fs/xfs/xfs_rtbitmap.c

   1 /*
   2  * Copyright (c) 2000-2005 Silicon Graphics, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #include "xfs.h"
  19 #include "xfs_fs.h"
  20 #include "xfs_shared.h"
  21 #include "xfs_format.h"
  22 #include "xfs_log_format.h"
  23 #include "xfs_trans_resv.h"
  24 #include "xfs_bit.h"
  25 #include "xfs_sb.h"
  26 #include "xfs_ag.h"
  27 #include "xfs_mount.h"
  28 #include "xfs_inode.h"
  29 #include "xfs_bmap.h"
  30 #include "xfs_bmap_util.h"
  31 #include "xfs_bmap_btree.h"
  32 #include "xfs_alloc.h"
  33 #include "xfs_error.h"
  34 #include "xfs_trans.h"
  35 #include "xfs_trans_space.h"
  36 #include "xfs_trace.h"
  37 #include "xfs_buf.h"
  38 #include "xfs_icache.h"
  39 #include "xfs_dinode.h"
  40 #include "xfs_rtalloc.h"
  41
  42
  43 /*
  44  * Realtime allocator bitmap functions shared with userspace.
  45  */
  46
  47 /*
  48  * Get a buffer for the bitmap or summary file block specified.
  49  * The buffer is returned read and locked.
  50  */
  51 int
  52 xfs_rtbuf_get(
  53         xfs_mount_t     *mp,            /* file system mount structure */
  54         xfs_trans_t     *tp,            /* transaction pointer */
  55         xfs_rtblock_t   block,          /* block number in bitmap or summary */
  56         int             issum,          /* is summary not bitmap */
  57         xfs_buf_t       **bpp)          /* output: buffer for the block */
  58 {
  59         xfs_buf_t       *bp;            /* block buffer, result */
  60         xfs_inode_t     *ip;            /* bitmap or summary inode */
  61         xfs_bmbt_irec_t map;
  62         int             nmap = 1;
  63         int             error;          /* error value */
  64
  65         ip = issum ? mp->m_rsumip : mp->m_rbmip;
  66
  67         error = xfs_bmapi_read(ip, block, 1, &map, &nmap, XFS_DATA_FORK);
  68         if (error)
  69                 return error;
  70
  71         ASSERT(map.br_startblock != NULLFSBLOCK);
  72         error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
  73                                    XFS_FSB_TO_DADDR(mp, map.br_startblock),
  74                                    mp->m_bsize, 0, &bp, NULL);
  75         if (error)
  76                 return error;
  77         *bpp = bp;
  78         return 0;
  79 }
  80
  81 /*
  82  * Searching backward from start to limit, find the first block whose
  83  * allocated/free state is different from start's.
  84  */
  85 int
  86 xfs_rtfind_back(
  87         xfs_mount_t     *mp,            /* file system mount point */
  88         xfs_trans_t     *tp,            /* transaction pointer */
  89         xfs_rtblock_t   start,          /* starting block to look at */
  90         xfs_rtblock_t   limit,          /* last block to look at */
  91         xfs_rtblock_t   *rtblock)       /* out: start block found */
  92 {
  93         xfs_rtword_t    *b;             /* current word in buffer */
  94         int             bit;            /* bit number in the word */
  95         xfs_rtblock_t   block;          /* bitmap block number */
  96         xfs_buf_t       *bp;            /* buf for the block */
  97         xfs_rtword_t    *bufp;          /* starting word in buffer */
  98         int             error;          /* error value */
  99         xfs_rtblock_t   firstbit;       /* first useful bit in the word */
 100         xfs_rtblock_t   i;              /* current bit number rel. to start */
 101         xfs_rtblock_t   len;            /* length of inspected area */
 102         xfs_rtword_t    mask;           /* mask of relevant bits for value */
 103         xfs_rtword_t    want;           /* mask for "good" values */
 104         xfs_rtword_t    wdiff;          /* difference from wanted value */
 105         int             word;           /* word number in the buffer */
 106
 107         /*
 108          * Compute and read in starting bitmap block for starting block.
 109          */
 110         block = XFS_BITTOBLOCK(mp, start);
 111         error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
 112         if (error) {
 113                 return error;
 114         }
 115         bufp = bp->b_addr;
 116         /*
 117          * Get the first word's index & point to it.
