diff options
Diffstat (limited to '')
| -rw-r--r-- | fs/btrfs/raid56.c | 2737 |
1 files changed, 2737 insertions, 0 deletions
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c new file mode 100644 index 000000000..a91f74cf5 --- /dev/null +++ b/fs/btrfs/raid56.c @@ -0,0 +1,2737 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2012 Fusion-io All rights reserved. + * Copyright (C) 2012 Intel Corp. All rights reserved. + */ + +#include <linux/sched.h> +#include <linux/bio.h> +#include <linux/slab.h> +#include <linux/blkdev.h> +#include <linux/raid/pq.h> +#include <linux/hash.h> +#include <linux/list_sort.h> +#include <linux/raid/xor.h> +#include <linux/mm.h> +#include "ctree.h" +#include "disk-io.h" +#include "volumes.h" +#include "raid56.h" +#include "async-thread.h" + +/* set when additional merges to this rbio are not allowed */ +#define RBIO_RMW_LOCKED_BIT 1 + +/* + * set when this rbio is sitting in the hash, but it is just a cache + * of past RMW + */ +#define RBIO_CACHE_BIT 2 + +/* + * set when it is safe to trust the stripe_pages for caching + */ +#define RBIO_CACHE_READY_BIT 3 + +#define RBIO_CACHE_SIZE 1024 + +enum btrfs_rbio_ops { + BTRFS_RBIO_WRITE, + BTRFS_RBIO_READ_REBUILD, + BTRFS_RBIO_PARITY_SCRUB, + BTRFS_RBIO_REBUILD_MISSING, +}; + +struct btrfs_raid_bio { + struct btrfs_fs_info *fs_info; + struct btrfs_bio *bbio; + + /* while we're doing rmw on a stripe + * we put it into a hash table so we can + * lock the stripe and merge more rbios + * into it. + */ + struct list_head hash_list; + + /* + * LRU list for the stripe cache + */ + struct list_head stripe_cache; + + /* + * for scheduling work in the helper threads + */ + struct btrfs_work work; + + /* + * bio list and bio_list_lock are used + * to add more bios into the stripe + * in hopes of avoiding the full rmw + */ + struct bio_list bio_list; + spinlock_t bio_list_lock; + + /* also protected by the bio_list_lock, the + * plug list is used by the plugging code + * to collect partial bios while plugged. The + * stripe locking code also uses it to hand off + * the stripe lock to the next pending IO + */ + struct list_head plug_list; + + /* + * flags that tell us if it is safe to + * merge with this bio + */ + unsigned long flags; + + /* size of each individual stripe on disk */ + int stripe_len; + + /* number of data stripes (no p/q) */ + int nr_data; + + int real_stripes; + + int stripe_npages; + /* + * set if we're doing a parity rebuild + * for a read from higher up, which is handled + * differently from a parity rebuild as part of + * rmw + */ + enum btrfs_rbio_ops operation; + + /* first bad stripe */ + int faila; + + /* second bad stripe (for raid6 use) */ + int failb; + + int scrubp; + /* + * number of pages needed to represent the full + * stripe + */ + int nr_pages; + + /* + * size of all the bios in the bio_list. This + * helps us decide if the rbio maps to a full + * stripe or not + */ + int bio_list_bytes; + + int generic_bio_cnt; + + refcount_t refs; + + atomic_t stripes_pending; + + atomic_t error; + /* + * these are two arrays of pointers. We allocate the + * rbio big enough to hold them both and setup their + * locations when the rbio is allocated + */ + + /* pointers to pages that we allocated for + * reading/writing stripes directly from the disk (including P/Q) + */ + struct page **stripe_pages; + + /* + * pointers to the pages in the bio_list. Stored + * here for faster lookup + */ + struct page **bio_pages; + + /* + * bitmap to record which horizontal stripe has data + */ + unsigned long *dbitmap; + + /* allocated with real_stripes-many pointers for finish_*() calls */ + void **finish_pointers; + + /* allocated with stripe_npages-many bits for finish_*() calls */ + unsigned long *finish_pbitmap; +}; + +static int __raid56_parity_recover(struct btrfs_raid_bio *rbio); +static noinline void finish_rmw(struct btrfs_raid_bio *rbio); +static void rmw_work(struct btrfs_work *work); +static void read_rebuild_work(struct btrfs_work *work); +static int fail_bio_stripe(struct btrfs_raid_bio *rbio, struct bio *bio); +static int fail_rbio_index(struct btrfs_raid_bio *rbio, int failed); +static void __free_raid_bio(struct btrfs_raid_bio *rbio); +static void index_rbio_pages(struct btrfs_raid_bio *rbio); +static int alloc_rbio_pages(struct btrfs_raid_bio *rbio); + +static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio, + int need_check); +static void scrub_parity_work(struct btrfs_work *work); + +static void start_async_work(struct btrfs_raid_bio *rbio, btrfs_func_t work_func) +{ + btrfs_init_work(&rbio->work, btrfs_rmw_helper, work_func, NULL, NULL); + btrfs_queue_work(rbio->fs_info->rmw_workers, &rbio->work); +} + +/* + * the stripe hash table is used for locking, and to collect + * bios in hopes of making a full stripe + */ +int btrfs_alloc_stripe_hash_table(struct btrfs_fs_info *info) +{ + struct btrfs_stripe_hash_table *table; + struct btrfs_stripe_hash_table *x; + struct btrfs_stripe_hash *cur; + struct btrfs_stripe_hash *h; + int num_entries = 1 << BTRFS_STRIPE_HASH_TABLE_BITS; + int i; + int table_size; + + if (info->stripe_hash_table) + return 0; + + /* + * The table is large, starting with order 4 and can go as high as + * order 7 in case lock debugging is turned on. + * + * Try harder to allocate and fallback to vmalloc to lower the chance + * of a failing mount. + */ + table_size = sizeof(*table) + sizeof(*h) * num_entries; + table = kvzalloc(table_size, GFP_KERNEL); + if (!table) + return -ENOMEM; + + spin_lock_init(&table->cache_lock); + INIT_LIST_HEAD(&table->stripe_cache); + + h = table->table; + + for (i = 0; i < num_entries; i++) { + cur = h + i; + INIT_LIST_HEAD(&cur->hash_list); + spin_lock_init(&cur->lock); + } + + x = cmpxchg(&info->stripe_hash_table, NULL, table); + if (x) + kvfree(x); + return 0; +} + +/* + * caching an rbio means to copy anything from the + * bio_pages array into the stripe_pages array. We + * use the page uptodate bit in the stripe cache array + * to indicate if it has valid data + * + * once the caching is done, we set the cache ready + * bit. + */ +static void cache_rbio_pages(struct btrfs_raid_bio *rbio) +{ + int i; + char *s; + char *d; + int ret; + + ret = alloc_rbio_pages(rbio); + if (ret) + return; + + for (i = 0; i < rbio->nr_pages; i++) { + if (!rbio->bio_pages[i]) + continue; + + s = kmap(rbio->bio_pages[i]); + d = kmap(rbio->stripe_pages[i]); + + copy_page(d, s); + + kunmap(rbio->bio_pages[i]); + kunmap(rbio->stripe_pages[i]); + SetPageUptodate(rbio->stripe_pages[i]); + } + set_bit(RBIO_CACHE_READY_BIT, &rbio->flags); +} + +/* + * we hash on the first logical address of the stripe + */ +static int rbio_bucket(struct btrfs_raid_bio *rbio) +{ + u64 num = rbio->bbio->raid_map[0]; + + /* + * we shift down quite a bit. We're using byte + * addressing, and most of the lower bits are zeros. + * This tends to upset hash_64, and it consistently + * returns just one or two different values. + * + * shifting off the lower bits fixes things. + */ + return hash_64(num >> 16, BTRFS_STRIPE_HASH_TABLE_BITS); +} + +/* + * stealing an rbio means taking all the uptodate pages from the stripe + * array in the source rbio and putting them into the destination rbio + */ +static void steal_rbio(struct btrfs_raid_bio *src, struct btrfs_raid_bio *dest) +{ + int i; + struct page *s; + struct page *d; + + if (!test_bit(RBIO_CACHE_READY_BIT, &src->flags)) + return; + + for (i = 0; i < dest->nr_pages; i++) { + s = src->stripe_pages[i]; + if (!s || !PageUptodate(s)) { + continue; + } + + d = dest->stripe_pages[i]; + if (d) + __free_page(d); + + dest->stripe_pages[i] = s; + src->stripe_pages[i] = NULL; + } +} + +/* + * merging means we take the bio_list from the victim and + * splice it into the destination. The victim should + * be discarded afterwards. + * + * must be called with dest->rbio_list_lock held + */ +static void merge_rbio(struct btrfs_raid_bio *dest, + struct btrfs_raid_bio *victim) +{ + bio_list_merge(&dest->bio_list, &victim->bio_list); + dest->bio_list_bytes += victim->bio_list_bytes; + dest->generic_bio_cnt += victim->generic_bio_cnt; + bio_list_init(&victim->bio_list); +} + +/* + * used to prune items that are in the cache. The caller + * must hold the hash table lock. + */ +static void __remove_rbio_from_cache(struct btrfs_raid_bio *rbio) +{ + int bucket = rbio_bucket(rbio); + struct btrfs_stripe_hash_table *table; + struct btrfs_stripe_hash *h; + int freeit = 0; + + /* + * check the bit again under the hash table lock. + */ + if (!test_bit(RBIO_CACHE_BIT, &rbio->flags)) + return; + + table = rbio->fs_info->stripe_hash_table; + h = table->table + bucket; + + /* hold the lock for the bucket because we may be + * removing it from the hash table + */ + spin_lock(&h->lock); + + /* + * hold the lock for the bio list because we need + * to make sure the bio list is empty + */ + spin_lock(&rbio->bio_list_lock); + + if (test_and_clear_bit(RBIO_CACHE_BIT, &rbio->flags)) { + list_del_init(&rbio->stripe_cache); + table->cache_size -= 1; + freeit = 1; + + /* if the bio list isn't empty, this rbio is + * still involved in an IO. We take it out + * of the cache list, and drop the ref that + * was held for the list. + * + * If the bio_list was empty, we also remove + * the rbio from the hash_table, and drop + * the corresponding ref + */ + if (bio_list_empty(&rbio->bio_list)) { + if (!list_empty(&rbio->hash_list)) { + list_del_init(&rbio->hash_list); + refcount_dec(&rbio->refs); + BUG_ON(!list_empty(&rbio->plug_list)); + } + } + } + + spin_unlock(&rbio->bio_list_lock); + spin_unlock(&h->lock); + + if (freeit) + __free_raid_bio(rbio); +} + +/* + * prune a given rbio from the cache + */ +static void remove_rbio_from_cache(struct btrfs_raid_bio *rbio) +{ + struct btrfs_stripe_hash_table *table; + unsigned long flags; + + if (!test_bit(RBIO_CACHE_BIT, &rbio->flags)) + return; + + table = rbio->fs_info->stripe_hash_table; + + spin_lock_irqsave(&table->cache_lock, flags); + __remove_rbio_from_cache(rbio); + spin_unlock_irqrestore(&table->cache_lock, flags); +} + +/* + * remove everything in the cache + */ +static void btrfs_clear_rbio_cache(struct btrfs_fs_info *info) +{ + struct btrfs_stripe_hash_table *table; + unsigned long flags; + struct btrfs_raid_bio *rbio; + + table = info->stripe_hash_table; + + spin_lock_irqsave(&table->cache_lock, flags); + while (!list_empty(&table->stripe_cache)) { + rbio = list_entry(table->stripe_cache.next, + struct btrfs_raid_bio, + stripe_cache); + __remove_rbio_from_cache(rbio); + } + spin_unlock_irqrestore(&table->cache_lock, flags); +} + +/* + * remove all cached entries and free the hash table + * used by unmount + */ +void btrfs_free_stripe_hash_table(struct btrfs_fs_info *info) +{ + if (!info->stripe_hash_table) + return; + btrfs_clear_rbio_cache(info); + kvfree(info->stripe_hash_table); + info->stripe_hash_table = NULL; +} + +/* + * insert an rbio into the stripe cache. It + * must have already been prepared by calling + * cache_rbio_pages + * + * If this rbio was already cached, it gets + * moved to the front of the lru. + * + * If the size of the rbio cache is too big, we + * prune an item. + */ +static void cache_rbio(struct btrfs_raid_bio *rbio) +{ + struct btrfs_stripe_hash_table *table; + unsigned long flags; + + if (!test_bit(RBIO_CACHE_READY_BIT, &rbio->flags)) + return; + + table = rbio->fs_info->stripe_hash_table; + + spin_lock_irqsave(&table->cache_lock, flags); + spin_lock(&rbio->bio_list_lock); + + /* bump our ref if we were not in the list before */ + if (!test_and_set_bit(RBIO_CACHE_BIT, &rbio->flags)) + refcount_inc(&rbio->refs); + + if (!list_empty(&rbio->stripe_cache)){ + list_move(&rbio->stripe_cache, &table->stripe_cache); + } else { + list_add(&rbio->stripe_cache, &table->stripe_cache); + table->cache_size += 