1 files changed, 385 insertions, 134 deletions

diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
index 44ad5baf3206..56b234683ee6 100644
--- a/drivers/md/raid5-ppl.c
+++ b/drivers/md/raid5-ppl.c
@@ -1,26 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Partial Parity Log for closing the RAID5 write hole
  * Copyright (c) 2017, Intel Corporation.
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, as published by the Free Software Foundation.
- *
- * This program is distributed in the hope it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
  */
 
 #include <linux/kernel.h>
 #include <linux/blkdev.h>
 #include <linux/slab.h>
 #include <linux/crc32c.h>
-#include <linux/flex_array.h>
 #include <linux/async_tx.h>
 #include <linux/raid/md_p.h>
 #include "md.h"
 #include "raid5.h"
+#include "raid5-log.h"
 
 /*
  * PPL consists of a 4KB header (struct ppl_header) and at least 128KB for
@@ -85,8 +77,13 @@
  * (for a single member disk). New io_units are added to the end of the list
  * and the first io_unit is submitted, if it is not submitted already.
  * The current io_unit accepting new stripes is always at the end of the list.
+ *
+ * If write-back cache is enabled for any of the disks in the array, its data
+ * must be flushed before next io_unit is submitted.
  */
 
+#define PPL_SPACE_SIZE (128 * 1024)
+
 struct ppl_conf {
 	struct mddev *mddev;
 
@@ -100,8 +97,9 @@ struct ppl_conf {
 	atomic64_t seq;		/* current log write sequence number */
 
 	struct kmem_cache *io_kc;
-	mempool_t *io_pool;
-	struct bio_set *bs;
+	mempool_t io_pool;
+	struct bio_set bs;
+	struct bio_set flush_bs;
 
 	/* used only for recovery */
 	int recovered_entries;
@@ -110,6 +108,8 @@ struct ppl_conf {
 	/* stripes to retry if failed to allocate io_unit */
 	struct list_head no_mem_stripes;
 	spinlock_t no_mem_stripes_lock;
+
+	unsigned short write_hint;
 };
 
 struct ppl_log {
@@ -122,6 +122,12 @@ struct ppl_log {
 					 * always at the end of io_list */
 	spinlock_t io_list_lock;
 	struct list_head io_list;	/* all io_units of this log */
+
+	sector_t next_io_sector;
+	unsigned int entry_space;
+	bool use_multippl;
+	bool wb_cache_on;
+	unsigned long disk_flush_bitmap;
 };
 
 #define PPL_IO_INLINE_BVECS 32
@@ -139,6 +145,7 @@ struct ppl_io_unit {
 
 	struct list_head stripe_list;	/* stripes added to the io_unit */
 	atomic_t pending_stripes;	/* how many stripes not written to raid */
+	atomic_t pending_flushes;	/* how many disk flushes are in progress */
 
 	bool submitted;			/* true if write to log started */
 
@@ -152,7 +159,7 @@ ops_run_partial_parity(struct stripe_head *sh, struct raid5_percpu *percpu,
 		       struct dma_async_tx_descriptor *tx)
 {
 	int disks = sh->disks;
-	struct page **srcs = flex_array_get(percpu->scribble, 0);
+	struct page **srcs = percpu->scribble;
 	int count = 0, pd_idx = sh->pd_idx, i;
 	struct async_submit_ctl submit;
 
@@ -183,8 +190,7 @@ ops_run_partial_parity(struct stripe_head *sh, struct raid5_percpu *percpu,
 	}
 
 	init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, tx,
-			  NULL, sh, flex_array_get(percpu->scribble, 0)
-			  + sizeof(struct page *) * (sh->disks + 2));
+			  NULL, sh, (void *) (srcs + sh->disks + 2));
 
 	if (count == 1)
 		tx = async_memcpy(sh->ppl_page, srcs[0], 0, 0, PAGE_SIZE,
@@ -231,7 +237,7 @@ static struct ppl_io_unit *ppl_new_iounit(struct ppl_log *log,
 	struct ppl_header *pplhdr;
 	struct page *header_page;
 
-	io = mempool_alloc(ppl_conf->io_pool, GFP_NOWAIT);
+	io = mempool_alloc(&ppl_conf->io_pool, GFP_NOWAIT);
 	if (!io)
 		return NULL;
 
@@ -243,14 +249,16 @@ static struct ppl_io_unit *ppl_new_iounit(struct ppl_log *log,
 	INIT_LIST_HEAD(&io->log_sibling);
 	INIT_LIST_HEAD(&io->stripe_list);
 	atomic_set(&io->pending_stripes, 0);
-	bio_init(&io->bio, io->biovec, PPL_IO_INLINE_BVECS);
+	atomic_set(&io->pending_flushes, 0);
+	bio_init(&io->bio, log->rdev->bdev, io->biovec, PPL_IO_INLINE_BVECS,
+		 REQ_OP_WRITE | REQ_FUA);
 
 	pplhdr = page_address(io->header_page);
 	clear_page(pplhdr);
 	memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
 	pplhdr->signature = cpu_to_le32(ppl_conf->signature);
 