 118          */
 119         word = XFS_BITTOWORD(mp, start);
 120         b = &bufp[word];
 121         bit = (int)(start & (XFS_NBWORD - 1));
 122         len = start - limit + 1;
 123         /*
 124          * Compute match value, based on the bit at start: if 1 (free)
 125          * then all-ones, else all-zeroes.
 126          */
 127         want = (*b & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
 128         /*
 129          * If the starting position is not word-aligned, deal with the
 130          * partial word.
 131          */
 132         if (bit < XFS_NBWORD - 1) {
 133                 /*
 134                  * Calculate first (leftmost) bit number to look at,
 135                  * and mask for all the relevant bits in this word.
 136                  */
 137                 firstbit = XFS_RTMAX((xfs_srtblock_t)(bit - len + 1), 0);
 138                 mask = (((xfs_rtword_t)1 << (bit - firstbit + 1)) - 1) <<
 139                         firstbit;
 140                 /*
 141                  * Calculate the difference between the value there
 142                  * and what we're looking for.
 143                  */
 144                 if ((wdiff = (*b ^ want) & mask)) {
 145                         /*
 146                          * Different.  Mark where we are and return.
 147                          */
 148                         xfs_trans_brelse(tp, bp);
 149                         i = bit - XFS_RTHIBIT(wdiff);
 150                         *rtblock = start - i + 1;
 151                         return 0;
 152                 }
 153                 i = bit - firstbit + 1;
 154                 /*
 155                  * Go on to previous block if that's where the previous word is
 156                  * and we need the previous word.
 157                  */
 158                 if (--word == -1 && i < len) {
 159                         /*
 160                          * If done with this block, get the previous one.
 161                          */
 162                         xfs_trans_brelse(tp, bp);
 163                         error = xfs_rtbuf_get(mp, tp, --block, 0, &bp);
 164                         if (error) {
 165                                 return error;
 166                         }
 167                         bufp = bp->b_addr;
 168                         word = XFS_BLOCKWMASK(mp);
 169                         b = &bufp[word];
 170                 } else {
 171                         /*
 172                          * Go on to the previous word in the buffer.
 173                          */
 174                         b--;
 175                 }
 176         } else {
 177                 /*
 178                  * Starting on a word boundary, no partial word.
 179                  */
 180                 i = 0;
 181         }
 182         /*
 183          * Loop over whole words in buffers.  When we use up one buffer
 184          * we move on to the previous one.
 185          */
 186         while (len - i >= XFS_NBWORD) {
 187                 /*
 188                  * Compute difference between actual and desired value.
 189                  */
 190                 if ((wdiff = *b ^ want)) {
 191                         /*
 192                          * Different, mark where we are and return.
 193                          */
 194                         xfs_trans_brelse(tp, bp);
 195                         i += XFS_NBWORD - 1 - XFS_RTHIBIT(wdiff);
 196                         *rtblock = start - i + 1;
 197                         return 0;
 198                 }
 199                 i += XFS_NBWORD;
 200                 /*
 201                  * Go on to previous block if that's where the previous word is
 202                  * and we need the previous word.
 203                  */
 204                 if (--word == -1 && i < len) {
 205                         /*
 206                          * If done with this block, get the previous one.
 207                          */
 208                         xfs_trans_brelse(tp, bp);
 209                         error = xfs_rtbuf_get(mp, tp, --block, 0, &bp);
 210                         if (error) {
 211                                 return error;
 212                         }
 213                         bufp = bp->b_addr;
 214                         word = XFS_BLOCKWMASK(mp);
 215                         b = &bufp[word];
 216                 } else {
 217                         /*
 218                          * Go on to the previous word in the buffer.
 219                          */
 220                         b--;
 221                 }
 222         }
 223         /*
 224          * If not ending on a word boundary, deal with the last
 225          * (partial) word.
 226          */
 227         if (len - i) {
 228                 /*
 229                  * Calculate first (leftmost) bit number to look at,
 230                  * and mask for all the relevant bits in this word.
 231                  */
 232                 firstbit = XFS_NBWORD - (len - i);
 233                 mask = (((xfs_rtword_t)1 << (len - i)) - 1) << firstbit;
 234                 /*
 235                  * Compute difference between actual and desired value.
 236                  */
 237                 if ((wdiff = (*b ^ want) & mask)) {
 238                         /*
 239                          * Different, mark where we are and return.
