diff options
Diffstat (limited to 'fs/xfs/xfs_alloc.c')
| -rw-r--r-- | fs/xfs/xfs_alloc.c | 844 |
1 files changed, 584 insertions, 260 deletions
diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c index 27d64d7..acdced8 100644 --- a/fs/xfs/xfs_alloc.c +++ b/fs/xfs/xfs_alloc.c @@ -41,19 +41,13 @@ #define XFSA_FIXUP_BNO_OK 1 #define XFSA_FIXUP_CNT_OK 2 -/* - * Prototypes for per-ag allocation routines - */ - STATIC int xfs_alloc_ag_vextent_exact(xfs_alloc_arg_t *); STATIC int xfs_alloc_ag_vextent_near(xfs_alloc_arg_t *); STATIC int xfs_alloc_ag_vextent_size(xfs_alloc_arg_t *); STATIC int xfs_alloc_ag_vextent_small(xfs_alloc_arg_t *, - xfs_btree_cur_t *, xfs_agblock_t *, xfs_extlen_t *, int *); - -/* - * Internal functions. - */ + xfs_btree_cur_t *, xfs_agblock_t *, xfs_extlen_t *, int *); +STATIC void xfs_alloc_busy_trim(struct xfs_alloc_arg *, + xfs_agblock_t, xfs_extlen_t, xfs_agblock_t *, xfs_extlen_t *); /* * Lookup the record equal to [bno, len] in the btree given by cur. @@ -154,19 +148,21 @@ xfs_alloc_compute_aligned( xfs_extlen_t *reslen) /* result length */ { xfs_agblock_t bno; - xfs_extlen_t diff; xfs_extlen_t len; - if (args->alignment > 1 && foundlen >= args->minlen) { - bno = roundup(foundbno, args->alignment); - diff = bno - foundbno; - len = diff >= foundlen ? 0 : foundlen - diff; + /* Trim busy sections out of found extent */ + xfs_alloc_busy_trim(args, foundbno, foundlen, &bno, &len); + + if (args->alignment > 1 && len >= args->minlen) { + xfs_agblock_t aligned_bno = roundup(bno, args->alignment); + xfs_extlen_t diff = aligned_bno - bno; + + *resbno = aligned_bno; + *reslen = diff >= len ? 0 : len - diff; } else { - bno = foundbno; - len = foundlen; + *resbno = bno; + *reslen = len; } - *resbno = bno; - *reslen = len; } /* @@ -280,7 +276,6 @@ xfs_alloc_fix_minleft( return 1; agf = XFS_BUF_TO_AGF(args->agbp); diff = be32_to_cpu(agf->agf_freeblks) - + be32_to_cpu(agf->agf_flcount) - args->len - args->minleft; if (diff >= 0) return 1; @@ -541,16 +536,8 @@ xfs_alloc_ag_vextent( if (error) return error; - /* - * Search the busylist for these blocks and mark the - * transaction as synchronous if blocks are found. This - * avoids the need to block due to a synchronous log - * force to ensure correct ordering as the synchronous - * transaction will guarantee that for us. - */ - if (xfs_alloc_busy_search(args->mp, args->agno, - args->agbno, args->len)) - xfs_trans_set_sync(args->tp); + ASSERT(!xfs_alloc_busy_search(args->mp, args->agno, + args->agbno, args->len)); } if (!args->isfl) { @@ -577,14 +564,14 @@ xfs_alloc_ag_vextent_exact( { xfs_btree_cur_t *bno_cur;/* by block-number btree cursor */ xfs_btree_cur_t *cnt_cur;/* by count btree cursor */ - xfs_agblock_t end; /* end of allocated extent */ int error; xfs_agblock_t fbno; /* start block of found extent */ - xfs_agblock_t fend; /* end block of found extent */ xfs_extlen_t flen; /* length of found extent */ + xfs_agblock_t tbno; /* start block of trimmed extent */ + xfs_extlen_t tlen; /* length of trimmed extent */ + xfs_agblock_t tend; /* end block of trimmed extent */ + xfs_agblock_t end; /* end of allocated extent */ int i; /* success/failure of operation */ - xfs_agblock_t maxend; /* end of maximal extent */ - xfs_agblock_t minend; /* end of minimal extent */ xfs_extlen_t rlen; /* length of returned extent */ ASSERT(args->alignment == 1); @@ -614,14 +601,22 @@ xfs_alloc_ag_vextent_exact( goto error0; XFS_WANT_CORRUPTED_GOTO(i == 1, error0); ASSERT(fbno <= args->agbno); - minend = args->agbno + args->minlen; - maxend = args->agbno + args->maxlen; - fend = fbno + flen; /* - * Give up if the freespace isn't long enough for the minimum request. + * Check for overlapping busy extents. + */ + xfs_alloc_busy_trim(args, fbno, flen, &tbno, &tlen); + + /* + * Give up if the start of the extent is busy, or the freespace isn't + * long enough for the minimum request. */ - if (fend < minend) + if (tbno > args->agbno) + goto not_found; + if (tlen < args->minlen) + goto not_found; + tend = tbno + tlen; + if (tend < args->agbno + args->minlen) goto not_found; /* @@ -630,14 +625,14 @@ xfs_alloc_ag_vextent_exact( * * Fix the length according to mod and prod