diff options
Diffstat (limited to 'drivers/md/dm-log-writes.c')
| -rw-r--r-- | drivers/md/dm-log-writes.c | 1041 |
1 files changed, 1041 insertions, 0 deletions
diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c new file mode 100644 index 000000000..e549392e0 --- /dev/null +++ b/drivers/md/dm-log-writes.c @@ -0,0 +1,1041 @@ +/* + * Copyright (C) 2014 Facebook. All rights reserved. + * + * This file is released under the GPL. + */ + +#include <linux/device-mapper.h> + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/blkdev.h> +#include <linux/bio.h> +#include <linux/dax.h> +#include <linux/slab.h> +#include <linux/kthread.h> +#include <linux/freezer.h> +#include <linux/uio.h> + +#define DM_MSG_PREFIX "log-writes" + +/* + * This target will sequentially log all writes to the target device onto the + * log device. This is helpful for replaying writes to check for fs consistency + * at all times. This target provides a mechanism to mark specific events to + * check data at a later time. So for example you would: + * + * write data + * fsync + * dmsetup message /dev/whatever mark mymark + * unmount /mnt/test + * + * Then replay the log up to mymark and check the contents of the replay to + * verify it matches what was written. + * + * We log writes only after they have been flushed, this makes the log describe + * close to the order in which the data hits the actual disk, not its cache. So + * for example the following sequence (W means write, C means complete) + * + * Wa,Wb,Wc,Cc,Ca,FLUSH,FUAd,Cb,CFLUSH,CFUAd + * + * Would result in the log looking like this: + * + * c,a,flush,fuad,b,<other writes>,<next flush> + * + * This is meant to help expose problems where file systems do not properly wait + * on data being written before invoking a FLUSH. FUA bypasses cache so once it + * completes it is added to the log as it should be on disk. + * + * We treat DISCARDs as if they don't bypass cache so that they are logged in + * order of completion along with the normal writes. If we didn't do it this + * way we would process all the discards first and then write all the data, when + * in fact we want to do the data and the discard in the order that they + * completed. + */ +#define LOG_FLUSH_FLAG (1 << 0) +#define LOG_FUA_FLAG (1 << 1) +#define LOG_DISCARD_FLAG (1 << 2) +#define LOG_MARK_FLAG (1 << 3) +#define LOG_METADATA_FLAG (1 << 4) + +#define WRITE_LOG_VERSION 1ULL +#define WRITE_LOG_MAGIC 0x6a736677736872ULL +#define WRITE_LOG_SUPER_SECTOR 0 + +/* + * The disk format for this is braindead simple. + * + * At byte 0 we have our super, followed by the following sequence for + * nr_entries: + * + * [ 1 sector ][ entry->nr_sectors ] + * [log_write_entry][ data written ] + * + * The log_write_entry takes up a full sector so we can have arbitrary length + * marks and it leaves us room for extra content in the future. + */ + +/* + * Basic info about the log for userspace. + */ +struct log_write_super { + __le64 magic; + __le64 version; + __le64 nr_entries; + __le32 sectorsize; +}; + +/* + * sector - the sector we wrote. + * nr_sectors - the number of sectors we wrote. + * flags - flags for this log entry. + * data_len - the size of the data in this log entry, this is for private log + * entry stuff, the MARK data provided by userspace for example. + */ +struct log_write_entry { + __le64 sector; + __le64 nr_sectors; + __le64 flags; + __le64 data_len; +}; + +struct