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-rw-r--r--Documentation/md/raid5-ppl.txt44
-rw-r--r--drivers/md/Makefile2
-rw-r--r--drivers/md/raid5-log.h24
-rw-r--r--drivers/md/raid5-ppl.c703
-rw-r--r--drivers/md/raid5.c64
-rw-r--r--drivers/md/raid5.h10
-rw-r--r--include/uapi/linux/raid/md_p.h27
7 files changed, 869 insertions, 5 deletions
diff --git a/Documentation/md/raid5-ppl.txt b/Documentation/md/raid5-ppl.txt
new file mode 100644
index 0000000..127072b
--- /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 3cbda1a..4d48714 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-log.h b/drivers/md/raid5-log.h
index 2da4bd3..a67fb58 100644
--- a/drivers/md/raid5-log.h
+++ b/drivers/md/raid5-log.h
@@ -31,6 +31,20 @@ 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 struct dma_async_tx_descriptor *
+ops_run_partial_parity(struct stripe_head *sh, struct raid5_percpu *percpu,
+ struct dma_async_tx_descriptor *tx);
+extern int ppl_init_log(struct r5conf *conf);
+extern void ppl_exit_log(struct r5conf *conf);
+extern int ppl_write_stripe(struct r5conf *conf, struct stripe_head *sh);
+extern void ppl_write_stripe_run(struct r5conf *conf);
+extern void ppl_stripe_write_finished(struct stripe_head *sh);
+
+static inline bool raid5_has_ppl(struct r5conf *conf)
+{
+ return test_bit(MD_HAS_PPL, &conf->mddev->flags);
+}
+
static inline int log_stripe(struct stripe_head *sh, struct stripe_head_state *s)
{
struct r5conf *conf = sh->raid_conf;
@@ -45,6 +59,8 @@ static inline int log_stripe(struct stripe_head *sh, struct stripe_head_state *s
/* caching phase */
return r5c_cache_data(conf->log, sh);
}
+ } else if (raid5_has_ppl(conf)) {
+ return ppl_write_stripe(conf, sh);
}
return -EAGAIN;
@@ -56,24 +72,32 @@ static inline void log_stripe_write_finished(struct stripe_head *sh)
if (conf->log)
r5l_stripe_write_finished(sh);
+ else if (raid5_has_ppl(conf))
+ ppl_stripe_write_finished(sh);
}
static inline void log_write_stripe_run(struct r5conf *conf)
{
if (conf->log)
r5l_write_stripe_run(conf->log);
+ else if (raid5_has_ppl(conf))
+ ppl_write_stripe_run(conf);
}
static inline void log_exit(struct r5conf *conf)
{
if (conf->log)
r5l_exit_log(conf);
+ else if (raid5_has_ppl(conf))
+ ppl_exit_log(conf);
}
static inline int log_init(struct r5conf *conf, struct md_rdev *journal_dev)
{
if (journal_dev)
return r5l_init_log(conf, journal_dev);
+ else if (raid5_has_ppl(conf))
+ return ppl_init_log(conf);
return 0;
}
diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
new file mode 100644
index 0000000..db5b72b
--- /dev/null
+++ b/drivers/md/raid5-ppl.c
@@ -0,0 +1,703 @@
+/*
+ * 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"
+
+/*
+ * 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
+ *
+ * An entry describes one or more consecutive stripe_heads, up to a full
+ * stripe. The modifed raid data chunks form an m-by-n matrix, where m is the
+ * number of stripe_heads in the entry and n is the number of modified data
+ * disks. Every stripe_head in the entry must write to the same data disks.