-	io->seq = atomic64_add_return(1, &ppl_conf->seq);
+	io->seq = atomic64_inc_return(&ppl_conf->seq);
 	pplhdr->generation = cpu_to_le64(io->seq);
 
 	return io;
@@ -264,13 +272,12 @@ static int ppl_log_stripe(struct ppl_log *log, struct stripe_head *sh)
 	int i;
 	sector_t data_sector = 0;
 	int data_disks = 0;
-	unsigned int entry_space = (log->rdev->ppl.size << 9) - PPL_HEADER_SIZE;
 	struct r5conf *conf = sh->raid_conf;
 
 	pr_debug("%s: stripe: %llu\n", __func__, (unsigned long long)sh->sector);
 
 	/* check if current io_unit is full */
-	if (io && (io->pp_size == entry_space ||
+	if (io && (io->pp_size == log->entry_space ||
 		   io->entries_count == PPL_HDR_MAX_ENTRIES)) {
 		pr_debug("%s: add io_unit blocked by seq: %llu\n",
 			 __func__, io->seq);
@@ -318,7 +325,7 @@ static int ppl_log_stripe(struct ppl_log *log, struct stripe_head *sh)
 		 * be just after the last logged stripe and write to the same
 		 * disks. Use bit shift and logarithm to avoid 64-bit division.
 		 */
-		if ((sh->sector == sh_last->sector + STRIPE_SECTORS) &&
+		if ((sh->sector == sh_last->sector + RAID5_STRIPE_SECTORS(conf)) &&
 		    (data_sector >> ilog2(conf->chunk_sectors) ==
 		     data_sector_last >> ilog2(conf->chunk_sectors)) &&
 		    ((data_sector - data_sector_last) * data_disks ==
@@ -339,9 +346,9 @@ static int ppl_log_stripe(struct ppl_log *log, struct stripe_head *sh)
 	if (!test_bit(STRIPE_FULL_WRITE, &sh->state)) {
 		le32_add_cpu(&e->pp_size, PAGE_SIZE);
 		io->pp_size += PAGE_SIZE;
-		e->checksum = cpu_to_le32(crc32c_le(le32_to_cpu(e->checksum),
-						    page_address(sh->ppl_page),
-						    PAGE_SIZE));
+		e->checksum = cpu_to_le32(crc32c(le32_to_cpu(e->checksum),
+						 page_address(sh->ppl_page),
+						 PAGE_SIZE));
 	}
 
 	list_add_tail(&sh->log_list, &io->stripe_list);
@@ -410,12 +417,10 @@ static void ppl_log_endio(struct bio *bio)
 
 static void ppl_submit_iounit_bio(struct ppl_io_unit *io, struct bio *bio)
 {
-	char b[BDEVNAME_SIZE];
-
-	pr_debug("%s: seq: %llu size: %u sector: %llu dev: %s\n",
+	pr_debug("%s: seq: %llu size: %u sector: %llu dev: %pg\n",
 		 __func__, io->seq, bio->bi_iter.bi_size,
 		 (unsigned long long)bio->bi_iter.bi_sector,
-		 bdevname(bio->bi_bdev, b));
+		 bio->bi_bdev);
 
 	submit_bio(bio);
 }
@@ -449,15 +454,37 @@ static void ppl_submit_iounit(struct ppl_io_unit *io)
 	}
 
 	pplhdr->entries_count = cpu_to_le32(io->entries_count);
-	pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PPL_HEADER_SIZE));
+	pplhdr->checksum = cpu_to_le32(~crc32c(~0, pplhdr, PPL_HEADER_SIZE));
+
+	/* Rewind the buffer if current PPL is larger then remaining space */
+	if (log->use_multippl &&
+	    log->rdev->ppl.sector + log->rdev->ppl.size - log->next_io_sector <
+	    (PPL_HEADER_SIZE + io->pp_size) >> 9)
+		log->next_io_sector = log->rdev->ppl.sector;
+
 
 	bio->bi_end_io = ppl_log_endio;
-	bio->bi_opf = REQ_OP_WRITE | REQ_FUA;
-	bio->bi_bdev = log->rdev->bdev;
-	bio->bi_iter.bi_sector = log->rdev->ppl.sector;
-	bio_add_page(bio, io->header_page, PAGE_SIZE, 0);
+	bio->bi_iter.bi_sector = log->next_io_sector;
+	__bio_add_page(bio, io->header_page, PAGE_SIZE, 0);
+
+	pr_debug("%s: log->current_io_sector: %llu\n", __func__,
+	    (unsigned long long)log->next_io_sector);
+
+	if (log->use_multippl)
+		log->next_io_sector += (PPL_HEADER_SIZE + io->pp_size) >> 9;
+
+	WARN_ON(log->disk_flush_bitmap != 0);
 
 	list_for_each_entry(sh, &io->stripe_list, log_list) {
+		for (i = 0; i < sh->disks; i++) {
+			struct r5dev *dev = &sh->dev[i];
+
+			if ((ppl_conf->child_logs[i].wb_cache_on) &&
+			    (test_bit(R5_Wantwrite, &dev->flags))) {
+				set_bit(i, &log->disk_flush_bitmap);
+			}
+		}
+
 		/* entries for full stripe writes have no partial parity */
 		if (test_bit(STRIPE_FULL_WRITE, &sh->state))
 			continue;
@@ -465,12 +492,11 @@ static void ppl_submit_iounit(struct ppl_io_unit *io)
 		if (!bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0)) {
 			struct bio *prev = bio;
 