if given. */ - end = XFS_AGBLOCK_MIN(fend, maxend); + end = XFS_AGBLOCK_MIN(tend, args->agbno + args->maxlen); args->len = end - args->agbno; xfs_alloc_fix_len(args); if (!xfs_alloc_fix_minleft(args)) goto not_found; rlen = args->len; - ASSERT(args->agbno + rlen <= fend); + ASSERT(args->agbno + rlen <= tend); end = args->agbno + rlen; /* @@ -686,11 +681,11 @@ xfs_alloc_find_best_extent( struct xfs_btree_cur **scur, /* searching cursor */ xfs_agblock_t gdiff, /* difference for search comparison */ xfs_agblock_t *sbno, /* extent found by search */ - xfs_extlen_t *slen, - xfs_extlen_t *slena, /* aligned length */ + xfs_extlen_t *slen, /* extent length */ + xfs_agblock_t *sbnoa, /* aligned extent found by search */ + xfs_extlen_t *slena, /* aligned extent length */ int dir) /* 0 = search right, 1 = search left */ { - xfs_agblock_t bno; xfs_agblock_t new; xfs_agblock_t sdiff; int error; @@ -708,16 +703,16 @@ xfs_alloc_find_best_extent( if (error) goto error0; XFS_WANT_CORRUPTED_GOTO(i == 1, error0); - xfs_alloc_compute_aligned(args, *sbno, *slen, &bno, slena); + xfs_alloc_compute_aligned(args, *sbno, *slen, sbnoa, slena); /* * The good extent is closer than this one. */ if (!dir) { - if (bno >= args->agbno + gdiff) + if (*sbnoa >= args->agbno + gdiff) goto out_use_good; } else { - if (bno <= args->agbno - gdiff) + if (*sbnoa <= args->agbno - gdiff) goto out_use_good; } @@ -729,8 +724,8 @@ xfs_alloc_find_best_extent( xfs_alloc_fix_len(args); sdiff = xfs_alloc_compute_diff(args->agbno, args->len, - args->alignment, *sbno, - *slen, &new); + args->alignment, *sbnoa, + *slena, &new); /* * Choose closer size and invalidate other cursor. @@ -780,7 +775,7 @@ xfs_alloc_ag_vextent_near( xfs_agblock_t gtbnoa; /* aligned ... */ xfs_extlen_t gtdiff; /* difference to right side entry */ xfs_extlen_t gtlen; /* length of right side entry */ - xfs_extlen_t gtlena = 0; /* aligned ... */ + xfs_extlen_t gtlena; /* aligned ... */ xfs_agblock_t gtnew; /* useful start bno of right side */ int error; /* error code */ int i; /* result code, temporary */ @@ -789,9 +784,10 @@ xfs_alloc_ag_vextent_near( xfs_agblock_t ltbnoa; /* aligned ... */ xfs_extlen_t ltdiff; /* difference to left side entry */ xfs_extlen_t ltlen; /* length of left side entry */ - xfs_extlen_t ltlena = 0; /* aligned ... */ + xfs_extlen_t ltlena; /* aligned ... */ xfs_agblock_t ltnew; /* useful start bno of left side */ xfs_extlen_t rlen; /* length of returned extent */ + int forced = 0; #if defined(DEBUG) && defined(__KERNEL__) /* * Randomly don't execute the first algorithm. @@ -800,13 +796,20 @@ xfs_alloc_ag_vextent_near( dofirst = random32() & 1; #endif + +restart: + bno_cur_lt = NULL; + bno_cur_gt = NULL; + ltlen = 0; + gtlena = 0; + ltlena = 0; + /* * Get a cursor for the by-size btree. */ cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp, args->agno, XFS_BTNUM_CNT); - ltlen = 0; - bno_cur_lt = bno_cur_gt = NULL; + /* * See if there are any free extents as big as maxlen. */ @@ -822,11 +825,13 @@ xfs_alloc_ag_vextent_near( goto error0; if (i == 0 || ltlen == 0) { xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR); + trace_xfs_alloc_near_noentry(args); return 0; } ASSERT(i == 1); } args->wasfromfl = 0; + /* * First algorithm. * If the requested extent is large wrt the freespaces available @@ -890,7 +895,7 @@ xfs_alloc_ag_vextent_near( if (args->len < blen) continue; ltdiff = xfs_alloc_compute_diff(args->agbno, args->len, - args->alignment, ltbno, ltlen, <new); + args->alignment, ltbnoa, ltlena, <new); if (ltnew != NULLAGBLOCK && (args->len > blen || ltdiff < bdiff)) { bdiff = ltdiff; @@ -1042,11 +1047,12 @@ xfs_alloc_ag_vextent_near( args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen); xfs_alloc_fix_len(args); ltdiff = xfs_alloc_compute_diff(args->agbno, args->len, - args->alignment, ltbno, ltlen, <new); + args->alignment, ltbnoa, ltlena, <new); error = xfs_alloc_find_best_extent(args, &bno_cur_lt, &bno_cur_gt, - ltdiff, >bno, >len, >lena, + ltdiff, >bno, >len, + >bnoa, >lena, 0 /* search right */); } else { ASSERT(gtlena >= args->minlen); @@ -1057,11 +1063,12 @@ xfs_alloc_ag_vextent_near( args->len = XFS_EXTLEN_MIN(gtlena, args->maxlen); xfs_alloc_fix_len(args); gtdiff = xfs_alloc_compute_diff(args->agbno, args->len, - args->alignment, gtbno, gtlen, >new); + args->alignment, gtbnoa, gtlena, >new); error = xfs_alloc_find_best_extent(args, &bno_cur_gt, &bno_cur_lt, - gtdiff, <bno, <len, <lena, + gtdiff, <bno, <len, + <bnoa, <lena, 1 /* search left */); } @@ -1073,6 +1080,12 @@ xfs_alloc_ag_vextent_near( * If we couldn't get anything, give up. */ if (bno_cur_lt == NULL && bno_cur_gt == NULL) { + if (!forced++) { + trace_xfs_alloc_near_busy(args); + xfs_log_force(args->mp, XFS_LOG_SYNC); + goto restart; + } + trace_xfs_alloc_size_neither(args); args->agbno = NULLAGBLOCK; return 0; @@ -1107,12 +1120,13 @@ xfs_alloc_ag_vextent_near( return 0; } rlen = args->len; - (void)xfs_alloc_compute_diff(args->agbno, rlen, args->alignment, ltbno, - ltlen, <new); + (void)xfs_alloc_compute_diff(args->agbno, rlen, args->alignment, + ltbnoa, ltlena, <new); ASSERT(ltnew >= ltbno); - ASSERT(ltnew + rlen <= ltbno + ltlen); + ASSERT(ltnew + rlen <= ltbnoa + ltlena); ASSERT(ltnew + rlen <= be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length)); args->agbno = ltnew; + if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur_lt, ltbno, ltlen, ltnew, rlen, XFSA_FIXUP_BNO_OK))) goto error0; @@ -1155,26 +1169,35 @@ xfs_alloc_ag_vextent_size( int i; /* temp status variable */ xfs_agblock_t rbno; /* returned block number */ xfs_extlen_t rlen; /* length of returned extent */ + int forced = 0; +restart: /* * Allocate and initialize a cursor for the by-size btree. */ cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp, args->agno, XFS_BTNUM_CNT); bno_cur = NULL; + /* * Look for an entry >= maxlen+alignment-1 blocks. */ if ((error = xfs_alloc_lookup_ge(cnt_cur, 0, args->maxlen + args->alignment - 1, &i))) goto error0; + /* - * If none, then pick up the last entry in the tree unless the - * tree is empty. + * If none or we have busy extents that we cannot allocate from, then + * we have to settle for a smaller extent. In the case that there are + * no large extents, this will return the last entry in the tree unless + * the tree is empty. In the case that there are only busy large + * extents, this will return the largest small extent unless there + * are no smaller extents available. */ - if (!i) { - if ((error = xfs_alloc_ag_vextent_small(args, cnt_cur, &fbno, - &flen, &i))) + if (!i || forced > 1) { + error = xfs_alloc_ag_vextent_small(args, cnt_cur, + &fbno, &flen, &i); + if (error) goto error0; if (i == 0 || flen == 0) { xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR); @@ -1182,22 +1205,56 @@ xfs_alloc_ag_vextent_size( return 0; } ASSERT(i == 1); + xfs_alloc_compute_aligned(args, fbno, flen, &rbno, &rlen); + } else { + /* + * Search for a non-busy extent that is large enough. + * If we are at low space, don't check, or if we fall of + * the end of the btree, turn off the busy check and + * restart. + */ + for (;;) { + error = xfs_alloc_get_rec(cnt_cur, &fbno, &flen, &i); + if (error) + goto error0; + XFS_WANT_CORRUPTED_GOTO(i == 1, error0); + + xfs_alloc_compute_aligned(args, fbno, flen, + &rbno, &rlen); + + if (rlen >= args->maxlen) + break; + + error = xfs_btree_increment(cnt_cur, 0, &i); + if (error) + goto error0; + if (i == 0) { + /* + * Our only valid extents must have been busy. + * Make it unbusy by forcing the log out and + * retrying. If we've been here before, forcing + * the log isn't making the extents available, + * which means they have probably been freed in + * this transaction. In that case, we have to + * give up on them and we'll attempt a minlen + * allocation the next time around. + */ + xfs_btree_del_cursor(cnt_cur, + XFS_BTREE_NOERROR); + trace_xfs_alloc_size_busy(args); + if (!forced++) + xfs_log_force(args->mp, XFS_LOG_SYNC); + goto restart; + } + } } - /* - * There's a freespace as big as maxlen+alignment-1, get it. - */ - else { - if ((error = xfs_alloc_get_rec(cnt_cur, &fbno, &flen, &i))) - goto error0; - XFS_WANT_CORRUPTED_GOTO(i == 1, error0); - } + /* * In the first case above, we got the last entry in the * by-size btree. Now we check to see if the space hits maxlen * once aligned; if not, we search left for something better. * This