn_dirty - check if znode is dirty.
  32  * @znode: znode to check
  33  *
  34  * This helper function returns %1 if @znode is dirty and %0 otherwise.
  35  */
  36 static inline int ubifs_zn_dirty(const struct ubifs_znode *znode)
  37 {
  38         return !!test_bit(DIRTY_ZNODE, &znode->flags);
  39 }
  40
  41 /**
  42  * ubifs_wake_up_bgt - wake up background thread.
  43  * @c: UBIFS file-system description object
  44  */
  45 static inline void ubifs_wake_up_bgt(struct ubifs_info *c)
  46 {
  47         if (c->bgt && !c->need_bgt) {
  48                 c->need_bgt = 1;
  49                 wake_up_process(c->bgt);
  50         }
  51 }
  52
  53 /**
  54  * ubifs_tnc_find_child - find next child in znode.
  55  * @znode: znode to search at
  56  * @start: the zbranch index to start at
  57  *
  58  * This helper function looks for znode child starting at index @start. Returns
  59  * the child or %NULL if no children were found.
  60  */
  61 static inline struct ubifs_znode *
  62 ubifs_tnc_find_child(struct ubifs_znode *znode, int start)
  63 {
  64         while (start < znode->child_cnt) {
  65                 if (znode->zbranch[start].znode)
  66                         return znode->zbranch[start].znode;
  67                 start += 1;
  68         }
  69
  70         return NULL;
  71 }
  72
  73 /**
  74  * ubifs_inode - get UBIFS inode information by VFS 'struct inode' object.
  75  * @inode: the VFS 'struct inode' pointer
  76  */
  77 static inline struct ubifs_inode *ubifs_inode(const struct inode *inode)
  78 {
  79         return container_of(inode, struct ubifs_inode, vfs_inode);
  80 }
  81
  82 /**
  83  * ubifs_ro_mode - switch UBIFS to read read-only mode.
  84  * @c: UBIFS file-system description object
  85  * @err: error code which is the reason of switching to R/O mode
  86  */
  87 static inline void ubifs_ro_mode(struct ubifs_info *c, int err)
  88 {
  89         if (!c->ro_media) {
  90                 c->ro_media = 1;
  91                 ubifs_warn("switched to read-only mode, error %d", err);
  92                 dbg_dump_stack();
  93         }
  94 }
  95
  96 /**
  97  * ubifs_compr_present - check if compressor was compiled in.
  98  * @compr_type: compressor type to check
  99  *
 100  * This function returns %1 of compressor of type @compr_type is present, and
 101  * %0 if not.
 102  */
 103 static inline int ubifs_compr_present(int compr_type)
 104 {
 105         ubifs_assert(compr_type >= 0 && compr_type < UBIFS_COMPR_TYPES_CNT);
 106         return !!ubifs_compressors[compr_type]->capi_name;
 107 }
 108
 109 /**
 110  * ubifs_compr_name - get compressor name string by its type.
 111  * @compr_type: compressor type
 112  *
 113  * This function returns compressor type string.
 114  */
 115 static inline const char *ubifs_compr_name(int compr_type)
 116 {
 117         ubifs_assert(compr_type >= 0 && compr_type < UBIFS_COMPR_TYPES_CNT);
 118         return ubifs_compressors[compr_type]->name;
 119 }
 120
 121 /**
 122  * ubifs_wbuf_sync - synchronize write-buffer.
 123  * @wbuf: write-buffer to synchronize
 124  *
 125  * This is the same as as 'ubifs_wbuf_sync_nolock()' but it does not assume
 126  * that the write-buffer is already locked.
 127  */
 128 static inline int ubifs_wbuf_sync(struct ubifs_wbuf *wbuf)
 129 {
 130         int err;
 131
 132         mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
 133         err = ubifs_wbuf_sync_nolock(wbuf);
 134         mutex_unlock(&wbuf->io_mutex);
 135         return err;
 136 }
 137
 138 /**
 139  * ubifs_leb_unmap - unmap an LEB.
