1 files changed, 782 insertions, 85 deletions

diff --git a/fs/xfs/xfs_discard.c b/fs/xfs/xfs_discard.c
index 93f07edafd81..6917de832191 100644
--- a/fs/xfs/xfs_discard.c
+++ b/fs/xfs/xfs_discard.c
@@ -1,42 +1,186 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * Copyright (C) 2010 Red Hat, Inc.
+ * Copyright (C) 2010, 2023 Red Hat, Inc.
  * All Rights Reserved.
  */
 #include "xfs.h"
+#include "xfs_shared.h"
 #include "xfs_format.h"
 #include "xfs_log_format.h"
 #include "xfs_trans_resv.h"
-#include "xfs_sb.h"
+#include "xfs_trans.h"
 #include "xfs_mount.h"
-#include "xfs_quota.h"
-#include "xfs_inode.h"
 #include "xfs_btree.h"
 #include "xfs_alloc_btree.h"
 #include "xfs_alloc.h"
+#include "xfs_discard.h"
 #include "xfs_error.h"
 #include "xfs_extent_busy.h"
-#include "xfs_discard.h"
 #include "xfs_trace.h"
 #include "xfs_log.h"
+#include "xfs_ag.h"
+#include "xfs_health.h"
+#include "xfs_rtbitmap.h"
+#include "xfs_rtgroup.h"
+
+/*
+ * Notes on an efficient, low latency fstrim algorithm
+ *
+ * We need to walk the filesystem free space and issue discards on the free
+ * space that meet the search criteria (size and location). We cannot issue
+ * discards on extents that might be in use, or are so recently in use they are
+ * still marked as busy. To serialise against extent state changes whilst we are
+ * gathering extents to trim, we must hold the AGF lock to lock out other
+ * allocations and extent free operations that might change extent state.
+ *
+ * However, we cannot just hold the AGF for the entire AG free space walk whilst
+ * we issue discards on each free space that is found. Storage devices can have
+ * extremely slow discard implementations (e.g. ceph RBD) and so walking a
+ * couple of million free extents and issuing synchronous discards on each
+ * extent can take a *long* time. Whilst we are doing this walk, nothing else
+ * can access the AGF, and we can stall transactions and hence the log whilst
+ * modifications wait for the AGF lock to be released. This can lead hung tasks
+ * kicking the hung task timer and rebooting the system. This is bad.
+ *
+ * Hence we need to take a leaf from the bulkstat playbook. It takes the AGI
+ * lock, gathers a range of inode cluster buffers that are allocated, drops the
+ * AGI lock and then reads all the inode cluster buffers and processes them. It
+ * loops doing this, using a cursor to keep track of where it is up to in the AG
+ * for each iteration to restart the INOBT lookup from.
+ *
+ * We can't do this exactly with free space - once we drop the AGF lock, the
+ * state of the free extent is out of our control and we cannot run a discard
+ * safely on it in this situation. Unless, of course, we've marked the free
+ * extent as busy and undergoing a discard operation whilst we held the AGF
+ * locked.
+ *
+ * This is exactly how online discard works - free extents are marked busy when
+ * they are freed, and once the extent free has been committed to the journal,
+ * the busy extent record is marked as "undergoing discard" and the discard is
+ * then issued on the free extent. Once the discard completes, the busy extent
+ * record is removed and the extent is able to be allocated again.
+ *
+ * In the context of fstrim, if we find a free extent we need to discard, we
+ * don't have to discard it immediately. All we need to do it record that free
+ * extent as being busy and under discard, and all the allocation routines will
+ * now avoid trying to allocate it. Hence if we mark the extent as busy under
+ * the AGF lock, we can safely discard it without holding the AGF lock because
+ * nothing will attempt to allocate that free space until the discard completes.
+ *
+ * This also allows us to issue discards asynchronously like we do with online
+ * discard, and so for fast devices fstrim will run much faster as we can have
+ * multiple discard operations in flight at once, as well as pipeline the free
+ * extent search so that it overlaps in flight discard IO.
+ */
+
+#define XFS_DISCARD_MAX_EXAMINE	(100)
+
+struct workqueue_struct *xfs_discard_wq;
+
+static void
+xfs_discard_endio_work(
+	struct work_struct	*work)
+{
+	struct xfs_busy_extents	*extents =
+		container_of(work, struct xfs_busy_extents, endio_work);
 