+ * An example of a valid case described by a single entry (writes to the first
+ * stripe of a 4 disk array, 16k chunk size):
+ *
+ * sh->sector dd0 dd1 dd2 ppl
+ * +-----+-----+-----+
+ * 0 | --- | --- | --- | +----+
+ * 8 | -W- | -W- | --- | | pp | data_sector = 8
+ * 16 | -W- | -W- | --- | | pp | data_size = 3 * 2 * 4k
+ * 24 | -W- | -W- | --- | | pp | pp_size = 3 * 4k
+ * +-----+-----+-----+ +----+
+ *
+ * data_sector is the first raid sector of the modified data, data_size is the
+ * total size of modified data and pp_size is the size of partial parity for
+ * this entry. Entries for full stripe writes contain no partial parity
+ * (pp_size = 0), they only mark the stripes for which parity should be
+ * recalculated after an unclean shutdown. Every entry holds a checksum of its
+ * partial parity, the header also has a checksum of the header itself.
+ *
+ * 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->log_private.
+ *
+ * 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_head
+ * can be appended to the last entry if it meets the conditions for a valid
+ * entry described above, otherwise a new entry is added. Checksums of entries
+ * are calculated incrementally as stripes containing partial parity are being
+ * added. 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 */
+};
+
+#define PPL_IO_INLINE_BVECS 32
+
+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 */
+
+ /* inline bio and its biovec for submitting the iounit */
+ struct bio bio;
+ struct bio_vec biovec[PPL_IO_INLINE_BVECS];
+};
+
+struct dma_async_tx_descriptor *
+ops_run_partial_parity(struct stripe_head *sh, struct raid5_percpu *percpu,
+ struct dma_async_tx_descriptor *tx)
+{
+ int disks = sh->disks;
+ struct page **xor_srcs = flex_array_get(percpu->scribble, 0);
+ int count = 0, pd_idx = sh->pd_idx, i;
+ struct async_submit_ctl submit;
+
+ pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
+
+ /*
+ * Partial parity is the XOR of stripe data chunks that are not changed
+ * during the write request. Depending on available data
+ * (read-modify-write vs. reconstruct-write case) we calculate it
+ * differently.
+ */
+ if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
+ /* rmw: xor old data and parity from updated disks */
+ for (i = disks; i--;) {
+ struct r5dev *dev = &sh->dev[i];
+ if (test_bit(R5_Wantdrain, &dev->flags) || i == pd_idx)
+ xor_srcs[count++] = dev->page;
+ }
+ } else if (sh->reconstruct_state == reconstruct_state_drain_run) {
+ /* rcw: xor data from all not updated disks */
+ for (i = disks; i--;) {
+ struct r5dev *dev = &sh->dev[i];
+ if (test_bit(R5_UPTODATE, &dev->flags))
+ xor_srcs[count++] = dev->page;
+ }
+ } else {
+ return tx;
+ }
+
+ 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));
+
+ if (count == 1)
+ tx = async_memcpy(sh->ppl_page, xor_srcs[0], 0, 0, PAGE_SIZE,
+ &submit);
+ else
+ tx = async_xor(sh->ppl_page, xor_srcs, 0, count, PAGE_SIZE,
+ &submit);
+
+ return tx;
+}
+
+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);
+ bio_init(&io->bio, io->biovec, PPL_IO_INLINE_BVECS);
+
+ 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];
+ struct stripe_head *sh_last = list_last_entry(
+ &io->stripe_list, struct stripe_head, log_list);
+ u64 data_sector_last = le64_to_cpu(last->data_sector);
+ u32 data_size_last = le32_to_cpu(last->data_size);
+
+ /*
+ * Check if we can append the stripe to the last entry. It must
+ * 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) &&
+ (data_sector >> ilog2(conf->chunk_sectors) ==
+ data_sector_last >> ilog2(conf->chunk_sectors)) &&
+ ((data_sector - data_sector_last) * data_disks ==
+ data_size_last >> 9))
+ 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_io = io;
+
+ return 0;
+}
+
+int ppl_write_stripe(struct r5conf *conf, struct stripe_head *sh)
+{
+ struct ppl_conf *ppl_conf = conf->log_private;
+ struct ppl_io_unit *io = sh->ppl_io;
+ struct ppl_log *log;
+
+ 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);
+
+ 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_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",
+ __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_iounit(struct ppl_io_unit *io)
+{
+ struct ppl_log *log = io->log;
+ struct ppl_conf *ppl_conf = log->ppl_conf;
