linux/fs/xfs/xfs_alloc.c
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   1/*
   2 * Copyright (c) 2000-2002,2005 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_types.h"
  21#include "xfs_bit.h"
  22#include "xfs_log.h"
  23#include "xfs_trans.h"
  24#include "xfs_sb.h"
  25#include "xfs_ag.h"
  26#include "xfs_mount.h"
  27#include "xfs_bmap_btree.h"
  28#include "xfs_alloc_btree.h"
  29#include "xfs_ialloc_btree.h"
  30#include "xfs_dinode.h"
  31#include "xfs_inode.h"
  32#include "xfs_btree.h"
  33#include "xfs_alloc.h"
  34#include "xfs_extent_busy.h"
  35#include "xfs_error.h"
  36#include "xfs_trace.h"
  37
  38struct workqueue_struct *xfs_alloc_wq;
  39
  40#define XFS_ABSDIFF(a,b)        (((a) <= (b)) ? ((b) - (a)) : ((a) - (b)))
  41
  42#define XFSA_FIXUP_BNO_OK       1
  43#define XFSA_FIXUP_CNT_OK       2
  44
  45STATIC int xfs_alloc_ag_vextent_exact(xfs_alloc_arg_t *);
  46STATIC int xfs_alloc_ag_vextent_near(xfs_alloc_arg_t *);
  47STATIC int xfs_alloc_ag_vextent_size(xfs_alloc_arg_t *);
  48STATIC int xfs_alloc_ag_vextent_small(xfs_alloc_arg_t *,
  49                xfs_btree_cur_t *, xfs_agblock_t *, xfs_extlen_t *, int *);
  50
  51/*
  52 * Lookup the record equal to [bno, len] in the btree given by cur.
  53 */
  54STATIC int                              /* error */
  55xfs_alloc_lookup_eq(
  56        struct xfs_btree_cur    *cur,   /* btree cursor */
  57        xfs_agblock_t           bno,    /* starting block of extent */
  58        xfs_extlen_t            len,    /* length of extent */
  59        int                     *stat)  /* success/failure */
  60{
  61        cur->bc_rec.a.ar_startblock = bno;
  62        cur->bc_rec.a.ar_blockcount = len;
  63        return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
  64}
  65
  66/*
  67 * Lookup the first record greater than or equal to [bno, len]
  68 * in the btree given by cur.
  69 */
  70int                             /* error */
  71xfs_alloc_lookup_ge(
  72        struct xfs_btree_cur    *cur,   /* btree cursor */
  73        xfs_agblock_t           bno,    /* starting block of extent */
  74        xfs_extlen_t            len,    /* length of extent */
  75        int                     *stat)  /* success/failure */
  76{
  77        cur->bc_rec.a.ar_startblock = bno;
  78        cur->bc_rec.a.ar_blockcount = len;
  79        return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
  80}
  81
  82/*
  83 * Lookup the first record less than or equal to [bno, len]
  84 * in the btree given by cur.
  85 */
  86int                                     /* error */
  87xfs_alloc_lookup_le(
  88        struct xfs_btree_cur    *cur,   /* btree cursor */
  89        xfs_agblock_t           bno,    /* starting block of extent */
  90        xfs_extlen_t            len,    /* length of extent */
  91        int                     *stat)  /* success/failure */
  92{
  93        cur->bc_rec.a.ar_startblock = bno;
  94        cur->bc_rec.a.ar_blockcount = len;
  95        return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
  96}
  97
  98/*
  99 * Update the record referred to by cur to the value given
 100 * by [bno, len].
 101 * This either works (return 0) or gets an EFSCORRUPTED error.
 102 */
 103STATIC int                              /* error */
 104xfs_alloc_update(
 105        struct xfs_btree_cur    *cur,   /* btree cursor */
 106        xfs_agblock_t           bno,    /* starting block of extent */
 107        xfs_extlen_t            len)    /* length of extent */
 108{
 109        union xfs_btree_rec     rec;
 110
 111        rec.alloc.ar_startblock = cpu_to_be32(bno);
 112        rec.alloc.ar_blockcount = cpu_to_be32(len);
 113        return xfs_btree_update(cur, &rec);
 114}
 115
 116/*
 117 * Get the data from the pointed-to record.
 118 */
 119int                                     /* error */
 120xfs_alloc_get_rec(
 121        struct xfs_btree_cur    *cur,   /* btree cursor */
 122        xfs_agblock_t           *bno,   /* output: starting block of extent */
 123        xfs_extlen_t            *len,   /* output: length of extent */
 124        int                     *stat)  /* output: success/failure */
 125{
 126        union xfs_btree_rec     *rec;
 127        int                     error;
 128
 129        error = xfs_btree_get_rec(cur, &rec, stat);
 130        if (!error && *stat == 1) {
 131                *bno = be32_to_cpu(rec->alloc.ar_startblock);
 132                *len = be32_to_cpu(rec->alloc.ar_blockcount);
 133        }
 134        return error;
 135}
 136
 137/*
 138 * Compute aligned version of the found extent.
 139 * Takes alignment and min length into account.
 140 */
 141STATIC void
 142xfs_alloc_compute_aligned(
 143        xfs_alloc_arg_t *args,          /* allocation argument structure */
 144        xfs_agblock_t   foundbno,       /* starting block in found extent */
 145        xfs_extlen_t    foundlen,       /* length in found extent */
 146        xfs_agblock_t   *resbno,        /* result block number */
 147        xfs_extlen_t    *reslen)        /* result length */
 148{
 149        xfs_agblock_t   bno;
 150        xfs_extlen_t    len;
 151
 152        /* Trim busy sections out of found extent */
 153        xfs_extent_busy_trim(args, foundbno, foundlen, &bno, &len);
 154
 155        if (args->alignment > 1 && len >= args->minlen) {
 156                xfs_agblock_t   aligned_bno = roundup(bno, args->alignment);
 157                xfs_extlen_t    diff = aligned_bno - bno;
 158
 159                *resbno = aligned_bno;
 160                *reslen = diff >= len ? 0 : len - diff;
 161        } else {
 162                *resbno = bno;
 163                *reslen = len;
 164        }
 165}
 166
 167/*
 168 * Compute best start block and diff for "near" allocations.
 169 * freelen >= wantlen already checked by caller.
 170 */
 171STATIC xfs_extlen_t                     /* difference value (absolute) */
 172xfs_alloc_compute_diff(
 173        xfs_agblock_t   wantbno,        /* target starting block */
 174        xfs_extlen_t    wantlen,        /* target length */
 175        xfs_extlen_t    alignment,      /* target alignment */
 176        xfs_agblock_t   freebno,        /* freespace's starting block */
 177        xfs_extlen_t    freelen,        /* freespace's length */
 178        xfs_agblock_t   *newbnop)       /* result: best start block from free */
 179{
 180        xfs_agblock_t   freeend;        /* end of freespace extent */
 181        xfs_agblock_t   newbno1;        /* return block number */
 182        xfs_agblock_t   newbno2;        /* other new block number */
 183        xfs_extlen_t    newlen1=0;      /* length with newbno1 */
 184        xfs_extlen_t    newlen2=0;      /* length with newbno2 */
 185        xfs_agblock_t   wantend;        /* end of target extent */
 186
 187        ASSERT(freelen >= wantlen);
 188        freeend = freebno + freelen;
 189        wantend = wantbno + wantlen;
 190        if (freebno >= wantbno) {
 191                if ((newbno1 = roundup(freebno, alignment)) >= freeend)
 192                        newbno1 = NULLAGBLOCK;
 193        } else if (freeend >= wantend && alignment > 1) {
 194                newbno1 = roundup(wantbno, alignment);
 195                newbno2 = newbno1 - alignment;
 196                if (newbno1 >= freeend)
 197                        newbno1 = NULLAGBLOCK;
 198                else
 199                        newlen1 = XFS_EXTLEN_MIN(wantlen, freeend - newbno1);
 200                if (newbno2 < freebno)
 201                        newbno2 = NULLAGBLOCK;
 202                else
 203                        newlen2 = XFS_EXTLEN_MIN(wantlen, freeend - newbno2);
 204                if (newbno1 != NULLAGBLOCK && newbno2 != NULLAGBLOCK) {
 205                        if (newlen1 < newlen2 ||
 206                            (newlen1 == newlen2 &&
 207                             XFS_ABSDIFF(newbno1, wantbno) >
 208                             XFS_ABSDIFF(newbno2, wantbno)))
 209                                newbno1 = newbno2;
 210                } else if (newbno2 != NULLAGBLOCK)
 211                        newbno1 = newbno2;
 212        } else if (freeend >= wantend) {
 213                newbno1 = wantbno;
 214        } else if (alignment > 1) {
 215                newbno1 = roundup(freeend - wantlen, alignment);
 216                if (newbno1 > freeend - wantlen &&
 217                    newbno1 - alignment >= freebno)
 218                        newbno1 -= alignment;
 219                else if (newbno1 >= freeend)
 220                        newbno1 = NULLAGBLOCK;
 221        } else
 222                newbno1 = freeend - wantlen;
 223        *newbnop = newbno1;
 224        return newbno1 == NULLAGBLOCK ? 0 : XFS_ABSDIFF(newbno1, wantbno);
 225}
 226
 227/*
 228 * Fix up the length, based on mod and prod.
 229 * len should be k * prod + mod for some k.
 230 * If len is too small it is returned unchanged.
 231 * If len hits maxlen it is left alone.
 232 */
 233STATIC void
 234xfs_alloc_fix_len(
 235        xfs_alloc_arg_t *args)          /* allocation argument structure */
 236{
 237        xfs_extlen_t    k;
 238        xfs_extlen_t    rlen;
 239
 240        ASSERT(args->mod < args->prod);
 241        rlen = args->len;
 242        ASSERT(rlen >= args->minlen);
 243        ASSERT(rlen <= args->maxlen);
 244        if (args->prod <= 1 || rlen < args->mod || rlen == args->maxlen ||
 245            (args->mod == 0 && rlen < args->prod))
 246                return;
 247        k = rlen % args->prod;
 248        if (k == args->mod)
 249                return;
 250        if (k > args->mod) {
 251                if ((int)(rlen = rlen - k - args->mod) < (int)args->minlen)
 252                        return;
 253        } else {
 254                if ((int)(rlen = rlen - args->prod - (args->mod - k)) <
 255                    (int)args->minlen)
 256                        return;
 257        }
 258        ASSERT(rlen >= args->minlen);
 259        ASSERT(rlen <= args->maxlen);
 260        args->len = rlen;
 261}
 262
 263/*
 264 * Fix up length if there is too little space left in the a.g.
 265 * Return 1 if ok, 0 if too little, should give up.
 266 */
 267STATIC int
 268xfs_alloc_fix_minleft(
 269        xfs_alloc_arg_t *args)          /* allocation argument structure */
 270{
 271        xfs_agf_t       *agf;           /* a.g. freelist header */
 272        int             diff;           /* free space difference */
 273
 274        if (args->minleft == 0)
 275                return 1;
 276        agf = XFS_BUF_TO_AGF(args->agbp);
 277        diff = be32_to_cpu(agf->agf_freeblks)
 278                - args->len - args->minleft;
 279        if (diff >= 0)
 280                return 1;
 281        args->len += diff;              /* shrink the allocated space */
 282        if (args->len >= args->minlen)
 283                return 1;
 284        args->agbno = NULLAGBLOCK;
 285        return 0;
 286}
 287
 288/*
 289 * Update the two btrees, logically removing from freespace the extent
 290 * starting at rbno, rlen blocks.  The extent is contained within the
 291 * actual (current) free extent fbno for flen blocks.
 292 * Flags are passed in indicating whether the cursors are set to the
 293 * relevant records.
 294 */
 295STATIC int                              /* error code */
 296xfs_alloc_fixup_trees(
 297        xfs_btree_cur_t *cnt_cur,       /* cursor for by-size btree */
 298        xfs_btree_cur_t *bno_cur,       /* cursor for by-block btree */
 299        xfs_agblock_t   fbno,           /* starting block of free extent */
 300        xfs_extlen_t    flen,           /* length of free extent */
 301        xfs_agblock_t   rbno,           /* starting block of returned extent */
 302        xfs_extlen_t    rlen,           /* length of returned extent */
 303        int             flags)          /* flags, XFSA_FIXUP_... */
 304{
 305        int             error;          /* error code */
 306        int             i;              /* operation results */
 307        xfs_agblock_t   nfbno1;         /* first new free startblock */
 308        xfs_agblock_t   nfbno2;         /* second new free startblock */
 309        xfs_extlen_t    nflen1=0;       /* first new free length */
 310        xfs_extlen_t    nflen2=0;       /* second new free length */
 311
 312        /*
 313         * Look up the record in the by-size tree if necessary.