-STATIC int
-xfs_trim_extents(
+	xfs_extent_busy_clear(&extents->extent_list, false);
+	kfree(extents->owner);
+}
+
+/*
+ * Queue up the actual completion to a thread to avoid IRQ-safe locking for
+ * eb_lock.
+ */
+static void
+xfs_discard_endio(
+	struct bio		*bio)
+{
+	struct xfs_busy_extents	*extents = bio->bi_private;
+
+	INIT_WORK(&extents->endio_work, xfs_discard_endio_work);
+	queue_work(xfs_discard_wq, &extents->endio_work);
+	bio_put(bio);
+}
+
+/*
+ * Walk the discard list and issue discards on all the busy extents in the
+ * list. We plug and chain the bios so that we only need a single completion
+ * call to clear all the busy extents once the discards are complete.
+ */
+int
+xfs_discard_extents(
 	struct xfs_mount	*mp,
-	xfs_agnumber_t		agno,
-	xfs_daddr_t		start,
-	xfs_daddr_t		end,
-	xfs_daddr_t		minlen,
-	uint64_t		*blocks_trimmed)
+	struct xfs_busy_extents	*extents)
 {
-	struct block_device	*bdev = mp->m_ddev_targp->bt_bdev;
+	struct xfs_extent_busy	*busyp;
+	struct bio		*bio = NULL;
+	struct blk_plug		plug;
+	int			error = 0;
+
+	blk_start_plug(&plug);
+	list_for_each_entry(busyp, &extents->extent_list, list) {
+		struct xfs_group	*xg = busyp->group;
+		struct xfs_buftarg	*btp =
+			xfs_group_type_buftarg(xg->xg_mount, xg->xg_type);
+
+		trace_xfs_discard_extent(xg, busyp->bno, busyp->length);
+
+		error = __blkdev_issue_discard(btp->bt_bdev,
+				xfs_gbno_to_daddr(xg, busyp->bno),
+				XFS_FSB_TO_BB(mp, busyp->length),
+				GFP_KERNEL, &bio);
+		if (error && error != -EOPNOTSUPP) {
+			xfs_info(mp,
+	 "discard failed for extent [0x%llx,%u], error %d",
+				 (unsigned long long)busyp->bno,
+				 busyp->length,
+				 error);
+			break;
+		}
+	}
+
+	if (bio) {
+		bio->bi_private = extents;
+		bio->bi_end_io = xfs_discard_endio;
+		submit_bio(bio);
+	} else {
+		xfs_discard_endio_work(&extents->endio_work);
+	}
+	blk_finish_plug(&plug);
+
+	return error;
+}
+
+/*
+ * Care must be taken setting up the trim cursor as the perags may not have been
+ * initialised when the cursor is initialised. e.g. a clean mount which hasn't
+ * read in AGFs and the first operation run on the mounted fs is a trim. This
+ * can result in perag fields that aren't initialised until
+ * xfs_trim_gather_extents() calls xfs_alloc_read_agf() to lock down the AG for
+ * the free space search.
+ */
+struct xfs_trim_cur {
+	xfs_agblock_t	start;
+	xfs_extlen_t	count;
+	xfs_agblock_t	end;
+	xfs_extlen_t	minlen;
+	bool		by_bno;
+};
+
+static int
+xfs_trim_gather_extents(
+	struct xfs_perag	*pag,
+	struct xfs_trim_cur	*tcur,
+	struct xfs_busy_extents	*extents)
+{
+	struct xfs_mount	*mp = pag_mount(pag);
+	struct xfs_trans	*tp;
 	struct xfs_btree_cur	*cur;
 	struct xfs_buf		*agbp;
-	struct xfs_perag	*pag;
 	int			error;
 	int			i;
-
-	pag = xfs_perag_get(mp, agno);
+	int			batch = XFS_DISCARD_MAX_EXAMINE;
 
 	/*
 	 * Force out the log.  This means any transactions that might have freed
@@ -45,97 +189,630 @@ xfs_trim_extents(
 	 */
 	xfs_log_force(mp, XFS_LOG_SYNC);
 
-	error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
-	if (error || !agbp)
-		goto out_put_perag;
+	tp = xfs_trans_alloc_empty(mp);
 
-	cur = xfs_allocbt_init_cursor(mp, NULL, agbp, agno, XFS_BTNUM_CNT);
+	error = xfs_alloc_read_agf(pag, tp, 0, &agbp);
+	if (error)
+		goto out_trans_cancel;
 