-			bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES,
-					       ppl_conf->bs);
-			bio->bi_opf = prev->bi_opf;
-			bio->bi_bdev = prev->bi_bdev;
+			bio = bio_alloc_bioset(prev->bi_bdev, BIO_MAX_VECS,
+					       prev->bi_opf, GFP_NOIO,
+					       &ppl_conf->bs);
 			bio->bi_iter.bi_sector = bio_end_sector(prev);
-			bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0);
+			__bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0);
 
 			bio_chain(bio, prev);
 			ppl_submit_iounit_bio(io, prev);
@@ -522,6 +548,7 @@ static void ppl_io_unit_finished(struct ppl_io_unit *io)
 {
 	struct ppl_log *log = io->log;
 	struct ppl_conf *ppl_conf = log->ppl_conf;
+	struct r5conf *conf = ppl_conf->mddev->private;
 	unsigned long flags;
 
 	pr_debug("%s: seq: %llu\n", __func__, io->seq);
@@ -532,7 +559,7 @@ static void ppl_io_unit_finished(struct ppl_io_unit *io)
 	list_del(&io->log_sibling);
 	spin_unlock(&log->io_list_lock);
 
-	mempool_free(io, ppl_conf->io_pool);
+	mempool_free(io, &ppl_conf->io_pool);
 
 	spin_lock(&ppl_conf->no_mem_stripes_lock);
 	if (!list_empty(&ppl_conf->no_mem_stripes)) {
@@ -547,6 +574,117 @@ static void ppl_io_unit_finished(struct ppl_io_unit *io)
 	spin_unlock(&ppl_conf->no_mem_stripes_lock);
 
 	local_irq_restore(flags);
+
+	wake_up(&conf->wait_for_quiescent);
+}
+
+static void ppl_flush_endio(struct bio *bio)
+{
+	struct ppl_io_unit *io = bio->bi_private;
+	struct ppl_log *log = io->log;
+	struct ppl_conf *ppl_conf = log->ppl_conf;
+	struct r5conf *conf = ppl_conf->mddev->private;
+
+	pr_debug("%s: dev: %pg\n", __func__, bio->bi_bdev);
+
+	if (bio->bi_status) {
+		struct md_rdev *rdev;
+
+		rcu_read_lock();
+		rdev = md_find_rdev_rcu(conf->mddev, bio_dev(bio));
+		if (rdev)
+			md_error(rdev->mddev, rdev);
+		rcu_read_unlock();
+	}
+
+	bio_put(bio);
+
+	if (atomic_dec_and_test(&io->pending_flushes)) {
+		ppl_io_unit_finished(io);
+		md_wakeup_thread(conf->mddev->thread);
+	}
+}
+
+static void ppl_do_flush(struct ppl_io_unit *io)
+{
+	struct ppl_log *log = io->log;
+	struct ppl_conf *ppl_conf = log->ppl_conf;
+	struct r5conf *conf = ppl_conf->mddev->private;
+	int raid_disks = conf->raid_disks;
+	int flushed_disks = 0;
+	int i;
+
+	atomic_set(&io->pending_flushes, raid_disks);
+
+	for_each_set_bit(i, &log->disk_flush_bitmap, raid_disks) {
+		struct md_rdev *rdev;
+		struct block_device *bdev = NULL;
+
+		rdev = conf->disks[i].rdev;
+		if (rdev && !test_bit(Faulty, &rdev->flags))
+			bdev = rdev->bdev;
+
+		if (bdev) {
+			struct bio *bio;
+
+			bio = bio_alloc_bioset(bdev, 0,
+					       REQ_OP_WRITE | REQ_PREFLUSH,
+					       GFP_NOIO, &ppl_conf->flush_bs);
+			bio->bi_private = io;
+			bio->bi_end_io = ppl_flush_endio;
+
+			pr_debug("%s: dev: %ps\n", __func__, bio->bi_bdev);
+
+			submit_bio(bio);
+			flushed_disks++;
+		}
+	}
+
+	log->disk_flush_bitmap = 0;
+
+	for (i = flushed_disks ; i < raid_disks; i++) {
+		if (atomic_dec_and_test(&io->pending_flushes))
+			ppl_io_unit_finished(io);
+	}
+}
+
+static inline bool ppl_no_io_unit_submitted(struct r5conf *conf,
+					    struct ppl_log *log)
+{
+	struct ppl_io_unit *io;
+
+	io = list_first_entry_or_null(&log->io_list, struct ppl_io_unit,
+				      log_sibling);
+
+	return !io || !io->submitted;
+}
+
+void ppl_quiesce(struct r5conf *conf, int quiesce)
+{
+	struct ppl_conf *ppl_conf = conf->log_private;
+	int i;
+
+	if (quiesce) {
+		for (i = 0; i < ppl_conf->count; i++) {
+			struct ppl_log *log = &ppl_conf->child_logs[i];
+
+			spin_lock_irq(&log->io_list_lock);
+			wait_event_lock_irq(conf->wait_for_quiescent,
+					    ppl_no_io_unit_submitted(conf, log),
+					    log->io_list_lock);
+			spin_unlock_irq(&log->io_list_lock);
+		}
+	}
+}
+
+int ppl_handle_flush_request(struct bio *bio)
+{
+	if (bio->bi_iter.bi_size == 0) {
+		bio_endio(bio);
+		return 0;
+	}
+	bio->bi_opf &= ~REQ_PREFLUSH;
+	return -EAGAIN;
 }
 