 140  * @c: UBIFS file-system description object
 141  * @lnum: LEB number to unmap
 142  *
 143  * This function returns %0 on success and a negative error code on failure.
 144  */
 145 static inline int ubifs_leb_unmap(const struct ubifs_info *c, int lnum)
 146 {
 147         int err;
 148
 149         if (c->ro_media)
 150                 return -EROFS;
 151         err = ubi_leb_unmap(c->ubi, lnum);
 152         if (err) {
 153                 ubifs_err("unmap LEB %d failed, error %d", lnum, err);
 154                 return err;
 155         }
 156
 157         return 0;
 158 }
 159
 160 /**
 161  * ubifs_leb_write - write to a LEB.
 162  * @c: UBIFS file-system description object
 163  * @lnum: LEB number to write
 164  * @buf: buffer to write from
 165  * @offs: offset within LEB to write to
 166  * @len: length to write
 167  * @dtype: data type
 168  *
 169  * This function returns %0 on success and a negative error code on failure.
 170  */
 171 static inline int ubifs_leb_write(const struct ubifs_info *c, int lnum,
 172                                   const void *buf, int offs, int len, int dtype)
 173 {
 174         int err;
 175
 176         if (c->ro_media)
 177                 return -EROFS;
 178         err = ubi_leb_write(c->ubi, lnum, buf, offs, len, dtype);
 179         if (err) {
 180                 ubifs_err("writing %d bytes at %d:%d, error %d",
 181                           len, lnum, offs, err);
 182                 return err;
 183         }
 184
 185         return 0;
 186 }
 187
 188 /**
 189  * ubifs_leb_change - atomic LEB change.
 190  * @c: UBIFS file-system description object
 191  * @lnum: LEB number to write
 192  * @buf: buffer to write from
 193  * @len: length to write
 194  * @dtype: data type
 195  *
 196  * This function returns %0 on success and a negative error code on failure.
 197  */
 198 static inline int ubifs_leb_change(const struct ubifs_info *c, int lnum,
 199                                    const void *buf, int len, int dtype)
 200 {
 201         int err;
 202
 203         if (c->ro_media)
 204                 return -EROFS;
 205         err = ubi_leb_change(c->ubi, lnum, buf, len, dtype);
 206         if (err) {
 207                 ubifs_err("changing %d bytes in LEB %d, error %d",
 208                           len, lnum, err);
 209                 return err;
 210         }
 211
 212         return 0;
 213 }
 214
 215 /**
 216  * ubifs_encode_dev - encode device node IDs.
 217  * @dev: UBIFS device node information
 218  * @rdev: device IDs to encode
 219  *
 220  * This is a helper function which encodes major/minor numbers of a device node
 221  * into UBIFS device node description. We use standard Linux "new" and "huge"
 222  * encodings.
 223  */
 224 static inline int ubifs_encode_dev(union ubifs_dev_desc *dev, dev_t rdev)
 225 {
 226         if (new_valid_dev(rdev)) {
 227                 dev->new = cpu_to_le32(new_encode_dev(rdev));
 228                 return sizeof(dev->new);
 229         } else {
 230                 dev->huge = cpu_to_le64(huge_encode_dev(rdev));
 231                 return sizeof(dev->huge);
 232         }
 233 }
 234
 235 /**
 236  * ubifs_add_dirt - add dirty space to LEB properties.
 237  * @c: the UBIFS file-system description object
 238  * @lnum: LEB to add dirty space for
 239  * @dirty: dirty space to add
 240  *
 241  * This is a helper function which increased amount of dirty LEB space. Returns
 242  * zero in case of success and a negative error code in case of failure.
 243  */
 244 static inline int ubifs_add_dirt(struct ubifs_info *c, int lnum, int dirty)
 245 {
 246         return ubifs_update_one_lp(c, lnum, LPROPS_NC, dirty, 0, 0);
 247 }
 248
 249 /**
 250  * ubifs_return_leb - return LEB to lprops.