 314         */
 315        if (flags & XFSA_FIXUP_CNT_OK) {
 316#ifdef DEBUG
 317                if ((error = xfs_alloc_get_rec(cnt_cur, &nfbno1, &nflen1, &i)))
 318                        return error;
 319                XFS_WANT_CORRUPTED_RETURN(
 320                        i == 1 && nfbno1 == fbno && nflen1 == flen);
 321#endif
 322        } else {
 323                if ((error = xfs_alloc_lookup_eq(cnt_cur, fbno, flen, &i)))
 324                        return error;
 325                XFS_WANT_CORRUPTED_RETURN(i == 1);
 326        }
 327        /*
 328         * Look up the record in the by-block tree if necessary.
 329         */
 330        if (flags & XFSA_FIXUP_BNO_OK) {
 331#ifdef DEBUG
 332                if ((error = xfs_alloc_get_rec(bno_cur, &nfbno1, &nflen1, &i)))
 333                        return error;
 334                XFS_WANT_CORRUPTED_RETURN(
 335                        i == 1 && nfbno1 == fbno && nflen1 == flen);
 336#endif
 337        } else {
 338                if ((error = xfs_alloc_lookup_eq(bno_cur, fbno, flen, &i)))
 339                        return error;
 340                XFS_WANT_CORRUPTED_RETURN(i == 1);
 341        }
 342
 343#ifdef DEBUG
 344        if (bno_cur->bc_nlevels == 1 && cnt_cur->bc_nlevels == 1) {
 345                struct xfs_btree_block  *bnoblock;
 346                struct xfs_btree_block  *cntblock;
 347
 348                bnoblock = XFS_BUF_TO_BLOCK(bno_cur->bc_bufs[0]);
 349                cntblock = XFS_BUF_TO_BLOCK(cnt_cur->bc_bufs[0]);
 350
 351                XFS_WANT_CORRUPTED_RETURN(
 352                        bnoblock->bb_numrecs == cntblock->bb_numrecs);
 353        }
 354#endif
 355
 356        /*
 357         * Deal with all four cases: the allocated record is contained
 358         * within the freespace record, so we can have new freespace
 359         * at either (or both) end, or no freespace remaining.
 360         */
 361        if (rbno == fbno && rlen == flen)
 362                nfbno1 = nfbno2 = NULLAGBLOCK;
 363        else if (rbno == fbno) {
 364                nfbno1 = rbno + rlen;
 365                nflen1 = flen - rlen;
 366                nfbno2 = NULLAGBLOCK;
 367        } else if (rbno + rlen == fbno + flen) {
 368                nfbno1 = fbno;
 369                nflen1 = flen - rlen;
 370                nfbno2 = NULLAGBLOCK;
 371        } else {
 372                nfbno1 = fbno;
 373                nflen1 = rbno - fbno;
 374                nfbno2 = rbno + rlen;
 375                nflen2 = (fbno + flen) - nfbno2;
 376        }
 377        /*
 378         * Delete the entry from the by-size btree.
 379         */
 380        if ((error = xfs_btree_delete(cnt_cur, &i)))
 381                return error;
 382        XFS_WANT_CORRUPTED_RETURN(i == 1);
 383        /*
 384         * Add new by-size btree entry(s).
 385         */
 386        if (nfbno1 != NULLAGBLOCK) {
 387                if ((error = xfs_alloc_lookup_eq(cnt_cur, nfbno1, nflen1, &i)))
 388                        return error;
 389                XFS_WANT_CORRUPTED_RETURN(i == 0);
 390                if ((error = xfs_btree_insert(cnt_cur, &i)))
 391                        return error;
 392                XFS_WANT_CORRUPTED_RETURN(i == 1);
 393        }
 394        if (nfbno2 != NULLAGBLOCK) {
 395                if ((error = xfs_alloc_lookup_eq(cnt_cur, nfbno2, nflen2, &i)))
 396                        return error;
 397                XFS_WANT_CORRUPTED_RETURN(i == 0);
 398                if ((error = xfs_btree_insert(cnt_cur, &i)))
 399                        return error;
 400                XFS_WANT_CORRUPTED_RETURN(i == 1);
 401        }
 402        /*
 403         * Fix up the by-block btree entry(s).
 404         */
 405        if (nfbno1 == NULLAGBLOCK) {
 406                /*
 407                 * No remaining freespace, just delete the by-block tree entry.
 408                 */
 409                if ((error = xfs_btree_delete(bno_cur, &i)))
 410                        return error;
 411                XFS_WANT_CORRUPTED_RETURN(i == 1);
 412        } else {
 413                /*
 414                 * Update the by-block entry to start later|be shorter.
 415                 */
 416                if ((error = xfs_alloc_update(bno_cur, nfbno1, nflen1)))
 417                        return error;
 418        }
 419        if (nfbno2 != NULLAGBLOCK) {
 420                /*
 421                 * 2 resulting free entries, need to add one.
 422                 */
 423                if ((error = xfs_alloc_lookup_eq(bno_cur, nfbno2, nflen2, &i)))
 424                        return error;
 425                XFS_WANT_CORRUPTED_RETURN(i == 0);
 426                if ((error = xfs_btree_insert(bno_cur, &i)))
 427                        return error;
 428                XFS_WANT_CORRUPTED_RETURN(i == 1);
 429        }
 430        return 0;
 431}
 432
 433/*
 434 * Read in the allocation group free block array.
 435 */
 436STATIC int                              /* error */
 437xfs_alloc_read_agfl(
 438        xfs_mount_t     *mp,            /* mount point structure */
 439        xfs_trans_t     *tp,            /* transaction pointer */
 440        xfs_agnumber_t  agno,           /* allocation group number */
 441        xfs_buf_t       **bpp)          /* buffer for the ag free block array */
 442{
 443        xfs_buf_t       *bp;            /* return value */
 444        int             error;
 445
 446        ASSERT(agno != NULLAGNUMBER);
 447        error = xfs_trans_read_buf(
 448                        mp, tp, mp->m_ddev_targp,
 449                        XFS_AG_DADDR(mp, agno, XFS_AGFL_DADDR(mp)),
 450                        XFS_FSS_TO_BB(mp, 1), 0, &bp);
 451        if (error)
 452                return error;
 453        ASSERT(!xfs_buf_geterror(bp));
 454        xfs_buf_set_ref(bp, XFS_AGFL_REF);
 455        *bpp = bp;
 456        return 0;
 457}
 458
 459STATIC int
 460xfs_alloc_update_counters(
 461        struct xfs_trans        *tp,
 462        struct xfs_perag        *pag,
 463        struct xfs_buf          *agbp,
 464        long                    len)
 465{
 466        struct xfs_agf          *agf = XFS_BUF_TO_AGF(agbp);
 467
 468        pag->pagf_freeblks += len;
 469        be32_add_cpu(&agf->agf_freeblks, len);
 470
 471        xfs_trans_agblocks_delta(tp, len);
 472        if (unlikely(be32_to_cpu(agf->agf_freeblks) >
 473                     be32_to_cpu(agf->agf_length)))
 474                return EFSCORRUPTED;
 475
 476        xfs_alloc_log_agf(tp, agbp, XFS_AGF_FREEBLKS);
 477        return 0;
 478}
 479
 480/*
 481 * Allocation group level functions.
 482 */
 483
 484/*
 485 * Allocate a variable extent in the allocation group agno.
 486 * Type and bno are used to determine where in the allocation group the
 487 * extent will start.
 488 * Extent's length (returned in *len) will be between minlen and maxlen,
 489 * and of the form k * prod + mod unless there's nothing that large.
 490 * Return the starting a.g. block, or NULLAGBLOCK if we can't do it.
 491 */
 492STATIC int                      /* error */
 493xfs_alloc_ag_vextent(
 494        xfs_alloc_arg_t *args)  /* argument structure for allocation */
 495{
 496        int             error=0;
 497
 498        ASSERT(args->minlen > 0);
 499        ASSERT(args->maxlen > 0);
 500        ASSERT(args->minlen <= args->maxlen);
 501        ASSERT(args->mod < args->prod);
 502        ASSERT(args->alignment > 0);
 503        /*
 504         * Branch to correct routine based on the type.
 505         */
 506        args->wasfromfl = 0;
 507        switch (args->type) {
 508        case XFS_ALLOCTYPE_THIS_AG:
 509                error = xfs_alloc_ag_vextent_size(args);
 510                break;
 511        case XFS_ALLOCTYPE_NEAR_BNO:
 512                error = xfs_alloc_ag_vextent_near(args);
 513                break;
 514        case XFS_ALLOCTYPE_THIS_BNO:
 515                error = xfs_alloc_ag_vextent_exact(args);
 516                break;
 517        default:
 518                ASSERT(0);
 519                /* NOTREACHED */
 520        }
 521
 522        if (error || args->agbno == NULLAGBLOCK)
 523                return error;
 524
 525        ASSERT(args->len >= args->minlen);
 526        ASSERT(args->len <= args->maxlen);
 527        ASSERT(!args->wasfromfl || !args->isfl);
 528        ASSERT(args->agbno % args->alignment == 0);
 529
 530        if (!args->wasfromfl) {
 531                error = xfs_alloc_update_counters(args->tp, args->pag,
 532                                                  args->agbp,
 533                                                  -((long)(args->len)));
 534                if (error)
 535                        return error;
 536
 537                ASSERT(!xfs_extent_busy_search(args->mp, args->agno,
 538                                              args->agbno, args->len));
 539        }
 540
 541        if (!args->isfl) {
 542                xfs_trans_mod_sb(args->tp, args->wasdel ?
 543                                 XFS_TRANS_SB_RES_FDBLOCKS :
 544                                 XFS_TRANS_SB_FDBLOCKS,
 545                                 -((long)(args->len)));
 546        }
 547
 548        XFS_STATS_INC(xs_allocx);
 549        XFS_STATS_ADD(xs_allocb, args->len);
 550        return error;
 551}
 552
 553/*
 554 * Allocate a variable extent at exactly agno/bno.
 555 * Extent's length (returned in *len) will be between minlen and maxlen,
 556 * and of the form k * prod + mod unless there's nothing that large.
 557 * Return the starting a.g. block (bno), or NULLAGBLOCK if we can't do it.
 558 */
 559STATIC int                      /* error */
 560xfs_alloc_ag_vextent_exact(
 561        xfs_alloc_arg_t *args)  /* allocation argument structure */
 562{
 563        xfs_btree_cur_t *bno_cur;/* by block-number btree cursor */
 564        xfs_btree_cur_t *cnt_cur;/* by count btree cursor */
 565        int             error;
 566        xfs_agblock_t   fbno;   /* start block of found extent */
 567        xfs_extlen_t    flen;   /* length of found extent */
 568        xfs_agblock_t   tbno;   /* start block of trimmed extent */
 569        xfs_extlen_t    tlen;   /* length of trimmed extent */
 570        xfs_agblock_t   tend;   /* end block of trimmed extent */
 571        int             i;      /* success/failure of operation */
 572
 573        ASSERT(args->alignment == 1);
 574
 575        /*
 576         * Allocate/initialize a cursor for the by-number freespace btree.
 577         */
 578        bno_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
 579                                          args->agno, XFS_BTNUM_BNO);
 580
 581        /*
 582         * Lookup bno and minlen in the btree (minlen is irrelevant, really).
 583         * Look for the closest free block <= bno, it must contain bno
 584         * if any free block does.
 585         */
 586        error = xfs_alloc_lookup_le(bno_cur, args->agbno, args->minlen, &i);
 587        if (error)
 588                goto error0;
 589        if (!i)
 590                goto not_found;
 591
 592        /*
 593         * Grab the freespace record.
 594         */
 595        error = xfs_alloc_get_rec(bno_cur, &fbno, &flen, &i);
 596        if (error)
 597                goto error0;
 598        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
 599        ASSERT(fbno <= args->agbno);
 600
 601        /*
 602         * Check for overlapping busy extents.
 603         */
 604        xfs_extent_busy_trim(args, fbno, flen, &tbno, &tlen);
 605
 606        /*
 607         * Give up if the start of the extent is busy, or the freespace isn't
 608         * long enough for the minimum request.
 609         */
 610        if (tbno > args->agbno)
 611                goto not_found;
 612        if (tlen < args->minlen)
 613                goto not_found;
 614        tend = tbno + tlen;
 615        if (tend < args->agbno + args->minlen)
 616                goto not_found;
 617
 618        /*
 619         * End of extent will be smaller of the freespace end and the
 620         * maximal requested end.
