This implements the PPL write logging functionality. The description
of PPL is added to the documentation. More details can be found in the
comments in raid5-ppl.c.
Put the PPL metadata structures to md_p.h because userspace tools
(mdadm) will also need to read/write PPL.
Warn about using PPL with enabled disk volatile write-back cache for
now. It can be removed once disk cache flushing before writing PPL is
implemented.
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@xxxxxxxxx>
---
Documentation/md/raid5-ppl.txt | 44 +++
drivers/md/Makefile | 2 +-
drivers/md/raid5-ppl.c | 617 +++++++++++++++++++++++++++++++++++++++++
drivers/md/raid5.c | 49 +++-
drivers/md/raid5.h | 8 +
include/uapi/linux/raid/md_p.h | 26 ++
6 files changed, 738 insertions(+), 8 deletions(-)
create mode 100644 Documentation/md/raid5-ppl.txt
create mode 100644 drivers/md/raid5-ppl.c
diff --git a/Documentation/md/raid5-ppl.txt b/Documentation/md/raid5-ppl.txt
new file mode 100644
index 000000000000..127072b09363
--- /dev/null
+++ b/Documentation/md/raid5-ppl.txt
@@ -0,0 +1,44 @@
+Partial Parity Log
+
+Partial Parity Log (PPL) is a feature available for RAID5 arrays. The issue
+addressed by PPL is that after a dirty shutdown, parity of a particular stripe
+may become inconsistent with data on other member disks. If the array is also
+in degraded state, there is no way to recalculate parity, because one of the
+disks is missing. This can lead to silent data corruption when rebuilding the
+array or using it is as degraded - data calculated from parity for array blocks
+that have not been touched by a write request during the unclean shutdown can
+be incorrect. Such condition is known as the RAID5 Write Hole. Because of
+this, md by default does not allow starting a dirty degraded array.
+
+Partial parity for a write operation is the XOR of stripe data chunks not
+modified by this write. It is just enough data needed for recovering from the
+write hole. XORing partial parity with the modified chunks produces parity for
+the stripe, consistent with its state before the write operation, regardless of
+which chunk writes have completed. If one of the not modified data disks of
+this stripe is missing, this updated parity can be used to recover its
+contents. PPL recovery is also performed when starting an array after an
+unclean shutdown and all disks are available, eliminating the need to resync
+the array. Because of this, using write-intent bitmap and PPL together is not
+supported.
+
+When handling a write request PPL writes partial parity before new data and
+parity are dispatched to disks. PPL is a distributed log - it is stored on
+array member drives in the metadata area, on the parity drive of a particular
+stripe. It does not require a dedicated journaling drive. Write performance is
+reduced by up to 30%-40% but it scales with the number of drives in the array
+and the journaling drive does not become a bottleneck or a single point of
+failure.
+
+Unlike raid5-cache, the other solution in md for closing the write hole, PPL is
+not a true journal. It does not protect from losing in-flight data, only from
+silent data corruption. If a dirty disk of a stripe is lost, no PPL recovery is
+performed for this stripe (parity is not updated). So it is possible to have
+arbitrary data in the written part of a stripe if that disk is lost. In such
+case the behavior is the same as in plain raid5.
+
+PPL is available for md version-1 metadata and external (specifically IMSM)
+metadata arrays. It can be enabled using mdadm option --consistency-policy=ppl.
+
+Currently, volatile write-back cache should be disabled on all member drives
+when using PPL. Otherwise it cannot guarantee consistency in case of power
+failure.