 240                          */
 241                         xfs_trans_brelse(tp, bp);
 242                         i += XFS_NBWORD - 1 - XFS_RTHIBIT(wdiff);
 243                         *rtblock = start - i + 1;
 244                         return 0;
 245                 } else
 246                         i = len;
 247         }
 248         /*
 249          * No match, return that we scanned the whole area.
 250          */
 251         xfs_trans_brelse(tp, bp);
 252         *rtblock = start - i + 1;
 253         return 0;
 254 }
 255
 256 /*
 257  * Searching forward from start to limit, find the first block whose
 258  * allocated/free state is different from start's.
 259  */
 260 int
 261 xfs_rtfind_forw(
 262         xfs_mount_t     *mp,            /* file system mount point */
 263         xfs_trans_t     *tp,            /* transaction pointer */
 264         xfs_rtblock_t   start,          /* starting block to look at */
 265         xfs_rtblock_t   limit,          /* last block to look at */
 266         xfs_rtblock_t   *rtblock)       /* out: start block found */
 267 {
 268         xfs_rtword_t    *b;             /* current word in buffer */
 269         int             bit;            /* bit number in the word */
 270         xfs_rtblock_t   block;          /* bitmap block number */
 271         xfs_buf_t       *bp;            /* buf for the block */
 272         xfs_rtword_t    *bufp;          /* starting word in buffer */
 273         int             error;          /* error value */
 274         xfs_rtblock_t   i;              /* current bit number rel. to start */
 275         xfs_rtblock_t   lastbit;        /* last useful bit in the word */
 276         xfs_rtblock_t   len;            /* length of inspected area */
 277         xfs_rtword_t    mask;           /* mask of relevant bits for value */
 278         xfs_rtword_t    want;           /* mask for "good" values */
 279         xfs_rtword_t    wdiff;          /* difference from wanted value */
 280         int             word;           /* word number in the buffer */
 281
 282         /*
 283          * Compute and read in starting bitmap block for starting block.
 284          */
 285         block = XFS_BITTOBLOCK(mp, start);
 286         error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
 287         if (error) {
 288                 return error;
 289         }
 290         bufp = bp->b_addr;
 291         /*
 292          * Get the first word's index & point to it.
 293          */
 294         word = XFS_BITTOWORD(mp, start);
 295         b = &bufp[word];
 296         bit = (int)(start & (XFS_NBWORD - 1));
 297         len = limit - start + 1;
 298         /*
 299          * Compute match value, based on the bit at start: if 1 (free)
 300          * then all-ones, else all-zeroes.
 301          */
 302         want = (*b & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
 303         /*
 304          * If the starting position is not word-aligned, deal with the
 305          * partial word.
 306          */
 307         if (bit) {
 308                 /*
 309                  * Calculate last (rightmost) bit number to look at,
 310                  * and mask for all the relevant bits in this word.
 311                  */
 312                 lastbit = XFS_RTMIN(bit + len, XFS_NBWORD);
 313                 mask = (((xfs_rtword_t)1 << (lastbit - bit)) - 1) << bit;
 314                 /*
 315                  * Calculate the difference between the value there
 316                  * and what we're looking for.
 317                  */
 318                 if ((wdiff = (*b ^ want) & mask)) {
 319                         /*
 320                          * Different.  Mark where we are and return.
 321                          */
 322                         xfs_trans_brelse(tp, bp);
 323                         i = XFS_RTLOBIT(wdiff) - bit;
 324                         *rtblock = start + i - 1;
 325                         return 0;
 326                 }
 327                 i = lastbit - bit;
 328                 /*
 329                  * Go on to next block if that's where the next word is
 330                  * and we need the next word.
 331                  */
 332                 if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
 333                         /*
 334                          * If done with this block, get the previous one.
 335                          */
 336                         xfs_trans_brelse(tp, bp);
 337                         error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
 338                         if (error) {
 339                                 return error;
 340                         }
 341                         b = bufp = bp->b_addr;
 342                         word = 0;
 343                 } else {
 344                         /*
 345                          * Go on to the previous word in the buffer.
 346                          */
 347                         b++;
 348                 }
 349         } else {
 350                 /*
 351                  * Starting on a word boundary, no partial word.
 352                  */
 353                 i = 0;
 354         }
 355         /*
 356          * Loop over whole words in buffers.  When we use up one buffer
 357          * we move on to the next one.
 358          */
 359         while (len - i >= XFS_NBWORD) {
 360                 /*
 361                  * Compute difference between actual and desired value.