 621         *
 622         * Fix the length according to mod and prod if given.
 623         */
 624        args->len = XFS_AGBLOCK_MIN(tend, args->agbno + args->maxlen)
 625                                                - args->agbno;
 626        xfs_alloc_fix_len(args);
 627        if (!xfs_alloc_fix_minleft(args))
 628                goto not_found;
 629
 630        ASSERT(args->agbno + args->len <= tend);
 631
 632        /*
 633         * We are allocating agbno for args->len
 634         * Allocate/initialize a cursor for the by-size btree.
 635         */
 636        cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
 637                args->agno, XFS_BTNUM_CNT);
 638        ASSERT(args->agbno + args->len <=
 639                be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
 640        error = xfs_alloc_fixup_trees(cnt_cur, bno_cur, fbno, flen, args->agbno,
 641                                      args->len, XFSA_FIXUP_BNO_OK);
 642        if (error) {
 643                xfs_btree_del_cursor(cnt_cur, XFS_BTREE_ERROR);
 644                goto error0;
 645        }
 646
 647        xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
 648        xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
 649
 650        args->wasfromfl = 0;
 651        trace_xfs_alloc_exact_done(args);
 652        return 0;
 653
 654not_found:
 655        /* Didn't find it, return null. */
 656        xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
 657        args->agbno = NULLAGBLOCK;
 658        trace_xfs_alloc_exact_notfound(args);
 659        return 0;
 660
 661error0:
 662        xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR);
 663        trace_xfs_alloc_exact_error(args);
 664        return error;
 665}
 666
 667/*
 668 * Search the btree in a given direction via the search cursor and compare
 669 * the records found against the good extent we've already found.
 670 */
 671STATIC int
 672xfs_alloc_find_best_extent(
 673        struct xfs_alloc_arg    *args,  /* allocation argument structure */
 674        struct xfs_btree_cur    **gcur, /* good cursor */
 675        struct xfs_btree_cur    **scur, /* searching cursor */
 676        xfs_agblock_t           gdiff,  /* difference for search comparison */
 677        xfs_agblock_t           *sbno,  /* extent found by search */
 678        xfs_extlen_t            *slen,  /* extent length */
 679        xfs_agblock_t           *sbnoa, /* aligned extent found by search */
 680        xfs_extlen_t            *slena, /* aligned extent length */
 681        int                     dir)    /* 0 = search right, 1 = search left */
 682{
 683        xfs_agblock_t           new;
 684        xfs_agblock_t           sdiff;
 685        int                     error;
 686        int                     i;
 687
 688        /* The good extent is perfect, no need to  search. */
 689        if (!gdiff)
 690                goto out_use_good;
 691
 692        /*
 693         * Look until we find a better one, run out of space or run off the end.
 694         */
 695        do {
 696                error = xfs_alloc_get_rec(*scur, sbno, slen, &i);
 697                if (error)
 698                        goto error0;
 699                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
 700                xfs_alloc_compute_aligned(args, *sbno, *slen, sbnoa, slena);
 701
 702                /*
 703                 * The good extent is closer than this one.
 704                 */
 705                if (!dir) {
 706                        if (*sbnoa >= args->agbno + gdiff)
 707                                goto out_use_good;
 708                } else {
 709                        if (*sbnoa <= args->agbno - gdiff)
 710                                goto out_use_good;
 711                }
 712
 713                /*
 714                 * Same distance, compare length and pick the best.
 715                 */
 716                if (*slena >= args->minlen) {
 717                        args->len = XFS_EXTLEN_MIN(*slena, args->maxlen);
 718                        xfs_alloc_fix_len(args);
 719
 720                        sdiff = xfs_alloc_compute_diff(args->agbno, args->len,
 721                                                       args->alignment, *sbnoa,
 722                                                       *slena, &new);
 723
 724                        /*
 725                         * Choose closer size and invalidate other cursor.
 726                         */
 727                        if (sdiff < gdiff)
 728                                goto out_use_search;
 729                        goto out_use_good;
 730                }
 731
 732                if (!dir)
 733                        error = xfs_btree_increment(*scur, 0, &i);
 734                else
 735                        error = xfs_btree_decrement(*scur, 0, &i);
 736                if (error)
 737                        goto error0;
 738        } while (i);
 739
 740out_use_good:
 741        xfs_btree_del_cursor(*scur, XFS_BTREE_NOERROR);
 742        *scur = NULL;
 743        return 0;
 744
 745out_use_search:
 746        xfs_btree_del_cursor(*gcur, XFS_BTREE_NOERROR);
 747        *gcur = NULL;
 748        return 0;
 749
 750error0:
 751        /* caller invalidates cursors */
 752        return error;
 753}
 754
 755/*
 756 * Allocate a variable extent near bno in the allocation group agno.
 757 * Extent's length (returned in len) will be between minlen and maxlen,
 758 * and of the form k * prod + mod unless there's nothing that large.
 759 * Return the starting a.g. block, or NULLAGBLOCK if we can't do it.
 760 */
 761STATIC int                              /* error */
 762xfs_alloc_ag_vextent_near(
 763        xfs_alloc_arg_t *args)          /* allocation argument structure */
 764{
 765        xfs_btree_cur_t *bno_cur_gt;    /* cursor for bno btree, right side */
 766        xfs_btree_cur_t *bno_cur_lt;    /* cursor for bno btree, left side */
 767        xfs_btree_cur_t *cnt_cur;       /* cursor for count btree */
 768        xfs_agblock_t   gtbno;          /* start bno of right side entry */
 769        xfs_agblock_t   gtbnoa;         /* aligned ... */
 770        xfs_extlen_t    gtdiff;         /* difference to right side entry */
 771        xfs_extlen_t    gtlen;          /* length of right side entry */
 772        xfs_extlen_t    gtlena;         /* aligned ... */
 773        xfs_agblock_t   gtnew;          /* useful start bno of right side */
 774        int             error;          /* error code */
 775        int             i;              /* result code, temporary */
 776        int             j;              /* result code, temporary */
 777        xfs_agblock_t   ltbno;          /* start bno of left side entry */
 778        xfs_agblock_t   ltbnoa;         /* aligned ... */
 779        xfs_extlen_t    ltdiff;         /* difference to left side entry */
 780        xfs_extlen_t    ltlen;          /* length of left side entry */
 781        xfs_extlen_t    ltlena;         /* aligned ... */
 782        xfs_agblock_t   ltnew;          /* useful start bno of left side */
 783        xfs_extlen_t    rlen;           /* length of returned extent */
 784        int             forced = 0;
 785#if defined(DEBUG) && defined(__KERNEL__)
 786        /*
 787         * Randomly don't execute the first algorithm.
 788         */
 789        int             dofirst;        /* set to do first algorithm */
 790
 791        dofirst = random32() & 1;
 792#endif
 793
 794restart:
 795        bno_cur_lt = NULL;
 796        bno_cur_gt = NULL;
 797        ltlen = 0;
 798        gtlena = 0;
 799        ltlena = 0;
 800
 801        /*
 802         * Get a cursor for the by-size btree.
 803         */
 804        cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
 805                args->agno, XFS_BTNUM_CNT);
 806
 807        /*
 808         * See if there are any free extents as big as maxlen.
 809         */
 810        if ((error = xfs_alloc_lookup_ge(cnt_cur, 0, args->maxlen, &i)))
 811                goto error0;
 812        /*
 813         * If none, then pick up the last entry in the tree unless the
 814         * tree is empty.
 815         */
 816        if (!i) {
 817                if ((error = xfs_alloc_ag_vextent_small(args, cnt_cur, &ltbno,
 818                                &ltlen, &i)))
 819                        goto error0;
 820                if (i == 0 || ltlen == 0) {
 821                        xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
 822                        trace_xfs_alloc_near_noentry(args);
 823                        return 0;
 824                }
 825                ASSERT(i == 1);
 826        }
 827        args->wasfromfl = 0;
 828
 829        /*
 830         * First algorithm.
 831         * If the requested extent is large wrt the freespaces available
 832         * in this a.g., then the cursor will be pointing to a btree entry
 833         * near the right edge of the tree.  If it's in the last btree leaf
 834         * block, then we just examine all the entries in that block
 835         * that are big enough, and pick the best one.
 836         * This is written as a while loop so we can break out of it,
 837         * but we never loop back to the top.
 838         */
 839        while (xfs_btree_islastblock(cnt_cur, 0)) {
 840                xfs_extlen_t    bdiff;
 841                int             besti=0;
 842                xfs_extlen_t    blen=0;
 843                xfs_agblock_t   bnew=0;
 844
 845#if defined(DEBUG) && defined(__KERNEL__)
 846                if (!dofirst)
 847                        break;
 848#endif
 849                /*
 850                 * Start from the entry that lookup found, sequence through
 851                 * all larger free blocks.  If we're actually pointing at a
 852                 * record smaller than maxlen, go to the start of this block,
 853                 * and skip all those smaller than minlen.
 854                 */
 855                if (ltlen || args->alignment > 1) {
 856                        cnt_cur->bc_ptrs[0] = 1;
 857                        do {
 858                                if ((error = xfs_alloc_get_rec(cnt_cur, &ltbno,
 859                                                &ltlen, &i)))
 860                                        goto error0;
 861                                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
 862                                if (ltlen >= args->minlen)
 863                                        break;
 864                                if ((error = xfs_btree_increment(cnt_cur, 0, &i)))
 865                                        goto error0;
 866                        } while (i);
 867                        ASSERT(ltlen >= args->minlen);
 868                        if (!i)
 869                                break;
 870                }
 871                i = cnt_cur->bc_ptrs[0];
 872                for (j = 1, blen = 0, bdiff = 0;
 873                     !error && j && (blen < args->maxlen || bdiff > 0);
 874                     error = xfs_btree_increment(cnt_cur, 0, &j)) {
 875                        /*
 876                         * For each entry, decide if it's better than
 877                         * the previous best entry.
 878                         */
 879                        if ((error = xfs_alloc_get_rec(cnt_cur, &ltbno, &ltlen, &i)))
 880                                goto error0;
 881                        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
 882                        xfs_alloc_compute_aligned(args, ltbno, ltlen,
 883                                                  &ltbnoa, &ltlena);
 884                        if (ltlena < args->minlen)
 885                                continue;
 886                        args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
 887                        xfs_alloc_fix_len(args);
 888                        ASSERT(args->len >= args->minlen);
 889                        if (args->len < blen)
 890                                continue;
 891                        ltdiff = xfs_alloc_compute_diff(args->agbno, args->len,
 892                                args->alignment, ltbnoa, ltlena, &ltnew);
 893                        if (ltnew != NULLAGBLOCK &&
 894                            (args->len > blen || ltdiff < bdiff)) {
 895                                bdiff = ltdiff;
 896                                bnew = ltnew;
 897                                blen = args->len;
 898                                besti = cnt_cur->bc_ptrs[0];
 899                        }
 900                }
 901                /*
 902                 * It didn't work.  We COULD be in a case where
 903                 * there's a good record somewhere, so try again.
 904                 */
 905                if (blen == 0)
 906                        break;
 907                /*
 908                 * Point at the best entry, and retrieve it again.
 909                 */
 910                cnt_cur->bc_ptrs[0] = besti;
 911                if ((error = xfs_alloc_get_rec(cnt_cur, &ltbno, &ltlen, &i)))
 912                        goto error0;
 913                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
 914                ASSERT(ltbno + ltlen <= be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
 915                args->len = blen;
 916                if (!xfs_alloc_fix_minleft(args)) {
 917                        xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
 918                        trace_xfs_alloc_near_nominleft(args);
 919                        return 0;
 920                }
 921                blen = args->len;
 922                /*
 923                 * We are allocating starting at bnew for blen blocks.
 924                 */
 925                args->agbno = bnew;
 926                ASSERT(bnew >= ltbno);
 927                ASSERT(bnew + blen <= ltbno + ltlen);
 928                /*
 929                 * Set up a cursor for the by-bno tree.
 930                 */
 931                bno_cur_lt = xfs_allocbt_init_cursor(args->mp, args->tp,
 932                        args->agbp, args->agno, XFS_BTNUM_BNO);
 933                /*
 934                 * Fix up the btree entries.