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index 3cbda1af87a0..4d48714ccc6b 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -18,7 +18,7 @@ dm-cache-cleaner-y += dm-cache-policy-cleaner.o
dm-era-y += dm-era-target.o
dm-verity-y += dm-verity-target.o
md-mod-y += md.o bitmap.o
-raid456-y += raid5.o raid5-cache.o
+raid456-y += raid5.o raid5-cache.o raid5-ppl.o
# Note: link order is important. All raid personalities
# and must come before md.o, as they each initialise
diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
new file mode 100644
index 000000000000..a00cabf1adf6
--- /dev/null
+++ b/drivers/md/raid5-ppl.c
@@ -0,0 +1,617 @@
+/*
+ * 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/raid/md_p.h>
+#include "md.h"
+#include "raid5.h"
+
+/*
+ * PPL consists of a 4KB header (struct ppl_header) and at least 128KB for
+ * partial parity data. The header contains an array of entries
+ * (struct ppl_header_entry) which describe the logged write requests.
+ * Partial parity for the entries comes after the header, written in the same
+ * sequence as the entries:
+ *
+ * Header
+ * entry0
+ * ...
+ * entryN
+ * PP data
+ * PP for entry0
+ * ...
+ * PP for entryN
+ *
+ * Every entry holds a checksum of its partial parity, the header also has a
+ * checksum of the header itself. Entries for full stripes writes contain no
+ * partial parity, they only mark the stripes for which parity should be
+ * recalculated after an unclean shutdown.
+ *
+ * A write request is always logged to the PPL instance stored on the parity
+ * disk of the corresponding stripe. For each member disk there is one ppl_log
+ * used to handle logging for this disk, independently from others. They are
+ * grouped in child_logs array in struct ppl_conf, which is assigned to
+ * r5conf->ppl and used in raid5 core.
+ *
+ * ppl_io_unit represents a full PPL write, header_page contains the ppl_header.
+ * PPL entries for logged stripes are added in ppl_log_stripe(). A stripe can
+ * be appended to the last entry if the chunks to write are the same, otherwise
+ * a new entry is added. Checksums of entries are calculated incrementally as
+ * stripes containing partial parity are being added to entries.
+ * ppl_submit_iounit() calculates the checksum of the header and submits a bio
+ * containing the header page and partial parity pages (sh->ppl_page) for all
+ * stripes of the io_unit. When the PPL write completes, the stripes associated
+ * with the io_unit are released and raid5d starts writing their data and
+ * parity. When all stripes are written, the io_unit is freed and the next can
+ * be submitted.
+ *
+ * An io_unit is used to gather stripes until it is submitted or becomes full
+ * (if the maximum number of entries or size of PPL is reached). Another io_unit
+ * can't be submitted until the previous has completed (PPL and stripe
+ * data+parity is written). The log->io_list tracks all io_units of a log
+ * (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.
+ */
+
+struct ppl_conf {
+ struct mddev *mddev;
+
+ /* array of child logs, one for each raid disk */
+ struct ppl_log *child_logs;
+ int count;
+
+ int block_size; /* the logical block size used for data_sector
+ * in ppl_header_entry */
+ u32 signature; /* raid array identifier */
+ atomic64_t seq; /* current log write sequence number */