+ struct ppl_header *pplhdr = page_address(io->header_page);
+ struct bio *bio = &io->bio;
+ struct stripe_head *sh;
+ int i;
+
+ for (i = 0; i < io->entries_count; i++) {
+ struct ppl_header_entry *e = &pplhdr->entries[i];
+
+ pr_debug("%s: seq: %llu entry: %d data_sector: %llu pp_size: %u data_size: %u\n",
+ __func__, io->seq, i, le64_to_cpu(e->data_sector),
+ le32_to_cpu(e->pp_size), le32_to_cpu(e->data_size));
+
+ e->data_sector = cpu_to_le64(le64_to_cpu(e->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));
+
+ 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);
+
+ list_for_each_entry(sh, &io->stripe_list, log_list) {
+ /* entries for full stripe writes have no partial parity */
+ if (test_bit(STRIPE_FULL_WRITE, &sh->state))
+ continue;
+
+ 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->bi_iter.bi_sector = bio_end_sector(prev);
+ bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0);
+
+ bio_chain(bio, prev);
+ ppl_submit_iounit_bio(io, prev);
+ }
+ }
+
+ ppl_submit_iounit_bio(io, 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 r5conf *conf)
+{
+ struct ppl_conf *ppl_conf = conf->log_private;
+ 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_io;
+ sh->ppl_io = NULL;
+
+ if (io && atomic_dec_and_test(&io->pending_stripes))
+ ppl_io_unit_finished(io);
+}
+
+static void __ppl_exit_log(struct ppl_conf *ppl_conf)
+{
+ clear_bit(MD_HAS_PPL, &ppl_conf->mddev->flags);
+
+ 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);
+}
+
+void ppl_exit_log(struct r5conf *conf)
+{
+ struct ppl_conf *ppl_conf = conf->log_private;
+
+ if (ppl_conf) {
+ __ppl_exit_log(ppl_conf);
+ conf->log_private = NULL;
+ }
+}
+
+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;
+
+ pr_debug("md/raid:%s: enabling distributed Partial Parity Log\n",
+ mdname(conf->mddev));
+
+ if (PAGE_SIZE != 4096)
+ return -EINVAL;
+
+ if (mddev->level != 5) {
+ pr_warn("md/raid:%s PPL is not compatible with raid level %d\n",
+ mdname(mddev), mddev->level);
+ 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->mddev = mddev;
+
+ 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->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->log_private = 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 f575f40..6b86e08 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -482,6 +482,11 @@ static void shrink_buffers(struct stripe_head *sh)
sh->dev[i].page = NULL;
put_page(p);
}
+
+ if (sh->ppl_page) {
+ put_page(sh->ppl_page);
+ sh->ppl_page = NULL;
+ }
}
static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
@@ -498,6 +503,13 @@ static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
sh->dev[i].page = page;
sh->dev[i].orig_page = page;
}
+
+ if (raid5_has_ppl(sh->raid_conf)) {
+ sh->ppl_page = alloc_page(gfp);
+ if (!sh->ppl_page)
+ return 1;
+ }
+
return 0;
}
@@ -746,7 +758,7 @@ static bool stripe_can_batch(struct stripe_head *sh)
{
struct r5conf *conf = sh->raid_conf;
- if (conf->log)
+ if (conf->log || raid5_has_ppl(conf))
return false;
return test_bit(STRIPE_BATCH_READY, &sh->state) &&
!test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
@@ -2093,6 +2105,9 @@ static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
async_tx_ack(tx);
}
+ if (test_bit(STRIPE_OP_PARTIAL_PARITY, &ops_request))
+ tx = ops_run_partial_parity(sh, percpu, tx);
+
if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
if (level < 6)
tx = ops_run_prexor5(sh, percpu, tx);
@@ -3168,6 +3183,12 @@ schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
s->locked++;
}
+ if (raid5_has_ppl(sh->raid_conf) &&
+ test_bit(STRIPE_OP_BIODRAIN, &s->ops_request) &&
+ !test_bit(STRIPE_FULL_WRITE, &sh->state) &&
+ test_bit(R5_Insync, &sh->dev[pd_idx].flags))
+ set_bit(STRIPE_OP_PARTIAL_PARITY, &s->ops_request);
+
pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
__func__, (unsigned long long)sh->sector,
s->locked, s->ops_request);
@@ -3215,6 +3236,36 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
goto overlap;
+ if (forwrite && raid5_has_ppl(conf)) {
+ /*
+ * With PPL only writes to consecutive data chunks within a
+ * stripe are allowed because for a single stripe_head we can
+ * only have one PPL entry at a time, which describes one data
+ * range. Not really an overlap, but wait_for_overlap can be
+ * used to handle this.
