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 <hch@xxxxxx>
Index: xfs/fs/xfs/xfs_alloc.c
===================================================================
--- xfs.orig/fs/xfs/xfs_alloc.c 2010-12-10 09:50:07.681023471 +0100
+++ xfs/fs/xfs/xfs_alloc.c 2010-12-10 09:51:32.874005592 +0100
@@ -665,6 +665,95 @@ error0:
}
/*
+ * 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,
* and of the form k * prod + mod unless there's nothing that large.
@@ -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.
*/
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