diff options
Diffstat (limited to 'drivers/md/raid5-ppl.c')
| -rw-r--r-- | drivers/md/raid5-ppl.c | 1529 |
1 files changed, 1529 insertions, 0 deletions
diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c new file mode 100644 index 000000000..eaea57aee --- /dev/null +++ b/drivers/md/raid5-ppl.c @@ -0,0 +1,1529 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Partial Parity Log for closing the RAID5 write hole + * Copyright (c) 2017, Intel Corporation. + */ + +#include <linux/kernel.h> +#include <linux/blkdev.h> +#include <linux/slab.h> +#include <linux/crc32c.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 + * 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. + * + * 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; + + /* 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; + struct bio_set flush_bs; + + /* used only for recovery */ + int recovered_entries; + int mismatch_count; + + /* 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 { + 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 */ + + 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 + +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 */ + atomic_t pending_flushes; /* how many disk flushes are in progress */ + + 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 **srcs = percpu->scribble; + 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 + * This is calculated earlier by ops_run_prexor5() so just copy + * the parity dev page. + */ + srcs[count++] = sh->dev[pd_idx].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)) + srcs[count++] = dev->page; + } + } else { + return tx; + } + + init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, tx, + NULL, sh, (void *) (srcs + sh->disks + 2)); + + if (count == 1) + tx = async_memcpy(sh->ppl_page, srcs[0], 0, 0, PAGE_SIZE, + &submit); + else + tx = async_xor(sh->ppl_page, srcs, 0, count, PAGE_SIZE, + &submit); + + return tx; +} + +static void *ppl_io_pool_alloc(gfp_t gfp_mask, void *pool_data) +{ + struct kmem_cache *kc = pool_data; + struct ppl_io_unit *io; + + io = kmem_cache_alloc(kc, gfp_mask); + if (!io) + return NULL; + + io->header_page = alloc_page(gfp_mask); + if (!io->header_page) { + kmem_cache_free(kc, io); + return NULL; + } + + return io; +} + +static void ppl_io_pool_free(void *element, void *pool_data) +{ + struct kmem_cache *kc = pool_data; + struct ppl_io_unit *io = element; + + __free_page(io->header_page); + kmem_cache_free(kc, io); +} + +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; + struct page *header_page; + + io = mempool_alloc(&ppl_conf->io_pool, GFP_NOWAIT); + if (!io) + return NULL; + + header_page = io->header_page; + memset(io, 0, sizeof(*io)); + io->header_page = header_page; + + io->log = log; + INIT_LIST_HEAD(&io->log_sibling); + INIT_LIST_HEAD(&io->stripe_list); + atomic_set(&io->pending_stripes, 0); + 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); + 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; + 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 == log->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 + RAID5_STRIPE_SECTORS(conf)) && + (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) || !sh->ppl_page || + !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(&ppl_conf->no_mem_stripes_lock); + list_add_tail(&sh->log_list, &ppl_conf->no_mem_stripes); + spin_unlock_irq(&ppl_conf->no_mem_stripes_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_status) + md_error(ppl_conf->mddev, log->rdev); + + 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) +{ + 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, + bio->bi_bdev); + + 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; + + bio->bi_private = io; + + if (!log->rdev || test_bit(Faulty, &log->rdev->flags)) { + ppl_log_endio(bio); + return; + } + + 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)); + + /* 