 void ppl_stripe_write_finished(struct stripe_head *sh)
@@ -556,8 +694,12 @@ void ppl_stripe_write_finished(struct stripe_head *sh)
 	io = sh->ppl_io;
 	sh->ppl_io = NULL;
 
-	if (io && atomic_dec_and_test(&io->pending_stripes))
-		ppl_io_unit_finished(io);
+	if (io && atomic_dec_and_test(&io->pending_stripes)) {
+		if (io->log->disk_flush_bitmap)
+			ppl_do_flush(io);
+		else
+			ppl_io_unit_finished(io);
+	}
 }
 
 static void ppl_xor(int size, struct page *page1, struct page *page2)
@@ -654,7 +796,6 @@ static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e,
 	int data_disks;
 	int i;
 	int ret = 0;
-	char b[BDEVNAME_SIZE];
 	unsigned int pp_size = le32_to_cpu(e->pp_size);
 	unsigned int data_size = le32_to_cpu(e->data_size);
 
@@ -691,9 +832,9 @@ static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e,
 
 	/* if start and end is 4k aligned, use a 4k block */
 	if (block_size == 512 &&
-	    (r_sector_first & (STRIPE_SECTORS - 1)) == 0 &&
-	    (r_sector_last & (STRIPE_SECTORS - 1)) == 0)
-		block_size = STRIPE_SIZE;
+	    (r_sector_first & (RAID5_STRIPE_SECTORS(conf) - 1)) == 0 &&
+	    (r_sector_last & (RAID5_STRIPE_SECTORS(conf) - 1)) == 0)
+		block_size = RAID5_STRIPE_SIZE(conf);
 
 	/* iterate through blocks in strip */
 	for (i = 0; i < strip_sectors; i += (block_size >> 9)) {
@@ -740,18 +881,19 @@ static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e,
 				 (unsigned long long)sector);
 
 			rdev = conf->disks[dd_idx].rdev;
-			if (!rdev) {
+			if (!rdev || (!test_bit(In_sync, &rdev->flags) &&
+				      sector >= rdev->recovery_offset)) {
 				pr_debug("%s:%*s data member disk %d missing\n",
 					 __func__, indent, "", dd_idx);
 				update_parity = false;
 				break;
 			}
 
-			pr_debug("%s:%*s reading data member disk %s sector %llu\n",
-				 __func__, indent, "", bdevname(rdev->bdev, b),
+			pr_debug("%s:%*s reading data member disk %pg sector %llu\n",
+				 __func__, indent, "", rdev->bdev,
 				 (unsigned long long)sector);
 			if (!sync_page_io(rdev, sector, block_size, page2,
-					REQ_OP_READ, 0, false)) {
+					REQ_OP_READ, false)) {
 				md_error(mddev, rdev);
 				pr_debug("%s:%*s read failed!\n", __func__,
 					 indent, "");
@@ -773,7 +915,7 @@ static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e,
 				 (unsigned long long)(ppl_sector + i));
 			if (!sync_page_io(log->rdev,
 					ppl_sector - log->rdev->data_offset + i,
-					block_size, page2, REQ_OP_READ, 0,
+					block_size, page2, REQ_OP_READ,
 					false)) {
 				pr_debug("%s:%*s read failed!\n", __func__,
 					 indent, "");
@@ -789,15 +931,16 @@ static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e,
 		parity_sector = raid5_compute_sector(conf, r_sector_first + i,
 				0, &disk, &sh);
 		BUG_ON(sh.pd_idx != le32_to_cpu(e->parity_disk));
+
 		parity_rdev = conf->disks[sh.pd_idx].rdev;
 
 		BUG_ON(parity_rdev->bdev->bd_dev != log->rdev->bdev->bd_dev);
-		pr_debug("%s:%*s write parity at sector %llu, disk %s\n",
+		pr_debug("%s:%*s write parity at sector %llu, disk %pg\n",
 			 __func__, indent, "",
 			 (unsigned long long)parity_sector,
-			 bdevname(parity_rdev->bdev, b));
+			 parity_rdev->bdev);
 		if (!sync_page_io(parity_rdev, parity_sector, block_size,
-				page1, REQ_OP_WRITE, 0, false)) {
+				  page1, REQ_OP_WRITE, false)) {
 			pr_debug("%s:%*s parity write error!\n", __func__,
 				 indent, "");
 			md_error(mddev, parity_rdev);
@@ -813,12 +956,14 @@ out:
 	return ret;
 }
 