 	/*
-	 * Look up the longest btree in the AGF and start with it.
+	 * First time through tcur->count will not have been initialised as
+	 * pag->pagf_longest is not guaranteed to be valid before we read
+	 * the AGF buffer above.
 	 */
-	error = xfs_alloc_lookup_ge(cur, 0,
-			    be32_to_cpu(XFS_BUF_TO_AGF(agbp)->agf_longest), &i);
+	if (!tcur->count)
+		tcur->count = pag->pagf_longest;
+
+	if (tcur->by_bno) {
+		/* sub-AG discard request always starts at tcur->start */
+		cur = xfs_bnobt_init_cursor(mp, tp, agbp, pag);
+		error = xfs_alloc_lookup_le(cur, tcur->start, 0, &i);
+		if (!error && !i)
+			error = xfs_alloc_lookup_ge(cur, tcur->start, 0, &i);
+	} else if (tcur->start == 0) {
+		/* first time through a by-len starts with max length */
+		cur = xfs_cntbt_init_cursor(mp, tp, agbp, pag);
+		error = xfs_alloc_lookup_ge(cur, 0, tcur->count, &i);
+	} else {
+		/* nth time through a by-len starts where we left off */
+		cur = xfs_cntbt_init_cursor(mp, tp, agbp, pag);
+		error = xfs_alloc_lookup_le(cur, tcur->start, tcur->count, &i);
+	}
 	if (error)
 		goto out_del_cursor;
+	if (i == 0) {
+		/* nothing of that length left in the AG, we are done */
+		tcur->count = 0;
+		goto out_del_cursor;
+	}
 
 	/*
 	 * Loop until we are done with all extents that are large
-	 * enough to be worth discarding.
+	 * enough to be worth discarding or we hit batch limits.
 	 */
 	while (i) {
 		xfs_agblock_t	fbno;
 		xfs_extlen_t	flen;
-		xfs_daddr_t	dbno;
-		xfs_extlen_t	dlen;
 
 		error = xfs_alloc_get_rec(cur, &fbno, &flen, &i);
 		if (error)
-			goto out_del_cursor;
-		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_del_cursor);
-		ASSERT(flen <= be32_to_cpu(XFS_BUF_TO_AGF(agbp)->agf_longest));
-
-		/*
-		 * use daddr format for all range/len calculations as that is
-		 * the format the range/len variables are supplied in by
-		 * userspace.
-		 */
-		dbno = XFS_AGB_TO_DADDR(mp, agno, fbno);
-		dlen = XFS_FSB_TO_BB(mp, flen);
+			break;
+		if (XFS_IS_CORRUPT(mp, i != 1)) {
+			xfs_btree_mark_sick(cur);
+			error = -EFSCORRUPTED;
+			break;
+		}
 
-		/*
-		 * Too small?  Give up.
-		 */
-		if (dlen < minlen) {
-			trace_xfs_discard_toosmall(mp, agno, fbno, flen);
-			goto out_del_cursor;
+		if (--batch <= 0) {
+			/*
+			 * Update the cursor to point at this extent so we
+			 * restart the next batch from this extent.
+			 */
+			tcur->start = fbno;
+			tcur->count = flen;
+			break;
 		}
 
 		/*
 		 * If the extent is entirely outside of the range we are
-		 * supposed to discard skip it.  Do not bother to trim
-		 * down partially overlapping ranges for now.
+		 * supposed to skip it.  Do not bother to trim down partially
+		 * overlapping ranges for now.
 		 */
-		if (dbno + dlen < start || dbno > end) {
-			trace_xfs_discard_exclude(mp, agno, fbno, flen);
+		if (fbno + flen < tcur->start) {
+			trace_xfs_discard_exclude(pag_group(pag), fbno, flen);
 			goto next_extent;
 		}
+		if (fbno > tcur->end) {
+			trace_xfs_discard_exclude(pag_group(pag), fbno, flen);
+			if (tcur->by_bno) {
+				tcur->count = 0;
+				break;
+			}
+			goto next_extent;
+		}
+
+		/* Trim the extent returned to the range we want. */
+		if (fbno < tcur->start) {
+			flen -= tcur->start - fbno;
+			fbno = tcur->start;
+		}
+		if (fbno + flen > tcur->end + 1)
+			flen = tcur->end - fbno + 1;
+
+		/* Too small?  Give up. */
+		if (flen < tcur->minlen) {
+			trace_xfs_discard_toosmall(pag_group(pag), fbno, flen);
+			if (tcur->by_bno)
+				goto next_extent;
+			tcur->count = 0;
+			break;
+		}
 
 		/*
 		 * If any blocks in the range are still busy, skip the
 		 * discard and try again the next time.
 		 */
-		if (xfs_extent_busy_search(mp, agno, fbno, flen)) {
-			trace_xfs_discard_busy(mp, agno, fbno, flen);
+		if (xfs_extent_busy_search(pag_group(pag), fbno, flen)) {
+			trace_xfs_discard_busy(pag_group(pag), fbno, flen);
 			goto next_extent;
 		}
 
