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authorChristoph Hellwig <hch@lst.de>2017-02-07 14:06:57 -0800
committerDarrick J. Wong <darrick.wong@oracle.com>2017-02-09 10:50:25 -0800
commitebf55872616c7d4754db5a318591a72a8d5e6896 (patch)
treefd88d14b7765f0834273807a14ee931519029438 /fs/xfs/libxfs/xfs_alloc.c
parent5e30c23d13919a718b22d4921dc5c0accc59da27 (diff)
downloadlinux-ebf55872616c7d4754db5a318591a72a8d5e6896.tar.bz2
xfs: improve handling of busy extents in the low-level allocator
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 <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/xfs/libxfs/xfs_alloc.c')
-rw-r--r--fs/xfs/libxfs/xfs_alloc.c93
1 files changed, 49 insertions, 44 deletions
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 9f06a211e157..fe98fbc4adf1 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -221,20 +221,22 @@ 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,
@@ -259,6 +261,8 @@ xfs_alloc_compute_aligned(
*resbno = bno;
*reslen = len;
}
+
+ return busy;
}
/*
@@ -737,10 +741,11 @@ 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);
@@ -773,7 +778,9 @@ 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
@@ -853,6 +860,7 @@ 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)
@@ -866,7 +874,8 @@ 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.
@@ -955,7 +964,8 @@ 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.
@@ -982,6 +992,7 @@ restart:
ltlen = 0;
gtlena = 0;
ltlena = 0;
+ busy = false;
/*
* Get a cursor for the by-size btree.
@@ -1064,8 +1075,8 @@ restart:
if ((error = xfs_alloc_get_rec(cnt_cur, &ltbno, &ltlen, &i)))
goto error0;
XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0);
- xfs_alloc_compute_aligned(args, ltbno, ltlen,
- &ltbnoa, &ltlena);
+ busy = xfs_alloc_compute_aligned(args, ltbno, ltlen,
+ &ltbnoa, &ltlena, &busy_gen);
if (ltlena < args->minlen)
continue;
if (ltbnoa < args->min_agbno || ltbnoa > args->max_agbno)
@@ -1183,8 +1194,8 @@ restart:
if ((error = xfs_alloc_get_rec(bno_cur_lt, &ltbno, &ltlen, &i)))
goto error0;
XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0);
- xfs_alloc_compute_aligned(args, ltbno, ltlen,
- &ltbnoa, &ltlena);
+ busy |= xfs_alloc_compute_aligned(args, ltbno, ltlen,
+ &ltbnoa, &ltlena, &busy_gen);
if (ltlena >= args->minlen && ltbnoa >= args->min_agbno)
break;
if ((error = xfs_btree_decrement(bno_cur_lt, 0, &i)))
@@ -1199,8 +1210,8 @@ restart:
if ((error = xfs_alloc_get_rec(bno_cur_gt, &gtbno, &gtlen, &i)))
goto error0;
XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0);
- xfs_alloc_compute_aligned(args, gtbno, gtlen,
- &gtbnoa, &gtlena);
+ busy |= xfs_alloc_compute_aligned(args, gtbno, gtlen,
+ &gtbnoa, &gtlena, &busy_gen);
if (gtlena >= args->minlen && gtbnoa <= args->max_agbno)
break;
if ((error = xfs_btree_increment(bno_cur_gt, 0, &i)))
@@ -1261,9 +1272,9 @@ 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);
@@ -1344,7 +1355,8 @@ 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:
/*
@@ -1353,6 +1365,7 @@ 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.
@@ -1362,14 +1375,13 @@ 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)
@@ -1380,13 +1392,11 @@ 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);
@@ -1394,8 +1404,8 @@ 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;
@@ -1407,18 +1417,13 @@ 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;
}
}
@@ -1454,8 +1459,8 @@ 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),
@@ -1484,10 +1489,10 @@ 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;