+
+ struct kmem_cache *io_kc;
+ mempool_t *io_pool;
+ struct bio_set *bs;
+ mempool_t *meta_pool;
+};
+
+struct ppl_log {
+ struct ppl_conf *ppl_conf; /* shared between all log instances */
+
+ struct md_rdev *rdev; /* array member disk associated with
+ * this log instance */
+ struct mutex io_mutex;
+ struct ppl_io_unit *current_io; /* current io_unit accepting new data
+ * always at the end of io_list */
+ spinlock_t io_list_lock;
+ struct list_head io_list; /* all io_units of this log */
+ struct list_head no_mem_stripes;/* stripes to retry if failed to
+ * allocate io_unit */
+};
+
+struct ppl_io_unit {
+ struct ppl_log *log;
+
+ struct page *header_page; /* for ppl_header */
+
+ unsigned int entries_count; /* number of entries in ppl_header */
+ unsigned int pp_size; /* total size current of partial parity */
+
+ u64 seq; /* sequence number of this log write */
+ struct list_head log_sibling; /* log->io_list */
+
+ struct list_head stripe_list; /* stripes added to the io_unit */
+ atomic_t pending_stripes; /* how many stripes not written to raid */
+
+ bool submitted; /* true if write to log started */
+};
+
+static struct ppl_io_unit *ppl_new_iounit(struct ppl_log *log,
+ struct stripe_head *sh)
+{
+ struct ppl_conf *ppl_conf = log->ppl_conf;
+ struct ppl_io_unit *io;
+ struct ppl_header *pplhdr;
+
+ io = mempool_alloc(ppl_conf->io_pool, GFP_ATOMIC);
+ if (!io)
+ return NULL;
+
+ memset(io, 0, sizeof(*io));
+ io->log = log;
+ INIT_LIST_HEAD(&io->log_sibling);
+ INIT_LIST_HEAD(&io->stripe_list);
+ atomic_set(&io->pending_stripes, 0);
+
+ io->header_page = mempool_alloc(ppl_conf->meta_pool, GFP_NOIO);
+ 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);
+ pplhdr->generation = cpu_to_le64(io->seq);
+
+ return io;
+}
+
+static int ppl_log_stripe(struct ppl_log *log, struct stripe_head *sh)
+{
+ struct ppl_io_unit *io = log->current_io;
+ struct ppl_header_entry *e = NULL;
+ struct ppl_header *pplhdr;
+ 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 ||
+ io->entries_count == PPL_HDR_MAX_ENTRIES)) {
+ pr_debug("%s: add io_unit blocked by seq: %llu\n",
+ __func__, io->seq);
+ io = NULL;
+ }
+
+ /* add a new unit if there is none or the current is full */
+ if (!io) {
+ io = ppl_new_iounit(log, sh);
+ if (!io)
+ return -ENOMEM;
+ spin_lock_irq(&log->io_list_lock);
+ list_add_tail(&io->log_sibling, &log->io_list);
+ spin_unlock_irq(&log->io_list_lock);
+
+ log->current_io = io;
+ }
+
+ for (i = 0; i < sh->disks; i++) {
+ struct r5dev *dev = &sh->dev[i];
+
+ if (i != sh->pd_idx && test_bit(R5_Wantwrite, &dev->flags)) {
+ if (!data_disks || dev->sector < data_sector)
+ data_sector = dev->sector;
+ data_disks++;
+ }
+ }
+ BUG_ON(!data_disks);
+
+ pr_debug("%s: seq: %llu data_sector: %llu data_disks: %d\n", __func__,
+ io->seq, (unsigned long long)data_sector, data_disks);
+
+ pplhdr = page_address(io->header_page);
+
+ if (io->entries_count > 0) {
+ struct ppl_header_entry *last =
+ &pplhdr->entries[io->entries_count - 1];
+ u64 data_sector_last = le64_to_cpu(last->data_sector);
+ u32 data_size_last = le32_to_cpu(last->data_size);
+ u32 pp_size_last = le32_to_cpu(last->pp_size);
+
+ /*
+ * Check if we can merge with the last entry. Must be on
+ * the same stripe and disks. Use bit shift and logarithm
+ * to avoid 64-bit division.