-		trace_xfs_discard_extent(mp, agno, fbno, flen);
-		error = blkdev_issue_discard(bdev, dbno, dlen, GFP_NOFS, 0);
-		if (error)
-			goto out_del_cursor;
-		*blocks_trimmed += flen;
-
+		xfs_extent_busy_insert_discard(pag_group(pag), fbno, flen,
+				&extents->extent_list);
 next_extent:
-		error = xfs_btree_decrement(cur, 0, &i);
+		if (tcur->by_bno)
+			error = xfs_btree_increment(cur, 0, &i);
+		else
+			error = xfs_btree_decrement(cur, 0, &i);
 		if (error)
-			goto out_del_cursor;
+			break;
 
-		if (fatal_signal_pending(current)) {
-			error = -ERESTARTSYS;
-			goto out_del_cursor;
-		}
+		/*
+		 * If there's no more records in the tree, we are done. Set the
+		 * cursor block count to 0 to indicate to the caller that there
+		 * is no more extents to search.
+		 */
+		if (i == 0)
+			tcur->count = 0;
 	}
 
+	/*
+	 * If there was an error, release all the gathered busy extents because
+	 * we aren't going to issue a discard on them any more.
+	 */
+	if (error)
+		xfs_extent_busy_clear(&extents->extent_list, false);
 out_del_cursor:
 	xfs_btree_del_cursor(cur, error);
-	xfs_buf_relse(agbp);
-out_put_perag:
-	xfs_perag_put(pag);
+out_trans_cancel:
+	xfs_trans_cancel(tp);
+	return error;
+}
+
+static bool
+xfs_trim_should_stop(void)
+{
+	return fatal_signal_pending(current) || freezing(current);
+}
+
+/*
+ * Iterate the free list gathering extents and discarding them. We need a cursor
+ * for the repeated iteration of gather/discard loop, so use the longest extent
+ * we found in the last batch as the key to start the next.
+ */
+static int
+xfs_trim_perag_extents(
+	struct xfs_perag	*pag,
+	xfs_agblock_t		start,
+	xfs_agblock_t		end,
+	xfs_extlen_t		minlen)
+{
+	struct xfs_trim_cur	tcur = {
+		.start		= start,
+		.end		= end,
+		.minlen		= minlen,
+	};
+	int			error = 0;
+
+	if (start != 0 || end != pag_group(pag)->xg_block_count)
+		tcur.by_bno = true;
+
+	do {
+		struct xfs_busy_extents	*extents;
+
+		extents = kzalloc(sizeof(*extents), GFP_KERNEL);
+		if (!extents) {
+			error = -ENOMEM;
+			break;
+		}
+
+		extents->owner = extents;
+		INIT_LIST_HEAD(&extents->extent_list);
+
+		error = xfs_trim_gather_extents(pag, &tcur, extents);
+		if (error) {
+			kfree(extents);
+			break;
+		}
+
+		/*
+		 * We hand the extent list to the discard function here so the
+		 * discarded extents can be removed from the busy extent list.
+		 * This allows the discards to run asynchronously with gathering
+		 * the next round of extents to discard.
+		 *
+		 * However, we must ensure that we do not reference the extent
+		 * list  after this function call, as it may have been freed by
+		 * the time control returns to us.
+		 */
+		error = xfs_discard_extents(pag_mount(pag), extents);
+		if (error)
+			break;
+
+		if (xfs_trim_should_stop())
+			break;
+
+	} while (tcur.count != 0);
+
 	return error;
+
+}
+
+static int
+xfs_trim_datadev_extents(
+	struct xfs_mount	*mp,
+	xfs_daddr_t		start,
+	xfs_daddr_t		end,
+	xfs_extlen_t		minlen)
+{
+	xfs_agnumber_t		start_agno, end_agno;
+	xfs_agblock_t		start_agbno, end_agbno;
+	struct xfs_perag	*pag = NULL;
+	xfs_daddr_t		ddev_end;
+	int			last_error = 0, error;
+
+	ddev_end = min_t(xfs_daddr_t, end,
+			 XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks) - 1);
+
+	start_agno = xfs_daddr_to_agno(mp, start);
+	start_agbno = xfs_daddr_to_agbno(mp, start);
+	end_agno = xfs_daddr_to_agno(mp, ddev_end);
+	end_agbno = xfs_daddr_to_agbno(mp, ddev_end);
+
+	while ((pag = xfs_perag_next_range(mp, pag, start_agno, end_agno))) {
+		xfs_agblock_t	agend = pag_group(pag)->xg_block_count;
+
+		if (pag_agno(pag) == end_agno)
+			agend = end_agbno;
+		error = xfs_trim_perag_extents(pag, start_agbno, agend, minlen);
+		if (error)
+			last_error = error;
+
+		if (xfs_trim_should_stop()) {
+			xfs_perag_rele(pag);
+			break;
+		}
+		start_agbno = 0;
+	}
+
+	return last_error;
+}
+
+#ifdef CONFIG_XFS_RT
+struct xfs_trim_rtdev {
+	/* list of rt extents to free */
+	struct list_head	extent_list;
+
+	/* minimum length that caller allows us to trim */
+	xfs_rtblock_t		minlen_fsb;
+
+	/* restart point for the rtbitmap walk */
+	xfs_rtxnum_t		restart_rtx;
+
+	/* stopping point for the current rtbitmap walk */
+	xfs_rtxnum_t		stop_rtx;
+};
+
+struct xfs_rtx_busy {
+	struct list_head	list;
+	xfs_rtblock_t		bno;
+	xfs_rtblock_t		length;
+};
+
+static void
+xfs_discard_free_rtdev_extents(
+	struct xfs_trim_rtdev	*tr)
+{
+	struct xfs_rtx_busy	*busyp, *n;
+
+	list_for_each_entry_safe(busyp, n, &tr->extent_list, list) {
+		list_del_init(&busyp->list);
+		kfree(busyp);
+	}
 }
 