 935                 */
 936                if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur_lt, ltbno,
 937                                ltlen, bnew, blen, XFSA_FIXUP_CNT_OK)))
 938                        goto error0;
 939                xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
 940                xfs_btree_del_cursor(bno_cur_lt, XFS_BTREE_NOERROR);
 941
 942                trace_xfs_alloc_near_first(args);
 943                return 0;
 944        }
 945        /*
 946         * Second algorithm.
 947         * Search in the by-bno tree to the left and to the right
 948         * simultaneously, until in each case we find a space big enough,
 949         * or run into the edge of the tree.  When we run into the edge,
 950         * we deallocate that cursor.
 951         * If both searches succeed, we compare the two spaces and pick
 952         * the better one.
 953         * With alignment, it's possible for both to fail; the upper
 954         * level algorithm that picks allocation groups for allocations
 955         * is not supposed to do this.
 956         */
 957        /*
 958         * Allocate and initialize the cursor for the leftward search.
 959         */
 960        bno_cur_lt = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
 961                args->agno, XFS_BTNUM_BNO);
 962        /*
 963         * Lookup <= bno to find the leftward search's starting point.
 964         */
 965        if ((error = xfs_alloc_lookup_le(bno_cur_lt, args->agbno, args->maxlen, &i)))
 966                goto error0;
 967        if (!i) {
 968                /*
 969                 * Didn't find anything; use this cursor for the rightward
 970                 * search.
 971                 */
 972                bno_cur_gt = bno_cur_lt;
 973                bno_cur_lt = NULL;
 974        }
 975        /*
 976         * Found something.  Duplicate the cursor for the rightward search.
 977         */
 978        else if ((error = xfs_btree_dup_cursor(bno_cur_lt, &bno_cur_gt)))
 979                goto error0;
 980        /*
 981         * Increment the cursor, so we will point at the entry just right
 982         * of the leftward entry if any, or to the leftmost entry.
 983         */
 984        if ((error = xfs_btree_increment(bno_cur_gt, 0, &i)))
 985                goto error0;
 986        if (!i) {
 987                /*
 988                 * It failed, there are no rightward entries.
 989                 */
 990                xfs_btree_del_cursor(bno_cur_gt, XFS_BTREE_NOERROR);
 991                bno_cur_gt = NULL;
 992        }
 993        /*
 994         * Loop going left with the leftward cursor, right with the
 995         * rightward cursor, until either both directions give up or
 996         * we find an entry at least as big as minlen.
 997         */
 998        do {
 999                if (bno_cur_lt) {
1000                        if ((error = xfs_alloc_get_rec(bno_cur_lt, &ltbno, &ltlen, &i)))
1001                                goto error0;
1002                        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1003                        xfs_alloc_compute_aligned(args, ltbno, ltlen,
1004                                                  &ltbnoa, &ltlena);
1005                        if (ltlena >= args->minlen)
1006                                break;
1007                        if ((error = xfs_btree_decrement(bno_cur_lt, 0, &i)))
1008                                goto error0;
1009                        if (!i) {
1010                                xfs_btree_del_cursor(bno_cur_lt,
1011                                                     XFS_BTREE_NOERROR);
1012                                bno_cur_lt = NULL;
1013                        }
1014                }
1015                if (bno_cur_gt) {
1016                        if ((error = xfs_alloc_get_rec(bno_cur_gt, &gtbno, &gtlen, &i)))
1017                                goto error0;
1018                        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1019                        xfs_alloc_compute_aligned(args, gtbno, gtlen,
1020                                                  &gtbnoa, &gtlena);
1021                        if (gtlena >= args->minlen)
1022                                break;
1023                        if ((error = xfs_btree_increment(bno_cur_gt, 0, &i)))
1024                                goto error0;
1025                        if (!i) {
1026                                xfs_btree_del_cursor(bno_cur_gt,
1027                                                     XFS_BTREE_NOERROR);
1028                                bno_cur_gt = NULL;
1029                        }
1030                }
1031        } while (bno_cur_lt || bno_cur_gt);
1032
1033        /*
1034         * Got both cursors still active, need to find better entry.
1035         */
1036        if (bno_cur_lt && bno_cur_gt) {
1037                if (ltlena >= args->minlen) {
1038                        /*
1039                         * Left side is good, look for a right side entry.
1040                         */
1041                        args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
1042                        xfs_alloc_fix_len(args);
1043                        ltdiff = xfs_alloc_compute_diff(args->agbno, args->len,
1044                                args->alignment, ltbnoa, ltlena, &ltnew);
1045
1046                        error = xfs_alloc_find_best_extent(args,
1047                                                &bno_cur_lt, &bno_cur_gt,
1048                                                ltdiff, &gtbno, &gtlen,
1049                                                &gtbnoa, &gtlena,
1050                                                0 /* search right */);
1051                } else {
1052                        ASSERT(gtlena >= args->minlen);
1053
1054                        /*
1055                         * Right side is good, look for a left side entry.
1056                         */
1057                        args->len = XFS_EXTLEN_MIN(gtlena, args->maxlen);
1058                        xfs_alloc_fix_len(args);
1059                        gtdiff = xfs_alloc_compute_diff(args->agbno, args->len,
1060                                args->alignment, gtbnoa, gtlena, &gtnew);
1061
1062                        error = xfs_alloc_find_best_extent(args,
1063                                                &bno_cur_gt, &bno_cur_lt,
1064                                                gtdiff, &ltbno, &ltlen,
1065                                                &ltbnoa, &ltlena,
1066                                                1 /* search left */);
1067                }
1068
1069                if (error)
1070                        goto error0;
1071        }
1072
1073        /*
1074         * If we couldn't get anything, give up.
1075         */
1076        if (bno_cur_lt == NULL && bno_cur_gt == NULL) {
1077                xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1078
1079                if (!forced++) {
1080                        trace_xfs_alloc_near_busy(args);
1081                        xfs_log_force(args->mp, XFS_LOG_SYNC);
1082                        goto restart;
1083                }
1084                trace_xfs_alloc_size_neither(args);
1085                args->agbno = NULLAGBLOCK;
1086                return 0;
1087        }
1088
1089        /*
1090         * At this point we have selected a freespace entry, either to the
1091         * left or to the right.  If it's on the right, copy all the
1092         * useful variables to the "left" set so we only have one
1093         * copy of this code.
1094         */
1095        if (bno_cur_gt) {
1096                bno_cur_lt = bno_cur_gt;
1097                bno_cur_gt = NULL;
1098                ltbno = gtbno;
1099                ltbnoa = gtbnoa;
1100                ltlen = gtlen;
1101                ltlena = gtlena;
1102                j = 1;
1103        } else
1104                j = 0;
1105
1106        /*
1107         * Fix up the length and compute the useful address.
1108         */
1109        args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
1110        xfs_alloc_fix_len(args);
1111        if (!xfs_alloc_fix_minleft(args)) {
1112                trace_xfs_alloc_near_nominleft(args);
1113                xfs_btree_del_cursor(bno_cur_lt, XFS_BTREE_NOERROR);
1114                xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1115                return 0;
1116        }
1117        rlen = args->len;
1118        (void)xfs_alloc_compute_diff(args->agbno, rlen, args->alignment,
1119                                     ltbnoa, ltlena, &ltnew);
1120        ASSERT(ltnew >= ltbno);
1121        ASSERT(ltnew + rlen <= ltbnoa + ltlena);
1122        ASSERT(ltnew + rlen <= be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
1123        args->agbno = ltnew;
1124
1125        if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur_lt, ltbno, ltlen,
1126                        ltnew, rlen, XFSA_FIXUP_BNO_OK)))
1127                goto error0;
1128
1129        if (j)
1130                trace_xfs_alloc_near_greater(args);
1131        else
1132                trace_xfs_alloc_near_lesser(args);
1133
1134        xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1135        xfs_btree_del_cursor(bno_cur_lt, XFS_BTREE_NOERROR);
1136        return 0;
1137
1138 error0:
1139        trace_xfs_alloc_near_error(args);
1140        if (cnt_cur != NULL)
1141                xfs_btree_del_cursor(cnt_cur, XFS_BTREE_ERROR);
1142        if (bno_cur_lt != NULL)
1143                xfs_btree_del_cursor(bno_cur_lt, XFS_BTREE_ERROR);
1144        if (bno_cur_gt != NULL)
1145                xfs_btree_del_cursor(bno_cur_gt, XFS_BTREE_ERROR);
1146        return error;
1147}
1148
1149/*
1150 * Allocate a variable extent anywhere in the allocation group agno.
1151 * Extent's length (returned in len) will be between minlen and maxlen,
1152 * and of the form k * prod + mod unless there's nothing that large.
1153 * Return the starting a.g. block, or NULLAGBLOCK if we can't do it.
1154 */
1155STATIC int                              /* error */
1156xfs_alloc_ag_vextent_size(
1157        xfs_alloc_arg_t *args)          /* allocation argument structure */
1158{
1159        xfs_btree_cur_t *bno_cur;       /* cursor for bno btree */
1160        xfs_btree_cur_t *cnt_cur;       /* cursor for cnt btree */
1161        int             error;          /* error result */
1162        xfs_agblock_t   fbno;           /* start of found freespace */
1163        xfs_extlen_t    flen;           /* length of found freespace */
1164        int             i;              /* temp status variable */
1165        xfs_agblock_t   rbno;           /* returned block number */
1166        xfs_extlen_t    rlen;           /* length of returned extent */
1167        int             forced = 0;
1168
1169restart:
1170        /*
1171         * Allocate and initialize a cursor for the by-size btree.
1172         */
1173        cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
1174                args->agno, XFS_BTNUM_CNT);
1175        bno_cur = NULL;
1176
1177        /*
1178         * Look for an entry >= maxlen+alignment-1 blocks.
1179         */
1180        if ((error = xfs_alloc_lookup_ge(cnt_cur, 0,
1181                        args->maxlen + args->alignment - 1, &i)))
1182                goto error0;
1183
1184        /*
1185         * If none or we have busy extents that we cannot allocate from, then
1186         * we have to settle for a smaller extent. In the case that there are
1187         * no large extents, this will return the last entry in the tree unless
1188         * the tree is empty. In the case that there are only busy large
1189         * extents, this will return the largest small extent unless there
1190         * are no smaller extents available.
1191         */
1192        if (!i || forced > 1) {
1193                error = xfs_alloc_ag_vextent_small(args, cnt_cur,
1194                                                   &fbno, &flen, &i);
1195                if (error)
1196                        goto error0;
1197                if (i == 0 || flen == 0) {
1198                        xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1199                        trace_xfs_alloc_size_noentry(args);
1200                        return 0;
1201                }
1202                ASSERT(i == 1);
1203                xfs_alloc_compute_aligned(args, fbno, flen, &rbno, &rlen);
1204        } else {
1205                /*
1206                 * Search for a non-busy extent that is large enough.
1207                 * If we are at low space, don't check, or if we fall of
1208                 * the end of the btree, turn off the busy check and
1209                 * restart.
1210                 */
1211                for (;;) {
1212                        error = xfs_alloc_get_rec(cnt_cur, &fbno, &flen, &i);
1213                        if (error)
1214                                goto error0;
1215                        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1216
1217                        xfs_alloc_compute_aligned(args, fbno, flen,
1218                                                  &rbno, &rlen);
1219
1220                        if (rlen >= args->maxlen)
1221                                break;
1222
1223                        error = xfs_btree_increment(cnt_cur, 0, &i);
1224                        if (error)
1225                                goto error0;
1226                        if (i == 0) {
1227                                /*
1228                                 * Our only valid extents must have been busy.
1229                                 * Make it unbusy by forcing the log out and
1230                                 * retrying. If we've been here before, forcing
1231                                 * the log isn't making the extents available,
1232                                 * which means they have probably been freed in
1233                                 * this transaction.  In that case, we have to
1234                                 * give up on them and we'll attempt a minlen
1235                                 * allocation the next time around.
1236                                 */
1237                                xfs_btree_del_cursor(cnt_cur,
1238                                                     XFS_BTREE_NOERROR);
1239                                trace_xfs_alloc_size_busy(args);
1240                                if (!forced++)
1241                                        xfs_log_force(args->mp, XFS_LOG_SYNC);
1242                                goto restart;
1243                        }
1244                }
1245        }
1246
1247        /*
1248         * In the first case above, we got the last entry in the
1249         * by-size btree.  Now we check to see if the space hits maxlen
1250         * once aligned; if not, we search left for something better.
1251         * This can't happen in the second case above.
