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@xxxxxx>
---
fs/xfs/libxfs/xfs_alloc.c | 93 +++++++++++++++++++++-------------------
fs/xfs/xfs_extent_busy.c | 107 +++++++++++++++++++++++++++++++++-------------
fs/xfs/xfs_extent_busy.h | 8 +++-
fs/xfs/xfs_mount.c | 1 +
fs/xfs/xfs_mount.h | 2 +
5 files changed, 135 insertions(+), 76 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 @@ xfs_alloc_ag_vextent_near(
ltlen = 0;
gtlena = 0;
ltlena = 0;
+ busy = false;
/*
* Get a cursor for the by-size btree.
@@ -1064,8 +1075,8 @@ xfs_alloc_ag_vextent_near(
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)
@@ -1183,8 +1194,8 @@ xfs_alloc_ag_vextent_near(
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)))
@@ -1199,8 +1210,8 @@ xfs_alloc_ag_vextent_near(
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)))
@@ -1261,9 +1272,9 @@ xfs_alloc_ag_vextent_near(
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 @@ xfs_alloc_ag_vextent_size(
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 @@ xfs_alloc_ag_vextent_size(
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 @@ xfs_alloc_ag_vextent_size(
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 @@ xfs_alloc_ag_vextent_size(
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 @@ xfs_alloc_ag_vextent_size(
/*
* 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 @@ xfs_alloc_ag_vextent_size(
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 @@ xfs_alloc_ag_vextent_size(
*/
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;
diff --git a/fs/xfs/xfs_extent_busy.c b/fs/xfs/xfs_extent_busy.c
index 29c2f997aedf..27c3ecb138e4 100644
--- a/fs/xfs/xfs_extent_busy.c
+++ b/fs/xfs/xfs_extent_busy.c
@@ -334,25 +334,30 @@ xfs_extent_busy_reuse(
* subset of the extent that is not busy. If *rlen is smaller than
* args->minlen no suitable extent could be found, and the higher level
* code needs to force out the log and retry the allocation.
+ *
+ * Return the current discard generation for the AG if the file system
+ * has online discard enabled. This value can be used to wait for
+ * the trimmed extent to become fully available if the AG is running out
+ * of space.
*/
-void
+bool
xfs_extent_busy_trim(
struct xfs_alloc_arg *args,
- xfs_agblock_t bno,
- xfs_extlen_t len,
- xfs_agblock_t *rbno,
- xfs_extlen_t *rlen)
+ xfs_agblock_t *bno,
+ xfs_extlen_t *len,
+ unsigned *busy_gen)
{
xfs_agblock_t fbno;
xfs_extlen_t flen;
struct rb_node *rbp;
+ bool ret = false;
ASSERT(len > 0);
spin_lock(&args->pag->pagb_lock);
restart:
- fbno = bno;
- flen = len;
+ fbno = *bno;
+ flen = *len;
rbp = args->pag->pagb_tree.rb_node;
while (rbp && flen >= args->minlen) {
struct xfs_extent_busy *busyp =
@@ -504,24 +509,24 @@ xfs_extent_busy_trim(
flen = fend - fbno;
}
- spin_unlock(&args->pag->pagb_lock);
-
- if (fbno != bno || flen != len) {
- trace_xfs_extent_busy_trim(args->mp, args->agno, bno, len,
+out:
+ if (fbno != *bno || flen != *len) {
+ trace_xfs_extent_busy_trim(args->mp, args->agno, *bno, *len,
fbno, flen);
+ *bno = fbno;
+ *len = flen;
+ *busy_gen = args->pag->pagb_gen;
+ ret = true;
}
- *rbno = fbno;
- *rlen = flen;
- return;
+ spin_unlock(&args->pag->pagb_lock);
+ return ret;
fail:
/*
* Return a zero extent length as failure indications. All callers
* re-check if the trimmed extent satisfies the minlen requirement.
*/
- spin_unlock(&args->pag->pagb_lock);
- trace_xfs_extent_busy_trim(args->mp, args->agno, bno, len, fbno, 0);
- *rbno = fbno;
- *rlen = 0;
+ flen = 0;
+ goto out;
}
STATIC void
@@ -540,6 +545,21 @@ xfs_extent_busy_clear_one(
kmem_free(busyp);
}
+static void
+xfs_extent_busy_put_pag(
+ struct xfs_perag *pag,
+ bool wakeup)
+ __releases(pag->pagb_lock)
+{
+ if (wakeup) {
+ pag->pagb_gen++;
+ wake_up_all(&pag->pagb_wait);
+ }
+
+ spin_unlock(&pag->pagb_lock);
+ xfs_perag_put(pag);
+}
+
/*
* Remove all extents on the passed in list from the busy extents tree.