 /*
+ * Walk the discard list and issue discards on all the busy extents in the
+ * list. We plug and chain the bios so that we only need a single completion
+ * call to clear all the busy extents once the discards are complete.
+ */
+static int
+xfs_discard_rtdev_extents(
+	struct xfs_mount	*mp,
+	struct xfs_trim_rtdev	*tr)
+{
+	struct block_device	*bdev = mp->m_rtdev_targp->bt_bdev;
+	struct xfs_rtx_busy	*busyp;
+	struct bio		*bio = NULL;
+	struct blk_plug		plug;
+	xfs_rtblock_t		start = NULLRTBLOCK, length = 0;
+	int			error = 0;
+
+	blk_start_plug(&plug);
+	list_for_each_entry(busyp, &tr->extent_list, list) {
+		if (start == NULLRTBLOCK)
+			start = busyp->bno;
+		length += busyp->length;
+
+		trace_xfs_discard_rtextent(mp, busyp->bno, busyp->length);
+
+		error = __blkdev_issue_discard(bdev,
+				xfs_rtb_to_daddr(mp, busyp->bno),
+				XFS_FSB_TO_BB(mp, busyp->length),
+				GFP_NOFS, &bio);
+		if (error)
+			break;
+	}
+	xfs_discard_free_rtdev_extents(tr);
+
+	if (bio) {
+		error = submit_bio_wait(bio);
+		if (error == -EOPNOTSUPP)
+			error = 0;
+		if (error)
+			xfs_info(mp,
+	 "discard failed for rtextent [0x%llx,%llu], error %d",
+				 (unsigned long long)start,
+				 (unsigned long long)length,
+				 error);
+		bio_put(bio);
+	}
+	blk_finish_plug(&plug);
+
+	return error;
+}
+
+static int
+xfs_trim_gather_rtextent(
+	struct xfs_rtgroup		*rtg,
+	struct xfs_trans		*tp,
+	const struct xfs_rtalloc_rec	*rec,
+	void				*priv)
+{
+	struct xfs_trim_rtdev		*tr = priv;
+	struct xfs_rtx_busy		*busyp;
+	xfs_rtblock_t			rbno, rlen;
+
+	if (rec->ar_startext > tr->stop_rtx) {
+		/*
+		 * If we've scanned a large number of rtbitmap blocks, update
+		 * the cursor to point at this extent so we restart the next
+		 * batch from this extent.
+		 */
+		tr->restart_rtx = rec->ar_startext;
+		return -ECANCELED;
+	}
+
+	rbno = xfs_rtx_to_rtb(rtg, rec->ar_startext);
+	rlen = xfs_rtbxlen_to_blen(rtg_mount(rtg), rec->ar_extcount);
+
+	/* Ignore too small. */
+	if (rlen < tr->minlen_fsb) {
+		trace_xfs_discard_rttoosmall(rtg_mount(rtg), rbno, rlen);
+		return 0;
+	}
+
+	busyp = kzalloc(sizeof(struct xfs_rtx_busy), GFP_KERNEL);
+	if (!busyp)
+		return -ENOMEM;
+
+	busyp->bno = rbno;
+	busyp->length = rlen;
+	INIT_LIST_HEAD(&busyp->list);
+	list_add_tail(&busyp->list, &tr->extent_list);
+
+	tr->restart_rtx = rec->ar_startext + rec->ar_extcount;
+	return 0;
+}
+
+/* Trim extents on an !rtgroups realtime device */
+static int
+xfs_trim_rtextents(
+	struct xfs_rtgroup	*rtg,
+	xfs_rtxnum_t		low,
+	xfs_rtxnum_t		high,
+	xfs_daddr_t		minlen)
+{
+	struct xfs_mount	*mp = rtg_mount(rtg);
+	struct xfs_trim_rtdev	tr = {
+		.minlen_fsb	= XFS_BB_TO_FSB(mp, minlen),
+		.extent_list	= LIST_HEAD_INIT(tr.extent_list),
+	};
+	struct xfs_trans	*tp;
+	int			error;
+
+	tp = xfs_trans_alloc_empty(mp);
+
+	/*
+	 * Walk the free ranges between low and high.  The query_range function
+	 * trims the extents returned.
+	 */
+	do {
+		tr.stop_rtx = low + xfs_rtbitmap_rtx_per_rbmblock(mp);
+		xfs_rtgroup_lock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
+		error = xfs_rtalloc_query_range(rtg, tp, low, high,
+				xfs_trim_gather_rtextent, &tr);
+
+		if (error == -ECANCELED)
+			error = 0;
+		if (error) {
+			xfs_rtgroup_unlock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
+			xfs_discard_free_rtdev_extents(&tr);
+			break;
+		}
+
+		if (list_empty(&tr.extent_list)) {
+			xfs_rtgroup_unlock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
+			break;
+		}
+