+ */
+ if ((data_sector >> ilog2(conf->chunk_sectors) ==
+ data_sector_last >> ilog2(conf->chunk_sectors)) &&
+ ((pp_size_last == 0 &&
+ test_bit(STRIPE_FULL_WRITE, &sh->state)) ||
+ ((data_sector_last + (pp_size_last >> 9) == data_sector) &&
+ (data_size_last == pp_size_last * data_disks))))
+ e = last;
+ }
+
+ if (!e) {
+ e = &pplhdr->entries[io->entries_count++];
+ e->data_sector = cpu_to_le64(data_sector);
+ e->parity_disk = cpu_to_le32(sh->pd_idx);
+ e->checksum = cpu_to_le32(~0);
+ }
+
+ le32_add_cpu(&e->data_size, data_disks << PAGE_SHIFT);
+
+ /* don't write any PP if full stripe write */
+ 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));
+ }
+
+ list_add_tail(&sh->log_list, &io->stripe_list);
+ atomic_inc(&io->pending_stripes);
+ sh->ppl_log_io = io;
+
+ return 0;
+}
+
+int ppl_write_stripe(struct ppl_conf *ppl_conf, struct stripe_head *sh)
+{
+ struct ppl_log *log;
+ struct ppl_io_unit *io = sh->ppl_log_io;
+
+ if (io || test_bit(STRIPE_SYNCING, &sh->state) ||
+ !test_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags) ||
+ !test_bit(R5_Insync, &sh->dev[sh->pd_idx].flags)) {
+ clear_bit(STRIPE_LOG_TRAPPED, &sh->state);
+ return -EAGAIN;
+ }
+
+ log = &ppl_conf->child_logs[sh->pd_idx];
+
+ mutex_lock(&log->io_mutex);
+
+ if (!log->rdev || test_bit(Faulty, &log->rdev->flags)) {
+ mutex_unlock(&log->io_mutex);
+ return -EAGAIN;
+ }
+
+ set_bit(STRIPE_LOG_TRAPPED, &sh->state);
+ clear_bit(STRIPE_DELAYED, &sh->state);
+ atomic_inc(&sh->count);
+
+ if (ppl_log_stripe(log, sh)) {
+ spin_lock_irq(&log->io_list_lock);
+ list_add_tail(&sh->log_list, &log->no_mem_stripes);
+ spin_unlock_irq(&log->io_list_lock);
+ }
+
+ mutex_unlock(&log->io_mutex);
+
+ return 0;
+}
+
+static void ppl_log_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 stripe_head *sh, *next;
+
+ pr_debug("%s: seq: %llu\n", __func__, io->seq);
+
+ if (bio->bi_error)
+ md_error(ppl_conf->mddev, log->rdev);
+
+ bio_put(bio);
+ mempool_free(io->header_page, ppl_conf->meta_pool);
+
+ list_for_each_entry_safe(sh, next, &io->stripe_list, log_list) {
+ list_del_init(&sh->log_list);
+
+ set_bit(STRIPE_HANDLE, &sh->state);
+ raid5_release_stripe(sh);
+ }
+}
+
+static void ppl_submit_iounit(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;
+ struct ppl_header *pplhdr = page_address(io->header_page);
+ struct bio *bio;
+ struct stripe_head *sh;
+ int i;
+ struct bio_list bios = BIO_EMPTY_LIST;
+ char b[BDEVNAME_SIZE];
+
+ bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES, ppl_conf->bs);
+ bio->bi_private = io;
+ 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_list_add(&bios, bio);
+
+ sh = list_first_entry(&io->stripe_list, struct stripe_head, log_list);
+
+ for (i = 0; i < io->entries_count; i++) {
+ struct ppl_header_entry *e = &pplhdr->entries[i];
+ u32 pp_size = le32_to_cpu(e->pp_size);
+ u32 data_size = le32_to_cpu(e->data_size);
+ u64 data_sector = le64_to_cpu(e->data_sector);
+ int stripes_count;
+
+ if (pp_size > 0)
+ stripes_count = pp_size >> PAGE_SHIFT;
+ else
+ stripes_count = (data_size /
+ (conf->raid_disks -
+ conf->max_degraded)) >> PAGE_SHIFT;
+
+ while (stripes_count--) {
+ /*
