v4.19.13 snapshot.
diff --git a/fs/xfs/xfs_extent_busy.c b/fs/xfs/xfs_extent_busy.c
new file mode 100644
index 0000000..0ed6837
--- /dev/null
+++ b/fs/xfs/xfs_extent_busy.c
@@ -0,0 +1,659 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
+ * Copyright (c) 2010 David Chinner.
+ * Copyright (c) 2011 Christoph Hellwig.
+ * All Rights Reserved.
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_shared.h"
+#include "xfs_trans_resv.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_alloc.h"
+#include "xfs_extent_busy.h"
+#include "xfs_trace.h"
+#include "xfs_trans.h"
+#include "xfs_log.h"
+
+void
+xfs_extent_busy_insert(
+ struct xfs_trans *tp,
+ xfs_agnumber_t agno,
+ xfs_agblock_t bno,
+ xfs_extlen_t len,
+ unsigned int flags)
+{
+ struct xfs_extent_busy *new;
+ struct xfs_extent_busy *busyp;
+ struct xfs_perag *pag;
+ struct rb_node **rbp;
+ struct rb_node *parent = NULL;
+
+ new = kmem_zalloc(sizeof(struct xfs_extent_busy), KM_SLEEP);
+ new->agno = agno;
+ new->bno = bno;
+ new->length = len;
+ INIT_LIST_HEAD(&new->list);
+ new->flags = flags;
+
+ /* trace before insert to be able to see failed inserts */
+ trace_xfs_extent_busy(tp->t_mountp, agno, bno, len);
+
+ pag = xfs_perag_get(tp->t_mountp, new->agno);
+ spin_lock(&pag->pagb_lock);
+ rbp = &pag->pagb_tree.rb_node;
+ while (*rbp) {
+ parent = *rbp;
+ busyp = rb_entry(parent, struct xfs_extent_busy, rb_node);
+
+ if (new->bno < busyp->bno) {
+ rbp = &(*rbp)->rb_left;
+ ASSERT(new->bno + new->length <= busyp->bno);
+ } else if (new->bno > busyp->bno) {
+ rbp = &(*rbp)->rb_right;
+ ASSERT(bno >= busyp->bno + busyp->length);
+ } else {
+ ASSERT(0);
+ }
+ }
+
+ rb_link_node(&new->rb_node, parent, rbp);
+ rb_insert_color(&new->rb_node, &pag->pagb_tree);
+
+ list_add(&new->list, &tp->t_busy);
+ spin_unlock(&pag->pagb_lock);
+ xfs_perag_put(pag);
+}
+
+/*
+ * Search for a busy extent within the range of the extent we are about to
+ * allocate. You need to be holding the busy extent tree lock when calling
+ * xfs_extent_busy_search(). This function returns 0 for no overlapping busy
+ * extent, -1 for an overlapping but not exact busy extent, and 1 for an exact
+ * match. This is done so that a non-zero return indicates an overlap that
+ * will require a synchronous transaction, but it can still be
+ * used to distinguish between a partial or exact match.
+ */
+int
+xfs_extent_busy_search(
+ struct xfs_mount *mp,
+ xfs_agnumber_t agno,
+ xfs_agblock_t bno,
+ xfs_extlen_t len)
+{
+ struct xfs_perag *pag;
+ struct rb_node *rbp;
+ struct xfs_extent_busy *busyp;
+ int match = 0;
+
+ pag = xfs_perag_get(mp, agno);
+ spin_lock(&pag->pagb_lock);
+
+ rbp = pag->pagb_tree.rb_node;
+
+ /* find closest start bno overlap */
+ while (rbp) {
+ busyp = rb_entry(rbp, struct xfs_extent_busy, rb_node);
+ if (bno < busyp->bno) {
+ /* may overlap, but exact start block is lower */
+ if (bno + len > busyp->bno)
+ match = -1;
+ rbp = rbp->rb_left;
+ } else if (bno > busyp->bno) {
+ /* may overlap, but exact start block is higher */
+ if (bno < busyp->bno + busyp->length)
+ match = -1;
+ rbp = rbp->rb_right;
+ } else {
+ /* bno matches busyp, length determines exact match */
+ match = (busyp->length == len) ? 1 : -1;
+ break;
+ }
+ }
+ spin_unlock(&pag->pagb_lock);
+ xfs_perag_put(pag);
+ return match;
+}
+
+/*
+ * The found free extent [fbno, fend] overlaps part or all of the given busy
+ * extent. If the overlap covers the beginning, the end, or all of the busy
+ * extent, the overlapping portion can be made unbusy and used for the
+ * allocation. We can't split a busy extent because we can't modify a
+ * transaction/CIL context busy list, but we can update an entry's block
+ * number or length.