can't happen in the second case above. */ - xfs_alloc_compute_aligned(args, fbno, flen, &rbno, &rlen); rlen = XFS_EXTLEN_MIN(args->maxlen, rlen); XFS_WANT_CORRUPTED_GOTO(rlen == 0 || (rlen <= flen && rbno + rlen <= fbno + flen), error0); @@ -1251,13 +1308,19 @@ xfs_alloc_ag_vextent_size( * Fix up the length. */ args->len = rlen; - xfs_alloc_fix_len(args); - if (rlen < args->minlen || !xfs_alloc_fix_minleft(args)) { - xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR); - trace_xfs_alloc_size_nominleft(args); - args->agbno = NULLAGBLOCK; - return 0; + if (rlen < args->minlen) { + if (!forced++) { + xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR); + trace_xfs_alloc_size_busy(args); + xfs_log_force(args->mp, XFS_LOG_SYNC); + goto restart; + } + goto out_nominleft; } + xfs_alloc_fix_len(args); + + if (!xfs_alloc_fix_minleft(args)) + goto out_nominleft; rlen = args->len; XFS_WANT_CORRUPTED_GOTO(rlen <= flen, error0); /* @@ -1287,6 +1350,12 @@ error0: if (bno_cur) xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR); return error; + +out_nominleft: + xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR); + trace_xfs_alloc_size_nominleft(args); + args->agbno = NULLAGBLOCK; + return 0; } /* @@ -1326,6 +1395,9 @@ xfs_alloc_ag_vextent_small( if (error) goto error0; if (fbno != NULLAGBLOCK) { + xfs_alloc_busy_reuse(args->mp, args->agno, fbno, 1, + args->userdata); + if (args->userdata) { xfs_buf_t *bp; @@ -1617,18 +1689,6 @@ xfs_free_ag_extent( trace_xfs_free_extent(mp, agno, bno, len, isfl, haveleft, haveright); - /* - * Since blocks move to the free list without the coordination - * used in xfs_bmap_finish, we can't allow block to be available - * for reallocation and non-transaction writing (user data) - * until we know that the transaction that moved it to the free - * list is permanently on disk. We track the blocks by declaring - * these blocks as "busy"; the busy list is maintained on a per-ag - * basis and each transaction records which entries should be removed - * when the iclog commits to disk. If a busy block is allocated, - * the iclog is pushed up to the LSN that freed the block. - */ - xfs_alloc_busy_insert(tp, agno, bno, len); return 0; error0: @@ -1923,21 +1983,6 @@ xfs_alloc_get_freelist( xfs_alloc_log_agf(tp, agbp, logflags); *bnop = bno; - /* - * As blocks are freed, they are added to the per-ag busy list and - * remain there until the freeing transaction is committed to disk. - * Now that we have allocated blocks, this list must be searched to see - * if a block is being reused. If one is, then the freeing transaction - * must be pushed to disk before this transaction. - * - * We do this by setting the current transaction to a sync transaction - * which guarantees that the freeing transaction is on disk before this - * transaction. This is done instead of a synchronous log force here so - * that we don't sit and wait with the AGF locked in the transaction - * during the log force. - */ - if (xfs_alloc_busy_search(mp, be32_to_cpu(agf->agf_seqno), bno, 1)) - xfs_trans_set_sync(tp); return 0; } @@ -2423,105 +2468,13 @@ xfs_free_extent( } error = xfs_free_ag_extent(tp, args.agbp, args.agno, args.agbno, len, 0); + if (!error) + xfs_alloc_busy_insert(tp, args.agno, args.agbno, len); error0: xfs_perag_put(args.pag); return error; } - -/* - * AG Busy list management - * The busy list contains block ranges that have been freed but whose - * transactions have not yet hit disk. If any block listed in a busy - * list is reused, the transaction that freed it must be forced to disk - * before continuing to use the block. - * - * xfs_alloc_busy_insert - add to the per-ag busy list - * xfs_alloc_busy_clear - remove an item from the per-ag busy list - * xfs_alloc_busy_search - search for a busy extent - */ - -/* - * Insert a new extent into the busy tree. - * - * The busy extent tree is indexed by the start block of the busy extent. - * there can be multiple overlapping ranges in the busy extent tree but only - * ever one entry at a given start block. The reason for this is that - * multi-block extents can be freed, then smaller chunks of that extent - * allocated and freed again before