+		error = xfs_discard_rtdev_extents(mp, &tr);
+		xfs_rtgroup_unlock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
+		if (error)
+			break;
+
+		low = tr.restart_rtx;
+	} while (!xfs_trim_should_stop() && low <= high);
+
+	xfs_trans_cancel(tp);
+	return error;
+}
+
+struct xfs_trim_rtgroup {
+	/* list of rtgroup extents to free */
+	struct xfs_busy_extents	*extents;
+
+	/* minimum length that caller allows us to trim */
+	xfs_rtblock_t		minlen_fsb;
+
+	/* restart point for the rtbitmap walk */
+	xfs_rtxnum_t		restart_rtx;
+
+	/* number of extents to examine before stopping to issue discard ios */
+	int			batch;
+
+	/* number of extents queued for discard */
+	int			queued;
+};
+
+static int
+xfs_trim_gather_rtgroup_extent(
+	struct xfs_rtgroup		*rtg,
+	struct xfs_trans		*tp,
+	const struct xfs_rtalloc_rec	*rec,
+	void				*priv)
+{
+	struct xfs_trim_rtgroup		*tr = priv;
+	xfs_rgblock_t			rgbno;
+	xfs_extlen_t			len;
+
+	if (--tr->batch <= 0) {
+		/*
+		 * If we've checked a large number of extents, update the
+		 * cursor to point at this extent so we restart the next batch
+		 * from this extent.
+		 */
+		tr->restart_rtx = rec->ar_startext;
+		return -ECANCELED;
+	}
+
+	rgbno = xfs_rtx_to_rgbno(rtg, rec->ar_startext);
+	len = xfs_rtxlen_to_extlen(rtg_mount(rtg), rec->ar_extcount);
+
+	/* Ignore too small. */
+	if (len < tr->minlen_fsb) {
+		trace_xfs_discard_toosmall(rtg_group(rtg), rgbno, len);
+		return 0;
+	}
+
+	/*
+	 * If any blocks in the range are still busy, skip the discard and try
+	 * again the next time.
+	 */
+	if (xfs_extent_busy_search(rtg_group(rtg), rgbno, len)) {
+		trace_xfs_discard_busy(rtg_group(rtg), rgbno, len);
+		return 0;
+	}
+
+	xfs_extent_busy_insert_discard(rtg_group(rtg), rgbno, len,
+			&tr->extents->extent_list);
+
+	tr->queued++;
+	tr->restart_rtx = rec->ar_startext + rec->ar_extcount;
+	return 0;
+}
+
+/* Trim extents in this rtgroup using the busy extent machinery. */
+static int
+xfs_trim_rtgroup_extents(
+	struct xfs_rtgroup	*rtg,
+	xfs_rtxnum_t		low,
+	xfs_rtxnum_t		high,
+	xfs_daddr_t		minlen)
+{
+	struct xfs_mount	*mp = rtg_mount(rtg);
+	struct xfs_trim_rtgroup	tr = {
+		.minlen_fsb	= XFS_BB_TO_FSB(mp, minlen),
+	};
+	struct xfs_trans	*tp;
+	int			error;
+
+	tp = xfs_trans_alloc_empty(mp);
+
+	/*
+	 * Walk the free ranges between low and high.  The query_range function
+	 * trims the extents returned.
+	 */
+	do {
+		tr.extents = kzalloc(sizeof(*tr.extents), GFP_KERNEL);
+		if (!tr.extents) {
+			error = -ENOMEM;
+			break;
+		}
+
+		tr.queued = 0;
+		tr.batch = XFS_DISCARD_MAX_EXAMINE;
+		tr.extents->owner = tr.extents;
+		INIT_LIST_HEAD(&tr.extents->extent_list);
+
+		xfs_rtgroup_lock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
+		error = xfs_rtalloc_query_range(rtg, tp, low, high,
+				xfs_trim_gather_rtgroup_extent, &tr);
+		xfs_rtgroup_unlock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
+		if (error == -ECANCELED)
+			error = 0;
+		if (error) {
+			kfree(tr.extents);
+			break;
+		}
+
+		if (!tr.queued) {
+			kfree(tr.extents);
+			break;
+		}
+
+		/*
+		 * We hand the extent list to the discard function here so the
+		 * discarded extents can be removed from the busy extent list.
+		 * This allows the discards to run asynchronously with
+		 * gathering the next round of extents to discard.
+		 *
+		 * However, we must ensure that we do not reference the extent
+		 * list  after this function call, as it may have been freed by
+		 * the time control returns to us.
+		 */
