From: Christoph Hellwig Date: Tue, 4 Apr 2017 20:37:44 +0000 (-0500) Subject: xfs: improve handling of busy extents in the low-level allocator X-Git-Tag: v4.11.0-rc1~22 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cd80de0463e77b884190bdd8c6d76e26d75c7b2d;p=thirdparty%2Fxfsprogs-dev.git xfs: improve handling of busy extents in the low-level allocator Source kernel commit: ebf55872616c7d4754db5a318591a72a8d5e6896 Currently we force the log and simply try again if we hit a busy extent, but especially with online discard enabled it might take a while after the log force for the busy extents to disappear, and we might have already completed our second pass. So instead we add a new waitqueue and a generation counter to the pag structure so that we can do wakeups once we've removed busy extents, and we replace the single retry with an unconditional one - after all we hold the AGF buffer lock, so no other allocations or frees can be racing with us in this AG. Signed-off-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Signed-off-by: Eric Sandeen --- diff --git a/libxfs/libxfs_priv.h b/libxfs/libxfs_priv.h index 14ae78897..839150088 100644 --- a/libxfs/libxfs_priv.h +++ b/libxfs/libxfs_priv.h @@ -411,11 +411,12 @@ roundup_64(__uint64_t x, __uint32_t y) xfs_agnumber_t __foo = ag; \ __foo = __foo; /* no set-but-unused warning */ \ }) -#define xfs_extent_busy_trim(args,fbno,flen,bno,len) \ -do { \ - *(bno) = (fbno); \ - *(len) = (flen); \ -} while (0) +#define xfs_extent_busy_trim(args,bno,len,busy_gen) ({ \ + unsigned __foo = *(busy_gen); \ + *(busy_gen) = __foo; \ + false; \ +}) +#define xfs_extent_busy_flush(mp,pag,busy_gen) (0) /* avoid unused variable warning */ #define xfs_alloc_busy_insert(tp,ag,b,len) ({ \ diff --git a/libxfs/xfs_alloc.c b/libxfs/xfs_alloc.c index c87975712..81695bfb1 100644 --- a/libxfs/xfs_alloc.c +++ b/libxfs/xfs_alloc.c @@ -217,20 +217,22 @@ xfs_alloc_get_rec( * Compute aligned version of the found extent. * Takes alignment and min length into account. */ -STATIC void +STATIC bool xfs_alloc_compute_aligned( xfs_alloc_arg_t *args, /* allocation argument structure */ xfs_agblock_t foundbno, /* starting block in found extent */ xfs_extlen_t foundlen, /* length in found extent */ xfs_agblock_t *resbno, /* result block number */ - xfs_extlen_t *reslen) /* result length */ + xfs_extlen_t *reslen, /* result length */ + unsigned *busy_gen) { - xfs_agblock_t bno; - xfs_extlen_t len; + xfs_agblock_t bno = foundbno; + xfs_extlen_t len = foundlen; xfs_extlen_t diff; + bool busy; /* Trim busy sections out of found extent */ - xfs_extent_busy_trim(args, foundbno, foundlen, &bno, &len); + busy = xfs_extent_busy_trim(args, &bno, &len, busy_gen); /* * If we have a largish extent that happens to start before min_agbno, @@ -255,6 +257,8 @@ xfs_alloc_compute_aligned( *resbno = bno; *reslen = len; } + + return busy; } /* @@ -733,10 +737,11 @@ xfs_alloc_ag_vextent_exact( int error; xfs_agblock_t fbno; /* start 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 tbno; /* start block of busy extent */ + xfs_extlen_t tlen; /* length of busy extent */ + xfs_agblock_t tend; /* end block of busy extent */ int i; /* success/failure of operation */ + unsigned busy_gen; ASSERT(args->alignment == 1); @@ -769,7 +774,9 @@ xfs_alloc_ag_vextent_exact( /* * Check for overlapping busy extents. */ - xfs_extent_busy_trim(args, fbno, flen, &tbno, &tlen); + tbno = fbno; + tlen = flen; + xfs_extent_busy_trim(args, &tbno, &tlen, &busy_gen); /* * Give up if the start of the extent is busy, or the freespace isn't @@ -849,6 +856,7 @@ xfs_alloc_find_best_extent( xfs_agblock_t sdiff; int error; int i; + unsigned busy_gen; /* The good extent is perfect, no need to search. */ if (!gdiff) @@ -862,7 +870,8 @@ xfs_alloc_find_best_extent( if (error) goto error0; XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0); - xfs_alloc_compute_aligned(args, *sbno, *slen, sbnoa, slena); + xfs_alloc_compute_aligned(args, *sbno, *slen, + sbnoa, slena, &busy_gen); /* * The good extent is closer than this one. @@ -951,7 +960,8 @@ xfs_alloc_ag_vextent_near( 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; + bool busy; + unsigned busy_gen; #ifdef DEBUG /* * Randomly don't execute the first algorithm. @@ -978,6 +988,7 @@ restart: ltlen = 0; gtlena = 0; ltlena = 0; + busy = false; /* * Get a cursor for the by-size btree. @@ -1060,8 +1071,8 @@ restart: if ((error = xfs_alloc_get_rec(cnt_cur, <bno, <len, &i))) goto error0; XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0); - xfs_alloc_compute_aligned(args, ltbno, ltlen, - <bnoa, <lena); + busy = xfs_alloc_compute_aligned(args, ltbno, ltlen, + <bnoa, <lena, &busy_gen); if (ltlena < args->minlen) continue; if (ltbnoa < args->min_agbno || ltbnoa > args->max_agbno) @@ -1179,8 +1190,8 @@ restart: if ((error = xfs_alloc_get_rec(bno_cur_lt, <bno, <len, &i))) goto error0; XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0); - xfs_alloc_compute_aligned(args, ltbno, ltlen, - <bnoa, <lena); + busy |= xfs_alloc_compute_aligned(args, ltbno, ltlen, + <bnoa, <lena, &busy_gen); if (ltlena >= args->minlen && ltbnoa >= args->min_agbno) break; if ((error = xfs_btree_decrement(bno_cur_lt, 0, &i))) @@ -1195,8 +1206,8 @@ restart: if ((error = xfs_alloc_get_rec(bno_cur_gt, >bno, >len, &i))) goto error0; XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0); - xfs_alloc_compute_aligned(args, gtbno, gtlen, - >bnoa, >lena); + busy |= xfs_alloc_compute_aligned(args, gtbno, gtlen, + >bnoa, >lena, &busy_gen); if (gtlena >= args->minlen && gtbnoa <= args->max_agbno) break; if ((error = xfs_btree_increment(bno_cur_gt, 0, &i))) @@ -1257,9 +1268,9 @@ restart: if (bno_cur_lt == NULL && bno_cur_gt == NULL) { xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR); - if (!forced++) { + if (busy) { trace_xfs_alloc_near_busy(args); - xfs_log_force(args->mp, XFS_LOG_SYNC); + xfs_extent_busy_flush(args->mp, args->pag, busy_gen); goto restart; } trace_xfs_alloc_size_neither(args); @@ -1340,7 +1351,8 @@ 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; + bool busy; + unsigned busy_gen; restart: /* @@ -1349,6 +1361,7 @@ restart: cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp, args->agno, XFS_BTNUM_CNT); bno_cur = NULL; + busy = false; /* * Look for an entry >= maxlen+alignment-1 blocks. @@ -1358,14 +1371,13 @@ restart: goto error0; /* - * 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 + * If none 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 || forced > 1) { + if (!i) { error = xfs_alloc_ag_vextent_small(args, cnt_cur, &fbno, &flen, &i); if (error) @@ -1376,13 +1388,11 @@ restart: return 0; } ASSERT(i == 1); - xfs_alloc_compute_aligned(args, fbno, flen, &rbno, &rlen); + busy = xfs_alloc_compute_aligned(args, fbno, flen, &rbno, + &rlen, &busy_gen); } 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); @@ -1390,8 +1400,8 @@ restart: goto error0; XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0); - xfs_alloc_compute_aligned(args, fbno, flen, - &rbno, &rlen); + busy = xfs_alloc_compute_aligned(args, fbno, flen, + &rbno, &rlen, &busy_gen); if (rlen >= args->maxlen) break; @@ -1403,18 +1413,13 @@ restart: /* * 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. + * retrying. */ 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); + xfs_extent_busy_flush(args->mp, + args->pag, busy_gen); goto restart; } } @@ -1450,8 +1455,8 @@ restart: XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0); if (flen < bestrlen) break; - xfs_alloc_compute_aligned(args, fbno, flen, - &rbno, &rlen); + busy = xfs_alloc_compute_aligned(args, fbno, flen, + &rbno, &rlen, &busy_gen); rlen = XFS_EXTLEN_MIN(args->maxlen, rlen); XFS_WANT_CORRUPTED_GOTO(args->mp, rlen == 0 || (rlen <= flen && rbno + rlen <= fbno + flen), @@ -1480,10 +1485,10 @@ restart: */ args->len = rlen; if (rlen < args->minlen) { - if (!forced++) { + if (busy) { xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR); trace_xfs_alloc_size_busy(args); - xfs_log_force(args->mp, XFS_LOG_SYNC); + xfs_extent_busy_flush(args->mp, args->pag, busy_gen); goto restart; } goto out_nominleft;