-static int ppl_recover(struct ppl_log *log, struct ppl_header *pplhdr)
+static int ppl_recover(struct ppl_log *log, struct ppl_header *pplhdr,
+		       sector_t offset)
 {
 	struct ppl_conf *ppl_conf = log->ppl_conf;
 	struct md_rdev *rdev = log->rdev;
 	struct mddev *mddev = rdev->mddev;
-	sector_t ppl_sector = rdev->ppl.sector + (PPL_HEADER_SIZE >> 9);
+	sector_t ppl_sector = rdev->ppl.sector + offset +
+			      (PPL_HEADER_SIZE >> 9);
 	struct page *page;
 	int i;
 	int ret = 0;
@@ -847,13 +992,13 @@ static int ppl_recover(struct ppl_log *log, struct ppl_header *pplhdr)
 			int s = pp_size > PAGE_SIZE ? PAGE_SIZE : pp_size;
 
 			if (!sync_page_io(rdev, sector - rdev->data_offset,
-					s, page, REQ_OP_READ, 0, false)) {
+					s, page, REQ_OP_READ, false)) {
 				md_error(mddev, rdev);
 				ret = -EIO;
 				goto out;
 			}
 
-			crc = crc32c_le(crc, page_address(page), s);
+			crc = crc32c(crc, page_address(page), s);
 
 			pp_size -= s;
 			sector += s >> 9;
@@ -881,7 +1026,7 @@ static int ppl_recover(struct ppl_log *log, struct ppl_header *pplhdr)
 	}
 
 	/* flush the disk cache after recovery if necessary */
-	ret = blkdev_issue_flush(rdev->bdev, GFP_KERNEL, NULL);
+	ret = blkdev_issue_flush(rdev->bdev);
 out:
 	__free_page(page);
 	return ret;
@@ -902,13 +1047,16 @@ static int ppl_write_empty_header(struct ppl_log *log)
 		return -ENOMEM;
 
 	pplhdr = page_address(page);
+	/* zero out PPL space to avoid collision with old PPLs */
+	blkdev_issue_zeroout(rdev->bdev, rdev->ppl.sector,
+			    log->rdev->ppl.size, GFP_NOIO, 0);
 	memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
 	pplhdr->signature = cpu_to_le32(log->ppl_conf->signature);
-	pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PAGE_SIZE));
+	pplhdr->checksum = cpu_to_le32(~crc32c(~0, pplhdr, PAGE_SIZE));
 
 	if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
 			  PPL_HEADER_SIZE, page, REQ_OP_WRITE | REQ_SYNC |
-			  REQ_FUA, 0, false)) {
+			  REQ_FUA, false)) {
 		md_error(rdev->mddev, rdev);
 		ret = -EIO;
 	}
@@ -922,63 +1070,108 @@ static int ppl_load_distributed(struct ppl_log *log)
 	struct ppl_conf *ppl_conf = log->ppl_conf;
 	struct md_rdev *rdev = log->rdev;
 	struct mddev *mddev = rdev->mddev;
-	struct page *page;
-	struct ppl_header *pplhdr;
+	struct page *page, *page2;
+	struct ppl_header *pplhdr = NULL, *prev_pplhdr = NULL;
 	u32 crc, crc_stored;
 	u32 signature;
-	int ret = 0;
+	int ret = 0, i;
+	sector_t pplhdr_offset = 0, prev_pplhdr_offset = 0;
 
 	pr_debug("%s: disk: %d\n", __func__, rdev->raid_disk);
-
-	/* read PPL header */
+	/* read PPL headers, find the recent one */
 	page = alloc_page(GFP_KERNEL);
 	if (!page)
 		return -ENOMEM;
 
-	if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
-			  PAGE_SIZE, page, REQ_OP_READ, 0, false)) {
-		md_error(mddev, rdev);
-		ret = -EIO;
-		goto out;
+	page2 = alloc_page(GFP_KERNEL);
+	if (!page2) {
+		__free_page(page);
+		return -ENOMEM;
 	}
-	pplhdr = page_address(page);
 