+ *
+ * Returns true if the extent can safely be reused, or false if the search
+ * needs to be restarted.
+ */
+STATIC bool
+xfs_extent_busy_update_extent(
+ struct xfs_mount *mp,
+ struct xfs_perag *pag,
+ struct xfs_extent_busy *busyp,
+ xfs_agblock_t fbno,
+ xfs_extlen_t flen,
+ bool userdata) __releases(&pag->pagb_lock)
+ __acquires(&pag->pagb_lock)
+{
+ xfs_agblock_t fend = fbno + flen;
+ xfs_agblock_t bbno = busyp->bno;
+ xfs_agblock_t bend = bbno + busyp->length;
+
+ /*
+ * This extent is currently being discarded. Give the thread
+ * performing the discard a chance to mark the extent unbusy
+ * and retry.
+ */
+ if (busyp->flags & XFS_EXTENT_BUSY_DISCARDED) {
+ spin_unlock(&pag->pagb_lock);
+ delay(1);
+ spin_lock(&pag->pagb_lock);
+ return false;
+ }
+
+ /*
+ * If there is a busy extent overlapping a user allocation, we have
+ * no choice but to force the log and retry the search.
+ *
+ * Fortunately this does not happen during normal operation, but
+ * only if the filesystem is very low on space and has to dip into
+ * the AGFL for normal allocations.
+ */
+ if (userdata)
+ goto out_force_log;
+
+ if (bbno < fbno && bend > fend) {
+ /*
+ * Case 1:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +---------+
+ * fbno fend
+ */
+
+ /*
+ * We would have to split the busy extent to be able to track
+ * it correct, which we cannot do because we would have to
+ * modify the list of busy extents attached to the transaction
+ * or CIL context, which is immutable.
+ *
+ * Force out the log to clear the busy extent and retry the
+ * search.
+ */
+ goto out_force_log;
+ } else if (bbno >= fbno && bend <= fend) {
+ /*
+ * Case 2:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +-----------------+
+ * fbno fend
+ *
+ * Case 3:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +--------------------------+
+ * fbno fend
+ *
+ * Case 4:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +--------------------------+
+ * fbno fend
+ *
+ * Case 5:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +-----------------------------------+
+ * fbno fend
+ *
+ */
+
+ /*
+ * The busy extent is fully covered by the extent we are
+ * allocating, and can simply be removed from the rbtree.
+ * However we cannot remove it from the immutable list
+ * tracking busy extents in the transaction or CIL context,
+ * so set the length to zero to mark it invalid.
+ *
+ * We also need to restart the busy extent search from the
+ * tree root, because erasing the node can rearrange the
+ * tree topology.
+ */
+ rb_erase(&busyp->rb_node, &pag->pagb_tree);
+ busyp->length = 0;
+ return false;
+ } else if (fend < bend) {
+ /*
+ * Case 6:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +---------+
+ * fbno fend
+ *
+ * Case 7:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +------------------+
+ * fbno fend
+ *
+ */
+ busyp->bno = fend;
+ } else if (bbno < fbno) {
+ /*
+ * Case 8:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +-------------+
+ * fbno fend
+ *
+ * Case 9:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +----------------------+
+ * fbno fend
+ */
+ busyp->length = fbno - busyp->bno;
+ } else {
+ ASSERT(0);
+ }
+
+ trace_xfs_extent_busy_reuse(mp, pag->pag_agno, fbno, flen);
+ return true;
+
+out_force_log:
+ spin_unlock(&pag->pagb_lock);
+ xfs_log_force(mp, XFS_LOG_SYNC);
+ trace_xfs_extent_busy_force(mp, pag->pag_agno, fbno, flen);
+ spin_lock(&pag->pagb_lock);
+ return false;
+}
+
+
+/*
+ * For a given extent [fbno, flen], make sure we can reuse it safely.
