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_compr_present - check if compressor was compiled in.
  84  * @compr_type: compressor type to check
  85  *
  86  * This function returns %1 of compressor of type @compr_type is present, and
  87  * %0 if not.
  88  */
  89 static inline int ubifs_compr_present(int compr_type)
  90 {
  91         ubifs_assert(compr_type >= 0 && compr_type < UBIFS_COMPR_TYPES_CNT);
  92         return !!ubifs_compressors[compr_type]->capi_name;
  93 }
  94
  95 /**
  96  * ubifs_compr_name - get compressor name string by its type.
  97  * @compr_type: compressor type
  98  *
  99  * This function returns compressor type string.
 100  */
 101 static inline const char *ubifs_compr_name(int compr_type)
 102 {
 103         ubifs_assert(compr_type >= 0 && compr_type < UBIFS_COMPR_TYPES_CNT);
 104         return ubifs_compressors[compr_type]->name;
 105 }
 106
 107 /**
 108  * ubifs_wbuf_sync - synchronize write-buffer.
 109  * @wbuf: write-buffer to synchronize
 110  *
 111  * This is the same as as 'ubifs_wbuf_sync_nolock()' but it does not assume
 112  * that the write-buffer is already locked.
 113  */
 114 static inline int ubifs_wbuf_sync(struct ubifs_wbuf *wbuf)
 115 {
 116         int err;
 117
 118         mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
 119         err = ubifs_wbuf_sync_nolock(wbuf);
 120         mutex_unlock(&wbuf->io_mutex);
 121         return err;
 122 }
 123
 124 /**
 125  * ubifs_leb_unmap - unmap an LEB.
 126  * @c: UBIFS file-system description object
 127  * @lnum: LEB number to unmap
 128  *
 129  * This function returns %0 on success and a negative error code on failure.
 130  */
 131 static inline int ubifs_leb_unmap(const struct ubifs_info *c, int lnum)
 132 {
 133         int err;
 134
 135         if (c->ro_media)
 136                 return -EROFS;
 137         err = ubi_leb_unmap(c->ubi, lnum);
 138         if (err) {
 139                 ubifs_err("unmap LEB %d failed, error %d", lnum, err);
 140                 return err;
 141         }
 142
 143         return 0;
 144 }
 145
 146 /**
 147  * ubifs_leb_write - write to a LEB.
 148  * @c: UBIFS file-system description object
 149  * @lnum: LEB number to write
 150  * @buf: buffer to write from
 151  * @offs: offset within LEB to write to
 152  * @len: length to write
 153  * @dtype: data type
 154  *
 155  * This function returns %0 on success and a negative error code on failure.
 156  */
 157 static inline int ubifs_leb_write(const struct ubifs_info *c, int lnum,
 158                                   const void *buf, int offs, int len, int dtype)
 159 {
 160         int err;
 161
 162         if (c->ro_media)
 163                 return -EROFS;
 164         err = ubi_leb_write(c->ubi, lnum, buf, offs, len, dtype);
 165         if (err) {
 166                 ubifs_err("writing %d bytes at %d:%d, error %d",
 167                           len, lnum, offs, err);
 168                 return err;
 169         }
 170
 171         return 0;
 172 }
 173
 174 /**
 175  * ubifs_leb_change - atomic LEB change.
 176  * @c: UBIFS file-system description object
 177  * @lnum: LEB number to write
 178  * @buf: buffer to write from
 179  * @len: length to write
 180  * @dtype: data type
 181  *
 182  * This function returns %0 on success and a negative error code on failure.
 183  */
 184 static inline int ubifs_leb_change(const struct ubifs_info *c, int lnum,
 185                                    const void *buf, int len, int dtype)
 186 {
 187         int err;
 188
 189         if (c->ro_media)
 190                 return -EROFS;
 191         err = ubi_leb_change(c->ubi, lnum, buf, len, dtype);
 192         if (err) {
 193                 ubifs_err("changing %d bytes in LEB %d, error %d",
 194                           len, lnum, err);
 195                 return err;
 196         }
 197
 198         return 0;
 199 }
 200
 201 /**
 202  * ubifs_encode_dev - encode device node IDs.
 203  * @dev: UBIFS device node information
 204  * @rdev: device IDs to encode
 205  *
 206  * This is a helper function which encodes major/minor numbers of a device node
 207  * into UBIFS device node description. We use standard Linux "new" and "huge"
 208  * encodings.