+ * if entry without partial parity just skip its stripes
+ * without adding pages to bio
+ */
+ if (pp_size > 0 &&
+ !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->bi_iter.bi_sector = bio_end_sector(prev);
+ bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0);
+ bio_chain(bio, prev);
+ bio_list_add(&bios, bio);
+ }
+ sh = list_next_entry(sh, log_list);
+ }
+
+ pr_debug("%s: seq: %llu entry: %d data_sector: %llu pp_size: %u data_size: %u\n",
+ __func__, io->seq, i, data_sector, pp_size, data_size);
+
+ e->data_sector = cpu_to_le64(data_sector >>
+ ilog2(ppl_conf->block_size >> 9));
+ e->checksum = cpu_to_le32(~le32_to_cpu(e->checksum));
+ }
+
+ pplhdr->entries_count = cpu_to_le32(io->entries_count);
+ pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PPL_HEADER_SIZE));
+
+ while ((bio = bio_list_pop(&bios))) {
+ pr_debug("%s: seq: %llu submit_bio() size: %u sector: %llu dev: %s\n",
+ __func__, io->seq, bio->bi_iter.bi_size,
+ (unsigned long long)bio->bi_iter.bi_sector,
+ bdevname(bio->bi_bdev, b));
+ submit_bio(bio);
+ }
+}
+
+static void ppl_submit_current_io(struct ppl_log *log)
+{
+ struct ppl_io_unit *io;
+
+ spin_lock_irq(&log->io_list_lock);
+
+ io = list_first_entry_or_null(&log->io_list, struct ppl_io_unit,
+ log_sibling);
+ if (io && io->submitted)
+ io = NULL;
+
+ spin_unlock_irq(&log->io_list_lock);
+
+ if (io) {
+ io->submitted = true;
+
+ if (io == log->current_io)
+ log->current_io = NULL;
+
+ ppl_submit_iounit(io);
+ }
+}
+
+void ppl_write_stripe_run(struct ppl_conf *ppl_conf)
+{
+ struct ppl_log *log;
+ int i;
+
+ for (i = 0; i < ppl_conf->count; i++) {
+ log = &ppl_conf->child_logs[i];
+
+ mutex_lock(&log->io_mutex);
+ ppl_submit_current_io(log);
+ mutex_unlock(&log->io_mutex);
+ }
+}
+
+static void ppl_io_unit_finished(struct ppl_io_unit *io)
+{
+ struct ppl_log *log = io->log;
+ unsigned long flags;
+
+ pr_debug("%s: seq: %llu\n", __func__, io->seq);
+
+ spin_lock_irqsave(&log->io_list_lock, flags);
+
+ list_del(&io->log_sibling);
+ mempool_free(io, log->ppl_conf->io_pool);
+
+ if (!list_empty(&log->no_mem_stripes)) {
+ struct stripe_head *sh = list_first_entry(&log->no_mem_stripes,
+ struct stripe_head,
+ log_list);
+ list_del_init(&sh->log_list);
+ set_bit(STRIPE_HANDLE, &sh->state);
+ raid5_release_stripe(sh);
+ }
+
+ spin_unlock_irqrestore(&log->io_list_lock, flags);
+}
+
+void ppl_stripe_write_finished(struct stripe_head *sh)
+{
+ struct ppl_io_unit *io;
+
+ io = sh->ppl_log_io;
+ sh->ppl_log_io = NULL;
+
+ if (io && atomic_dec_and_test(&io->pending_stripes))
+ ppl_io_unit_finished(io);
+}
+
+void ppl_exit_log(struct ppl_conf *ppl_conf)
+{
+ kfree(ppl_conf->child_logs);
+
+ mempool_destroy(ppl_conf->meta_pool);
+ if (ppl_conf->bs)
+ bioset_free(ppl_conf->bs);
+ mempool_destroy(ppl_conf->io_pool);
+ kmem_cache_destroy(ppl_conf->io_kc);
+
+ kfree(ppl_conf);
+}
+
+static int ppl_validate_rdev(struct md_rdev *rdev)
+{
+ char b[BDEVNAME_SIZE];
+ int ppl_data_sectors;
+ int ppl_size_new;
+
+ /*
+ * The configured PPL size must be enough to store
+ * the header and (at the very least) partial parity
+ * for one stripe. Round it down to ensure the data
+ * space is cleanly divisible by stripe size.