 362                  */
 363                 if ((wdiff = *b ^ want)) {
 364                         /*
 365                          * Different, mark where we are and return.
 366                          */
 367                         xfs_trans_brelse(tp, bp);
 368                         i += XFS_RTLOBIT(wdiff);
 369                         *rtblock = start + i - 1;
 370                         return 0;
 371                 }
 372                 i += XFS_NBWORD;
 373                 /*
 374                  * Go on to next block if that's where the next word is
 375                  * and we need the next word.
 376                  */
 377                 if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
 378                         /*
 379                          * If done with this block, get the next one.
 380                          */
 381                         xfs_trans_brelse(tp, bp);
 382                         error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
 383                         if (error) {
 384                                 return error;
 385                         }
 386                         b = bufp = bp->b_addr;
 387                         word = 0;
 388                 } else {
 389                         /*
 390                          * Go on to the next word in the buffer.
 391                          */
 392                         b++;
 393                 }
 394         }
 395         /*
 396          * If not ending on a word boundary, deal with the last
 397          * (partial) word.
 398          */
 399         if ((lastbit = len - i)) {
 400                 /*
 401                  * Calculate mask for all the relevant bits in this word.
 402                  */
 403                 mask = ((xfs_rtword_t)1 << lastbit) - 1;
 404                 /*
 405                  * Compute difference between actual and desired value.
 406                  */
 407                 if ((wdiff = (*b ^ want) & mask)) {
 408                         /*
 409                          * Different, mark where we are and return.
 410                          */
 411                         xfs_trans_brelse(tp, bp);
 412                         i += XFS_RTLOBIT(wdiff);
 413                         *rtblock = start + i - 1;
 414                         return 0;
 415                 } else
 416                         i = len;
 417         }
 418         /*
 419          * No match, return that we scanned the whole area.
 420          */
 421         xfs_trans_brelse(tp, bp);
 422         *rtblock = start + i - 1;
 423         return 0;
 424 }
 425
 426 /*
 427  * Read and modify the summary information for a given extent size,
 428  * bitmap block combination.
 429  * Keeps track of a current summary block, so we don't keep reading
 430  * it from the buffer cache.
 431  */
 432 int
 433 xfs_rtmodify_summary(
 434         xfs_mount_t     *mp,            /* file system mount point */
 435         xfs_trans_t     *tp,            /* transaction pointer */
 436         int             log,            /* log2 of extent size */
 437         xfs_rtblock_t   bbno,           /* bitmap block number */
 438         int             delta,          /* change to make to summary info */
 439         xfs_buf_t       **rbpp,         /* in/out: summary block buffer */
 440         xfs_fsblock_t   *rsb)           /* in/out: summary block number */
 441 {
 442         xfs_buf_t       *bp;            /* buffer for the summary block */
 443         int             error;          /* error value */
 444         xfs_fsblock_t   sb;             /* summary fsblock */
 445         int             so;             /* index into the summary file */
 446         xfs_suminfo_t   *sp;            /* pointer to returned data */
 447
 448         /*
 449          * Compute entry number in the summary file.
 450          */
 451         so = XFS_SUMOFFS(mp, log, bbno);
 452         /*
 453          * Compute the block number in the summary file.
 454          */
 455         sb = XFS_SUMOFFSTOBLOCK(mp, so);
 456         /*
 457          * If we have an old buffer, and the block number matches, use that.
 458          */
 459         if (rbpp && *rbpp && *rsb == sb)
 460                 bp = *rbpp;
 461         /*
 462          * Otherwise we have to get the buffer.
 463          */
 464         else {
 465                 /*
 466                  * If there was an old one, get rid of it first.
 467                  */
 468                 if (rbpp && *rbpp)
 469                         xfs_trans_brelse(tp, *rbpp);
 470                 error = xfs_rtbuf_get(mp, tp, sb, 1, &bp);
 471                 if (error) {
 472                         return error;
 473                 }
 474                 /*
 475                  * Remember this buffer and block for the next call.
 476                  */
 477                 if (rbpp) {
 478                         *rbpp = bp;
 479                         *rsb = sb;
 480                 }
 481         }
 482         /*
 483          * Point to the summary information, modify and log it.