1252         */
1253        rlen = XFS_EXTLEN_MIN(args->maxlen, rlen);
1254        XFS_WANT_CORRUPTED_GOTO(rlen == 0 ||
1255                        (rlen <= flen && rbno + rlen <= fbno + flen), error0);
1256        if (rlen < args->maxlen) {
1257                xfs_agblock_t   bestfbno;
1258                xfs_extlen_t    bestflen;
1259                xfs_agblock_t   bestrbno;
1260                xfs_extlen_t    bestrlen;
1261
1262                bestrlen = rlen;
1263                bestrbno = rbno;
1264                bestflen = flen;
1265                bestfbno = fbno;
1266                for (;;) {
1267                        if ((error = xfs_btree_decrement(cnt_cur, 0, &i)))
1268                                goto error0;
1269                        if (i == 0)
1270                                break;
1271                        if ((error = xfs_alloc_get_rec(cnt_cur, &fbno, &flen,
1272                                        &i)))
1273                                goto error0;
1274                        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1275                        if (flen < bestrlen)
1276                                break;
1277                        xfs_alloc_compute_aligned(args, fbno, flen,
1278                                                  &rbno, &rlen);
1279                        rlen = XFS_EXTLEN_MIN(args->maxlen, rlen);
1280                        XFS_WANT_CORRUPTED_GOTO(rlen == 0 ||
1281                                (rlen <= flen && rbno + rlen <= fbno + flen),
1282                                error0);
1283                        if (rlen > bestrlen) {
1284                                bestrlen = rlen;
1285                                bestrbno = rbno;
1286                                bestflen = flen;
1287                                bestfbno = fbno;
1288                                if (rlen == args->maxlen)
1289                                        break;
1290                        }
1291                }
1292                if ((error = xfs_alloc_lookup_eq(cnt_cur, bestfbno, bestflen,
1293                                &i)))
1294                        goto error0;
1295                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1296                rlen = bestrlen;
1297                rbno = bestrbno;
1298                flen = bestflen;
1299                fbno = bestfbno;
1300        }
1301        args->wasfromfl = 0;
1302        /*
1303         * Fix up the length.
1304         */
1305        args->len = rlen;
1306        if (rlen < args->minlen) {
1307                if (!forced++) {
1308                        xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1309                        trace_xfs_alloc_size_busy(args);
1310                        xfs_log_force(args->mp, XFS_LOG_SYNC);
1311                        goto restart;
1312                }
1313                goto out_nominleft;
1314        }
1315        xfs_alloc_fix_len(args);
1316
1317        if (!xfs_alloc_fix_minleft(args))
1318                goto out_nominleft;
1319        rlen = args->len;
1320        XFS_WANT_CORRUPTED_GOTO(rlen <= flen, error0);
1321        /*
1322         * Allocate and initialize a cursor for the by-block tree.
1323         */
1324        bno_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
1325                args->agno, XFS_BTNUM_BNO);
1326        if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur, fbno, flen,
1327                        rbno, rlen, XFSA_FIXUP_CNT_OK)))
1328                goto error0;
1329        xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1330        xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
1331        cnt_cur = bno_cur = NULL;
1332        args->len = rlen;
1333        args->agbno = rbno;
1334        XFS_WANT_CORRUPTED_GOTO(
1335                args->agbno + args->len <=
1336                        be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length),
1337                error0);
1338        trace_xfs_alloc_size_done(args);
1339        return 0;
1340
1341error0:
1342        trace_xfs_alloc_size_error(args);
1343        if (cnt_cur)
1344                xfs_btree_del_cursor(cnt_cur, XFS_BTREE_ERROR);
1345        if (bno_cur)
1346                xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR);
1347        return error;
1348
1349out_nominleft:
1350        xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1351        trace_xfs_alloc_size_nominleft(args);
1352        args->agbno = NULLAGBLOCK;
1353        return 0;
1354}
1355
1356/*
1357 * Deal with the case where only small freespaces remain.
1358 * Either return the contents of the last freespace record,
1359 * or allocate space from the freelist if there is nothing in the tree.
1360 */
1361STATIC int                      /* error */
1362xfs_alloc_ag_vextent_small(
1363        xfs_alloc_arg_t *args,  /* allocation argument structure */
1364        xfs_btree_cur_t *ccur,  /* by-size cursor */
1365        xfs_agblock_t   *fbnop, /* result block number */
1366        xfs_extlen_t    *flenp, /* result length */
1367        int             *stat)  /* status: 0-freelist, 1-normal/none */
1368{
1369        int             error;
1370        xfs_agblock_t   fbno;
1371        xfs_extlen_t    flen;
1372        int             i;
1373
1374        if ((error = xfs_btree_decrement(ccur, 0, &i)))
1375                goto error0;
1376        if (i) {
1377                if ((error = xfs_alloc_get_rec(ccur, &fbno, &flen, &i)))
1378                        goto error0;
1379                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1380        }
1381        /*
1382         * Nothing in the btree, try the freelist.  Make sure
1383         * to respect minleft even when pulling from the
1384         * freelist.
1385         */
1386        else if (args->minlen == 1 && args->alignment == 1 && !args->isfl &&
1387                 (be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_flcount)
1388                  > args->minleft)) {
1389                error = xfs_alloc_get_freelist(args->tp, args->agbp, &fbno, 0);
1390                if (error)
1391                        goto error0;
1392                if (fbno != NULLAGBLOCK) {
1393                        xfs_extent_busy_reuse(args->mp, args->agno, fbno, 1,
1394                                             args->userdata);
1395
1396                        if (args->userdata) {
1397                                xfs_buf_t       *bp;
1398
1399                                bp = xfs_btree_get_bufs(args->mp, args->tp,
1400                                        args->agno, fbno, 0);
1401                                xfs_trans_binval(args->tp, bp);
1402                        }
1403                        args->len = 1;
1404                        args->agbno = fbno;
1405                        XFS_WANT_CORRUPTED_GOTO(
1406                                args->agbno + args->len <=
1407                                be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length),
1408                                error0);
1409                        args->wasfromfl = 1;
1410                        trace_xfs_alloc_small_freelist(args);
1411                        *stat = 0;
1412                        return 0;
1413                }
1414                /*
1415                 * Nothing in the freelist.
1416                 */
1417                else
1418                        flen = 0;
1419        }
1420        /*
1421         * Can't allocate from the freelist for some reason.
1422         */
1423        else {
1424                fbno = NULLAGBLOCK;
1425                flen = 0;
1426        }
1427        /*
1428         * Can't do the allocation, give up.
1429         */
1430        if (flen < args->minlen) {
1431                args->agbno = NULLAGBLOCK;
1432                trace_xfs_alloc_small_notenough(args);
1433                flen = 0;
1434        }
1435        *fbnop = fbno;
1436        *flenp = flen;
1437        *stat = 1;
1438        trace_xfs_alloc_small_done(args);
1439        return 0;
1440
1441error0:
1442        trace_xfs_alloc_small_error(args);
1443        return error;
1444}
1445
1446/*
1447 * Free the extent starting at agno/bno for length.
1448 */
1449STATIC int                      /* error */
1450xfs_free_ag_extent(
1451        xfs_trans_t     *tp,    /* transaction pointer */
1452        xfs_buf_t       *agbp,  /* buffer for a.g. freelist header */
1453        xfs_agnumber_t  agno,   /* allocation group number */
1454        xfs_agblock_t   bno,    /* starting block number */
1455        xfs_extlen_t    len,    /* length of extent */
1456        int             isfl)   /* set if is freelist blocks - no sb acctg */
1457{
1458        xfs_btree_cur_t *bno_cur;       /* cursor for by-block btree */
1459        xfs_btree_cur_t *cnt_cur;       /* cursor for by-size btree */
1460        int             error;          /* error return value */
1461        xfs_agblock_t   gtbno;          /* start of right neighbor block */
1462        xfs_extlen_t    gtlen;          /* length of right neighbor block */
1463        int             haveleft;       /* have a left neighbor block */
1464        int             haveright;      /* have a right neighbor block */
1465        int             i;              /* temp, result code */
1466        xfs_agblock_t   ltbno;          /* start of left neighbor block */
1467        xfs_extlen_t    ltlen;          /* length of left neighbor block */
1468        xfs_mount_t     *mp;            /* mount point struct for filesystem */
1469        xfs_agblock_t   nbno;           /* new starting block of freespace */
1470        xfs_extlen_t    nlen;           /* new length of freespace */
1471        xfs_perag_t     *pag;           /* per allocation group data */
1472
1473        mp = tp->t_mountp;
1474        /*
1475         * Allocate and initialize a cursor for the by-block btree.
1476         */
1477        bno_cur = xfs_allocbt_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_BNO);
1478        cnt_cur = NULL;
1479        /*
1480         * Look for a neighboring block on the left (lower block numbers)
1481         * that is contiguous with this space.
1482         */
1483        if ((error = xfs_alloc_lookup_le(bno_cur, bno, len, &haveleft)))
1484                goto error0;
1485        if (haveleft) {
1486                /*
1487                 * There is a block to our left.
1488                 */
1489                if ((error = xfs_alloc_get_rec(bno_cur, &ltbno, &ltlen, &i)))
1490                        goto error0;
1491                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1492                /*
1493                 * It's not contiguous, though.
1494                 */
1495                if (ltbno + ltlen < bno)
1496                        haveleft = 0;
1497                else {
1498                        /*
1499                         * If this failure happens the request to free this
1500                         * space was invalid, it's (partly) already free.
1501                         * Very bad.
1502                         */
1503                        XFS_WANT_CORRUPTED_GOTO(ltbno + ltlen <= bno, error0);
1504                }
1505        }
1506        /*
1507         * Look for a neighboring block on the right (higher block numbers)
1508         * that is contiguous with this space.
1509         */
1510        if ((error = xfs_btree_increment(bno_cur, 0, &haveright)))
1511                goto error0;
1512        if (haveright) {
1513                /*
1514                 * There is a block to our right.
1515                 */
1516                if ((error = xfs_alloc_get_rec(bno_cur, &gtbno, &gtlen, &i)))
1517                        goto error0;
1518                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1519                /*
1520                 * It's not contiguous, though.
1521                 */
1522                if (bno + len < gtbno)
1523                        haveright = 0;
1524                else {
1525                        /*
1526                         * If this failure happens the request to free this
1527                         * space was invalid, it's (partly) already free.
1528                         * Very bad.
1529                         */
1530                        XFS_WANT_CORRUPTED_GOTO(gtbno >= bno + len, error0);
1531                }
1532        }
1533        /*
1534         * Now allocate and initialize a cursor for the by-size tree.
1535         */
1536        cnt_cur = xfs_allocbt_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_CNT);
1537        /*
1538         * Have both left and right contiguous neighbors.
1539         * Merge all three into a single free block.
1540         */
1541        if (haveleft && haveright) {
1542                /*
1543                 * Delete the old by-size entry on the left.
1544                 */
1545                if ((error = xfs_alloc_lookup_eq(cnt_cur, ltbno, ltlen, &i)))
1546                        goto error0;
1547                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1548                if ((error = xfs_btree_delete(cnt_cur, &i)))
1549                        goto error0;
1550                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1551                /*
1552                 * Delete the old by-size entry on the right.
1553                 */
1554                if ((error = xfs_alloc_lookup_eq(cnt_cur, gtbno, gtlen, &i)))
1555                        goto error0;
1556                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1557                if ((error = xfs_btree_delete(cnt_cur, &i)))
1558                        goto error0;
1559                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1560                /*
1561                 * Delete the old by-block entry for the right block.
1562                 */
1563                if ((error = xfs_btree_delete(bno_cur, &i)))
1564                        goto error0;
1565                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1566                /*
1567                 * Move the by-block cursor back to the left neighbor.
1568                 */
1569                if ((error = xfs_btree_decrement(bno_cur, 0, &i)))
1570                        goto error0;
1571                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1572#ifdef DEBUG
1573                /*
1574                 * Check that this is the right record: delete didn't
1575                 * mangle the cursor.
1576                 */
1577                {
1578                        xfs_agblock_t   xxbno;
1579                        xfs_extlen_t    xxlen;
1580
1581                        if ((error = xfs_alloc_get_rec(bno_cur, &xxbno, &xxlen,
1582                                        &i)))
1583                                goto error0;
1584                        XFS_WANT_CORRUPTED_GOTO(
1585                                i == 1 && xxbno == ltbno && xxlen == ltlen,
1586                                error0);
1587                }
1588#endif
1589                /*
1590                 * Update remaining by-block entry to the new, joined block.
1591                 */
1592                nbno = ltbno;
1593                nlen = len + ltlen + gtlen;
1594                if ((error = xfs_alloc_update(bno_cur, nbno, nlen)))
1595                        goto error0;
1596        }
1597        /*
1598         * Have only a left contiguous neighbor.