+ */
+ ppl_data_sectors = rdev->ppl.size - (PPL_HEADER_SIZE >> 9);
+
+ if (ppl_data_sectors > 0)
+ ppl_data_sectors = rounddown(ppl_data_sectors, STRIPE_SECTORS);
+
+ if (ppl_data_sectors <= 0) {
+ pr_warn("md/raid:%s: PPL space too small on %s\n",
+ mdname(rdev->mddev), bdevname(rdev->bdev, b));
+ return -ENOSPC;
+ }
+
+ ppl_size_new = ppl_data_sectors + (PPL_HEADER_SIZE >> 9);
+
+ if ((rdev->ppl.sector < rdev->data_offset &&
+ 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));
+ 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));
+ return -EINVAL;
+ }
+
+ rdev->ppl.size = ppl_size_new;
+
+ return 0;
+}
+
+int ppl_init_log(struct r5conf *conf)
+{
+ struct ppl_conf *ppl_conf;
+ struct mddev *mddev = conf->mddev;
+ int ret = 0;
+ int i;
+ bool need_cache_flush;
+
+ if (PAGE_SIZE != 4096)
+ return -EINVAL;
+
+ if (mddev->bitmap_info.file || mddev->bitmap_info.offset) {
+ pr_warn("md/raid:%s PPL is not compatible with bitmap\n",
+ mdname(mddev));
+ return -EINVAL;
+ }
+
+ if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
+ pr_warn("md/raid:%s PPL is not compatible with journal\n",
+ mdname(mddev));
+ return -EINVAL;
+ }
+
+ ppl_conf = kzalloc(sizeof(struct ppl_conf), GFP_KERNEL);
+ if (!ppl_conf)
+ return -ENOMEM;
+
+ ppl_conf->io_kc = KMEM_CACHE(ppl_io_unit, 0);
+ if (!ppl_conf->io_kc) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ ppl_conf->io_pool = mempool_create_slab_pool(conf->raid_disks, ppl_conf->io_kc);
+ if (!ppl_conf->io_pool) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ ppl_conf->bs = bioset_create(conf->raid_disks, 0);
+ if (!ppl_conf->bs) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ ppl_conf->meta_pool = mempool_create_page_pool(conf->raid_disks, 0);
+ if (!ppl_conf->meta_pool) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ ppl_conf->mddev = mddev;
+ ppl_conf->count = conf->raid_disks;
+ ppl_conf->child_logs = kcalloc(ppl_conf->count, sizeof(struct ppl_log),
+ GFP_KERNEL);
+ if (!ppl_conf->child_logs) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ atomic64_set(&ppl_conf->seq, 0);
+
+ if (!mddev->external) {
+ ppl_conf->signature = ~crc32c_le(~0, mddev->uuid, sizeof(mddev->uuid));
+ ppl_conf->block_size = 512;
+ } else {
+ ppl_conf->block_size = queue_logical_block_size(mddev->queue);
+ }
+
+ for (i = 0; i < ppl_conf->count; i++) {
+ struct ppl_log *log = &ppl_conf->child_logs[i];
+ struct md_rdev *rdev = conf->disks[i].rdev;
+
+ mutex_init(&log->io_mutex);
+ spin_lock_init(&log->io_list_lock);
+ INIT_LIST_HEAD(&log->io_list);
+ INIT_LIST_HEAD(&log->no_mem_stripes);
+
+ log->ppl_conf = ppl_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;
+ }
+ }
+
+ 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));
+
+ conf->ppl = ppl_conf;
+
+ return 0;
+err:
+ ppl_exit_log(ppl_conf);
+ return ret;
+}
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 02e02fe5b04e..21440b594878 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -739,7 +739,7 @@ static bool stripe_can_batch(struct stripe_head *sh)
{
struct r5conf *conf = sh->raid_conf;
- if (conf->log)
+ if (conf->log || conf->ppl)