the first transaction commit is on disk. - * If the exact same start block is freed a second time, we have to wait for - * that busy extent to pass out of the tree before the new extent is inserted. - * There are two main cases we have to handle here. - * - * The first case is a transaction that triggers a "free - allocate - free" - * cycle. This can occur during btree manipulations as a btree block is freed - * to the freelist, then allocated from the free list, then freed again. In - * this case, the second extxpnet free is what triggers the duplicate and as - * such the transaction IDs should match. Because the extent was allocated in - * this transaction, the transaction must be marked as synchronous. This is - * true for all cases where the free/alloc/free occurs in the one transaction, - * hence the addition of the ASSERT(tp->t_flags & XFS_TRANS_SYNC) to this case. - * This serves to catch violations of the second case quite effectively. - * - * The second case is where the free/alloc/free occur in different - * transactions. In this case, the thread freeing the extent the second time - * can't mark the extent busy immediately because it is already tracked in a - * transaction that may be committing. When the log commit for the existing - * busy extent completes, the busy extent will be removed from the tree. If we - * allow the second busy insert to continue using that busy extent structure, - * it can be freed before this transaction is safely in the log. Hence our - * only option in this case is to force the log to remove the existing busy - * extent from the list before we insert the new one with the current - * transaction ID. - * - * The problem we are trying to avoid in the free-alloc-free in separate - * transactions is most easily described with a timeline: - * - * Thread 1 Thread 2 Thread 3 xfslogd - * xact alloc - * free X - * mark busy - * commit xact - * free xact - * xact alloc - * alloc X - * busy search - * mark xact sync - * commit xact - * free xact - * force log - * checkpoint starts - * .... - * xact alloc - * free X - * mark busy - * finds match - * *** KABOOM! *** - * .... - * log IO completes - * unbusy X - * checkpoint completes - * - * By issuing a log force in thread 3 @ "KABOOM", the thread will block until - * the checkpoint completes, and the busy extent it matched will have been - * removed from the tree when it is woken. Hence it can then continue safely. - * - * However, to ensure this matching process is robust, we need to use the - * transaction ID for identifying transaction, as delayed logging results in - * the busy extent and transaction lifecycles being different. i.e. the busy - * extent is active for a lot longer than the transaction. Hence the - * transaction structure can be freed and reallocated, then mark the same - * extent busy again in the new transaction. In this case the new transaction - * will have a different tid but can have the same address, and hence we need - * to check against the tid. - * - * Future: for delayed logging, we could avoid the log force if the extent was - * first freed in the current checkpoint sequence. This, however, requires the - * ability to pin the current checkpoint in memory until this transaction - * commits to ensure that both the original free and the current one combine - * logically into the one checkpoint. If the checkpoint sequences are - * different, however, we still need to wait on a log force. - */ void xfs_alloc_busy_insert( struct xfs_trans *tp, @@ -2533,9 +2486,7 @@ xfs_alloc_busy_insert( struct xfs_busy_extent *busyp; struct xfs_perag *pag; struct rb_node **rbp; - struct rb_node *parent; - int match; - + struct rb_node *parent = NULL; new = kmem_zalloc(sizeof(struct xfs_busy_extent), KM_MAYFAIL); if (!new) { @@ -2544,7 +2495,7 @@ xfs_alloc_busy_insert( * block, make this a synchronous transaction to insure that * the block is not reused before this transaction commits. */ - trace_xfs_alloc_busy(tp, agno, bno, len, 1); + trace_xfs_alloc_busy_enomem(tp->t_mountp, agno, bno, len); xfs_trans_set_sync(tp); return; } @@ -2552,66 +2503,28 @@ xfs_alloc_busy_insert( new->agno = agno; new->bno = bno; new->length = len; - new->tid = xfs_log_get_trans_ident(tp); - INIT_LIST_HEAD(&new->list); /* trace before insert to be able to see failed inserts */ - trace_xfs_alloc_busy(tp, agno, bno, len, 0); + trace_xfs_alloc_busy(tp->t_mountp, agno, bno, len); pag = xfs_perag_get(tp->t_mountp, new->agno); -restart: spin_lock(&pag->pagb_lock); rbp = &pag->pagb_tree.rb_node; - parent = NULL; - busyp = NULL; - match = 0; - while (*rbp && match >= 0) { + while (*rbp) { parent = *rbp; busyp = rb_entry(parent, struct xfs_busy_extent, rb_node); if (new->bno < busyp->bno) { - /* may overlap, but exact start block is lower */ rbp = &(*rbp)->rb_left; - if (new->bno + new->length > busyp->bno) - match = busyp->tid == new->tid ? 1 : -1; + ASSERT(new->bno + new->length <= busyp->bno); } else if (new->bno > busyp->bno) { - /* may overlap, but exact start block is higher */ rbp = &(*rbp)->rb_right; - if (bno < busyp->bno + busyp->length) - match = busyp->tid == new->tid ? 1 : -1; + ASSERT(bno >= busyp->bno + busyp->length); } else { - match = busyp->tid == new->tid ? 1 : -1; - break; + ASSERT(0); } } - if (match < 0) { - /* overlap marked busy in different transaction */ - spin_unlock(&pag->pagb_lock); - xfs_log_force(tp->t_mountp, XFS_LOG_SYNC); - goto restart; - } - if (match > 0) { - /* - * overlap marked busy in same transaction. Update if exact - * start block match, otherwise combine the busy extents into - * a single range. - */ - if (busyp->bno == new->bno) { - busyp->length = max(busyp->length, new->length); - spin_unlock(&pag->pagb_lock); - ASSERT(tp->t_flags & XFS_TRANS_SYNC); - xfs_perag_put(pag); - kmem_free(new); - return; - } - rb_erase(&busyp->rb_node, &pag->pagb_tree); - new->length = max(busyp->bno + busyp->length, - new->bno + new->length) - - min(busyp->bno, new->bno); - new->bno = min(busyp->bno, new->bno); - } else - busyp = NULL; rb_link_node(&new->rb_node, parent, rbp); rb_insert_color(&new->rb_node, &pag->pagb_tree); @@ -2619,7 +2532,6 @@ restart: list_add(&new->list, &tp->t_busy); spin_unlock(&pag->pagb_lock); xfs_perag_put(pag); - kmem_free(busyp); } /* @@ -2668,31 +2580,443 @@ xfs_alloc_busy_search( } } spin_unlock(&pag->pagb_lock); - trace_xfs_alloc_busysearch(mp, agno, bno, len, !!match); xfs_perag_put(pag); return match; } +/* + * The found free extent [fbno, fend] overlaps part or all of the given busy + * extent. If the overlap covers the beginning, the end, or all of the busy + * extent, the overlapping portion can be made unbusy and used for the + * allocation. We can't split a busy extent because we can't modify a + * transaction/CIL context busy list, but we can update an entries block + * number or length. + * + * Returns true if the extent can safely be reused, or false if the search + * needs to be restarted. + */ +STATIC bool +xfs_alloc_busy_update_extent( + struct xfs_mount *mp, + struct xfs_perag *pag, + struct xfs_busy_extent *busyp, + xfs_agblock_t fbno, + xfs_extlen_t flen, + bool userdata) +{ + xfs_agblock_t fend = fbno + flen; + xfs_agblock_t bbno = busyp->bno; + xfs_agblock_t bend = bbno + busyp->length; + + /* + * If there is a busy extent overlapping a user allocation, we have + * no choice but to force the log and retry the search. + * + * Fortunately this does not happen during normal operation, but + * only if the filesystem is very low on space and has to dip into + * the AGFL for normal allocations. + */ + if (userdata) + goto out_force_log; + + if (bbno < fbno && bend > fend) { + /* + * Case 1: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +---------+ + * fbno fend + */ + + /* + * We would have to split the busy extent to be able to track + * it correct, which we cannot do because we would have to + * modify the list of busy extents attached to the transaction + * or CIL context, which is immutable. + * + * Force out the log to clear the busy extent and retry the + * search. + */ + goto out_force_log; + } else if (bbno >= fbno && bend <= fend) { + /* + * Case 2: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-----------------+ + * fbno fend + * + * Case 3: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +--------------------------+ + * fbno fend + * + * Case 