+		error = xfs_discard_extents(rtg_mount(rtg), tr.extents);
+		if (error)
+			break;
+
+		low = tr.restart_rtx;
+	} while (!xfs_trim_should_stop() && low <= high);
+
+	xfs_trans_cancel(tp);
+	return error;
+}
+
+static int
+xfs_trim_rtdev_extents(
+	struct xfs_mount	*mp,
+	xfs_daddr_t		start,
+	xfs_daddr_t		end,
+	xfs_daddr_t		minlen)
+{
+	xfs_rtblock_t		start_rtbno, end_rtbno;
+	xfs_rtxnum_t		start_rtx, end_rtx;
+	xfs_rgnumber_t		start_rgno, end_rgno;
+	xfs_daddr_t		daddr_offset;
+	int			last_error = 0, error;
+	struct xfs_rtgroup	*rtg = NULL;
+
+	/* Shift the start and end downwards to match the rt device. */
+	daddr_offset = XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
+	if (start > daddr_offset)
+		start -= daddr_offset;
+	else
+		start = 0;
+	start_rtbno = xfs_daddr_to_rtb(mp, start);
+	start_rtx = xfs_rtb_to_rtx(mp, start_rtbno);
+	start_rgno = xfs_rtb_to_rgno(mp, start_rtbno);
+
+	if (end <= daddr_offset)
+		return 0;
+	else
+		end -= daddr_offset;
+	end_rtbno = xfs_daddr_to_rtb(mp, end);
+	end_rtx = xfs_rtb_to_rtx(mp, end_rtbno + mp->m_sb.sb_rextsize - 1);
+	end_rgno = xfs_rtb_to_rgno(mp, end_rtbno);
+
+	while ((rtg = xfs_rtgroup_next_range(mp, rtg, start_rgno, end_rgno))) {
+		xfs_rtxnum_t	rtg_end = rtg->rtg_extents;
+
+		if (rtg_rgno(rtg) == end_rgno)
+			rtg_end = min(rtg_end, end_rtx);
+
+		if (xfs_has_rtgroups(mp))
+			error = xfs_trim_rtgroup_extents(rtg, start_rtx,
+					rtg_end, minlen);
+		else
+			error = xfs_trim_rtextents(rtg, start_rtx, rtg_end,
+					minlen);
+		if (error)
+			last_error = error;
+
+		if (xfs_trim_should_stop()) {
+			xfs_rtgroup_rele(rtg);
+			break;
+		}
+		start_rtx = 0;
+	}
+
+	return last_error;
+}
+#else
+# define xfs_trim_rtdev_extents(...)	(-EOPNOTSUPP)
+#endif /* CONFIG_XFS_RT */
+
+/*
  * trim a range of the filesystem.
  *
  * Note: the parameters passed from userspace are byte ranges into the
@@ -143,27 +820,50 @@ out_put_perag:
  * addressing. FSB addressing is sparse (AGNO|AGBNO), while the incoming format
  * is a linear address range. Hence we need to use DADDR based conversions and
  * comparisons for determining the correct offset and regions to trim.
+ *
+ * The realtime device is mapped into the FITRIM "address space" immediately
+ * after the data device.
  */
 int
 xfs_ioc_trim(
 	struct xfs_mount		*mp,
 	struct fstrim_range __user	*urange)
 {
-	struct request_queue	*q = bdev_get_queue(mp->m_ddev_targp->bt_bdev);
-	unsigned int		granularity = q->limits.discard_granularity;
+	unsigned int		granularity =
+		bdev_discard_granularity(mp->m_ddev_targp->bt_bdev);
+	struct block_device	*rt_bdev = NULL;
 	struct fstrim_range	range;
-	xfs_daddr_t		start, end, minlen;
-	xfs_agnumber_t		start_agno, end_agno, agno;
-	uint64_t		blocks_trimmed = 0;
+	xfs_daddr_t		start, end;
+	xfs_extlen_t		minlen;
+	xfs_rfsblock_t		max_blocks;
 	int			error, last_error = 0;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
-	if (!blk_queue_discard(q))
+
+	if (mp->m_rtdev_targp && !xfs_has_zoned(mp) &&
+	    bdev_max_discard_sectors(mp->m_rtdev_targp->bt_bdev))
+		rt_bdev = mp->m_rtdev_targp->bt_bdev;
+	if (!bdev_max_discard_sectors(mp->m_ddev_targp->bt_bdev) && !rt_bdev)
 		return -EOPNOTSUPP;
+
+	if (rt_bdev)
+		granularity = max(granularity,
+				  bdev_discard_granularity(rt_bdev));
+
+	/*
+	 * We haven't recovered the log, so we cannot use our bnobt-guided
+	 * storage zapping commands.
+	 */
+	if (xfs_has_norecovery(mp))
+		return -EROFS;
+
 	if (copy_from_user(&range, urange, sizeof(range)))
 		return -EFAULT;
 