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_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; + + if (!bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0)) { + struct bio *prev = bio; + + 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_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; + 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); + + local_irq_save(flags); + + spin_lock(&log->io_list_lock); + list_del(&io->log_sibling); + spin_unlock(&log->io_list_lock); + + mempool_free(io, &ppl_conf->io_pool); + + spin_lock(&ppl_conf->no_mem_stripes_lock); + if (!list_empty(&ppl_conf->no_mem_stripes)) { + struct stripe_head *sh; + + sh = list_first_entry(&ppl_conf->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(&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; + + rcu_read_lock(); + rdev = rcu_dereference(conf->disks[i].rdev); + if (rdev && !test_bit(Faulty, &rdev->flags)) + bdev = rdev->bdev; + rcu_read_unlock(); + + 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) +{ + struct ppl_io_unit *io; + + io = sh->ppl_io; + sh->ppl_io = NULL; + + 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) +{ + struct async_submit_ctl submit; + struct dma_async_tx_descriptor *tx; + struct page *xor_srcs[] = { page1, page2 }; + + init_async_submit(&submit, ASYNC_TX_ACK|ASYNC_TX_XOR_DROP_DST, + NULL, NULL, NULL, NULL); + tx = async_xor(page1, xor_srcs, 0, 2, size, &submit); + + async_tx_quiesce(&tx); +} + +/* + * PPL recovery strategy: xor partial parity and data from all modified data + * disks within a stripe and write the result as the new stripe parity. If all + * stripe data disks are modified (full stripe write), no partial parity is + * available, so just xor the data disks. + * + * Recovery of a PPL entry shall occur only if all modified data disks are + * available and read from all of them succeeds. + * + * A PPL entry applies to a stripe, partial parity size for an entry is at most + * the size of the chunk. Examples of possible cases for a single entry: + * + * case 0: single data disk write: + * data0 data1 data2 ppl parity + * +--------+--------+--------+ +--------------------+ + * | ------ | ------ | ------ | +----+ | (no change) | + * | ------ | -data- | ------ | | pp | -> | data1 ^ pp | + * | ------ | -data- | ------ | | pp | -> | data1 ^ pp | + * | ------ | ------ | ------ | +----+ | (no change) | + * +--------+--------+--------+ +--------------------+ + * pp_size = data_size + * + * case 1: more than one data disk write: + * data0 data1 data2 ppl parity + * +--------+--------+--------+ +--------------------+ + * | ------ | ------ | ------ | +----+ | (no change) | + * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp | + * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp | + * | ------ | ------ | ------ | +----+ | (no change) | + * +--------+--------+--------+ +--------------------+ + * pp_size = data_size / modified_data_disks + * + * case 2: write to all data disks (also full stripe write): + * data0 data1 data2 parity + * +--------+--------+--------+ +--------------------+ + * | ------ | ------ | ------ | | (no change) | + * | -data- | -data- | -data- | --------> | xor all data | + * | ------ | ------ | ------ | --------> | (no change) | + * | ------ | ------ | ------ | | (no change) | + * +--------+--------+--------+ +--------------------+ + * pp_size = 0 + * + * The following cases are possible only in other implementations. The recovery + * code can handle them, but they are not generated at runtime because they can + * be reduced to cases 0, 1 and 2: + * + * case 3: + * data0 data1 data2 ppl parity + * +--------+--------+--------+ +----+ +--------------------+ + * | ------ | -data- | -data- | | pp | | data1 ^ data2 ^ pp | + * | ------ | -data- | -data- | | pp | -> | data1 ^ data2 ^ pp | + * | -data- | -data- | -data- | | -- | -> | xor all data | + * | -data- | -data- | ------ | | pp | | data0 ^ data1 ^ pp | + * +--------+--------+--------+ +----+ +--------------------+ + * pp_size = chunk_size + * + * case 4: + * data0 data1 data2 ppl parity + * +--------+--------+--------+ +----+ +--------------------+ + * | ------ | -data- | ------ | | pp | | data1 ^ pp | + * | ------ | ------ | ------ | | -- | -> | (no change) | + * | ------ | ------ | ------ | | -- | -> | (no change) | + * | -data- | ------ | ------ | | pp | | data0 ^ pp | + * +--------+--------+--------+ +----+ +--------------------+ + * pp_size = chunk_size + */ +static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e, + sector_t ppl_sector) +{ + struct ppl_conf *ppl_conf = log->ppl_conf; + struct mddev *mddev = ppl_conf->mddev; + struct r5conf *conf = mddev->private; + int block_size = ppl_conf->block_size; + struct page *page1; + struct page *page2; + sector_t r_sector_first; + sector_t r_sector_last; + int strip_sectors; + int data_disks; + int i; + int ret = 0; + unsigned int pp_size = le32_to_cpu(e->pp_size); + unsigned int data_size = le32_to_cpu(e->data_size); + + page1 = alloc_page(GFP_KERNEL); + page2 = alloc_page(GFP_KERNEL); + + if (!page1 || !page2) { + ret = -ENOMEM; + goto out; + } + + r_sector_first = le64_to_cpu(e->data_sector) * (block_size >> 9); + + if ((pp_size >> 9) < conf->chunk_sectors) { + if (pp_size > 0) { + data_disks = data_size / pp_size; + strip_sectors = pp_size >> 9; + } else { + data_disks = conf->raid_disks - conf->max_degraded; + strip_sectors = (data_size >> 9) / data_disks; + } + r_sector_last = r_sector_first + + (data_disks - 1) * conf->chunk_sectors + + strip_sectors; + } else { + data_disks = conf->raid_disks - conf->max_degraded; + strip_sectors = conf->chunk_sectors; + r_sector_last = r_sector_first + (data_size >> 9); + } + + pr_debug("%s: array sector first: %llu last: %llu\n", __func__, + (unsigned long long)r_sector_first, + (unsigned long long)r_sector_last); + + /* if start and end is 4k aligned, use a 4k block */ + if (block_size == 512 && + (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)) { + bool update_parity = false; + sector_t parity_sector; + struct md_rdev *parity_rdev; + struct stripe_head sh; + int disk; + int indent = 0; + + pr_debug("%s:%*s iter %d start\n", __func__, indent, "", i); + indent += 2; + + memset(page_address(page1), 0, PAGE_SIZE); + + /* iterate through data member disks */ + for (disk = 0; disk < data_disks; disk++) { + int dd_idx; + struct md_rdev *rdev; + sector_t sector; + sector_t r_sector = r_sector_first + i + + (disk * conf->chunk_sectors); + + pr_debug("%s:%*s data member disk %d start\n", + __func__, indent, "", disk); + indent += 2; + + if (r_sector >= r_sector_last) { + pr_debug("%s:%*s array sector %llu doesn't need parity update\n", + __func__, indent, "", + (unsigned long long)r_sector); + indent -= 2; + continue; + } + + update_parity = true; + + /* map raid sector to member disk */ + sector = raid5_compute_sector(conf, r_sector, 0, + &dd_idx, NULL); + pr_debug("%s:%*s processing array sector %llu => data member disk %d, sector %llu\n", + __func__, indent, "", + (unsigned long long)r_sector, dd_idx, + (unsigned long long)sector); + + /* Array has not started so rcu dereference is safe */ + rdev = rcu_dereference_protected( + conf->disks[dd_idx].rdev, 1); + 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 %pg sector %llu\n", + __func__, indent, "", rdev->bdev, + (unsigned long long)sector); + if (!sync_page_io(rdev, sector, block_size, page2, + REQ_OP_READ, false)) { + md_error(mddev, rdev); + pr_debug("%s:%*s read failed!\n", __func__, + indent, ""); + ret = -EIO; + goto out; + } + + ppl_xor(block_size, page1, page2); + + indent -= 2; + } + + if (!update_parity) + continue; + + if (pp_size > 0) { + pr_debug("%s:%*s reading pp disk sector %llu\n", + __func__, indent, "", + (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, + false)) { + pr_debug("%s:%*s read failed!