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xfs: track best extent from cntbt lastblock scan in alloc cursor 

If the size lookup lands in the last block of the by-size btree, the
near mode algorithm scans the entire block for the extent with best
available locality. In preparation for similar best available
extent tracking across both btrees, extend the allocation cursor
with best extent data and lift the associated state from the cntbt
last block scan code. No functional changes.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Brian Foster 2019-10-13 17:10:32 -07:00 committed by Darrick J. Wong
parent d6d3aff203
commit c62321a2a0
1 changed files with 33 additions and 30 deletions
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63
fs/xfs/libxfs/xfs_alloc.c
View File

@ -716,6 +716,11 @@ struct xfs_alloc_cur {
struct xfs_btree_cur *cnt; /* btree cursors */
struct xfs_btree_cur *bnolt;
struct xfs_btree_cur *bnogt;
xfs_agblock_t rec_bno;/* extent startblock */
xfs_extlen_t rec_len;/* extent length */
xfs_agblock_t bno; /* alloc bno */
xfs_extlen_t len; /* alloc len */
xfs_extlen_t diff; /* diff from search bno */
unsigned int busy_gen;/* busy state */
bool busy;
};
@ -735,6 +740,11 @@ xfs_alloc_cur_setup(
ASSERT(args->alignment == 1 || args->type != XFS_ALLOCTYPE_THIS_BNO);
acur->rec_bno = 0;
acur->rec_len = 0;
acur->bno = 0;
acur->len = 0;
acur->diff = 0;
acur->busy = false;
acur->busy_gen = 0;
@ -1247,10 +1257,7 @@ restart:
* but we never loop back to the top.
*/
while (xfs_btree_islastblock(acur.cnt, 0)) {
xfs_extlen_t bdiff;
int besti=0;
xfs_extlen_t blen=0;
xfs_agblock_t bnew=0;
xfs_extlen_t diff;
#ifdef DEBUG
if (dofirst)
@ -1281,8 +1288,8 @@ restart:
break;
}
i = acur.cnt->bc_ptrs[0];
for (j = 1, blen = 0, bdiff = 0;
!error && j && (blen < args->maxlen || bdiff > 0);
for (j = 1;
!error && j && (acur.len < args->maxlen || acur.diff > 0);
error = xfs_btree_increment(acur.cnt, 0, &j)) {
/*
* For each entry, decide if it's better than
@ -1301,44 +1308,40 @@ restart:
args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
xfs_alloc_fix_len(args);
ASSERT(args->len >= args->minlen);
if (args->len < blen)
if (args->len < acur.len)
continue;
ltdiff = xfs_alloc_compute_diff(args->agbno, args->len,
diff = xfs_alloc_compute_diff(args->agbno, args->len,
args->alignment, args->datatype, ltbnoa,
ltlena, &ltnew);
if (ltnew != NULLAGBLOCK &&
(args->len > blen || ltdiff < bdiff)) {
bdiff = ltdiff;
bnew = ltnew;
blen = args->len;
besti = acur.cnt->bc_ptrs[0];
(args->len > acur.len || diff < acur.diff)) {
acur.rec_bno = ltbno;
acur.rec_len = ltlen;
acur.diff = diff;
acur.bno = ltnew;
acur.len = args->len;
}
}
/*
* It didn't work. We COULD be in a case where
* there's a good record somewhere, so try again.
*/
if (blen == 0)
if (acur.len == 0)
break;
/*
* Point at the best entry, and retrieve it again.
*/
acur.cnt->bc_ptrs[0] = besti;
error = xfs_alloc_get_rec(acur.cnt, &ltbno, &ltlen, &i);
if (error)
goto out;
XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, out);
ASSERT(ltbno + ltlen <= be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
args->len = blen;
/*
* We are allocating starting at bnew for blen blocks.
* Allocate at the bno/len tracked in the cursor.
*/
args->agbno = bnew;
ASSERT(bnew >= ltbno);
ASSERT(bnew + blen <= ltbno + ltlen);
error = xfs_alloc_fixup_trees(acur.cnt, acur.bnolt, ltbno,
ltlen, bnew, blen, XFSA_FIXUP_CNT_OK);
args->agbno = acur.bno;
args->len = acur.len;
ASSERT(acur.bno >= acur.rec_bno);
ASSERT(acur.bno + acur.len <= acur.rec_bno + acur.rec_len);
ASSERT(acur.rec_bno + acur.rec_len <=
be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
error = xfs_alloc_fixup_trees(acur.cnt, acur.bnolt,
acur.rec_bno, acur.rec_len, acur.bno, acur.len,
0);
if (error)
goto out;
trace_xfs_alloc_near_first(args);