log_writes_c { + struct dm_dev *dev; + struct dm_dev *logdev; + u64 logged_entries; + u32 sectorsize; + u32 sectorshift; + atomic_t io_blocks; + atomic_t pending_blocks; + sector_t next_sector; + sector_t end_sector; + bool logging_enabled; + bool device_supports_discard; + spinlock_t blocks_lock; + struct list_head unflushed_blocks; + struct list_head logging_blocks; + wait_queue_head_t wait; + struct task_struct *log_kthread; + struct completion super_done; +}; + +struct pending_block { + int vec_cnt; + u64 flags; + sector_t sector; + sector_t nr_sectors; + char *data; + u32 datalen; + struct list_head list; + struct bio_vec vecs[0]; +}; + +struct per_bio_data { + struct pending_block *block; +}; + +static inline sector_t bio_to_dev_sectors(struct log_writes_c *lc, + sector_t sectors) +{ + return sectors >> (lc->sectorshift - SECTOR_SHIFT); +} + +static inline sector_t dev_to_bio_sectors(struct log_writes_c *lc, + sector_t sectors) +{ + return sectors << (lc->sectorshift - SECTOR_SHIFT); +} + +static void put_pending_block(struct log_writes_c *lc) +{ + if (atomic_dec_and_test(&lc->pending_blocks)) { + smp_mb__after_atomic(); + if (waitqueue_active(&lc->wait)) + wake_up(&lc->wait); + } +} + +static void put_io_block(struct log_writes_c *lc) +{ + if (atomic_dec_and_test(&lc->io_blocks)) { + smp_mb__after_atomic(); + if (waitqueue_active(&lc->wait)) + wake_up(&lc->wait); + } +} + +static void log_end_io(struct bio *bio) +{ + struct log_writes_c *lc = bio->bi_private; + + if (bio->bi_status) { + unsigned long flags; + + DMERR("Error writing log block, error=%d", bio->bi_status); + spin_lock_irqsave(&lc->blocks_lock, flags); + lc->logging_enabled = false; + spin_unlock_irqrestore(&lc->blocks_lock, flags); + } + + bio_free_pages(bio); + put_io_block(lc); + bio_put(bio); +} + +static void log_end_super(struct bio *bio) +{ + struct log_writes_c *lc = bio->bi_private; + + complete(&lc->super_done); + log_end_io(bio); +} + +/* + * Meant to be called if there is an error, it will free all the pages + * associated with the block. + */ +static void free_pending_block(struct log_writes_c *lc, + struct pending_block *block) +{ + int i; + + for (i = 0; i < block->vec_cnt; i++) { + if (block->vecs[i].bv_page) + __free_page(block->vecs[i].bv_page); + } + kfree(block->data); + kfree(block); + put_pending_block(lc); +} + +static int write_metadata(struct log_writes_c *lc, void *entry, + size_t entrylen, void *data, size_t datalen, + sector_t sector) +{ + struct bio *bio; + struct page *page; + void *ptr; + size_t ret; + + bio = bio_alloc(GFP_KERNEL, 1); + if (!bio) { + DMERR("Couldn't alloc log bio"); + goto error; + } + bio->bi_iter.bi_size = 0; + bio->bi_iter.bi_sector = sector; + bio_set_dev(bio, lc->logdev->bdev); + bio->bi_end_io = (sector == WRITE_LOG_SUPER_SECTOR) ? + log_end_super : log_end_io; + bio->bi_private = lc; + bio_set_op_attrs(bio, REQ_OP_WRITE, 0); + + page = alloc_page(GFP_KERNEL); + if (!page) { + DMERR("Couldn't alloc log page"); + bio_put(bio); + goto error; + } + + ptr = kmap_atomic(page); + memcpy(ptr, entry, entrylen); + if (datalen) + memcpy(ptr + entrylen, data, datalen); + memset(ptr + entrylen + datalen, 0, + lc->sectorsize - entrylen - datalen); + kunmap_atomic(ptr); + + ret = bio_add_page(bio, page, lc->sectorsize, 0); + if (ret != lc->sectorsize) { + DMERR("Couldn't add page to the log block"); + goto error_bio; + } + submit_bio(bio); + return 0; +error_bio: + bio_put(bio); + __free_page(page); +error: + put_io_block(lc); + return -1; +} + +static int write_inline_data(struct log_writes_c *lc, void *entry, + size_t entrylen, void *data, size_t datalen, + sector_t sector) +{ + int num_pages, bio_pages, pg_datalen, pg_sectorlen, i; + struct page *page; + struct bio *bio; + size_t ret; + void *ptr; + + while (datalen) { + num_pages = ALIGN(datalen, PAGE_SIZE) >> PAGE_SHIFT; + bio_pages = min(num_pages, BIO_MAX_PAGES); + + atomic_inc(&lc->io_blocks); + + bio = bio_alloc(GFP_KERNEL, bio_pages); + if (!bio) { + DMERR("Couldn't alloc inline data bio"); + goto error; + } + + bio->bi_iter.bi_size = 0; + bio->bi_iter.bi_sector = sector; + bio_set_dev(bio, lc->logdev->bdev); + bio->bi_end_io = log_end_io; + bio->bi_private = lc; + bio_set_op_attrs(bio, REQ_OP_WRITE, 0); + + for (i = 0; i < bio_pages; i++) { + pg_datalen = min_t(int, datalen, PAGE_SIZE); + pg_sectorlen = ALIGN(pg_datalen, lc->sectorsize); + + page = alloc_page(GFP_KERNEL); + if (!page) { + DMERR("Couldn't alloc inline data page"); + goto error_bio; + } + + ptr = kmap_atomic(page); + memcpy(ptr, data, pg_datalen); + if (pg_sectorlen > pg_datalen) + memset(ptr + pg_datalen, 0, pg_sectorlen - pg_datalen); + kunmap_atomic(ptr); + + ret = bio_add_page(bio, page, pg_sectorlen, 0); + if (ret != pg_sectorlen) { + DMERR("Couldn't add page of inline data"); + __free_page(page); + goto error_bio; + } + + datalen -= pg_datalen; + data += pg_datalen; + } + submit_bio(bio); + + sector += bio_pages * PAGE_SECTORS; + } + return 0; +error_bio: + bio_free_pages(bio); + bio_put(bio); +error: + put_io_block(lc); + return -1; +} + +static int log_one_block(struct log_writes_c *lc, + struct pending_block *block, sector_t sector) +{ + struct bio *bio; + struct log_write_entry entry; + size_t metadatalen, ret; + int i; + + entry.sector = cpu_to_le64(block->sector); + entry.nr_sectors = cpu_to_le64(block->nr_sectors); + entry.flags = cpu_to_le64(block->flags); + entry.data_len = cpu_to_le64(block->datalen); + + metadatalen = (block->flags & LOG_MARK_FLAG) ? block->datalen : 0; + if (write_metadata(lc, &entry, sizeof(entry), block->data, + metadatalen, sector)) { + free_pending_block(lc, block); + return -1; + } + + sector += dev_to_bio_sectors(lc, 1); + + if (block->datalen && metadatalen == 0) { + if (write_inline_data(lc, &entry, sizeof(entry), block->data, + block->datalen, sector)) { + free_pending_block(lc, block); + return -1; + } + /* we don't support both inline data & bio data */ + goto out; + } + + if (!block->vec_cnt) + goto out; + + atomic_inc(&lc->io_blocks); + bio = bio_alloc(GFP_KERNEL, min(block->vec_cnt, BIO_MAX_PAGES)); + if (!bio) { + DMERR("Couldn't alloc log bio"); + goto error; + } + bio->bi_iter.bi_size = 0; + bio->bi_iter.bi_sector = sector; + bio_set_dev(bio, lc->logdev->bdev); + bio->bi_end_io = log_end_io; + bio->bi_private = lc; + bio_set_op_attrs(bio, REQ_OP_WRITE, 0); + + for (i = 0; i < block->vec_cnt; i++) { + /* + * The page offset is always 0 because we allocate a new page + * for every bvec in the original bio for simplicity sake. + */ + ret = bio_add_page(bio, block->vecs[i].bv_page, + block->vecs[i].bv_len, 0); + if (ret != block->vecs[i].bv_len) { + atomic_inc(&lc->io_blocks); + submit_bio(bio); + bio = bio_alloc(GFP_KERNEL, min(block->vec_cnt - i, BIO_MAX_PAGES)); + if (!bio) { + DMERR("Couldn't alloc log bio"); + goto error; + } + bio->bi_iter.bi_size = 0; + bio->bi_iter.bi_sector = sector; + bio_set_dev(bio, lc->logdev->bdev); + bio->bi_end_io = log_end_io; + bio->bi_private = lc; + bio_set_op_attrs(bio, REQ_OP_WRITE, 0); + + ret = bio_add_page(bio, block->vecs[i].bv_page, + block->vecs[i].bv_len, 0); + if (ret != block->vecs[i].bv_len) { + DMERR("Couldn't add page on new bio?"); + bio_put(bio); + goto error; + } + } + sector += block->vecs[i].bv_len >> SECTOR_SHIFT; + } + submit_bio(bio); +out: + kfree(block->data); + kfree(block); + put_pending_block(lc); + return 0; +error: + free_pending_block(lc, block); + put_io_block(lc); + return -1; +} + +static int log_super(struct log_writes_c *lc) +{ + struct log_write_super super; + + super.magic = cpu_to_le64(WRITE_LOG_MAGIC); + super.version = cpu_to_le64(WRITE_LOG_VERSION); + super.nr_entries = cpu_to_le64(lc->logged_entries); + super.sectorsize = cpu_to_le32(lc->sectorsize); + + if (write_metadata(lc, &super, sizeof(super), NULL, 0, + WRITE_LOG_SUPER_SECTOR)) { + DMERR("Couldn't write super"); + return -1; + } + + /* + * Super sector should be writen in-order, otherwise the + * nr_entries could be rewritten incorrectly by an old bio. + */ + wait_for_completion_io(&lc->super_done); + + return 0; +} + +static inline sector_t logdev_last_sector(struct log_writes_c *lc) +{ + return i_size_read(lc->logdev->bdev->bd_inode) >> SECTOR_SHIFT; +} + +static int log_writes_kthread(void *arg) +{ + struct log_writes_c *lc = (struct log_writes_c *)arg; + sector_t sector = 0; + + while (!kthread_should_stop()) { + bool super = false; + bool logging_enabled; + struct pending_block *block = NULL; + int ret; + + spin_lock_irq(&lc->blocks_lock); + if (!list_empty(&lc->logging_blocks)) { + block = list_first_entry(&lc->logging_blocks, + struct pending_block, list); + list_del_init(&block->list); + if (!lc->logging_enabled) + goto next; + + sector = lc->next_sector; + if (!(block->flags & LOG_DISCARD_FLAG)) + lc->next_sector += dev_to_bio_sectors(lc, block->nr_sectors); + lc->next_sector += dev_to_bio_sectors(lc, 1); + + /* + * Apparently the size of the device may not be known + * right away, so handle this properly. + */ + if (!lc->end_sector) + lc->end_sector = logdev_last_sector(lc); + if (lc->end_sector && + lc->next_sector >= lc->end_sector) { + DMERR("Ran out of space on the logdev"); + lc->logging_enabled = false; + goto next; + } + lc->logged_entries++; + atomic_inc(&lc->io_blocks); + + super = (block->flags & (LOG_FUA_FLAG | LOG_MARK_FLAG)); + if (super) + atomic_inc(&lc->io_blocks); + } +next: + logging_enabled = lc->logging_enabled; + spin_unlock_irq(&lc->blocks_lock); + if (block) { + if (logging_enabled) { + ret = log_one_block(lc, block, sector); + if (!ret && super) + ret = log_super(lc); + if (ret) { + spin_lock_irq(&lc->blocks_lock); + lc->logging_enabled = false; + spin_unlock_irq(&lc->blocks_lock); + } + } else + free_pending_block(lc, block); + continue; + } + + if (!try_to_freeze()) { + set_current_state(TASK_INTERRUPTIBLE); + if (!kthread_should_stop() && + list_empty(&lc->logging_blocks)) + schedule(); + __set_current_state(TASK_RUNNING); + } + } + return 0; +} + +/* + * Construct a log-writes mapping: + * log-writes <dev_path> <log_dev_path> + */ +static int log_writes_ctr(struct dm_target *ti, unsigned int argc, char **argv) +{ + struct log_writes_c *lc; + struct dm_arg_set as; + const char *devname, *logdevname; + int ret; + + as.argc = argc; + as.argv = argv; + + if (argc < 2) { + ti->error = "Invalid argument count"; + return -EINVAL; + } + + lc = kzalloc(sizeof(struct log_writes_c), GFP_KERNEL); + if (!lc) { + ti->error = "Cannot allocate context"; + return -ENOMEM; + } + spin_lock_init(&lc->blocks_lock); + INIT_LIST_HEAD(&lc->unflushed_blocks); + INIT_LIST_HEAD(&lc->logging_blocks); + init_waitqueue_head(&lc->wait); + init_completion(&lc->super_done); + atomic_set(&lc->io_blocks, 0); + atomic_set(&lc->pending_blocks, 0); + + devname = dm_shift_arg(&as); + ret = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &lc->dev); + if (ret) { + ti->error = "Device lookup failed"; + goto bad; + } + + logdevname = dm_shift_arg(&as); + ret = dm_get_device(ti, logdevname, dm_table_get_mode(ti->table), + &lc->logdev); + if (ret) { + ti->error = "Log device lookup failed"; + dm_put_device(ti, lc->dev); + goto bad; + } + + lc->sectorsize = bdev_logical_block_size(lc->dev->bdev); + lc->sectorshift = ilog2(lc->sectorsize); + lc->log_kthread = kthread_run(log_writes_kthread, lc, "log-write"); + if (IS_ERR(lc->log_kthread)) { + ret = PTR_ERR(lc->log_kthread); + ti->error = "Couldn't alloc kthread"; + dm_put_device(ti, lc->dev); + dm_put_device(ti, lc->logdev); + goto bad; + } + + /* + * next_sector is in 512b sectors to correspond to what bi_sector expects. + * The super starts at sector 0, and the next_sector is the next logical + * one based on the sectorsize of the device. + */ + lc->next_sector = lc->sectorsize >> SECTOR_SHIFT; + lc->logging_enabled = true; + lc->end_sector = logdev_last_sector(lc); + lc->device_supports_discard = true; + + ti->num_flush_bios = 1; + ti->flush_supported = true; + ti->num_discard_bios = 1; + ti->discards_supported = true; + ti->per_io_data_size = sizeof(struct per_bio_data); + ti->private = lc; + return 0; + +bad: + kfree(lc); + return ret; +} + +static int log_mark(struct log_writes_c *lc, char *data) +{ + struct pending_block *block; + size_t maxsize = lc->sectorsize - sizeof(struct log_write_entry); + + block = kzalloc(sizeof(struct pending_block), GFP_KERNEL); + if (!block) { + DMERR("Error allocating pending block"); + return -ENOMEM; + } + + block->data = kstrndup(data, maxsize - 1, GFP_KERNEL); + if (!block->data) { + DMERR("Error copying mark data"); + kfree(block); + return -ENOMEM; + } + atomic_inc(&lc->pending_blocks); + block->datalen = strlen(block->data); + block->flags |= LOG_MARK_FLAG; + spin_lock_irq(&lc->blocks_lock); + list_add_tail(&block->list, &lc->logging_blocks); + spin_unlock_irq(&lc->blocks_lock); + wake_up_process(lc->log_kthread); + return 0; +} + +static void log_writes_dtr(struct dm_target *ti) +{ + struct log_writes_c *lc = ti->private; + + spin_lock_irq(&lc->blocks_lock); + list_splice_init(&lc->unflushed_blocks, &lc->logging_blocks); + spin_unlock_irq(&lc->blocks_lock); + + /* + * This is just nice to have since it'll update the super to include the + * unflushed blocks, if it fails we don't really care. + */ + log_mark(lc, "dm-log-writes-end"); + wake_up_process(lc->log_kthread); + wait_event(lc->wait, !atomic_read(&lc->io_blocks) && + !atomic_read(&lc->pending_blocks)); + kthread_stop(lc->log_kthread); + + WARN_ON(!list_empty(&lc->logging_blocks)); + WARN_ON(!list_empty(&lc->unflushed_blocks)); + dm_put_device(ti, lc->dev); + dm_put_device(ti, lc->logdev); + kfree(lc); +} + +static void normal_map_bio(struct dm_target *ti, struct bio *bio) +{ + struct