-	/* check header validity */
-	crc_stored = le32_to_cpu(pplhdr->checksum);
-	pplhdr->checksum = 0;
-	crc = ~crc32c_le(~0, pplhdr, PAGE_SIZE);
+	/* searching ppl area for latest ppl */
+	while (pplhdr_offset < rdev->ppl.size - (PPL_HEADER_SIZE >> 9)) {
+		if (!sync_page_io(rdev,
+				  rdev->ppl.sector - rdev->data_offset +
+				  pplhdr_offset, PAGE_SIZE, page, REQ_OP_READ,
+				  false)) {
+			md_error(mddev, rdev);
+			ret = -EIO;
+			/* if not able to read - don't recover any PPL */
+			pplhdr = NULL;
+			break;
+		}
+		pplhdr = page_address(page);
+
+		/* check header validity */
+		crc_stored = le32_to_cpu(pplhdr->checksum);
+		pplhdr->checksum = 0;
+		crc = ~crc32c(~0, pplhdr, PAGE_SIZE);
+
+		if (crc_stored != crc) {
+			pr_debug("%s: ppl header crc does not match: stored: 0x%x calculated: 0x%x (offset: %llu)\n",
+				 __func__, crc_stored, crc,
+				 (unsigned long long)pplhdr_offset);
+			pplhdr = prev_pplhdr;
+			pplhdr_offset = prev_pplhdr_offset;
+			break;
+		}
+
+		signature = le32_to_cpu(pplhdr->signature);
 
-	if (crc_stored != crc) {
-		pr_debug("%s: ppl header crc does not match: stored: 0x%x calculated: 0x%x\n",
-			 __func__, crc_stored, crc);
-		ppl_conf->mismatch_count++;
-		goto out;
-	}
+		if (mddev->external) {
+			/*
+			 * For external metadata the header signature is set and
+			 * validated in userspace.
+			 */
+			ppl_conf->signature = signature;
+		} else if (ppl_conf->signature != signature) {
+			pr_debug("%s: ppl header signature does not match: stored: 0x%x configured: 0x%x (offset: %llu)\n",
+				 __func__, signature, ppl_conf->signature,
+				 (unsigned long long)pplhdr_offset);
+			pplhdr = prev_pplhdr;
+			pplhdr_offset = prev_pplhdr_offset;
+			break;
+		}
+
+		if (prev_pplhdr && le64_to_cpu(prev_pplhdr->generation) >
+		    le64_to_cpu(pplhdr->generation)) {
+			/* previous was newest */
+			pplhdr = prev_pplhdr;
+			pplhdr_offset = prev_pplhdr_offset;
+			break;
+		}
 
-	signature = le32_to_cpu(pplhdr->signature);
+		prev_pplhdr_offset = pplhdr_offset;
+		prev_pplhdr = pplhdr;
 
-	if (mddev->external) {
-		/*
-		 * For external metadata the header signature is set and
-		 * validated in userspace.
-		 */
-		ppl_conf->signature = signature;
-	} else if (ppl_conf->signature != signature) {
-		pr_debug("%s: ppl header signature does not match: stored: 0x%x configured: 0x%x\n",
-			 __func__, signature, ppl_conf->signature);
-		ppl_conf->mismatch_count++;
-		goto out;
+		swap(page, page2);
+
+		/* calculate next potential ppl offset */
+		for (i = 0; i < le32_to_cpu(pplhdr->entries_count); i++)
+			pplhdr_offset +=
+			    le32_to_cpu(pplhdr->entries[i].pp_size) >> 9;
+		pplhdr_offset += PPL_HEADER_SIZE >> 9;
 	}
 
+	/* no valid ppl found */
+	if (!pplhdr)
+		ppl_conf->mismatch_count++;
+	else
+		pr_debug("%s: latest PPL found at offset: %llu, with generation: %llu\n",
+		    __func__, (unsigned long long)pplhdr_offset,
+		    le64_to_cpu(pplhdr->generation));
+
 	/* attempt to recover from log if we are starting a dirty array */
-	if (!mddev->pers && mddev->recovery_cp != MaxSector)
-		ret = ppl_recover(log, pplhdr);
-out:
+	if (pplhdr && !mddev->pers && mddev->resync_offset != MaxSector)
+		ret = ppl_recover(log, pplhdr, pplhdr_offset);
+
 	/* write empty header if we are starting the array */
 	if (!ret && !mddev->pers)
 		ret = ppl_write_empty_header(log);
 
 	__free_page(page);
+	__free_page(page2);
 
 	pr_debug("%s: return: %d mismatch_count: %d recovered_entries: %d\n",
 		 __func__, ret, ppl_conf->mismatch_count,
@@ -1031,12 +1224,13 @@ static int ppl_load(struct ppl_conf *ppl_conf)
 static void __ppl_exit_log(struct ppl_conf *ppl_conf)
 {
 	clear_bit(MD_HAS_PPL, &ppl_conf->mddev->flags);
+	clear_bit(MD_HAS_MULTIPLE_PPLS, &ppl_conf->mddev->flags);
 
 	kfree(ppl_conf->child_logs);
 
-	if (ppl_conf->bs)
-		bioset_free(ppl_conf->bs);
-	mempool_destroy(ppl_conf->io_pool);
+	bioset_exit(&ppl_conf->bs);
+	bioset_exit(&ppl_conf->flush_bs);
+	mempool_exit(&ppl_conf->io_pool);
 	kmem_cache_destroy(ppl_conf->io_kc);
 
 	kfree(ppl_conf);
@@ -1054,7 +1248,6 @@ void ppl_exit_log(struct r5conf *conf)
 
 static int ppl_validate_rdev(struct md_rdev *rdev)
 {
-	char b[BDEVNAME_SIZE];
 	int ppl_data_sectors;
 	int ppl_size_new;
 