+	range.minlen = max_t(u64, granularity, range.minlen);
+	minlen = XFS_B_TO_FSB(mp, range.minlen);
+
 	/*
 	 * Truncating down the len isn't actually quite correct, but using
 	 * BBTOB would mean we trivially get overflows for values
@@ -171,35 +871,32 @@ xfs_ioc_trim(
 	 * used by the fstrim application.  In the end it really doesn't
 	 * matter as trimming blocks is an advisory interface.
 	 */
-	if (range.start >= XFS_FSB_TO_B(mp, mp->m_sb.sb_dblocks) ||
+	max_blocks = mp->m_sb.sb_dblocks + mp->m_sb.sb_rblocks;
+	if (range.start >= XFS_FSB_TO_B(mp, max_blocks) ||
 	    range.minlen > XFS_FSB_TO_B(mp, mp->m_ag_max_usable) ||
 	    range.len < mp->m_sb.sb_blocksize)
 		return -EINVAL;
 
 	start = BTOBB(range.start);
 	end = start + BTOBBT(range.len) - 1;
-	minlen = BTOBB(max_t(u64, granularity, range.minlen));
 
-	if (end > XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks) - 1)
-		end = XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks)- 1;
-
-	start_agno = xfs_daddr_to_agno(mp, start);
-	end_agno = xfs_daddr_to_agno(mp, end);
+	if (bdev_max_discard_sectors(mp->m_ddev_targp->bt_bdev)) {
+		error = xfs_trim_datadev_extents(mp, start, end, minlen);
+		if (error)
+			last_error = error;
+	}
 
-	for (agno = start_agno; agno <= end_agno; agno++) {
-		error = xfs_trim_extents(mp, agno, start, end, minlen,
-					  &blocks_trimmed);
-		if (error) {
+	if (rt_bdev && !xfs_trim_should_stop()) {
+		error = xfs_trim_rtdev_extents(mp, start, end, minlen);
+		if (error)
 			last_error = error;
-			if (error == -ERESTARTSYS)
-				break;
-		}
 	}
 
 	if (last_error)
 		return last_error;
 
-	range.len = XFS_FSB_TO_B(mp, blocks_trimmed);
+	range.len = min_t(unsigned long long, range.len,
+			  XFS_FSB_TO_B(mp, max_blocks) - range.start);
 	if (copy_to_user(urange, &range, sizeof(range)))
 		return -EFAULT;
 	return 0;