log_writes_c *lc = ti->private; + + bio_set_dev(bio, lc->dev->bdev); +} + +static int log_writes_map(struct dm_target *ti, struct bio *bio) +{ + struct log_writes_c *lc = ti->private; + struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); + struct pending_block *block; + struct bvec_iter iter; + struct bio_vec bv; + size_t alloc_size; + int i = 0; + bool flush_bio = (bio->bi_opf & REQ_PREFLUSH); + bool fua_bio = (bio->bi_opf & REQ_FUA); + bool discard_bio = (bio_op(bio) == REQ_OP_DISCARD); + bool meta_bio = (bio->bi_opf & REQ_META); + + pb->block = NULL; + + /* Don't bother doing anything if logging has been disabled */ + if (!lc->logging_enabled) + goto map_bio; + + /* + * Map reads as normal. + */ + if (bio_data_dir(bio) == READ) + goto map_bio; + + /* No sectors and not a flush? Don't care */ + if (!bio_sectors(bio) && !flush_bio) + goto map_bio; + + /* + * Discards will have bi_size set but there's no actual data, so just + * allocate the size of the pending block. + */ + if (discard_bio) + alloc_size = sizeof(struct pending_block); + else + alloc_size = sizeof(struct pending_block) + sizeof(struct bio_vec) * bio_segments(bio); + + block = kzalloc(alloc_size, GFP_NOIO); + if (!block) { + DMERR("Error allocating pending block"); + spin_lock_irq(&lc->blocks_lock); + lc->logging_enabled = false; + spin_unlock_irq(&lc->blocks_lock); + return DM_MAPIO_KILL; + } + INIT_LIST_HEAD(&block->list); + pb->block = block; + atomic_inc(&lc->pending_blocks); + + if (flush_bio) + block->flags |= LOG_FLUSH_FLAG; + if (fua_bio) + block->flags |= LOG_FUA_FLAG; + if (discard_bio) + block->flags |= LOG_DISCARD_FLAG; + if (meta_bio) + block->flags |= LOG_METADATA_FLAG; + + block->sector = bio_to_dev_sectors(lc, bio->bi_iter.bi_sector); + block->nr_sectors = bio_to_dev_sectors(lc, bio_sectors(bio)); + + /* We don't need the data, just submit */ + if (discard_bio) { + WARN_ON(flush_bio || fua_bio); + if (lc->device_supports_discard) + goto map_bio; + bio_endio(bio); + return DM_MAPIO_SUBMITTED; + } + + /* Flush bio, splice the unflushed blocks onto this list and submit */ + if (flush_bio && !bio_sectors(bio)) { + spin_lock_irq(&lc->blocks_lock); + list_splice_init(&lc->unflushed_blocks, &block->list); + spin_unlock_irq(&lc->blocks_lock); + goto map_bio; + } + + /* + * We will write this bio somewhere else way later so we need to copy + * the actual contents into new pages so we know the data will always be + * there. + * + * We do this because this could be a bio from O_DIRECT in which case we + * can't just hold onto the page until some later point, we have to + * manually copy the contents. + */ + bio_for_each_segment(bv, bio, iter) { + struct page *page; + void *src, *dst; + + page = alloc_page(GFP_NOIO); + if (!page) { + DMERR("Error allocing page"); + free_pending_block(lc, block); + spin_lock_irq(&lc->blocks_lock); + lc->logging_enabled = false; + spin_unlock_irq(&lc->blocks_lock); + return DM_MAPIO_KILL; + } + + src = kmap_atomic(bv.bv_page); + dst = kmap_atomic(page); + memcpy(dst, src + bv.bv_offset, bv.bv_len); + kunmap_atomic(dst); + kunmap_atomic(src); + block->vecs[i].bv_page = page; + block->vecs[i].bv_len = bv.bv_len; + block->vec_cnt++; + i++; + } + + /* Had a flush with data in it, weird */ + if (flush_bio) { + spin_lock_irq(&lc->blocks_lock); + list_splice_init(&lc->unflushed_blocks, &block->list); + spin_unlock_irq(&lc->blocks_lock); + } +map_bio: + normal_map_bio(ti, bio); + return DM_MAPIO_REMAPPED; +} + +static int normal_end_io(struct dm_target *ti, struct bio *bio, + blk_status_t *error) +{ + struct log_writes_c *lc = ti->private; + struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); + + if (bio_data_dir(bio) == WRITE && pb->block) { + struct pending_block *block = pb->block; + unsigned long flags; + + spin_lock_irqsave(&lc->blocks_lock, flags); + if (block->flags & LOG_FLUSH_FLAG) { + list_splice_tail_init(&block->list, &lc->logging_blocks); + list_add_tail(&block->list, &lc->logging_blocks); + wake_up_process(lc->log_kthread); + } else if (block->flags & LOG_FUA_FLAG) { + list_add_tail(&block->list, &lc->logging_blocks); + wake_up_process(lc->log_kthread); + } else + list_add_tail(&block->list, &lc->unflushed_blocks); + spin_unlock_irqrestore(&lc->blocks_lock, flags); + } + + return DM_ENDIO_DONE; +} + +/* + * INFO format: <logged entries> <highest allocated sector> + */ +static void log_writes_status(struct dm_target *ti, status_type_t type, + unsigned status_flags, char *result, + unsigned maxlen) +{ + unsigned sz = 0; + struct log_writes_c *lc = ti->private; + + switch (type) { + case STATUSTYPE_INFO: + DMEMIT("%llu %llu", lc->logged_entries, + (unsigned long long)lc->next_sector - 1); + if (!lc->logging_enabled) + DMEMIT(" logging_disabled"); + break; + + case STATUSTYPE_TABLE: + DMEMIT("%s %s", lc->dev->name, lc->logdev->name); + break; + } +} + +static int log_writes_prepare_ioctl(struct dm_target *ti, + struct block_device **bdev) +{ + struct log_writes_c *lc = ti->private; + struct dm_dev *dev = lc->dev; + + *bdev = dev->bdev; + /* + * Only pass ioctls through if the device sizes match exactly. + */ + if (ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT) + return 1; + return 0; +} + +static int log_writes_iterate_devices(struct dm_target *ti, + iterate_devices_callout_fn fn, + void *data) +{ + struct log_writes_c *lc = ti->private; + + return fn(ti, lc->dev, 0, ti->len, data); +} + +/* + * Messages supported: + * mark <mark data> - specify the marked data. + */ +static int log_writes_message(struct dm_target *ti, unsigned argc, char **argv, + char *result, unsigned maxlen) +{ + int r = -EINVAL; + struct log_writes_c *lc = ti->private; + + if (argc != 2) { + DMWARN("Invalid log-writes message arguments, expect 2 arguments, got %d", argc); + return r; + } + + if (!strcasecmp(argv[0], "mark")) + r = log_mark(lc, argv[1]); + else + DMWARN("Unrecognised log writes target message received: %s", argv[0]); + + return r; +} + +static void log_writes_io_hints(struct dm_target *ti, struct queue_limits *limits) +{ + struct log_writes_c *lc = ti->private; + struct request_queue *q = bdev_get_queue(lc->dev->bdev); + + if (!q || !blk_queue_discard(q)) { + lc->device_supports_discard = false; + limits->discard_granularity = lc->sectorsize; + limits->max_discard_sectors = (UINT_MAX >> SECTOR_SHIFT); + } + limits->logical_block_size = bdev_logical_block_size(lc->dev->bdev); + limits->physical_block_size = bdev_physical_block_size(lc->dev->bdev); + limits->io_min = limits->physical_block_size; +} + +#if IS_ENABLED(CONFIG_DAX_DRIVER) +static int log_dax(struct log_writes_c *lc, sector_t sector, size_t bytes, + struct iov_iter *i) +{ + struct pending_block *block; + + if (!bytes) + return 0; + + block = kzalloc(sizeof(struct pending_block), GFP_KERNEL); + if (!block) { + DMERR("Error allocating dax pending