+ */
+void
+xfs_extent_busy_reuse(
+ struct xfs_mount *mp,
+ xfs_agnumber_t agno,
+ xfs_agblock_t fbno,
+ xfs_extlen_t flen,
+ bool userdata)
+{
+ struct xfs_perag *pag;
+ struct rb_node *rbp;
+
+ ASSERT(flen > 0);
+
+ pag = xfs_perag_get(mp, agno);
+ spin_lock(&pag->pagb_lock);
+restart:
+ rbp = pag->pagb_tree.rb_node;
+ while (rbp) {
+ struct xfs_extent_busy *busyp =
+ rb_entry(rbp, struct xfs_extent_busy, rb_node);
+ xfs_agblock_t bbno = busyp->bno;
+ xfs_agblock_t bend = bbno + busyp->length;
+
+ if (fbno + flen <= bbno) {
+ rbp = rbp->rb_left;
+ continue;
+ } else if (fbno >= bend) {
+ rbp = rbp->rb_right;
+ continue;
+ }
+
+ if (!xfs_extent_busy_update_extent(mp, pag, busyp, fbno, flen,
+ userdata))
+ goto restart;
+ }
+ spin_unlock(&pag->pagb_lock);
+ xfs_perag_put(pag);
+}
+
+/*
+ * For a given extent [fbno, flen], search the busy extent list to find a
+ * 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 busy generation for the AG if the extent is busy. This
+ * value can be used to wait for at least one of the currently busy extents
+ * to be cleared. Note that the busy list is not guaranteed to be empty after
+ * the gen is woken. The state of a specific extent must always be confirmed
+ * with another call to xfs_extent_busy_trim() before it can be used.
+ */
+bool
+xfs_extent_busy_trim(
+ struct xfs_alloc_arg *args,
+ 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;
+ rbp = args->pag->pagb_tree.rb_node;
+ while (rbp && flen >= args->minlen) {
+ struct xfs_extent_busy *busyp =
+ rb_entry(rbp, struct xfs_extent_busy, rb_node);
+ xfs_agblock_t fend = fbno + flen;
+ xfs_agblock_t bbno = busyp->bno;
+ xfs_agblock_t bend = bbno + busyp->length;
+
+ if (fend <= bbno) {
+ rbp = rbp->rb_left;
+ continue;
+ } else if (fbno >= bend) {
+ rbp = rbp->rb_right;
+ continue;
+ }
+
+ /*
+ * If this is a metadata allocation, try to reuse the busy
+ * extent instead of trimming the allocation.
+ */
+ if (!xfs_alloc_is_userdata(args->datatype) &&
+ !(busyp->flags & XFS_EXTENT_BUSY_DISCARDED)) {
+ if (!xfs_extent_busy_update_extent(args->mp, args->pag,
+ busyp, fbno, flen,
+ false))
+ goto restart;
+ continue;
+ }
+
+ if (bbno <= fbno) {
+ /* start overlap */
+
+ /*
+ * Case 1:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +---------+
+ * fbno fend
+ *
+ * Case 2:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +-------------+
+ * fbno fend
+ *
+ * Case 3:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +-------------+
+ * fbno fend
+ *
+ * Case 4:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +-----------------+
+ * fbno fend
+ *
+ * No unbusy region in extent, return failure.