1599         * Merge it together with the new freespace.
1600         */
1601        else if (haveleft) {
1602                /*
1603                 * Delete the old by-size entry on the left.
1604                 */
1605                if ((error = xfs_alloc_lookup_eq(cnt_cur, ltbno, ltlen, &i)))
1606                        goto error0;
1607                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1608                if ((error = xfs_btree_delete(cnt_cur, &i)))
1609                        goto error0;
1610                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1611                /*
1612                 * Back up the by-block cursor to the left neighbor, and
1613                 * update its length.
1614                 */
1615                if ((error = xfs_btree_decrement(bno_cur, 0, &i)))
1616                        goto error0;
1617                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1618                nbno = ltbno;
1619                nlen = len + ltlen;
1620                if ((error = xfs_alloc_update(bno_cur, nbno, nlen)))
1621                        goto error0;
1622        }
1623        /*
1624         * Have only a right contiguous neighbor.
1625         * Merge it together with the new freespace.
1626         */
1627        else if (haveright) {
1628                /*
1629                 * Delete the old by-size entry on the right.
1630                 */
1631                if ((error = xfs_alloc_lookup_eq(cnt_cur, gtbno, gtlen, &i)))
1632                        goto error0;
1633                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1634                if ((error = xfs_btree_delete(cnt_cur, &i)))
1635                        goto error0;
1636                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1637                /*
1638                 * Update the starting block and length of the right
1639                 * neighbor in the by-block tree.
1640                 */
1641                nbno = bno;
1642                nlen = len + gtlen;
1643                if ((error = xfs_alloc_update(bno_cur, nbno, nlen)))
1644                        goto error0;
1645        }
1646        /*
1647         * No contiguous neighbors.
1648         * Insert the new freespace into the by-block tree.
1649         */
1650        else {
1651                nbno = bno;
1652                nlen = len;
1653                if ((error = xfs_btree_insert(bno_cur, &i)))
1654                        goto error0;
1655                XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1656        }
1657        xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
1658        bno_cur = NULL;
1659        /*
1660         * In all cases we need to insert the new freespace in the by-size tree.
1661         */
1662        if ((error = xfs_alloc_lookup_eq(cnt_cur, nbno, nlen, &i)))
1663                goto error0;
1664        XFS_WANT_CORRUPTED_GOTO(i == 0, error0);
1665        if ((error = xfs_btree_insert(cnt_cur, &i)))
1666                goto error0;
1667        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1668        xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1669        cnt_cur = NULL;
1670
1671        /*
1672         * Update the freespace totals in the ag and superblock.
1673         */
1674        pag = xfs_perag_get(mp, agno);
1675        error = xfs_alloc_update_counters(tp, pag, agbp, len);
1676        xfs_perag_put(pag);
1677        if (error)
1678                goto error0;
1679
1680        if (!isfl)
1681                xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (long)len);
1682        XFS_STATS_INC(xs_freex);
1683        XFS_STATS_ADD(xs_freeb, len);
1684
1685        trace_xfs_free_extent(mp, agno, bno, len, isfl, haveleft, haveright);
1686
1687        return 0;
1688
1689 error0:
1690        trace_xfs_free_extent(mp, agno, bno, len, isfl, -1, -1);
1691        if (bno_cur)
1692                xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR);
1693        if (cnt_cur)
1694                xfs_btree_del_cursor(cnt_cur, XFS_BTREE_ERROR);
1695        return error;
1696}
1697
1698/*
1699 * Visible (exported) allocation/free functions.
1700 * Some of these are used just by xfs_alloc_btree.c and this file.
1701 */
1702
1703/*
1704 * Compute and fill in value of m_ag_maxlevels.
1705 */
1706void
1707xfs_alloc_compute_maxlevels(
1708        xfs_mount_t     *mp)    /* file system mount structure */
1709{
1710        int             level;
1711        uint            maxblocks;
1712        uint            maxleafents;
1713        int             minleafrecs;
1714        int             minnoderecs;
1715
1716        maxleafents = (mp->m_sb.sb_agblocks + 1) / 2;
1717        minleafrecs = mp->m_alloc_mnr[0];
1718        minnoderecs = mp->m_alloc_mnr[1];
1719        maxblocks = (maxleafents + minleafrecs - 1) / minleafrecs;
1720        for (level = 1; maxblocks > 1; level++)
1721                maxblocks = (maxblocks + minnoderecs - 1) / minnoderecs;
1722        mp->m_ag_maxlevels = level;
1723}
1724
1725/*
1726 * Find the length of the longest extent in an AG.
1727 */
1728xfs_extlen_t
1729xfs_alloc_longest_free_extent(
1730        struct xfs_mount        *mp,
1731        struct xfs_perag        *pag)
1732{
1733        xfs_extlen_t            need, delta = 0;
1734
1735        need = XFS_MIN_FREELIST_PAG(pag, mp);
1736        if (need > pag->pagf_flcount)
1737                delta = need - pag->pagf_flcount;
1738
1739        if (pag->pagf_longest > delta)
1740                return pag->pagf_longest - delta;
1741        return pag->pagf_flcount > 0 || pag->pagf_longest > 0;
1742}
1743
1744/*
1745 * Decide whether to use this allocation group for this allocation.
1746 * If so, fix up the btree freelist's size.
1747 */
1748STATIC int                      /* error */
1749xfs_alloc_fix_freelist(
1750        xfs_alloc_arg_t *args,  /* allocation argument structure */
1751        int             flags)  /* XFS_ALLOC_FLAG_... */
1752{
1753        xfs_buf_t       *agbp;  /* agf buffer pointer */
1754        xfs_agf_t       *agf;   /* a.g. freespace structure pointer */
1755        xfs_buf_t       *agflbp;/* agfl buffer pointer */
1756        xfs_agblock_t   bno;    /* freelist block */
1757        xfs_extlen_t    delta;  /* new blocks needed in freelist */
1758        int             error;  /* error result code */
1759        xfs_extlen_t    longest;/* longest extent in allocation group */
1760        xfs_mount_t     *mp;    /* file system mount point structure */
1761        xfs_extlen_t    need;   /* total blocks needed in freelist */
1762        xfs_perag_t     *pag;   /* per-ag information structure */
1763        xfs_alloc_arg_t targs;  /* local allocation arguments */
1764        xfs_trans_t     *tp;    /* transaction pointer */
1765
1766        mp = args->mp;
1767
1768        pag = args->pag;
1769        tp = args->tp;
1770        if (!pag->pagf_init) {
1771                if ((error = xfs_alloc_read_agf(mp, tp, args->agno, flags,
1772                                &agbp)))
1773                        return error;
1774                if (!pag->pagf_init) {
1775                        ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
1776                        ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
1777                        args->agbp = NULL;
1778                        return 0;
1779                }
1780        } else
1781                agbp = NULL;
1782
1783        /*
1784         * If this is a metadata preferred pag and we are user data
1785         * then try somewhere else if we are not being asked to
1786         * try harder at this point
1787         */
1788        if (pag->pagf_metadata && args->userdata &&
1789            (flags & XFS_ALLOC_FLAG_TRYLOCK)) {
1790                ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
1791                args->agbp = NULL;
1792                return 0;
1793        }
1794
1795        if (!(flags & XFS_ALLOC_FLAG_FREEING)) {
1796                /*
1797                 * If it looks like there isn't a long enough extent, or enough
1798                 * total blocks, reject it.
1799                 */
1800                need = XFS_MIN_FREELIST_PAG(pag, mp);
1801                longest = xfs_alloc_longest_free_extent(mp, pag);
1802                if ((args->minlen + args->alignment + args->minalignslop - 1) >
1803                                longest ||
1804                    ((int)(pag->pagf_freeblks + pag->pagf_flcount -
1805                           need - args->total) < (int)args->minleft)) {
1806                        if (agbp)
1807                                xfs_trans_brelse(tp, agbp);
1808                        args->agbp = NULL;
1809                        return 0;
1810                }
1811        }
1812
1813        /*
1814         * Get the a.g. freespace buffer.
1815         * Can fail if we're not blocking on locks, and it's held.
1816         */
1817        if (agbp == NULL) {
1818                if ((error = xfs_alloc_read_agf(mp, tp, args->agno, flags,
1819                                &agbp)))
1820                        return error;
1821                if (agbp == NULL) {
1822                        ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
1823                        ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
1824                        args->agbp = NULL;
1825                        return 0;
1826                }
1827        }
1828        /*
1829         * Figure out how many blocks we should have in the freelist.
1830         */
1831        agf = XFS_BUF_TO_AGF(agbp);
1832        need = XFS_MIN_FREELIST(agf, mp);
1833        /*
1834         * If there isn't enough total or single-extent, reject it.
1835         */
1836        if (!(flags & XFS_ALLOC_FLAG_FREEING)) {
1837                delta = need > be32_to_cpu(agf->agf_flcount) ?
1838                        (need - be32_to_cpu(agf->agf_flcount)) : 0;
1839                longest = be32_to_cpu(agf->agf_longest);
1840                longest = (longest > delta) ? (longest - delta) :
1841                        (be32_to_cpu(agf->agf_flcount) > 0 || longest > 0);
1842                if ((args->minlen + args->alignment + args->minalignslop - 1) >
1843                                longest ||
1844                    ((int)(be32_to_cpu(agf->agf_freeblks) +
1845                     be32_to_cpu(agf->agf_flcount) - need - args->total) <
1846                                (int)args->minleft)) {
1847                        xfs_trans_brelse(tp, agbp);
1848                        args->agbp = NULL;
1849                        return 0;
1850                }
1851        }
1852        /*
1853         * Make the freelist shorter if it's too long.
1854         */
1855        while (be32_to_cpu(agf->agf_flcount) > need) {
1856                xfs_buf_t       *bp;
1857
1858                error = xfs_alloc_get_freelist(tp, agbp, &bno, 0);
1859                if (error)
1860                        return error;
1861                if ((error = xfs_free_ag_extent(tp, agbp, args->agno, bno, 1, 1)))
1862                        return error;
1863                bp = xfs_btree_get_bufs(mp, tp, args->agno, bno, 0);
1864                xfs_trans_binval(tp, bp);
1865        }
1866        /*
1867         * Initialize the args structure.
1868         */
1869        memset(&targs, 0, sizeof(targs));
1870        targs.tp = tp;
1871        targs.mp = mp;
1872        targs.agbp = agbp;
1873        targs.agno = args->agno;
1874        targs.mod = targs.minleft = targs.wasdel = targs.userdata =
1875                targs.minalignslop = 0;
1876        targs.alignment = targs.minlen = targs.prod = targs.isfl = 1;
1877        targs.type = XFS_ALLOCTYPE_THIS_AG;
1878        targs.pag = pag;
1879        if ((error = xfs_alloc_read_agfl(mp, tp, targs.agno, &agflbp)))
1880                return error;
1881        /*
1882         * Make the freelist longer if it's too short.
1883         */
1884        while (be32_to_cpu(agf->agf_flcount) < need) {
1885                targs.agbno = 0;
1886                targs.maxlen = need - be32_to_cpu(agf->agf_flcount);
1887                /*
1888                 * Allocate as many blocks as possible at once.
1889                 */
1890                if ((error = xfs_alloc_ag_vextent(&targs))) {
1891                        xfs_trans_brelse(tp, agflbp);
1892                        return error;
1893                }
1894                /*
1895                 * Stop if we run out.  Won't happen if callers are obeying
1896                 * the restrictions correctly.  Can happen for free calls
1897                 * on a completely full ag.
1898                 */
1899                if (targs.agbno == NULLAGBLOCK) {
1900                        if (flags & XFS_ALLOC_FLAG_FREEING)
1901                                break;
1902                        xfs_trans_brelse(tp, agflbp);
1903                        args->agbp = NULL;
1904                        return 0;
1905                }
1906                /*
1907                 * Put each allocated block on the list.
1908                 */
1909                for (bno = targs.agbno; bno < targs.agbno + targs.len; bno++) {
1910                        error = xfs_alloc_put_freelist(tp, agbp,
1911                                                        agflbp, bno, 0);
1912                        if (error)
1913                                return error;
1914                }
1915        }
1916        xfs_trans_brelse(tp, agflbp);
1917        args->agbp = agbp;
1918        return 0;
1919}
1920
1921/*
1922 * Get a block from the freelist.
1923 * Returns with the buffer for the block gotten.
