From 489a150f6454e2cd93d9e0ee6d7c5a361844f62a Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 10 Dec 2010 15:04:11 +0000 Subject: [PATCH] xfs: factor duplicate code in xfs_alloc_ag_vextent_near into a helper Add a new xfs_alloc_find_best_extent that does a forward/backward search in the allocation btree. That code previously was existed two times in xfs_alloc_ag_vextent_near, once for each search direction. Based on an earlier patch from Dave Chinner. Signed-off-by: Christoph Hellwig Signed-off-by: Alex Elder --- fs/xfs/xfs_alloc.c | 293 +++++++++++++++++---------------------------- 1 file changed, 113 insertions(+), 180 deletions(-) diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c index d9133f10d2b1..fa8723f5870a 100644 --- a/fs/xfs/xfs_alloc.c +++ b/fs/xfs/xfs_alloc.c @@ -664,6 +664,95 @@ xfs_alloc_ag_vextent_exact( return error; } +/* + * Search the btree in a given direction via the search cursor and compare + * the records found against the good extent we've already found. + */ +STATIC int +xfs_alloc_find_best_extent( + struct xfs_alloc_arg *args, /* allocation argument structure */ + struct xfs_btree_cur **gcur, /* good cursor */ + 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 */ + int dir) /* 0 = search right, 1 = search left */ +{ + xfs_agblock_t bno; + xfs_agblock_t new; + xfs_agblock_t sdiff; + int error; + int i; + + /* The good extent is perfect, no need to search. */ + if (!gdiff) + goto out_use_good; + + /* + * Look until we find a better one, run out of space or run off the end. + */ + do { + error = xfs_alloc_get_rec(*scur, sbno, slen, &i); + if (error) + goto error0; + XFS_WANT_CORRUPTED_GOTO(i == 1, error0); + xfs_alloc_compute_aligned(*sbno, *slen, args->alignment, + args->minlen, &bno, slena); + + /* + * The good extent is closer than this one. + */ + if (!dir) { + if (bno >= args->agbno + gdiff) + goto out_use_good; + } else { + if (bno <= args->agbno - gdiff) + goto out_use_good; + } + + /* + * Same distance, compare length and pick the best. + */ + if (*slena >= args->minlen) { + args->len = XFS_EXTLEN_MIN(*slena, args->maxlen); + xfs_alloc_fix_len(args); + + sdiff = xfs_alloc_compute_diff(args->agbno, args->len, + args->alignment, *sbno, + *slen, &new); + + /* + * Choose closer size and invalidate other cursor. + */ + if (sdiff < gdiff) + goto out_use_search; + goto out_use_good; + } + + if (!dir) + error = xfs_btree_increment(*scur, 0, &i); + else + error = xfs_btree_decrement(*scur, 0, &i); + if (error) + goto error0; + } while (i); + +out_use_good: + xfs_btree_del_cursor(*scur, XFS_BTREE_NOERROR); + *scur = NULL; + return 0; + +out_use_search: + xfs_btree_del_cursor(*gcur, XFS_BTREE_NOERROR); + *gcur = NULL; + return 0; + +error0: + /* caller invalidates cursors */ + return error; +} + /* * Allocate a variable extent near bno in the allocation group agno. * Extent's length (returned in len) will be between minlen and maxlen, @@ -931,203 +1020,45 @@ xfs_alloc_ag_vextent_near( } } } while (bno_cur_lt || bno_cur_gt); + /* * Got both cursors still active, need to find better entry. */ if (bno_cur_lt && bno_cur_gt) { - /* - * Left side is long enough, look for a right side entry. - */ if (ltlena >= args->minlen) { /* - * Fix up the length. + * Left side is good, look for a right side entry. */ args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen); xfs_alloc_fix_len(args); - rlen = args->len; - ltdiff = xfs_alloc_compute_diff(args->agbno, rlen, + ltdiff = xfs_alloc_compute_diff(args->agbno, args->len, args->alignment, ltbno, ltlen, <new); + + error = xfs_alloc_find_best_extent(args, + &bno_cur_lt, &bno_cur_gt, + ltdiff, >bno, >len, >lena, + 0 /* search right */); + } else { + ASSERT(gtlena >= args->minlen); + /* - * Not perfect. - */ - if (ltdiff) { - /* - * Look until we find a better one, run out of - * space, or run off the end. - */ - while (bno_cur_lt && bno_cur_gt) { - if ((error = xfs_alloc_get_rec( - bno_cur_gt, >bno, - >len, &i))) - goto error0; - XFS_WANT_CORRUPTED_GOTO(i == 1, error0); - xfs_alloc_compute_aligned(gtbno, gtlen, - args->alignment, args->minlen, - >bnoa, >lena); - /* - * The left one is clearly better. - */ - if (gtbnoa >= args->agbno + ltdiff) { - xfs_btree_del_cursor( - bno_cur_gt, - XFS_BTREE_NOERROR); - bno_cur_gt = NULL; - break; - } - /* - * If we reach a big enough entry, - * compare the two and pick the best. - */ - if (gtlena >= args->minlen) { - args->len = - XFS_EXTLEN_MIN(gtlena, - args->maxlen); - xfs_alloc_fix_len(args); - rlen = args->len; - gtdiff = xfs_alloc_compute_diff( - args->agbno, rlen, - args->alignment, - gtbno, gtlen, >new); - /* - * Right side is better. - */ - if (gtdiff < ltdiff) { - xfs_btree_del_cursor( - bno_cur_lt, - XFS_BTREE_NOERROR); - bno_cur_lt = NULL; - } - /* - * Left side is better. - */ - else { - xfs_btree_del_cursor( - bno_cur_gt, - XFS_BTREE_NOERROR); - bno_cur_gt = NULL; - } - break; - } - /* - * Fell off the right end. - */ - if ((error = xfs_btree_increment( - bno_cur_gt, 0, &i))) - goto error0; - if (!i) { - xfs_btree_del_cursor( - bno_cur_gt, - XFS_BTREE_NOERROR); - bno_cur_gt = NULL; - break; - } - } - } - /* - * The left side is perfect, trash the right side. - */ - else { - xfs_btree_del_cursor(bno_cur_gt, - XFS_BTREE_NOERROR); - bno_cur_gt = NULL; - } - } - /* - * It's the right side that was found first, look left. - */ - else { - /* - * Fix up the length. + * Right side is good, look for a left side entry. */ args->len = XFS_EXTLEN_MIN(gtlena, args->maxlen); xfs_alloc_fix_len(args); - rlen = args->len; - gtdiff = xfs_alloc_compute_diff(args->agbno, rlen, + gtdiff = xfs_alloc_compute_diff(args->agbno, args->len, args->alignment, gtbno, gtlen, >new); - /* - * Right side entry isn't perfect. - */ - if (gtdiff) { - /* - * Look until we find a better one, run out of - * space, or run off the end. - */ - while (bno_cur_lt && bno_cur_gt) { - if ((error = xfs_alloc_get_rec( - bno_cur_lt, <bno, - <len, &i))) - goto error0; - XFS_WANT_CORRUPTED_GOTO(i == 1, error0); - xfs_alloc_compute_aligned(ltbno, ltlen, - args->alignment, args->minlen, - <bnoa, <lena); - /* - * The right one is clearly better. - */ - if (ltbnoa <= args->agbno - gtdiff) { - xfs_btree_del_cursor( - bno_cur_lt, - XFS_BTREE_NOERROR); - bno_cur_lt = NULL; - break; - } - /* - * If we reach a big enough entry, - * compare the two and pick the best. - */ - if (ltlena >= args->minlen) { - args->len = XFS_EXTLEN_MIN( - ltlena, args->maxlen); - xfs_alloc_fix_len(args); - rlen = args->len; - ltdiff = xfs_alloc_compute_diff( - args->agbno, rlen, - args->alignment, - ltbno, ltlen, <new); - /* - * Left side is better. - */ - if (ltdiff < gtdiff) { - xfs_btree_del_cursor( - bno_cur_gt, - XFS_BTREE_NOERROR); - bno_cur_gt = NULL; - } - /* - * Right side is better. - */ - else { - xfs_btree_del_cursor( - bno_cur_lt, - XFS_BTREE_NOERROR); - bno_cur_lt = NULL; - } - break; - } - /* - * Fell off the left end. - */ - if ((error = xfs_btree_decrement( - bno_cur_lt, 0, &i))) - goto error0; - if (!i) { - xfs_btree_del_cursor(bno_cur_lt, - XFS_BTREE_NOERROR); - bno_cur_lt = NULL; - break; - } - } - } - /* - * The right side is perfect, trash the left side. - */ - else { - xfs_btree_del_cursor(bno_cur_lt, - XFS_BTREE_NOERROR); - bno_cur_lt = NULL; - } + + error = xfs_alloc_find_best_extent(args, + &bno_cur_gt, &bno_cur_lt, + gtdiff, <bno, <len, <lena, + 1 /* search left */); } + + if (error) + goto error0; } + /* * If we couldn't get anything, give up. */ @@ -1136,6 +1067,7 @@ xfs_alloc_ag_vextent_near( args->agbno = NULLAGBLOCK; return 0; } + /* * At this point we have selected a freespace entry, either to the * left or to the right. If it's on the right, copy all the @@ -1152,6 +1084,7 @@ xfs_alloc_ag_vextent_near( j = 1; } else j = 0; + /* * Fix up the length and compute the useful address. */ -- GitLab