 251  * @c: the UBIFS file-system description object
 252  * @lnum: LEB to return
 253  *
 254  * This helper function cleans the "taken" flag of a logical eraseblock in the
 255  * lprops. Returns zero in case of success and a negative error code in case of
 256  * failure.
 257  */
 258 static inline int ubifs_return_leb(struct ubifs_info *c, int lnum)
 259 {
 260         return ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
 261                                    LPROPS_TAKEN, 0);
 262 }
 263
 264 /**
 265  * ubifs_idx_node_sz - return index node size.
 266  * @c: the UBIFS file-system description object
 267  * @child_cnt: number of children of this index node
 268  */
 269 static inline int ubifs_idx_node_sz(const struct ubifs_info *c, int child_cnt)
 270 {
 271         return UBIFS_IDX_NODE_SZ + (UBIFS_BRANCH_SZ + c->key_len) * child_cnt;
 272 }
 273
 274 /**
 275  * ubifs_idx_branch - return pointer to an index branch.
 276  * @c: the UBIFS file-system description object
 277  * @idx: index node
 278  * @bnum: branch number
 279  */
 280 static inline
 281 struct ubifs_branch *ubifs_idx_branch(const struct ubifs_info *c,
 282                                       const struct ubifs_idx_node *idx,
 283                                       int bnum)
 284 {
 285         return (struct ubifs_branch *)((void *)idx->branches +
 286                                        (UBIFS_BRANCH_SZ + c->key_len) * bnum);
 287 }
 288
 289 /**
 290  * ubifs_idx_key - return pointer to an index key.
 291  * @c: the UBIFS file-system description object
 292  * @idx: index node
 293  */
 294 static inline void *ubifs_idx_key(const struct ubifs_info *c,
 295                                   const struct ubifs_idx_node *idx)
 296 {
 297         return (void *)((struct ubifs_branch *)idx->branches)->key;
 298 }
 299
 300 /**
 301  * ubifs_reported_space - calculate reported free space.
 302  * @c: the UBIFS file-system description object
 303  * @free: amount of free space
 304  *
 305  * This function calculates amount of free space which will be reported to
 306  * user-space. User-space application tend to expect that if the file-system
 307  * (e.g., via the 'statfs()' call) reports that it has N bytes available, they
 308  * are able to write a file of size N. UBIFS attaches node headers to each data
 309  * node and it has to write indexind nodes as well. This introduces additional
 310  * overhead, and UBIFS it has to report sligtly less free space to meet the
 311  * above expectetion.
 312  *
 313  * This function assumes free space is made up of uncompressed data nodes and
 314  * full index nodes (one per data node, doubled because we always allow enough
 315  * space to write the index twice).
 316  *
 317  * Note, the calculation is pessimistic, which means that most of the time
 318  * UBIFS reports less space than it actually has.
 319  */
 320 static inline long long ubifs_reported_space(const struct ubifs_info *c,
 321                                              uint64_t free)
 322 {
 323         int divisor, factor;
 324
 325         divisor = UBIFS_MAX_DATA_NODE_SZ + (c->max_idx_node_sz << 1);
 326         factor = UBIFS_MAX_DATA_NODE_SZ - UBIFS_DATA_NODE_SZ;
 327         do_div(free, divisor);
 328
 329         return free * factor;
 330 }
 331
 332 /**
 333  * ubifs_current_time - round current time to time granularity.
 334  * @inode: inode
 335  */
 336 static inline struct timespec ubifs_current_time(struct inode *inode)
 337 {
 338         return (inode->i_sb->s_time_gran < NSEC_PER_SEC) ?
 339                 current_fs_time(inode->i_sb) : CURRENT_TIME_SEC;
 340 }
 341
 342 #endif /* __UBIFS_MISC_H__ */