@@ -1067,11 +1260,12 @@ static int ppl_validate_rdev(struct md_rdev *rdev)
 	ppl_data_sectors = rdev->ppl.size - (PPL_HEADER_SIZE >> 9);
 
 	if (ppl_data_sectors > 0)
-		ppl_data_sectors = rounddown(ppl_data_sectors, STRIPE_SECTORS);
+		ppl_data_sectors = rounddown(ppl_data_sectors,
+				RAID5_STRIPE_SECTORS((struct r5conf *)rdev->mddev->private));
 
 	if (ppl_data_sectors <= 0) {
-		pr_warn("md/raid:%s: PPL space too small on %s\n",
-			mdname(rdev->mddev), bdevname(rdev->bdev, b));
+		pr_warn("md/raid:%s: PPL space too small on %pg\n",
+			mdname(rdev->mddev), rdev->bdev);
 		return -ENOSPC;
 	}
 
@@ -1081,16 +1275,16 @@ static int ppl_validate_rdev(struct md_rdev *rdev)
 	     rdev->ppl.sector + ppl_size_new > rdev->data_offset) ||
 	    (rdev->ppl.sector >= rdev->data_offset &&
 	     rdev->data_offset + rdev->sectors > rdev->ppl.sector)) {
-		pr_warn("md/raid:%s: PPL space overlaps with data on %s\n",
-			mdname(rdev->mddev), bdevname(rdev->bdev, b));
+		pr_warn("md/raid:%s: PPL space overlaps with data on %pg\n",
+			mdname(rdev->mddev), rdev->bdev);
 		return -EINVAL;
 	}
 
 	if (!rdev->mddev->external &&
 	    ((rdev->ppl.offset > 0 && rdev->ppl.offset < (rdev->sb_size >> 9)) ||
 	     (rdev->ppl.offset <= 0 && rdev->ppl.offset + ppl_size_new > 0))) {
-		pr_warn("md/raid:%s: PPL space overlaps with superblock on %s\n",
-			mdname(rdev->mddev), bdevname(rdev->bdev, b));
+		pr_warn("md/raid:%s: PPL space overlaps with superblock on %pg\n",
+			mdname(rdev->mddev), rdev->bdev);
 		return -EINVAL;
 	}
 
@@ -1099,13 +1293,32 @@ static int ppl_validate_rdev(struct md_rdev *rdev)
 	return 0;
 }
 
+static void ppl_init_child_log(struct ppl_log *log, struct md_rdev *rdev)
+{
+	if ((rdev->ppl.size << 9) >= (PPL_SPACE_SIZE +
+				      PPL_HEADER_SIZE) * 2) {
+		log->use_multippl = true;
+		set_bit(MD_HAS_MULTIPLE_PPLS,
+			&log->ppl_conf->mddev->flags);
+		log->entry_space = PPL_SPACE_SIZE;
+	} else {
+		log->use_multippl = false;
+		log->entry_space = (log->rdev->ppl.size << 9) -
+				   PPL_HEADER_SIZE;
+	}
+	log->next_io_sector = rdev->ppl.sector;
+
+	if (bdev_write_cache(rdev->bdev))
+		log->wb_cache_on = true;
+}
+
 int ppl_init_log(struct r5conf *conf)
 {
 	struct ppl_conf *ppl_conf;
 	struct mddev *mddev = conf->mddev;
 	int ret = 0;
+	int max_disks;
 	int i;
-	bool need_cache_flush = false;
 
 	pr_debug("md/raid:%s: enabling distributed Partial Parity Log\n",
 		 mdname(conf->mddev));
@@ -1131,6 +1344,14 @@ int ppl_init_log(struct r5conf *conf)
 		return -EINVAL;
 	}
 
+	max_disks = sizeof_field(struct ppl_log, disk_flush_bitmap) *
+		BITS_PER_BYTE;
+	if (conf->raid_disks > max_disks) {
+		pr_warn("md/raid:%s PPL doesn't support over %d disks in the array\n",
+			mdname(mddev), max_disks);
+		return -EINVAL;
+	}
+
 	ppl_conf = kzalloc(sizeof(struct ppl_conf), GFP_KERNEL);
 	if (!ppl_conf)
 		return -ENOMEM;
@@ -1143,18 +1364,18 @@ int ppl_init_log(struct r5conf *conf)
 		goto err;
 	}
 
-	ppl_conf->io_pool = mempool_create(conf->raid_disks, ppl_io_pool_alloc,
-					   ppl_io_pool_free, ppl_conf->io_kc);
-	if (!ppl_conf->io_pool) {
-		ret = -ENOMEM;
+	ret = mempool_init(&ppl_conf->io_pool, conf->raid_disks, ppl_io_pool_alloc,
+			   ppl_io_pool_free, ppl_conf->io_kc);
+	if (ret)
 		goto err;
-	}
 