 484          */
 485         sp = XFS_SUMPTR(mp, bp, so);
 486         *sp += delta;
 487         xfs_trans_log_buf(tp, bp, (uint)((char *)sp - (char *)bp->b_addr),
 488                 (uint)((char *)sp - (char *)bp->b_addr + sizeof(*sp) - 1));
 489         return 0;
 490 }
 491
 492 /*
 493  * Set the given range of bitmap bits to the given value.
 494  * Do whatever I/O and logging is required.
 495  */
 496 int
 497 xfs_rtmodify_range(
 498         xfs_mount_t     *mp,            /* file system mount point */
 499         xfs_trans_t     *tp,            /* transaction pointer */
 500         xfs_rtblock_t   start,          /* starting block to modify */
 501         xfs_extlen_t    len,            /* length of extent to modify */
 502         int             val)            /* 1 for free, 0 for allocated */
 503 {
 504         xfs_rtword_t    *b;             /* current word in buffer */
 505         int             bit;            /* bit number in the word */
 506         xfs_rtblock_t   block;          /* bitmap block number */
 507         xfs_buf_t       *bp;            /* buf for the block */
 508         xfs_rtword_t    *bufp;          /* starting word in buffer */
 509         int             error;          /* error value */
 510         xfs_rtword_t    *first;         /* first used word in the buffer */
 511         int             i;              /* current bit number rel. to start */
 512         int             lastbit;        /* last useful bit in word */
 513         xfs_rtword_t    mask;           /* mask o frelevant bits for value */
 514         int             word;           /* word number in the buffer */
 515
 516         /*
 517          * Compute starting bitmap block number.
 518          */
 519         block = XFS_BITTOBLOCK(mp, start);
 520         /*
 521          * Read the bitmap block, and point to its data.
 522          */
 523         error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
 524         if (error) {
 525                 return error;
 526         }
 527         bufp = bp->b_addr;
 528         /*
 529          * Compute the starting word's address, and starting bit.
 530          */
 531         word = XFS_BITTOWORD(mp, start);
 532         first = b = &bufp[word];
 533         bit = (int)(start & (XFS_NBWORD - 1));
 534         /*
 535          * 0 (allocated) => all zeroes; 1 (free) => all ones.
 536          */
 537         val = -val;
 538         /*
 539          * If not starting on a word boundary, deal with the first
 540          * (partial) word.
 541          */
 542         if (bit) {
 543                 /*
 544                  * Compute first bit not changed and mask of relevant bits.
 545                  */
 546                 lastbit = XFS_RTMIN(bit + len, XFS_NBWORD);
 547                 mask = (((xfs_rtword_t)1 << (lastbit - bit)) - 1) << bit;
 548                 /*
 549                  * Set/clear the active bits.
 550                  */
 551                 if (val)
 552                         *b |= mask;
 553                 else
 554                         *b &= ~mask;
 555                 i = lastbit - bit;
 556                 /*
 557                  * Go on to the next block if that's where the next word is
 558                  * and we need the next word.
 559                  */
 560                 if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
 561                         /*
 562                          * Log the changed part of this block.
 563                          * Get the next one.
 564                          */
 565                         xfs_trans_log_buf(tp, bp,
 566                                 (uint)((char *)first - (char *)bufp),
 567                                 (uint)((char *)b - (char *)bufp));
 568                         error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
 569                         if (error) {
 570                                 return error;
 571                         }
 572                         first = b = bufp = bp->b_addr;
 573                         word = 0;
 574                 } else {
 575                         /*
 576                          * Go on to the next word in the buffer
 577                          */
 578                         b++;
 579                 }
 580         } else {
 581                 /*
 582                  * Starting on a word boundary, no partial word.
 583                  */
 584                 i = 0;
 585         }
 586         /*
 587          * Loop over whole words in buffers.  When we use up one buffer
 588          * we move on to the next one.
 589          */
 590         while (len - i >= XFS_NBWORD) {
 591                 /*
 592                  * Set the word value correctly.
 593                  */
 594                 *b = val;
 595                 i += XFS_NBWORD;
 596                 /*
 597                  * Go on to the next block if that's where the next word is
 598                  * and we need the next word.
 599                  */
 600                 if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
 601                         /*
 602                          * Log the changed part of this block.
 603                          * Get the next one.