1924 */
1925int                             /* error */
1926xfs_alloc_get_freelist(
1927        xfs_trans_t     *tp,    /* transaction pointer */
1928        xfs_buf_t       *agbp,  /* buffer containing the agf structure */
1929        xfs_agblock_t   *bnop,  /* block address retrieved from freelist */
1930        int             btreeblk) /* destination is a AGF btree */
1931{
1932        xfs_agf_t       *agf;   /* a.g. freespace structure */
1933        xfs_agfl_t      *agfl;  /* a.g. freelist structure */
1934        xfs_buf_t       *agflbp;/* buffer for a.g. freelist structure */
1935        xfs_agblock_t   bno;    /* block number returned */
1936        int             error;
1937        int             logflags;
1938        xfs_mount_t     *mp;    /* mount structure */
1939        xfs_perag_t     *pag;   /* per allocation group data */
1940
1941        agf = XFS_BUF_TO_AGF(agbp);
1942        /*
1943         * Freelist is empty, give up.
1944         */
1945        if (!agf->agf_flcount) {
1946                *bnop = NULLAGBLOCK;
1947                return 0;
1948        }
1949        /*
1950         * Read the array of free blocks.
1951         */
1952        mp = tp->t_mountp;
1953        if ((error = xfs_alloc_read_agfl(mp, tp,
1954                        be32_to_cpu(agf->agf_seqno), &agflbp)))
1955                return error;
1956        agfl = XFS_BUF_TO_AGFL(agflbp);
1957        /*
1958         * Get the block number and update the data structures.
1959         */
1960        bno = be32_to_cpu(agfl->agfl_bno[be32_to_cpu(agf->agf_flfirst)]);
1961        be32_add_cpu(&agf->agf_flfirst, 1);
1962        xfs_trans_brelse(tp, agflbp);
1963        if (be32_to_cpu(agf->agf_flfirst) == XFS_AGFL_SIZE(mp))
1964                agf->agf_flfirst = 0;
1965
1966        pag = xfs_perag_get(mp, be32_to_cpu(agf->agf_seqno));
1967        be32_add_cpu(&agf->agf_flcount, -1);
1968        xfs_trans_agflist_delta(tp, -1);
1969        pag->pagf_flcount--;
1970        xfs_perag_put(pag);
1971
1972        logflags = XFS_AGF_FLFIRST | XFS_AGF_FLCOUNT;
1973        if (btreeblk) {
1974                be32_add_cpu(&agf->agf_btreeblks, 1);
1975                pag->pagf_btreeblks++;
1976                logflags |= XFS_AGF_BTREEBLKS;
1977        }
1978
1979        xfs_alloc_log_agf(tp, agbp, logflags);
1980        *bnop = bno;
1981
1982        return 0;
1983}
1984
1985/*
1986 * Log the given fields from the agf structure.
1987 */
1988void
1989xfs_alloc_log_agf(
1990        xfs_trans_t     *tp,    /* transaction pointer */
1991        xfs_buf_t       *bp,    /* buffer for a.g. freelist header */
1992        int             fields) /* mask of fields to be logged (XFS_AGF_...) */
1993{
1994        int     first;          /* first byte offset */
1995        int     last;           /* last byte offset */
1996        static const short      offsets[] = {
1997                offsetof(xfs_agf_t, agf_magicnum),
1998                offsetof(xfs_agf_t, agf_versionnum),
1999                offsetof(xfs_agf_t, agf_seqno),
2000                offsetof(xfs_agf_t, agf_length),
2001                offsetof(xfs_agf_t, agf_roots[0]),
2002                offsetof(xfs_agf_t, agf_levels[0]),
2003                offsetof(xfs_agf_t, agf_flfirst),
2004                offsetof(xfs_agf_t, agf_fllast),
2005                offsetof(xfs_agf_t, agf_flcount),
2006                offsetof(xfs_agf_t, agf_freeblks),
2007                offsetof(xfs_agf_t, agf_longest),
2008                offsetof(xfs_agf_t, agf_btreeblks),
2009                sizeof(xfs_agf_t)
2010        };
2011
2012        trace_xfs_agf(tp->t_mountp, XFS_BUF_TO_AGF(bp), fields, _RET_IP_);
2013
2014        xfs_btree_offsets(fields, offsets, XFS_AGF_NUM_BITS, &first, &last);
2015        xfs_trans_log_buf(tp, bp, (uint)first, (uint)last);
2016}
2017
2018/*
2019 * Interface for inode allocation to force the pag data to be initialized.
2020 */
2021int                                     /* error */
2022xfs_alloc_pagf_init(
2023        xfs_mount_t             *mp,    /* file system mount structure */
2024        xfs_trans_t             *tp,    /* transaction pointer */
2025        xfs_agnumber_t          agno,   /* allocation group number */
2026        int                     flags)  /* XFS_ALLOC_FLAGS_... */
2027{
2028        xfs_buf_t               *bp;
2029        int                     error;
2030
2031        if ((error = xfs_alloc_read_agf(mp, tp, agno, flags, &bp)))
2032                return error;
2033        if (bp)
2034                xfs_trans_brelse(tp, bp);
2035        return 0;
2036}
2037
2038/*
2039 * Put the block on the freelist for the allocation group.
2040 */
2041int                                     /* error */
2042xfs_alloc_put_freelist(
2043        xfs_trans_t             *tp,    /* transaction pointer */
2044        xfs_buf_t               *agbp,  /* buffer for a.g. freelist header */
2045        xfs_buf_t               *agflbp,/* buffer for a.g. free block array */
2046        xfs_agblock_t           bno,    /* block being freed */
2047        int                     btreeblk) /* block came from a AGF btree */
2048{
2049        xfs_agf_t               *agf;   /* a.g. freespace structure */
2050        xfs_agfl_t              *agfl;  /* a.g. free block array */
2051        __be32                  *blockp;/* pointer to array entry */
2052        int                     error;
2053        int                     logflags;
2054        xfs_mount_t             *mp;    /* mount structure */
2055        xfs_perag_t             *pag;   /* per allocation group data */
2056
2057        agf = XFS_BUF_TO_AGF(agbp);
2058        mp = tp->t_mountp;
2059
2060        if (!agflbp && (error = xfs_alloc_read_agfl(mp, tp,
2061                        be32_to_cpu(agf->agf_seqno), &agflbp)))
2062                return error;
2063        agfl = XFS_BUF_TO_AGFL(agflbp);
2064        be32_add_cpu(&agf->agf_fllast, 1);
2065        if (be32_to_cpu(agf->agf_fllast) == XFS_AGFL_SIZE(mp))
2066                agf->agf_fllast = 0;
2067
2068        pag = xfs_perag_get(mp, be32_to_cpu(agf->agf_seqno));
2069        be32_add_cpu(&agf->agf_flcount, 1);
2070        xfs_trans_agflist_delta(tp, 1);
2071        pag->pagf_flcount++;
2072
2073        logflags = XFS_AGF_FLLAST | XFS_AGF_FLCOUNT;
2074        if (btreeblk) {
2075                be32_add_cpu(&agf->agf_btreeblks, -1);
2076                pag->pagf_btreeblks--;
2077                logflags |= XFS_AGF_BTREEBLKS;
2078        }
2079        xfs_perag_put(pag);
2080
2081        xfs_alloc_log_agf(tp, agbp, logflags);
2082
2083        ASSERT(be32_to_cpu(agf->agf_flcount) <= XFS_AGFL_SIZE(mp));
2084        blockp = &agfl->agfl_bno[be32_to_cpu(agf->agf_fllast)];
2085        *blockp = cpu_to_be32(bno);
2086        xfs_alloc_log_agf(tp, agbp, logflags);
2087        xfs_trans_log_buf(tp, agflbp,
2088                (int)((xfs_caddr_t)blockp - (xfs_caddr_t)agfl),
2089                (int)((xfs_caddr_t)blockp - (xfs_caddr_t)agfl +
2090                        sizeof(xfs_agblock_t) - 1));
2091        return 0;
2092}
2093
2094/*
2095 * Read in the allocation group header (free/alloc section).
2096 */
2097int                                     /* error */
2098xfs_read_agf(
2099        struct xfs_mount        *mp,    /* mount point structure */
2100        struct xfs_trans        *tp,    /* transaction pointer */
2101        xfs_agnumber_t          agno,   /* allocation group number */
2102        int                     flags,  /* XFS_BUF_ */
2103        struct xfs_buf          **bpp)  /* buffer for the ag freelist header */
2104{
2105        struct xfs_agf  *agf;           /* ag freelist header */
2106        int             agf_ok;         /* set if agf is consistent */
2107        int             error;
2108
2109        ASSERT(agno != NULLAGNUMBER);
2110        error = xfs_trans_read_buf(
2111                        mp, tp, mp->m_ddev_targp,
2112                        XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
2113                        XFS_FSS_TO_BB(mp, 1), flags, bpp);
2114        if (error)
2115                return error;
2116        if (!*bpp)
2117                return 0;
2118
2119        ASSERT(!(*bpp)->b_error);
2120        agf = XFS_BUF_TO_AGF(*bpp);
2121
2122        /*
2123         * Validate the magic number of the agf block.
2124         */
2125        agf_ok =
2126                agf->agf_magicnum == cpu_to_be32(XFS_AGF_MAGIC) &&
2127                XFS_AGF_GOOD_VERSION(be32_to_cpu(agf->agf_versionnum)) &&
2128                be32_to_cpu(agf->agf_freeblks) <= be32_to_cpu(agf->agf_length) &&
2129                be32_to_cpu(agf->agf_flfirst) < XFS_AGFL_SIZE(mp) &&
2130                be32_to_cpu(agf->agf_fllast) < XFS_AGFL_SIZE(mp) &&
2131                be32_to_cpu(agf->agf_flcount) <= XFS_AGFL_SIZE(mp) &&
2132                be32_to_cpu(agf->agf_seqno) == agno;
2133        if (xfs_sb_version_haslazysbcount(&mp->m_sb))
2134                agf_ok = agf_ok && be32_to_cpu(agf->agf_btreeblks) <=
2135                                                be32_to_cpu(agf->agf_length);
2136        if (unlikely(XFS_TEST_ERROR(!agf_ok, mp, XFS_ERRTAG_ALLOC_READ_AGF,
2137                        XFS_RANDOM_ALLOC_READ_AGF))) {
2138                XFS_CORRUPTION_ERROR("xfs_alloc_read_agf",
2139                                     XFS_ERRLEVEL_LOW, mp, agf);
2140                xfs_trans_brelse(tp, *bpp);
2141                return XFS_ERROR(EFSCORRUPTED);
2142        }
2143        xfs_buf_set_ref(*bpp, XFS_AGF_REF);
2144        return 0;
2145}
2146
2147/*
2148 * Read in the allocation group header (free/alloc section).
2149 */
2150int                                     /* error */
2151xfs_alloc_read_agf(
2152        struct xfs_mount        *mp,    /* mount point structure */
2153        struct xfs_trans        *tp,    /* transaction pointer */
2154        xfs_agnumber_t          agno,   /* allocation group number */
2155        int                     flags,  /* XFS_ALLOC_FLAG_... */
2156        struct xfs_buf          **bpp)  /* buffer for the ag freelist header */
2157{
2158        struct xfs_agf          *agf;           /* ag freelist header */
2159        struct xfs_perag        *pag;           /* per allocation group data */
2160        int                     error;
2161
2162        ASSERT(agno != NULLAGNUMBER);
2163
2164        error = xfs_read_agf(mp, tp, agno,
2165                        (flags & XFS_ALLOC_FLAG_TRYLOCK) ? XBF_TRYLOCK : 0,
2166                        bpp);
2167        if (error)
2168                return error;
2169        if (!*bpp)
2170                return 0;
2171        ASSERT(!(*bpp)->b_error);
2172
2173        agf = XFS_BUF_TO_AGF(*bpp);
2174        pag = xfs_perag_get(mp, agno);
2175        if (!pag->pagf_init) {
2176                pag->pagf_freeblks = be32_to_cpu(agf->agf_freeblks);
2177                pag->pagf_btreeblks = be32_to_cpu(agf->agf_btreeblks);
2178                pag->pagf_flcount = be32_to_cpu(agf->agf_flcount);
2179                pag->pagf_longest = be32_to_cpu(agf->agf_longest);
2180                pag->pagf_levels[XFS_BTNUM_BNOi] =
2181                        be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNOi]);
2182                pag->pagf_levels[XFS_BTNUM_CNTi] =
2183                        be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNTi]);
2184                spin_lock_init(&pag->pagb_lock);
2185                pag->pagb_count = 0;
2186                pag->pagb_tree = RB_ROOT;
2187                pag->pagf_init = 1;
2188        }
2189#ifdef DEBUG
2190        else if (!XFS_FORCED_SHUTDOWN(mp)) {
2191                ASSERT(pag->pagf_freeblks == be32_to_cpu(agf->agf_freeblks));
2192                ASSERT(pag->pagf_btreeblks == be32_to_cpu(agf->agf_btreeblks));
2193                ASSERT(pag->pagf_flcount == be32_to_cpu(agf->agf_flcount));
2194                ASSERT(pag->pagf_longest == be32_to_cpu(agf->agf_longest));
2195                ASSERT(pag->pagf_levels[XFS_BTNUM_BNOi] ==
2196                       be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNOi]));
2197                ASSERT(pag->pagf_levels[XFS_BTNUM_CNTi] ==
2198                       be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNTi]));
2199        }
2200#endif
2201        xfs_perag_put(pag);
2202        return 0;
2203}
2204
2205/*
2206 * Allocate an extent (variable-size).