+ */
+ if (fend <= bend)
+ goto fail;
+
+ /*
+ * Case 5:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +----------------------+
+ * fbno fend
+ *
+ * Case 6:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +--------------------------+
+ * fbno fend
+ *
+ * Needs to be trimmed to:
+ * +-------+
+ * fbno fend
+ */
+ fbno = bend;
+ } else if (bend >= fend) {
+ /* end overlap */
+
+ /*
+ * Case 7:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +------------------+
+ * fbno fend
+ *
+ * Case 8:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +--------------------------+
+ * fbno fend
+ *
+ * Needs to be trimmed to:
+ * +-------+
+ * fbno fend
+ */
+ fend = bbno;
+ } else {
+ /* middle overlap */
+
+ /*
+ * Case 9:
+ * bbno bend
+ * +BBBBBBBBBBBBBBBBB+
+ * +-----------------------------------+
+ * fbno fend
+ *
+ * Can be trimmed to:
+ * +-------+ OR +-------+
+ * fbno fend fbno fend
+ *
+ * Backward allocation leads to significant
+ * fragmentation of directories, which degrades
+ * directory performance, therefore we always want to
+ * choose the option that produces forward allocation
+ * patterns.
+ * Preferring the lower bno extent will make the next
+ * request use "fend" as the start of the next
+ * allocation; if the segment is no longer busy at
+ * that point, we'll get a contiguous allocation, but
+ * even if it is still busy, we will get a forward
+ * allocation.
+ * We try to avoid choosing the segment at "bend",
+ * because that can lead to the next allocation
+ * taking the segment at "fbno", which would be a
+ * backward allocation. We only use the segment at
+ * "fbno" if it is much larger than the current
+ * requested size, because in that case there's a
+ * good chance subsequent allocations will be
+ * contiguous.
+ */
+ if (bbno - fbno >= args->maxlen) {
+ /* left candidate fits perfect */
+ fend = bbno;
+ } else if (fend - bend >= args->maxlen * 4) {
+ /* right candidate has enough free space */
+ fbno = bend;
+ } else if (bbno - fbno >= args->minlen) {
+ /* left candidate fits minimum requirement */
+ fend = bbno;
+ } else {
+ goto fail;
+ }
+ }
+
+ flen = fend - fbno;
+ }
+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;
+ }
+ 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.
+ */
+ flen = 0;
+ goto out;
+}
+
+STATIC void
+xfs_extent_busy_clear_one(
+ struct xfs_mount *mp,
+ struct xfs_perag *pag,
+ struct xfs_extent_busy *busyp)
+{
+ if (busyp->length) {
+ trace_xfs_extent_busy_clear(mp, busyp->agno, busyp->bno,
+ busyp->length);
+ rb_erase(&busyp->rb_node, &pag->pagb_tree);
+ }
+
+ list_del_init(&busyp->list);
+ 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
+ * these as undergoing a discard operation instead.
+ */
+void
+xfs_extent_busy_clear(
+ struct xfs_mount *mp,
+ struct list_head *list,
+ bool do_discard)
+{
+ 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)
+ 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_DISCARDED;
+ } else {
+ xfs_extent_busy_clear_one(mp, pag, busyp);
+ wakeup = true;
+ }
+ }
+
+ 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 error;
+
+ error = xfs_log_force(mp, XFS_LOG_SYNC);
+ 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);
+}
+
+void
+xfs_extent_busy_wait_all(
+ struct xfs_mount *mp)
+{
+ DEFINE_WAIT (wait);
+ xfs_agnumber_t agno;
+
+ for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
+ struct xfs_perag *pag = xfs_perag_get(mp, agno);
+
+ do {
+ prepare_to_wait(&pag->pagb_wait, &wait, TASK_KILLABLE);
+ if (RB_EMPTY_ROOT(&pag->pagb_tree))
+ break;
+ schedule();
+ } while (1);
+ finish_wait(&pag->pagb_wait, &wait);
+
+ xfs_perag_put(pag);
+ }
+}
+
+/*
+ * Callback for list_sort to sort busy extents by the AG they reside in.
+ */
+int
+xfs_extent_busy_ag_cmp(
+ void *priv,
+ struct list_head *l1,
+ struct list_head *l2)
+{
+ struct xfs_extent_busy *b1 =
+ container_of(l1, struct xfs_extent_busy, list);
+ struct xfs_extent_busy *b2 =
+ container_of(l2, struct xfs_extent_busy, list);
+ s32 diff;
+
+ diff = b1->agno - b2->agno;
+ if (!diff)
+ diff = b1->bno - b2->bno;
+ return diff;
+}