* If do_discard is set skip extents that need to be discarded, and mark
@@ -554,29 +574,56 @@ xfs_extent_busy_clear(
struct xfs_extent_busy *busyp, *n;
struct xfs_perag *pag = NULL;
xfs_agnumber_t agno = NULLAGNUMBER;
+ bool wakeup = false;
list_for_each_entry_safe(busyp, n, list, list) {
if (busyp->agno != agno) {
- if (pag) {
- spin_unlock(&pag->pagb_lock);
- xfs_perag_put(pag);
- }
- pag = xfs_perag_get(mp, busyp->agno);
- spin_lock(&pag->pagb_lock);
+ if (pag)
+ xfs_extent_busy_put_pag(pag, wakeup);
agno = busyp->agno;
+ pag = xfs_perag_get(mp, agno);
+ spin_lock(&pag->pagb_lock);
+ wakeup = false;
}
if (do_discard && busyp->length &&
- !(busyp->flags & XFS_EXTENT_BUSY_SKIP_DISCARD))
+ !(busyp->flags & XFS_EXTENT_BUSY_SKIP_DISCARD)) {
busyp->flags = XFS_EXTENT_BUSY_DISCARDED;
- else
+ } else {
xfs_extent_busy_clear_one(mp, pag, busyp);
+ wakeup = true;
+ }
}
- if (pag) {
- spin_unlock(&pag->pagb_lock);
- xfs_perag_put(pag);
- }
+ if (pag)
+ xfs_extent_busy_put_pag(pag, wakeup);
+}
+
+/*
+ * Flush out all busy extents for this AG.
+ */
+void
+xfs_extent_busy_flush(
+ struct xfs_mount *mp,
+ struct xfs_perag *pag,
+ unsigned busy_gen)
+{
+ DEFINE_WAIT (wait);
+ int log_flushed = 0, error;
+
+ trace_xfs_log_force(mp, 0, _THIS_IP_);
+ error = _xfs_log_force(mp, XFS_LOG_SYNC, &log_flushed);
+ if (error)
+ return;
+
+ do {
+ prepare_to_wait(&pag->pagb_wait, &wait, TASK_KILLABLE);
+ if (busy_gen != READ_ONCE(pag->pagb_gen))
+ break;
+ schedule();
+ } while (1);
+
+ finish_wait(&pag->pagb_wait, &wait);
}
/*
diff --git a/fs/xfs/xfs_extent_busy.h b/fs/xfs/xfs_extent_busy.h
index bfff284d2dcc..bcb99463cfbb 100644
--- a/fs/xfs/xfs_extent_busy.h
+++ b/fs/xfs/xfs_extent_busy.h
@@ -58,9 +58,13 @@ void
xfs_extent_busy_reuse(struct xfs_mount *mp, xfs_agnumber_t agno,
xfs_agblock_t fbno, xfs_extlen_t flen, bool userdata);
+bool
+xfs_extent_busy_trim(struct xfs_alloc_arg *args, xfs_agblock_t *bno,
+ xfs_extlen_t *len, unsigned *busy_gen);
+
void
-xfs_extent_busy_trim(struct xfs_alloc_arg *args, xfs_agblock_t bno,
- xfs_extlen_t len, xfs_agblock_t *rbno, xfs_extlen_t *rlen);
+xfs_extent_busy_flush(struct xfs_mount *mp, struct xfs_perag *pag,
+ unsigned discards);
int
xfs_extent_busy_ag_cmp(void *priv, struct list_head *a, struct list_head *b);
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 9b9540db17a6..4e9feb1dc15d 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -215,6 +215,7 @@ xfs_initialize_perag(
INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
if (xfs_buf_hash_init(pag))
goto out_unwind;
+ init_waitqueue_head(&pag->pagb_wait);
if (radix_tree_preload(GFP_NOFS))
goto out_unwind;
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 7f351f706b7a..20e2981a4aec 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -384,6 +384,8 @@ typedef struct xfs_perag {
xfs_agino_t pagl_rightrec;
spinlock_t pagb_lock; /* lock for pagb_tree */
struct rb_root pagb_tree; /* ordered tree of busy extents */
+ unsigned int pagb_gen; /* generation count for pagb_tree */
+ wait_queue_head_t pagb_wait; /* woken when pagb_gen changes */
atomic_t pagf_fstrms; /* # of filestreams active in this AG */
--
2.11.0
--
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