return false;
return test_bit(STRIPE_BATCH_READY, &sh->state) &&
!test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
@@ -936,6 +936,9 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
}
}
+ if (conf->ppl && ppl_write_stripe(conf->ppl, sh) == 0)
+ return;
+
for (i = disks; i--; ) {
int op, op_flags = 0;
int replace_only = 0;
@@ -3308,6 +3311,16 @@ static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
&dd_idx, sh);
}
+static void log_stripe_write_finished(struct stripe_head *sh)
+{
+ struct r5conf *conf = sh->raid_conf;
+
+ if (conf->log)
+ r5l_stripe_write_finished(sh);
+ else if (conf->ppl)
+ ppl_stripe_write_finished(sh);
+}
+
static void
handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
struct stripe_head_state *s, int disks,
@@ -3347,7 +3360,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
if (bi)
bitmap_end = 1;
- r5l_stripe_write_finished(sh);
+ log_stripe_write_finished(sh);
if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
wake_up(&conf->wait_for_overlap);
@@ -3766,7 +3779,7 @@ static void handle_stripe_clean_event(struct r5conf *conf,
discard_pending = 1;
}
- r5l_stripe_write_finished(sh);
+ log_stripe_write_finished(sh);
if (!discard_pending &&
test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
@@ -4756,7 +4769,7 @@ static void handle_stripe(struct stripe_head *sh)
if (s.just_cached)
r5c_handle_cached_data_endio(conf, sh, disks, &s.return_bi);
- r5l_stripe_write_finished(sh);
+ log_stripe_write_finished(sh);
/* Now we might consider reading some blocks, either to check/generate
* parity, or to satisfy requests
@@ -6120,6 +6133,14 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
return handled;
}
+static void log_write_stripe_run(struct r5conf *conf)
+{
+ if (conf->log)
+ r5l_write_stripe_run(conf->log);
+ else if (conf->ppl)
+ ppl_write_stripe_run(conf->ppl);
+}
+
static int handle_active_stripes(struct r5conf *conf, int group,
struct r5worker *worker,
struct list_head *temp_inactive_list)
@@ -6157,7 +6178,7 @@ static int handle_active_stripes(struct r5conf *conf, int group,
for (i = 0; i < batch_size; i++)
handle_stripe(batch[i]);
- r5l_write_stripe_run(conf->log);
+ log_write_stripe_run(conf);
cond_resched();
@@ -6735,6 +6756,8 @@ static void free_conf(struct r5conf *conf)
if (conf->log)
r5l_exit_log(conf->log);
+ if (conf->ppl)
+ ppl_exit_log(conf->ppl);
if (conf->shrinker.nr_deferred)
unregister_shrinker(&conf->shrinker);
@@ -7196,6 +7219,13 @@ static int raid5_run(struct mddev *mddev)
BUG_ON(mddev->delta_disks != 0);
}
+ if (test_bit(MD_HAS_JOURNAL, &mddev->flags) &&
+ test_bit(MD_HAS_PPL, &mddev->flags)) {
+ pr_warn("md/raid:%s: using journal device and PPL not allowed - disabling PPL\n",
+ mdname(mddev));
+ clear_bit(MD_HAS_PPL, &mddev->flags);
+ }
+
if (mddev->private == NULL)
conf = setup_conf(mddev);
else
@@ -7422,6 +7452,11 @@ static int raid5_run(struct mddev *mddev)
mdname(mddev), bdevname(journal_dev->bdev, b));
if (r5l_init_log(conf, journal_dev))
goto abort;
+ } else if (test_bit(MD_HAS_PPL, &mddev->flags)) {
+ pr_debug("md/raid:%s: enabling distributed Partial Parity Log\n",