4: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +--------------------------+ + * fbno fend + * + * Case 5: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-----------------------------------+ + * fbno fend + * + */ + + /* + * The busy extent is fully covered by the extent we are + * allocating, and can simply be removed from the rbtree. + * However we cannot remove it from the immutable list + * tracking busy extents in the transaction or CIL context, + * so set the length to zero to mark it invalid. + * + * We also need to restart the busy extent search from the + * tree root, because erasing the node can rearrange the + * tree topology. + */ + rb_erase(&busyp->rb_node, &pag->pagb_tree); + busyp->length = 0; + return false; + } else if (fend < bend) { + /* + * Case 6: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +---------+ + * fbno fend + * + * Case 7: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +------------------+ + * fbno fend + * + */ + busyp->bno = fend; + } else if (bbno < fbno) { + /* + * Case 8: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-------------+ + * fbno fend + * + * Case 9: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +----------------------+ + * fbno fend + */ + busyp->length = fbno - busyp->bno; + } else { + ASSERT(0); + } + + trace_xfs_alloc_busy_reuse(mp, pag->pag_agno, fbno, flen); + return true; + +out_force_log: + spin_unlock(&pag->pagb_lock); + xfs_log_force(mp, XFS_LOG_SYNC); + trace_xfs_alloc_busy_force(mp, pag->pag_agno, fbno, flen); + spin_lock(&pag->pagb_lock); + return false; +} + + +/* + * For a given extent [fbno, flen], make sure we can reuse it safely. + */ void -xfs_alloc_busy_clear( +xfs_alloc_busy_reuse( struct xfs_mount *mp, - struct xfs_busy_extent *busyp) + xfs_agnumber_t agno, + xfs_agblock_t fbno, + xfs_extlen_t flen, + bool userdata) { struct xfs_perag *pag; + struct rb_node *rbp; - trace_xfs_alloc_unbusy(mp, busyp->agno, busyp->bno, - busyp->length); + ASSERT(flen > 0); - ASSERT(xfs_alloc_busy_search(mp, busyp->agno, busyp->bno, - busyp->length) == 1); + pag = xfs_perag_get(mp, agno); + spin_lock(&pag->pagb_lock); +restart: + rbp = pag->pagb_tree.rb_node; + while (rbp) { + struct xfs_busy_extent *busyp = + rb_entry(rbp, struct xfs_busy_extent, rb_node); + xfs_agblock_t bbno = busyp->bno; + xfs_agblock_t bend = bbno + busyp->length; - list_del_init(&busyp->list); + if (fbno + flen <= bbno) { + rbp = rbp->rb_left; + continue; + } else if (fbno >= bend) { + rbp = rbp->rb_right; + continue; + } - pag = xfs_perag_get(mp, busyp->agno); - spin_lock(&pag->pagb_lock); - rb_erase(&busyp->rb_node, &pag->pagb_tree); + if (!xfs_alloc_busy_update_extent(mp, pag, busyp, fbno, flen, + userdata)) + goto restart; + } spin_unlock(&pag->pagb_lock); xfs_perag_put(pag); +} + +/* + * For a given extent [fbno, flen], search the busy extent list to find a + * subset of the extent that is not busy. If *rlen is smaller than + * args->minlen no suitable extent could be found, and the higher level + * code needs to force out the log and retry the allocation. + */ +STATIC void +xfs_alloc_busy_trim( + struct xfs_alloc_arg *args, + xfs_agblock_t bno, + xfs_extlen_t len, + xfs_agblock_t *rbno, + xfs_extlen_t *rlen) +{ + xfs_agblock_t fbno; + xfs_extlen_t flen; + struct rb_node *rbp; + + ASSERT(len > 0); + spin_lock(&args->pag->pagb_lock); +restart: + fbno = bno; + flen = len; + rbp = args->pag->pagb_tree.rb_node; + while (rbp && flen >= args->minlen) { + struct xfs_busy_extent *busyp = + rb_entry(rbp, struct xfs_busy_extent, rb_node); + xfs_agblock_t fend = fbno + flen; + xfs_agblock_t bbno = busyp->bno; + xfs_agblock_t bend = bbno + busyp->length; + + if (fend <= bbno) { + rbp = rbp->rb_left; + continue; + } else if (fbno >= bend) { + rbp = rbp->rb_right; + continue; + } + + /* + * If this is a metadata allocation, try to reuse the busy + * extent instead of trimming the allocation. + */ + if (!args->userdata) { + if (!xfs_alloc_busy_update_extent(args->mp, args->pag, + busyp, fbno, flen, + false)) + goto restart; + continue; + } + + if (bbno <= fbno) { + /* start overlap */ + + /* + * Case 1: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +---------+ + * fbno fend + * + * Case 2: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-------------+ + * fbno fend + * + * Case 3: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-------------+ + * fbno fend + * + * Case 4: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-----------------+ + * fbno fend + * + * No unbusy region in extent, return failure. + */ + if (fend <= bend) + goto fail; + + /* + * Case 5: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +----------------------+ + * fbno fend + * + * Case 6: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +--------------------------+ + * fbno fend + * + * Needs to be trimmed to: + * +-------+ + * fbno fend + */ + fbno = bend; + } else if (bend >= fend) { + /* end overlap */ + + /* + * Case 7: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +------------------+ + * fbno fend + * + * Case 8: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +--------------------------+ + * fbno fend + * + * Needs to be trimmed to: + * +-------+ + * fbno fend + */ + fend = bbno; + } else { + /* middle overlap */ + + /* + * Case 9: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-----------------------------------+ + * fbno fend + * + * Can be trimmed to: + * +-------+ OR +-------+ + * fbno fend fbno fend + * + * Backward allocation leads to significant + * fragmentation of directories, which degrades + * directory performance, therefore we always want to + * choose the option that produces forward allocation + * patterns. + * Preferring the lower bno extent will make the next + * request use "fend" as the start of the next + * allocation; if the segment is no longer busy at + * that point, we'll get a contiguous allocation, but + * even if it is still busy, we will get a forward + * allocation. + * We try to avoid choosing the segment at "bend", + * because that can lead to the next allocation + * taking the segment at "fbno", which would be a + * backward allocation. We only use the segment at + * "fbno" if it is much larger than the current + * requested size, because in that case there's a + * good chance subsequent allocations will be + * contiguous. + */ + if (bbno - fbno >= args->maxlen) { + /* left candidate fits perfect */ + fend = bbno; + } else if (fend - bend >= args->maxlen * 4) { + /* right candidate has enough free space */ + fbno = bend; + } else if (bbno - fbno >= args->minlen) { + /* left candidate fits minimum requirement */ + fend = bbno; + } else { + goto fail; + } + } + + flen = fend - fbno; + } + spin_unlock(&args->pag->pagb_lock); + + if (fbno != bno || flen != len) { + trace_xfs_alloc_busy_trim(args->mp, args->agno, bno, len, + fbno, flen); + } + *rbno = fbno; + *rlen = flen; + return; +fail: + /* + * Return a zero extent length as failure indications. All callers + * re-check if the trimmed extent satisfies the minlen requirement. + */ + spin_unlock(&args->pag->pagb_lock); + trace_xfs_alloc_busy_trim(args->mp, args->agno, bno, len, fbno, 0); + *rbno = fbno; + *rlen = 0; +} + +static void +xfs_alloc_busy_clear_one( + struct xfs_mount *mp, + struct xfs_perag *pag, + struct xfs_busy_extent *busyp) +{ + if (busyp->length) { + trace_xfs_alloc_busy_clear(mp, busyp->agno, busyp->bno, + busyp->length); + rb_erase(&busyp->rb_node, &pag->pagb_tree); + } + + list_del_init(&busyp->list); kmem_free(busyp); } + +void +xfs_alloc_busy_clear( + struct xfs_mount *mp, + struct list_head *list) +{ + struct xfs_busy_extent *busyp, *n; + struct xfs_perag *pag = NULL; + xfs_agnumber_t agno = NULLAGNUMBER; + + list_for_each_entry_safe(busyp, n, list, list) { + if (busyp->agno != agno) { + if (pag) { + spin_unlock(&pag->pagb_lock); + xfs_perag_put(pag); + } + pag = xfs_perag_get(mp, busyp->agno); + spin_lock(&pag->pagb_lock); + agno = busyp->agno; + } + + xfs_alloc_busy_clear_one(mp, pag, busyp); + } + + if (pag) { + spin_unlock(&pag->pagb_lock); + xfs_perag_put(pag); + } +} + +/* + * Callback for list_sort to sort busy extents by the AG they reside in. + */ +int +xfs_busy_extent_ag_cmp( + void *priv, + struct list_head *a, + struct list_head *b) +{ + return container_of(a, struct xfs_busy_extent, list)->agno - + container_of(b, struct xfs_busy_extent, list)->agno; +} |