 604                          */
 605                         xfs_trans_log_buf(tp, bp,
 606                                 (uint)((char *)first - (char *)bufp),
 607                                 (uint)((char *)b - (char *)bufp));
 608                         error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
 609                         if (error) {
 610                                 return error;
 611                         }
 612                         first = b = bufp = bp->b_addr;
 613                         word = 0;
 614                 } else {
 615                         /*
 616                          * Go on to the next word in the buffer
 617                          */
 618                         b++;
 619                 }
 620         }
 621         /*
 622          * If not ending on a word boundary, deal with the last
 623          * (partial) word.
 624          */
 625         if ((lastbit = len - i)) {
 626                 /*
 627                  * Compute a mask of relevant bits.
 628                  */
 629                 bit = 0;
 630                 mask = ((xfs_rtword_t)1 << lastbit) - 1;
 631                 /*
 632                  * Set/clear the active bits.
 633                  */
 634                 if (val)
 635                         *b |= mask;
 636                 else
 637                         *b &= ~mask;
 638                 b++;
 639         }
 640         /*
 641          * Log any remaining changed bytes.
 642          */
 643         if (b > first)
 644                 xfs_trans_log_buf(tp, bp, (uint)((char *)first - (char *)bufp),
 645                         (uint)((char *)b - (char *)bufp - 1));
 646         return 0;
 647 }
 648
 649 /*
 650  * Mark an extent specified by start and len freed.
 651  * Updates all the summary information as well as the bitmap.
 652  */
 653 int
 654 xfs_rtfree_range(
 655         xfs_mount_t     *mp,            /* file system mount point */
 656         xfs_trans_t     *tp,            /* transaction pointer */
 657         xfs_rtblock_t   start,          /* starting block to free */
 658         xfs_extlen_t    len,            /* length to free */
 659         xfs_buf_t       **rbpp,         /* in/out: summary block buffer */
 660         xfs_fsblock_t   *rsb)           /* in/out: summary block number */
 661 {
 662         xfs_rtblock_t   end;            /* end of the freed extent */
 663         int             error;          /* error value */
 664         xfs_rtblock_t   postblock;      /* first block freed > end */
 665         xfs_rtblock_t   preblock;       /* first block freed < start */
 666
 667         end = start + len - 1;
 668         /*
 669          * Modify the bitmap to mark this extent freed.
 670          */
 671         error = xfs_rtmodify_range(mp, tp, start, len, 1);
 672         if (error) {
 673                 return error;
 674         }
 675         /*
 676          * Assume we're freeing out of the middle of an allocated extent.
 677          * We need to find the beginning and end of the extent so we can
 678          * properly update the summary.
 679          */
 680         error = xfs_rtfind_back(mp, tp, start, 0, &preblock);
 681         if (error) {
 682                 return error;
 683         }
 684         /*
 685          * Find the next allocated block (end of allocated extent).
 686          */
 687         error = xfs_rtfind_forw(mp, tp, end, mp->m_sb.sb_rextents - 1,
 688                 &postblock);
 689         if (error)
 690                 return error;
 691         /*
 692          * If there are blocks not being freed at the front of the
 693          * old extent, add summary data for them to be allocated.
 694          */
 695         if (preblock < start) {
 696                 error = xfs_rtmodify_summary(mp, tp,
 697                         XFS_RTBLOCKLOG(start - preblock),
 698                         XFS_BITTOBLOCK(mp, preblock), -1, rbpp, rsb);
 699                 if (error) {
 700                         return error;
 701                 }
 702         }
 703         /*
 704          * If there are blocks not being freed at the end of the
 705          * old extent, add summary data for them to be allocated.
 706          */
 707         if (postblock > end) {
 708                 error = xfs_rtmodify_summary(mp, tp,
 709                         XFS_RTBLOCKLOG(postblock - end),
 710                         XFS_BITTOBLOCK(mp, end + 1), -1, rbpp, rsb);
 711                 if (error) {
 712                         return error;
 713                 }
 714         }
 715         /*
 716          * Increment the summary information corresponding to the entire
 717          * (new) free extent.
 718          */
 719         error = xfs_rtmodify_summary(mp, tp,
 720                 XFS_RTBLOCKLOG(postblock + 1 - preblock),
 721                 XFS_BITTOBLOCK(mp, preblock), 1, rbpp, rsb);
 722         return error;
 723 }
 724
 725 /*
 726  * Check that the given range is either all allocated (val = 0) or
 727  * all free (val = 1).