\n", __func__, + indent, ""); + md_error(mddev, log->rdev); + ret = -EIO; + goto out; + } + + ppl_xor(block_size, page1, page2); + } + + /* map raid sector to parity disk */ + parity_sector = raid5_compute_sector(conf, r_sector_first + i, + 0, &disk, &sh); + BUG_ON(sh.pd_idx != le32_to_cpu(e->parity_disk)); + + /* Array has not started so rcu dereference is safe */ + parity_rdev = rcu_dereference_protected( + conf->disks[sh.pd_idx].rdev, 1); + + BUG_ON(parity_rdev->bdev->bd_dev != log->rdev->bdev->bd_dev); + pr_debug("%s:%*s write parity at sector %llu, disk %pg\n", + __func__, indent, "", + (unsigned long long)parity_sector, + parity_rdev->bdev); + if (!sync_page_io(parity_rdev, parity_sector, block_size, + page1, REQ_OP_WRITE, false)) { + pr_debug("%s:%*s parity write error!\n", __func__, + indent, ""); + md_error(mddev, parity_rdev); + ret = -EIO; + goto out; + } + } +out: + if (page1) + __free_page(page1); + if (page2) + __free_page(page2); + return ret; +} + +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 + offset + + (PPL_HEADER_SIZE >> 9); + struct page *page; + int i; + int ret = 0; + + page = alloc_page(GFP_KERNEL); + if (!page) + return -ENOMEM; + + /* iterate through all PPL entries saved */ + for (i = 0; i < le32_to_cpu(pplhdr->entries_count); i++) { + struct ppl_header_entry *e = &pplhdr->entries[i]; + u32 pp_size = le32_to_cpu(e->pp_size); + sector_t sector = ppl_sector; + int ppl_entry_sectors = pp_size >> 9; + u32 crc, crc_stored; + + pr_debug("%s: disk: %d entry: %d ppl_sector: %llu pp_size: %u\n", + __func__, rdev->raid_disk, i, + (unsigned long long)ppl_sector, pp_size); + + crc = ~0; + crc_stored = le32_to_cpu(e->checksum); + + /* read parial parity for this entry and calculate its checksum */ + while (pp_size) { + int s = pp_size > PAGE_SIZE ? PAGE_SIZE : pp_size; + + if (!sync_page_io(rdev, sector - rdev->data_offset, + s, page, REQ_OP_READ, false)) { + md_error(mddev, rdev); + ret = -EIO; + goto out; + } + + crc = crc32c_le(crc, page_address(page), s); + + pp_size -= s; + sector += s >> 9; + } + + crc = ~crc; + + if (crc != crc_stored) { + /* + * Don't recover this entry if the checksum does not + * match, but keep going and try to recover other + * entries. + */ + pr_debug("%s: ppl entry crc does not match: stored: 0x%x calculated: 0x%x\n", + __func__, crc_stored, crc); + ppl_conf->mismatch_count++; + } else { + ret = ppl_recover_entry(log, e, ppl_sector); + if (ret) + goto out; + ppl_conf->recovered_entries++; + } + + ppl_sector += ppl_entry_sectors; + } + + /* flush the disk cache after recovery if necessary */ + ret = blkdev_issue_flush(rdev->bdev); +out: + __free_page(page); + return ret; +} + +static int ppl_write_empty_header(struct ppl_log *log) +{ + struct page *page; + struct ppl_header *pplhdr; + struct md_rdev *rdev = log->rdev; + int ret = 0; + + pr_debug("%s: disk: %d ppl_sector: %llu\n", __func__, + rdev->raid_disk, (unsigned long long)rdev->ppl.sector); + + page = alloc_page(GFP_NOIO | __GFP_ZERO); + if (!page) + 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)); + + if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset, + PPL_HEADER_SIZE, page, REQ_OP_WRITE | REQ_SYNC | + REQ_FUA, false)) { + md_error(rdev->mddev, rdev); + ret = -EIO; + } + + __free_page(page); + return ret; +} + +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, *page2; + struct ppl_header *pplhdr = NULL, *prev_pplhdr = NULL; + u32 crc, crc_stored; + u32 signature; + 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 headers, find the recent one */ + page = alloc_page(GFP_KERNEL); + if (!page) + return -ENOMEM; + + page2 = alloc_page(GFP_KERNEL); + if (!page2) { + __free_page(page); + return -ENOMEM; + } + + /* 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_le(~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 (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; + } + + prev_pplhdr_offset = pplhdr_offset; + prev_pplhdr = pplhdr; + + 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 (pplhdr && !mddev->pers && mddev->recovery_cp != 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, + ppl_conf->recovered_entries); + return ret; +} + +static int ppl_load(struct ppl_conf *ppl_conf) +{ + int ret = 0; + u32 signature = 0; + bool signature_set = false; + int i; + + for (i = 0; i < ppl_conf->count; i++) { + struct ppl_log *log = &ppl_conf->child_logs[i]; + + /* skip missing drive */ + if (!log->rdev) + continue; + + ret = ppl_load_distributed(log); + if (ret) + break; + + /* + * For external metadata we can't check if the signature is + * correct on a single drive, but we can check if it is the same + * on all drives. + */ + if (ppl_conf->mddev->external) { + if (!signature_set) { + signature = ppl_conf->signature; + signature_set = true; + } else if (signature != ppl_conf->signature) { + pr_warn("md/raid:%s: PPL header signature does not match on all member drives\n", + mdname(ppl_conf->mddev)); + ret = -EINVAL; + break; + } + } + } + + pr_debug("%s: return: %d mismatch_count: %d recovered_entries: %d\n", + __func__, ret, ppl_conf->mismatch_count, + ppl_conf->recovered_entries); + return ret; +} + +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); + + 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); +} + +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) +{ + 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, + RAID5_STRIPE_SECTORS((struct r5conf *)rdev->mddev->private)); + + if (ppl_data_sectors <= 0) { + pr_warn("md/raid:%s: PPL space too small on %pg\n", + mdname(rdev->mddev), rdev->bdev); + 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 %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 %pg\n", + mdname(rdev->mddev), rdev->bdev); + return -EINVAL; + } + + rdev->ppl.size = ppl_size_new; + + 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; + + 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; + } + + 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; + + ppl_conf->mddev = mddev; + + ppl_conf->io_kc = KMEM_CACHE(ppl_io_unit, 0); + if (!ppl_conf->io_kc) { + ret = -ENOMEM; + goto err; + } + + 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; + + 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), + GFP_KERNEL); + if (!ppl_conf->child_logs) { + ret = -ENOMEM; + goto err; + } + + atomic64_set(&ppl_conf->seq, 0); + INIT_LIST_HEAD(&ppl_conf->no_mem_stripes); + 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->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]; + /* Array has not started so rcu dereference is safe */ + struct md_rdev *rdev = + rcu_dereference_protected(conf->disks[i].rdev, 1); + + mutex_init(&log->io_mutex); + spin_lock_init(&log->io_list_lock); + INIT_LIST_HEAD(&log->io_list); + + log->ppl_conf = ppl_conf; + log->rdev = rdev; + + if (rdev) { + ret = ppl_validate_rdev(rdev); + if (ret) + goto err; + + ppl_init_child_log(log, rdev); + } + } + + /* 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 && + 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; + 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 */ + ret = -EINVAL; + goto err; + } + + conf->log_private = ppl_conf; + set_bit(MD_HAS_PPL, &ppl_conf->mddev->flags); + + return 0; +err: + __ppl_exit_log(ppl_conf); + return ret; +} + +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; + + if (!rdev) + return -EINVAL; + + pr_debug("%s: disk: %d operation: %s dev: %pg\n", + __func__, rdev->raid_disk, add ? "add" : "remove", + rdev->bdev); + + if (rdev->raid_disk < 0) + return 0; + + if (rdev->raid_disk >= ppl_conf->count) + return -ENODEV; + + log = &ppl_conf->child_logs[rdev->raid_disk]; + + mutex_lock(&log->io_mutex); + if (add) { + ret = ppl_validate_rdev(rdev); + if (!ret) { + log->rdev = rdev; + ret = ppl_write_empty_header(log); + ppl_init_child_log(log, rdev); + } + } else { + log->rdev = NULL; + } + mutex_unlock(&log->io_mutex); + + 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); |