 209  */
 210 static inline int ubifs_encode_dev(union ubifs_dev_desc *dev, dev_t rdev)
 211 {
 212         if (new_valid_dev(rdev)) {
 213                 dev->new = cpu_to_le32(new_encode_dev(rdev));
 214                 return sizeof(dev->new);
 215         } else {
 216                 dev->huge = cpu_to_le64(huge_encode_dev(rdev));
 217                 return sizeof(dev->huge);
 218         }
 219 }
 220
 221 /**
 222  * ubifs_add_dirt - add dirty space to LEB properties.
 223  * @c: the UBIFS file-system description object
 224  * @lnum: LEB to add dirty space for
 225  * @dirty: dirty space to add
 226  *
 227  * This is a helper function which increased amount of dirty LEB space. Returns
 228  * zero in case of success and a negative error code in case of failure.
 229  */
 230 static inline int ubifs_add_dirt(struct ubifs_info *c, int lnum, int dirty)
 231 {
 232         return ubifs_update_one_lp(c, lnum, LPROPS_NC, dirty, 0, 0);
 233 }
 234
 235 /**
 236  * ubifs_return_leb - return LEB to lprops.
 237  * @c: the UBIFS file-system description object
 238  * @lnum: LEB to return
 239  *
 240  * This helper function cleans the "taken" flag of a logical eraseblock in the
 241  * lprops. Returns zero in case of success and a negative error code in case of
 242  * failure.
 243  */
 244 static inline int ubifs_return_leb(struct ubifs_info *c, int lnum)
 245 {
 246         return ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
 247                                    LPROPS_TAKEN, 0);
 248 }
 249
 250 /**
 251  * ubifs_idx_node_sz - return index node size.
 252  * @c: the UBIFS file-system description object
 253  * @child_cnt: number of children of this index node
 254  */
 255 static inline int ubifs_idx_node_sz(const struct ubifs_info *c, int child_cnt)
 256 {
 257         return UBIFS_IDX_NODE_SZ + (UBIFS_BRANCH_SZ + c->key_len) * child_cnt;
 258 }
 259
 260 /**
 261  * ubifs_idx_branch - return pointer to an index branch.
 262  * @c: the UBIFS file-system description object
 263  * @idx: index node
 264  * @bnum: branch number
 265  */
 266 static inline
 267 struct ubifs_branch *ubifs_idx_branch(const struct ubifs_info *c,
 268                                       const struct ubifs_idx_node *idx,
 269                                       int bnum)
 270 {
 271         return (struct ubifs_branch *)((void *)idx->branches +
 272                                        (UBIFS_BRANCH_SZ + c->key_len) * bnum);
 273 }
 274
 275 /**
 276  * ubifs_idx_key - return pointer to an index key.
 277  * @c: the UBIFS file-system description object
 278  * @idx: index node
 279  */
 280 static inline void *ubifs_idx_key(const struct ubifs_info *c,
 281                                   const struct ubifs_idx_node *idx)
 282 {
 283         return (void *)((struct ubifs_branch *)idx->branches)->key;
 284 }
 285
 286 /**
 287  * ubifs_reported_space - calculate reported free space.
 288  * @c: the UBIFS file-system description object
 289  * @free: amount of free space
 290  *
 291  * This function calculates amount of free space which will be reported to
 292  * user-space. User-space application tend to expect that if the file-system
 293  * (e.g., via the 'statfs()' call) reports that it has N bytes available, they
 294  * are able to write a file of size N. UBIFS attaches node headers to each data
 295  * node and it has to write indexind nodes as well. This introduces additional
 296  * overhead, and UBIFS it has to report sligtly less free space to meet the
 297  * above expectetion.
 298  *
 299  * This function assumes free space is made up of uncompressed data nodes and
 300  * full index nodes (one per data node, doubled because we always allow enough
 301  * space to write the index twice).
 302  *
 303  * Note, the calculation is pessimistic, which means that most of the time
 304  * UBIFS reports less space than it actually has.
 305  */
 306 static inline long long ubifs_reported_space(const struct ubifs_info *c,
 307                                              uint64_t free)
 308 {
 309         int divisor, factor;
 310
 311         divisor = UBIFS_MAX_DATA_NODE_SZ + (c->max_idx_node_sz * 3);
 312         factor = UBIFS_MAX_DATA_NODE_SZ - UBIFS_DATA_NODE_SZ;
 313         do_div(free, divisor);
 314
 315         return free * factor;
 316 }
 317
 318 /**
 319  * ubifs_current_time - round current time to time granularity.
 320  * @inode: inode
 321  */
 322 static inline struct timespec ubifs_current_time(struct inode *inode)
 323 {
 324         return (inode->i_sb->s_time_gran < NSEC_PER_SEC) ?
 325                 current_fs_time(inode->i_sb) : CURRENT_TIME_SEC;
 326 }
 327
 328 #endif /* __UBIFS_MISC_H__ */