+ mdname(mddev));
+ if (ppl_init_log(conf))
+ goto abort;
}
return 0;
@@ -7690,7 +7725,7 @@ static int raid5_resize(struct mddev *mddev, sector_t sectors)
sector_t newsize;
struct r5conf *conf = mddev->private;
- if (conf->log)
+ if (conf->log || conf->ppl)
return -EINVAL;
sectors &= ~((sector_t)conf->chunk_sectors - 1);
newsize = raid5_size(mddev, sectors, mddev->raid_disks);
@@ -7743,7 +7778,7 @@ static int check_reshape(struct mddev *mddev)
{
struct r5conf *conf = mddev->private;
- if (conf->log)
+ if (conf->log || conf->ppl)
return -EINVAL;
if (mddev->delta_disks == 0 &&
mddev->new_layout == mddev->layout &&
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 3cc4cb28f7e6..f915a7a0e752 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -230,6 +230,7 @@ struct stripe_head {
struct list_head r5c; /* for r5c_cache->stripe_in_journal */
struct page *ppl_page; /* partial parity of this stripe */
+ struct ppl_io_unit *ppl_log_io;
/**
* struct stripe_operations
* @target - STRIPE_OP_COMPUTE_BLK target
@@ -689,6 +690,7 @@ struct r5conf {
int group_cnt;
int worker_cnt_per_group;
struct r5l_log *log;
+ struct ppl_conf *ppl;
struct bio_list pending_bios;
spinlock_t pending_bios_lock;
@@ -798,4 +800,10 @@ extern void r5c_check_cached_full_stripe(struct r5conf *conf);
extern struct md_sysfs_entry r5c_journal_mode;
extern void r5c_update_on_rdev_error(struct mddev *mddev);
extern bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect);
+
+extern int ppl_init_log(struct r5conf *conf);
+extern void ppl_exit_log(struct ppl_conf *log);
+extern int ppl_write_stripe(struct ppl_conf *log, struct stripe_head *sh);
+extern void ppl_write_stripe_run(struct ppl_conf *log);
+extern void ppl_stripe_write_finished(struct stripe_head *sh);
#endif
diff --git a/include/uapi/linux/raid/md_p.h b/include/uapi/linux/raid/md_p.h
index fe2112810c43..2c28711cc5f1 100644
--- a/include/uapi/linux/raid/md_p.h
+++ b/include/uapi/linux/raid/md_p.h
@@ -398,4 +398,30 @@ struct r5l_meta_block {
#define R5LOG_VERSION 0x1
#define R5LOG_MAGIC 0x6433c509
+
+struct ppl_header_entry {
+ __le64 data_sector; /* Raid sector of the new data */
+ __le32 pp_size; /* Length of partial parity */
+ __le32 data_size; /* Length of data */
+ __le32 parity_disk; /* Member disk containing parity */
+ __le32 checksum; /* Checksum of this entry */
+} __attribute__ ((__packed__));
+
+#define PPL_HEADER_SIZE 4096
+#define PPL_HDR_RESERVED 512
+#define PPL_HDR_ENTRY_SPACE \
+ (PPL_HEADER_SIZE - PPL_HDR_RESERVED - 4 * sizeof(u32) - sizeof(u64))
+#define PPL_HDR_MAX_ENTRIES \
+ (PPL_HDR_ENTRY_SPACE / sizeof(struct ppl_header_entry))
+
+struct ppl_header {
+ __u8 reserved[PPL_HDR_RESERVED];/* Reserved space */
+ __le32 signature; /* Signature (family number of volume) */
+ __le32 padding;
+ __le64 generation; /* Generation number of PP Header */
+ __le32 entries_count; /* Number of entries in entry array */
+ __le32 checksum; /* Checksum of PP Header */
+ struct ppl_header_entry entries[PPL_HDR_MAX_ENTRIES];
+} __attribute__ ((__packed__));
+
#endif
--
2.11.0
--
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