2207 * Depending on the allocation type, we either look in a single allocation
2208 * group or loop over the allocation groups to find the result.
2209 */
2210int                             /* error */
2211xfs_alloc_vextent(
2212        xfs_alloc_arg_t *args)  /* allocation argument structure */
2213{
2214        xfs_agblock_t   agsize; /* allocation group size */
2215        int             error;
2216        int             flags;  /* XFS_ALLOC_FLAG_... locking flags */
2217        xfs_extlen_t    minleft;/* minimum left value, temp copy */
2218        xfs_mount_t     *mp;    /* mount structure pointer */
2219        xfs_agnumber_t  sagno;  /* starting allocation group number */
2220        xfs_alloctype_t type;   /* input allocation type */
2221        int             bump_rotor = 0;
2222        int             no_min = 0;
2223        xfs_agnumber_t  rotorstep = xfs_rotorstep; /* inode32 agf stepper */
2224
2225        mp = args->mp;
2226        type = args->otype = args->type;
2227        args->agbno = NULLAGBLOCK;
2228        /*
2229         * Just fix this up, for the case where the last a.g. is shorter
2230         * (or there's only one a.g.) and the caller couldn't easily figure
2231         * that out (xfs_bmap_alloc).
2232         */
2233        agsize = mp->m_sb.sb_agblocks;
2234        if (args->maxlen > agsize)
2235                args->maxlen = agsize;
2236        if (args->alignment == 0)
2237                args->alignment = 1;
2238        ASSERT(XFS_FSB_TO_AGNO(mp, args->fsbno) < mp->m_sb.sb_agcount);
2239        ASSERT(XFS_FSB_TO_AGBNO(mp, args->fsbno) < agsize);
2240        ASSERT(args->minlen <= args->maxlen);
2241        ASSERT(args->minlen <= agsize);
2242        ASSERT(args->mod < args->prod);
2243        if (XFS_FSB_TO_AGNO(mp, args->fsbno) >= mp->m_sb.sb_agcount ||
2244            XFS_FSB_TO_AGBNO(mp, args->fsbno) >= agsize ||
2245            args->minlen > args->maxlen || args->minlen > agsize ||
2246            args->mod >= args->prod) {
2247                args->fsbno = NULLFSBLOCK;
2248                trace_xfs_alloc_vextent_badargs(args);
2249                return 0;
2250        }
2251        minleft = args->minleft;
2252
2253        switch (type) {
2254        case XFS_ALLOCTYPE_THIS_AG:
2255        case XFS_ALLOCTYPE_NEAR_BNO:
2256        case XFS_ALLOCTYPE_THIS_BNO:
2257                /*
2258                 * These three force us into a single a.g.
2259                 */
2260                args->agno = XFS_FSB_TO_AGNO(mp, args->fsbno);
2261                args->pag = xfs_perag_get(mp, args->agno);
2262                args->minleft = 0;
2263                error = xfs_alloc_fix_freelist(args, 0);
2264                args->minleft = minleft;
2265                if (error) {
2266                        trace_xfs_alloc_vextent_nofix(args);
2267                        goto error0;
2268                }
2269                if (!args->agbp) {
2270                        trace_xfs_alloc_vextent_noagbp(args);
2271                        break;
2272                }
2273                args->agbno = XFS_FSB_TO_AGBNO(mp, args->fsbno);
2274                if ((error = xfs_alloc_ag_vextent(args)))
2275                        goto error0;
2276                break;
2277        case XFS_ALLOCTYPE_START_BNO:
2278                /*
2279                 * Try near allocation first, then anywhere-in-ag after
2280                 * the first a.g. fails.
2281                 */
2282                if ((args->userdata  == XFS_ALLOC_INITIAL_USER_DATA) &&
2283                    (mp->m_flags & XFS_MOUNT_32BITINODES)) {
2284                        args->fsbno = XFS_AGB_TO_FSB(mp,
2285                                        ((mp->m_agfrotor / rotorstep) %
2286                                        mp->m_sb.sb_agcount), 0);
2287                        bump_rotor = 1;
2288                }
2289                args->agbno = XFS_FSB_TO_AGBNO(mp, args->fsbno);
2290                args->type = XFS_ALLOCTYPE_NEAR_BNO;
2291                /* FALLTHROUGH */
2292        case XFS_ALLOCTYPE_ANY_AG:
2293        case XFS_ALLOCTYPE_START_AG:
2294        case XFS_ALLOCTYPE_FIRST_AG:
2295                /*
2296                 * Rotate through the allocation groups looking for a winner.
2297                 */
2298                if (type == XFS_ALLOCTYPE_ANY_AG) {
2299                        /*
2300                         * Start with the last place we left off.
2301                         */
2302                        args->agno = sagno = (mp->m_agfrotor / rotorstep) %
2303                                        mp->m_sb.sb_agcount;
2304                        args->type = XFS_ALLOCTYPE_THIS_AG;
2305                        flags = XFS_ALLOC_FLAG_TRYLOCK;
2306                } else if (type == XFS_ALLOCTYPE_FIRST_AG) {
2307                        /*
2308                         * Start with allocation group given by bno.
2309                         */
2310                        args->agno = XFS_FSB_TO_AGNO(mp, args->fsbno);
2311                        args->type = XFS_ALLOCTYPE_THIS_AG;
2312                        sagno = 0;
2313                        flags = 0;
2314                } else {
2315                        if (type == XFS_ALLOCTYPE_START_AG)
2316                                args->type = XFS_ALLOCTYPE_THIS_AG;
2317                        /*
2318                         * Start with the given allocation group.
2319                         */
2320                        args->agno = sagno = XFS_FSB_TO_AGNO(mp, args->fsbno);
2321                        flags = XFS_ALLOC_FLAG_TRYLOCK;
2322                }
2323                /*
2324                 * Loop over allocation groups twice; first time with
2325                 * trylock set, second time without.
2326                 */
2327                for (;;) {
2328                        args->pag = xfs_perag_get(mp, args->agno);
2329                        if (no_min) args->minleft = 0;
2330                        error = xfs_alloc_fix_freelist(args, flags);
2331                        args->minleft = minleft;
2332                        if (error) {
2333                                trace_xfs_alloc_vextent_nofix(args);
2334                                goto error0;
2335                        }
2336                        /*
2337                         * If we get a buffer back then the allocation will fly.
2338                         */
2339                        if (args->agbp) {
2340                                if ((error = xfs_alloc_ag_vextent(args)))
2341                                        goto error0;
2342                                break;
2343                        }
2344
2345                        trace_xfs_alloc_vextent_loopfailed(args);
2346
2347                        /*
2348                         * Didn't work, figure out the next iteration.
2349                         */
2350                        if (args->agno == sagno &&
2351                            type == XFS_ALLOCTYPE_START_BNO)
2352                                args->type = XFS_ALLOCTYPE_THIS_AG;
2353                        /*
2354                        * For the first allocation, we can try any AG to get
2355                        * space.  However, if we already have allocated a
2356                        * block, we don't want to try AGs whose number is below
2357                        * sagno. Otherwise, we may end up with out-of-order
2358                        * locking of AGF, which might cause deadlock.
2359                        */
2360                        if (++(args->agno) == mp->m_sb.sb_agcount) {
2361                                if (args->firstblock != NULLFSBLOCK)
2362                                        args->agno = sagno;
2363                                else
2364                                        args->agno = 0;
2365                        }
2366                        /*
2367                         * Reached the starting a.g., must either be done
2368                         * or switch to non-trylock mode.
2369                         */
2370                        if (args->agno == sagno) {
2371                                if (no_min == 1) {
2372                                        args->agbno = NULLAGBLOCK;
2373                                        trace_xfs_alloc_vextent_allfailed(args);
2374                                        break;
2375                                }
2376                                if (flags == 0) {
2377                                        no_min = 1;
2378                                } else {
2379                                        flags = 0;
2380                                        if (type == XFS_ALLOCTYPE_START_BNO) {
2381                                                args->agbno = XFS_FSB_TO_AGBNO(mp,
2382                                                        args->fsbno);
2383                                                args->type = XFS_ALLOCTYPE_NEAR_BNO;
2384                                        }
2385                                }
2386                        }
2387                        xfs_perag_put(args->pag);
2388                }
2389                if (bump_rotor || (type == XFS_ALLOCTYPE_ANY_AG)) {
2390                        if (args->agno == sagno)
2391                                mp->m_agfrotor = (mp->m_agfrotor + 1) %
2392                                        (mp->m_sb.sb_agcount * rotorstep);
2393                        else
2394                                mp->m_agfrotor = (args->agno * rotorstep + 1) %
2395                                        (mp->m_sb.sb_agcount * rotorstep);
2396                }
2397                break;
2398        default:
2399                ASSERT(0);
2400                /* NOTREACHED */
2401        }
2402        if (args->agbno == NULLAGBLOCK)
2403                args->fsbno = NULLFSBLOCK;
2404        else {
2405                args->fsbno = XFS_AGB_TO_FSB(mp, args->agno, args->agbno);
2406#ifdef DEBUG
2407                ASSERT(args->len >= args->minlen);
2408                ASSERT(args->len <= args->maxlen);
2409                ASSERT(args->agbno % args->alignment == 0);
2410                XFS_AG_CHECK_DADDR(mp, XFS_FSB_TO_DADDR(mp, args->fsbno),
2411                        args->len);
2412#endif
2413        }
2414        xfs_perag_put(args->pag);
2415        return 0;
2416error0:
2417        xfs_perag_put(args->pag);
2418        return error;
2419}
2420
2421/*
2422 * Free an extent.
2423 * Just break up the extent address and hand off to xfs_free_ag_extent
2424 * after fixing up the freelist.
2425 */
2426int                             /* error */
2427xfs_free_extent(
2428        xfs_trans_t     *tp,    /* transaction pointer */
2429        xfs_fsblock_t   bno,    /* starting block number of extent */
2430        xfs_extlen_t    len)    /* length of extent */
2431{
2432        xfs_alloc_arg_t args;
2433        int             error;
2434
2435        ASSERT(len != 0);
2436        memset(&args, 0, sizeof(xfs_alloc_arg_t));
2437        args.tp = tp;
2438        args.mp = tp->t_mountp;
2439
2440        /*
2441         * validate that the block number is legal - the enables us to detect
2442         * and handle a silent filesystem corruption rather than crashing.
2443         */
2444        args.agno = XFS_FSB_TO_AGNO(args.mp, bno);
2445        if (args.agno >= args.mp->m_sb.sb_agcount)
2446                return EFSCORRUPTED;
2447
2448        args.agbno = XFS_FSB_TO_AGBNO(args.mp, bno);
2449        if (args.agbno >= args.mp->m_sb.sb_agblocks)
2450                return EFSCORRUPTED;
2451
2452        args.pag = xfs_perag_get(args.mp, args.agno);
2453        ASSERT(args.pag);
2454
2455        error = xfs_alloc_fix_freelist(&args, XFS_ALLOC_FLAG_FREEING);
2456        if (error)
2457                goto error0;
2458
2459        /* validate the extent size is legal now we have the agf locked */
2460        if (args.agbno + len >
2461                        be32_to_cpu(XFS_BUF_TO_AGF(args.agbp)->agf_length)) {
2462                error = EFSCORRUPTED;
2463                goto error0;
2464        }
2465
2466        error = xfs_free_ag_extent(tp, args.agbp, args.agno, args.agbno, len, 0);
2467        if (!error)
2468                xfs_extent_busy_insert(tp, args.agno, args.agbno, len, 0);
2469error0:
2470        xfs_perag_put(args.pag);
2471        return error;
2472}
2473
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