-	ppl_conf->bs = bioset_create(conf->raid_disks, 0, BIOSET_NEED_BVECS);
-	if (!ppl_conf->bs) {
-		ret = -ENOMEM;
+	ret = bioset_init(&ppl_conf->bs, conf->raid_disks, 0, BIOSET_NEED_BVECS);
+	if (ret)
+		goto err;
+
+	ret = bioset_init(&ppl_conf->flush_bs, conf->raid_disks, 0, 0);
+	if (ret)
 		goto err;
-	}
 
 	ppl_conf->count = conf->raid_disks;
 	ppl_conf->child_logs = kcalloc(ppl_conf->count, sizeof(struct ppl_log),
@@ -1169,10 +1390,11 @@ int ppl_init_log(struct r5conf *conf)
 	spin_lock_init(&ppl_conf->no_mem_stripes_lock);
 
 	if (!mddev->external) {
-		ppl_conf->signature = ~crc32c_le(~0, mddev->uuid, sizeof(mddev->uuid));
+		ppl_conf->signature = ~crc32c(~0, mddev->uuid, sizeof(mddev->uuid));
 		ppl_conf->block_size = 512;
 	} else {
-		ppl_conf->block_size = queue_logical_block_size(mddev->queue);
+		ppl_conf->block_size =
+			queue_logical_block_size(mddev->gendisk->queue);
 	}
 
 	for (i = 0; i < ppl_conf->count; i++) {
@@ -1187,36 +1409,27 @@ int ppl_init_log(struct r5conf *conf)
 		log->rdev = rdev;
 
 		if (rdev) {
-			struct request_queue *q;
-
 			ret = ppl_validate_rdev(rdev);
 			if (ret)
 				goto err;
 
-			q = bdev_get_queue(rdev->bdev);
-			if (test_bit(QUEUE_FLAG_WC, &q->queue_flags))
-				need_cache_flush = true;
+			ppl_init_child_log(log, rdev);
 		}
 	}
 
-	if (need_cache_flush)
-		pr_warn("md/raid:%s: Volatile write-back cache should be disabled on all member drives when using PPL!\n",
-			mdname(mddev));
-
 	/* load and possibly recover the logs from the member disks */
 	ret = ppl_load(ppl_conf);
 
 	if (ret) {
 		goto err;
-	} else if (!mddev->pers &&
-		   mddev->recovery_cp == 0 && !mddev->degraded &&
+	} else if (!mddev->pers && mddev->resync_offset == 0 &&
 		   ppl_conf->recovered_entries > 0 &&
 		   ppl_conf->mismatch_count == 0) {
 		/*
 		 * If we are starting a dirty array and the recovery succeeds
 		 * without any issues, set the array as clean.
 		 */
-		mddev->recovery_cp = MaxSector;
+		mddev->resync_offset = MaxSector;
 		set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
 	} else if (mddev->pers && ppl_conf->mismatch_count > 0) {
 		/* no mismatch allowed when enabling PPL for a running array */
@@ -1238,14 +1451,13 @@ int ppl_modify_log(struct r5conf *conf, struct md_rdev *rdev, bool add)
 	struct ppl_conf *ppl_conf = conf->log_private;
 	struct ppl_log *log;
 	int ret = 0;
-	char b[BDEVNAME_SIZE];
 
 	if (!rdev)
 		return -EINVAL;
 
-	pr_debug("%s: disk: %d operation: %s dev: %s\n",
+	pr_debug("%s: disk: %d operation: %s dev: %pg\n",
 		 __func__, rdev->raid_disk, add ? "add" : "remove",
-		 bdevname(rdev->bdev, b));
+		 rdev->bdev);
 
 	if (rdev->raid_disk < 0)
 		return 0;
@@ -1261,6 +1473,7 @@ int ppl_modify_log(struct r5conf *conf, struct md_rdev *rdev, bool add)
 		if (!ret) {
 			log->rdev = rdev;
 			ret = ppl_write_empty_header(log);
+			ppl_init_child_log(log, rdev);
 		}
 	} else {
 		log->rdev = NULL;
@@ -1269,3 +1482,41 @@ int ppl_modify_log(struct r5conf *conf, struct md_rdev *rdev, bool add)
 
 	return ret;
 }
+
+static ssize_t
+ppl_write_hint_show(struct mddev *mddev, char *buf)
+{
+	return sprintf(buf, "%d\n", 0);
+}
+
+static ssize_t
+ppl_write_hint_store(struct mddev *mddev, const char *page, size_t len)
+{
+	struct r5conf *conf;
+	int err = 0;
+	unsigned short new;
+
+	if (len >= PAGE_SIZE)
+		return -EINVAL;
+	if (kstrtou16(page, 10, &new))
+		return -EINVAL;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+
+	conf = mddev->private;
+	if (!conf)
+		err = -ENODEV;
+	else if (!raid5_has_ppl(conf) || !conf->log_private)
+		err = -EINVAL;
+
+	mddev_unlock(mddev);
+
+	return err ?: len;
+}
+
+struct md_sysfs_entry
+ppl_write_hint = __ATTR(ppl_write_hint, S_IRUGO | S_IWUSR,
+			ppl_write_hint_show,
+			ppl_write_hint_store);