 728  */
 729 int
 730 xfs_rtcheck_range(
 731         xfs_mount_t     *mp,            /* file system mount point */
 732         xfs_trans_t     *tp,            /* transaction pointer */
 733         xfs_rtblock_t   start,          /* starting block number of extent */
 734         xfs_extlen_t    len,            /* length of extent */
 735         int             val,            /* 1 for free, 0 for allocated */
 736         xfs_rtblock_t   *new,           /* out: first block not matching */
 737         int             *stat)          /* out: 1 for matches, 0 for not */
 738 {
 739         xfs_rtword_t    *b;             /* current word in buffer */
 740         int             bit;            /* bit number in the word */
 741         xfs_rtblock_t   block;          /* bitmap block number */
 742         xfs_buf_t       *bp;            /* buf for the block */
 743         xfs_rtword_t    *bufp;          /* starting word in buffer */
 744         int             error;          /* error value */
 745         xfs_rtblock_t   i;              /* current bit number rel. to start */
 746         xfs_rtblock_t   lastbit;        /* last useful bit in word */
 747         xfs_rtword_t    mask;           /* mask of relevant bits for value */
 748         xfs_rtword_t    wdiff;          /* difference from wanted value */
 749         int             word;           /* word number in the buffer */
 750
 751         /*
 752          * Compute starting bitmap block number
 753          */
 754         block = XFS_BITTOBLOCK(mp, start);
 755         /*
 756          * Read the bitmap block.
 757          */
 758         error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
 759         if (error) {
 760                 return error;
 761         }
 762         bufp = bp->b_addr;
 763         /*
 764          * Compute the starting word's address, and starting bit.
 765          */
 766         word = XFS_BITTOWORD(mp, start);
 767         b = &bufp[word];
 768         bit = (int)(start & (XFS_NBWORD - 1));
 769         /*
 770          * 0 (allocated) => all zero's; 1 (free) => all one's.
 771          */
 772         val = -val;
 773         /*
 774          * If not starting on a word boundary, deal with the first
 775          * (partial) word.
 776          */
 777         if (bit) {
 778                 /*
 779                  * Compute first bit not examined.
 780                  */
 781                 lastbit = XFS_RTMIN(bit + len, XFS_NBWORD);
 782                 /*
 783                  * Mask of relevant bits.
 784                  */
 785                 mask = (((xfs_rtword_t)1 << (lastbit - bit)) - 1) << bit;
 786                 /*
 787                  * Compute difference between actual and desired value.
 788                  */
 789                 if ((wdiff = (*b ^ val) & mask)) {
 790                         /*
 791                          * Different, compute first wrong bit and return.
 792                          */
 793                         xfs_trans_brelse(tp, bp);
 794                         i = XFS_RTLOBIT(wdiff) - bit;
 795                         *new = start + i;
 796                         *stat = 0;
 797                         return 0;
 798                 }
 799                 i = lastbit - bit;
 800                 /*
 801                  * Go on to next block if that's where the next word is
 802                  * and we need the next word.
 803                  */
 804                 if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
 805                         /*
 806                          * If done with this block, get the next one.
 807                          */
 808                         xfs_trans_brelse(tp, bp);
 809                         error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
 810                         if (error) {
 811                                 return error;
 812                         }
 813                         b = bufp = bp->b_addr;
 814                         word = 0;
 815                 } else {
 816                         /*
 817                          * Go on to the next word in the buffer.
 818                          */
 819                         b++;
 820                 }
 821         } else {
 822                 /*
 823                  * Starting on a word boundary, no partial word.
 824                  */
 825                 i = 0;
 826         }
 827         /*
 828          * Loop over whole words in buffers.  When we use up one buffer
 829          * we move on to the next one.
 830          */
 831         while (len - i >= XFS_NBWORD) {
 832                 /*
 833                  * Compute difference between actual and desired value.
 834                  */
 835                 if ((wdiff = *b ^ val)) {
 836                         /*
 837                          * Different, compute first wrong bit and return.
 838                          */
 839                         xfs_trans_brelse(tp, bp);
 840                         i += XFS_RTLOBIT(wdiff);
 841                         *new = start + i;
 842                         *stat = 0;
 843                         return 0;
 844                 }
 845                 i += XFS_NBWORD;
 846                 /*
 847                  * Go on to next block if that's where the next word is
 848                  * and we need the next word.
 849                  */
 850                 if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
 851                         /*
 852                          * If done with this block, get the next one.