block"); + return -ENOMEM; + } + + block->data = kzalloc(bytes, GFP_KERNEL); + if (!block->data) { + DMERR("Error allocating dax data space"); + kfree(block); + return -ENOMEM; + } + + /* write data provided via the iterator */ + if (!copy_from_iter(block->data, bytes, i)) { + DMERR("Error copying dax data"); + kfree(block->data); + kfree(block); + return -EIO; + } + + /* rewind the iterator so that the block driver can use it */ + iov_iter_revert(i, bytes); + + block->datalen = bytes; + block->sector = bio_to_dev_sectors(lc, sector); + block->nr_sectors = ALIGN(bytes, lc->sectorsize) >> lc->sectorshift; + + atomic_inc(&lc->pending_blocks); + spin_lock_irq(&lc->blocks_lock); + list_add_tail(&block->list, &lc->unflushed_blocks); + spin_unlock_irq(&lc->blocks_lock); + wake_up_process(lc->log_kthread); + + return 0; +} + +static long log_writes_dax_direct_access(struct dm_target *ti, pgoff_t pgoff, + long nr_pages, void **kaddr, pfn_t *pfn) +{ + struct log_writes_c *lc = ti->private; + sector_t sector = pgoff * PAGE_SECTORS; + int ret; + + ret = bdev_dax_pgoff(lc->dev->bdev, sector, nr_pages * PAGE_SIZE, &pgoff); + if (ret) + return ret; + return dax_direct_access(lc->dev->dax_dev, pgoff, nr_pages, kaddr, pfn); +} + +static size_t log_writes_dax_copy_from_iter(struct dm_target *ti, + pgoff_t pgoff, void *addr, size_t bytes, + struct iov_iter *i) +{ + struct log_writes_c *lc = ti->private; + sector_t sector = pgoff * PAGE_SECTORS; + int err; + + if (bdev_dax_pgoff(lc->dev->bdev, sector, ALIGN(bytes, PAGE_SIZE), &pgoff)) + return 0; + + /* Don't bother doing anything if logging has been disabled */ + if (!lc->logging_enabled) + goto dax_copy; + + err = log_dax(lc, sector, bytes, i); + if (err) { + DMWARN("Error %d logging DAX write", err); + return 0; + } +dax_copy: + return dax_copy_from_iter(lc->dev->dax_dev, pgoff, addr, bytes, i); +} + +static size_t log_writes_dax_copy_to_iter(struct dm_target *ti, + pgoff_t pgoff, void *addr, size_t bytes, + struct iov_iter *i) +{ + struct log_writes_c *lc = ti->private; + sector_t sector = pgoff * PAGE_SECTORS; + + if (bdev_dax_pgoff(lc->dev->bdev, sector, ALIGN(bytes, PAGE_SIZE), &pgoff)) + return 0; + return dax_copy_to_iter(lc->dev->dax_dev, pgoff, addr, bytes, i); +} + +#else +#define log_writes_dax_direct_access NULL +#define log_writes_dax_copy_from_iter NULL +#define log_writes_dax_copy_to_iter NULL +#endif + +static struct target_type log_writes_target = { + .name = "log-writes", + .version = {1, 1, 0}, + .module = THIS_MODULE, + .ctr = log_writes_ctr, + .dtr = log_writes_dtr, + .map = log_writes_map, + .end_io = normal_end_io, + .status = log_writes_status, + .prepare_ioctl = log_writes_prepare_ioctl, + .message = log_writes_message, + .iterate_devices = log_writes_iterate_devices, + .io_hints = log_writes_io_hints, + .direct_access = log_writes_dax_direct_access, + .dax_copy_from_iter = log_writes_dax_copy_from_iter, + .dax_copy_to_iter = log_writes_dax_copy_to_iter, +}; + +static int __init dm_log_writes_init(void) +{ + int r = dm_register_target(&log_writes_target); + + if (r < 0) + DMERR("register failed %d", r); + + return r; +} + +static void __exit dm_log_writes_exit(void) +{ + dm_unregister_target(&log_writes_target); +} + +module_init(dm_log_writes_init); +module_exit(dm_log_writes_exit); + +MODULE_DESCRIPTION(DM_NAME " log writes target"); +MODULE_AUTHOR("Josef Bacik <jbacik@fb.com>"); +MODULE_LICENSE("GPL"); |