+ */
+ sector_t sector;
+ sector_t first = 0;
+ sector_t last = 0;
+ int count = 0;
+ int i;
+
+ for (i = 0; i < sh->disks; i++) {
+ if (i != sh->pd_idx &&
+ (i == dd_idx || sh->dev[i].towrite)) {
+ sector = sh->dev[i].sector;
+ if (count == 0 || sector < first)
+ first = sector;
+ if (sector > last)
+ last = sector;
+ count++;
+ }
+ }
+
+ if (first + conf->chunk_sectors * (count - 1) != last)
+ goto overlap;
+ }
+
if (!forwrite || previous)
clear_bit(STRIPE_BATCH_READY, &sh->state);
@@ -7208,6 +7259,13 @@ 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
@@ -7689,7 +7747,7 @@ static int raid5_resize(struct mddev *mddev, sector_t sectors)
sector_t newsize;
struct r5conf *conf = mddev->private;
- if (conf->log)
+ if (conf->log || raid5_has_ppl(conf))
return -EINVAL;
sectors &= ~((sector_t)conf->chunk_sectors - 1);
newsize = raid5_size(mddev, sectors, mddev->raid_disks);
@@ -7740,7 +7798,7 @@ static int check_reshape(struct mddev *mddev)
{
struct r5conf *conf = mddev->private;
- if (conf->log)
+ if (conf->log || raid5_has_ppl(conf))
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 6dd295a..ba5b7a3 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -224,10 +224,16 @@ struct stripe_head {
spinlock_t batch_lock; /* only header's lock is useful */
struct list_head batch_list; /* protected by head's batch lock*/
- struct r5l_io_unit *log_io;
+ union {
+ struct r5l_io_unit *log_io;
+ struct ppl_io_unit *ppl_io;
+ };
+
struct list_head log_list;
sector_t log_start; /* first meta block on the journal */
struct list_head r5c; /* for r5c_cache->stripe_in_journal */
+
+ struct page *ppl_page; /* partial parity of this stripe */
/**
* struct stripe_operations
* @target - STRIPE_OP_COMPUTE_BLK target
@@ -400,6 +406,7 @@ enum {
STRIPE_OP_BIODRAIN,
STRIPE_OP_RECONSTRUCT,
STRIPE_OP_CHECK,
+ STRIPE_OP_PARTIAL_PARITY,
};
/*
@@ -696,6 +703,7 @@ struct r5conf {
int group_cnt;
int worker_cnt_per_group;
struct r5l_log *log;
+ void *log_private;
spinlock_t pending_bios_lock;
bool batch_bio_dispatch;
diff --git a/include/uapi/linux/raid/md_p.h b/include/uapi/linux/raid/md_p.h
index fe21128..d9a1ead 100644
--- a/include/uapi/linux/raid/md_p.h
+++ b/include/uapi/linux/raid/md_p.h
@@ -398,4 +398,31 @@ 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 partial parity data for this
+ * entry (~crc32c) */
+} __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, fill with 0xff */
+ __le32 signature; /* signature (family number of volume) */
+ __le32 padding; /* zero pad */
+ __le64 generation; /* generation number of the header */
+ __le32 entries_count; /* number of entries in entry array */
+ __le32 checksum; /* checksum of the header (~crc32c) */
+ struct ppl_header_entry entries[PPL_HDR_MAX_ENTRIES];
+} __attribute__ ((__packed__));
+
#endif
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