 853                          */
 854                         xfs_trans_brelse(tp, bp);
 855                         error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
 856                         if (error) {
 857                                 return error;
 858                         }
 859                         b = bufp = bp->b_addr;
 860                         word = 0;
 861                 } else {
 862                         /*
 863                          * Go on to the next word in the buffer.
 864                          */
 865                         b++;
 866                 }
 867         }
 868         /*
 869          * If not ending on a word boundary, deal with the last
 870          * (partial) word.
 871          */
 872         if ((lastbit = len - i)) {
 873                 /*
 874                  * Mask of relevant bits.
 875                  */
 876                 mask = ((xfs_rtword_t)1 << lastbit) - 1;
 877                 /*
 878                  * Compute difference between actual and desired value.
 879                  */
 880                 if ((wdiff = (*b ^ val) & mask)) {
 881                         /*
 882                          * Different, compute first wrong bit and return.
 883                          */
 884                         xfs_trans_brelse(tp, bp);
 885                         i += XFS_RTLOBIT(wdiff);
 886                         *new = start + i;
 887                         *stat = 0;
 888                         return 0;
 889                 } else
 890                         i = len;
 891         }
 892         /*
 893          * Successful, return.
 894          */
 895         xfs_trans_brelse(tp, bp);
 896         *new = start + i;
 897         *stat = 1;
 898         return 0;
 899 }
 900
 901 #ifdef DEBUG
 902 /*
 903  * Check that the given extent (block range) is allocated already.
 904  */
 905 STATIC int                              /* error */
 906 xfs_rtcheck_alloc_range(
 907         xfs_mount_t     *mp,            /* file system mount point */
 908         xfs_trans_t     *tp,            /* transaction pointer */
 909         xfs_rtblock_t   bno,            /* starting block number of extent */
 910         xfs_extlen_t    len)            /* length of extent */
 911 {
 912         xfs_rtblock_t   new;            /* dummy for xfs_rtcheck_range */
 913         int             stat;
 914         int             error;
 915
 916         error = xfs_rtcheck_range(mp, tp, bno, len, 0, &new, &stat);
 917         if (error)
 918                 return error;
 919         ASSERT(stat);
 920         return 0;
 921 }
 922 #else
 923 #define xfs_rtcheck_alloc_range(m,t,b,l)        (0)
 924 #endif
 925 /*
 926  * Free an extent in the realtime subvolume.  Length is expressed in
 927  * realtime extents, as is the block number.
 928  */
 929 int                                     /* error */
 930 xfs_rtfree_extent(
 931         xfs_trans_t     *tp,            /* transaction pointer */
 932         xfs_rtblock_t   bno,            /* starting block number to free */
 933         xfs_extlen_t    len)            /* length of extent freed */
 934 {
 935         int             error;          /* error value */
 936         xfs_mount_t     *mp;            /* file system mount structure */
 937         xfs_fsblock_t   sb;             /* summary file block number */
 938         xfs_buf_t       *sumbp = NULL;  /* summary file block buffer */
 939
 940         mp = tp->t_mountp;
 941
 942         ASSERT(mp->m_rbmip->i_itemp != NULL);
 943         ASSERT(xfs_isilocked(mp->m_rbmip, XFS_ILOCK_EXCL));
 944
 945         error = xfs_rtcheck_alloc_range(mp, tp, bno, len);
 946         if (error)
 947                 return error;
 948
 949         /*
 950          * Free the range of realtime blocks.
 951          */
 952         error = xfs_rtfree_range(mp, tp, bno, len, &sumbp, &sb);
 953         if (error) {
 954                 return error;
 955         }
 956         /*
 957          * Mark more blocks free in the superblock.
 958          */
 959         xfs_trans_mod_sb(tp, XFS_TRANS_SB_FREXTENTS, (long)len);
 960         /*
 961          * If we've now freed all the blocks, reset the file sequence
 962          * number to 0.
 963          */
 964         if (tp->t_frextents_delta + mp->m_sb.sb_frextents ==
 965             mp->m_sb.sb_rextents) {
 966                 if (!(mp->m_rbmip->i_d.di_flags & XFS_DIFLAG_NEWRTBM))
 967                         mp->m_rbmip->i_d.di_flags |= XFS_DIFLAG_NEWRTBM;
 968                 *(__uint64_t *)&mp->m_rbmip->i_d.di_atime = 0;
 969                 xfs_trans_log_inode(tp, mp->m_rbmip, XFS_ILOG_CORE);
 970         }
 971         return 0;
 972 }
 973