1; + } + + spin_unlock(&rbio->bio_list_lock); + + if (table->cache_size > RBIO_CACHE_SIZE) { + struct btrfs_raid_bio *found; + + found = list_entry(table->stripe_cache.prev, + struct btrfs_raid_bio, + stripe_cache); + + if (found != rbio) + __remove_rbio_from_cache(found); + } + + spin_unlock_irqrestore(&table->cache_lock, flags); +} + +/* + * helper function to run the xor_blocks api. It is only + * able to do MAX_XOR_BLOCKS at a time, so we need to + * loop through. + */ +static void run_xor(void **pages, int src_cnt, ssize_t len) +{ + int src_off = 0; + int xor_src_cnt = 0; + void *dest = pages[src_cnt]; + + while(src_cnt > 0) { + xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS); + xor_blocks(xor_src_cnt, len, dest, pages + src_off); + + src_cnt -= xor_src_cnt; + src_off += xor_src_cnt; + } +} + +/* + * Returns true if the bio list inside this rbio covers an entire stripe (no + * rmw required). + */ +static int rbio_is_full(struct btrfs_raid_bio *rbio) +{ + unsigned long flags; + unsigned long size = rbio->bio_list_bytes; + int ret = 1; + + spin_lock_irqsave(&rbio->bio_list_lock, flags); + if (size != rbio->nr_data * rbio->stripe_len) + ret = 0; + BUG_ON(size > rbio->nr_data * rbio->stripe_len); + spin_unlock_irqrestore(&rbio->bio_list_lock, flags); + + return ret; +} + +/* + * returns 1 if it is safe to merge two rbios together. + * The merging is safe if the two rbios correspond to + * the same stripe and if they are both going in the same + * direction (read vs write), and if neither one is + * locked for final IO + * + * The caller is responsible for locking such that + * rmw_locked is safe to test + */ +static int rbio_can_merge(struct btrfs_raid_bio *last, + struct btrfs_raid_bio *cur) +{ + if (test_bit(RBIO_RMW_LOCKED_BIT, &last->flags) || + test_bit(RBIO_RMW_LOCKED_BIT, &cur->flags)) + return 0; + + /* + * we can't merge with cached rbios, since the + * idea is that when we merge the destination + * rbio is going to run our IO for us. We can + * steal from cached rbios though, other functions + * handle that. + */ + if (test_bit(RBIO_CACHE_BIT, &last->flags) || + test_bit(RBIO_CACHE_BIT, &cur->flags)) + return 0; + + if (last->bbio->raid_map[0] != + cur->bbio->raid_map[0]) + return 0; + + /* we can't merge with different operations */ + if (last->operation != cur->operation) + return 0; + /* + * We've need read the full stripe from the drive. + * check and repair the parity and write the new results. + * + * We're not allowed to add any new bios to the + * bio list here, anyone else that wants to + * change this stripe needs to do their own rmw. + */ + if (last->operation == BTRFS_RBIO_PARITY_SCRUB) + return 0; + + if (last->operation == BTRFS_RBIO_REBUILD_MISSING) + return 0; + + if (last->operation == BTRFS_RBIO_READ_REBUILD) { + int fa = last->faila; + int fb = last->failb; + int cur_fa = cur->faila; + int cur_fb = cur->failb; + + if (last->faila >= last->failb) { + fa = last->failb; + fb = last->faila; + } + + if (cur->faila >= cur->failb) { + cur_fa = cur->failb; + cur_fb = cur->faila; + } + + if (fa != cur_fa || fb != cur_fb) + return 0; + } + return 1; +} + +static int rbio_stripe_page_index(struct btrfs_raid_bio *rbio, int stripe, + int index) +{ + return stripe * rbio->stripe_npages + index; +} + +/* + * these are just the pages from the rbio array, not from anything + * the FS sent down to us + */ +static struct page *rbio_stripe_page(struct btrfs_raid_bio *rbio, int stripe, + int index) +{ + return rbio->stripe_pages[rbio_stripe_page_index(rbio, stripe, index)]; +} + +/* + * helper to index into the pstripe + */ +static struct page *rbio_pstripe_page(struct btrfs_raid_bio *rbio, int index) +{ + return rbio_stripe_page(rbio, rbio->nr_data, index); +} + +/* + * helper to index into the qstripe, returns null + * if there is no qstripe + */ +static struct page *rbio_qstripe_page(struct btrfs_raid_bio *rbio, int index) +{ + if (rbio->nr_data + 1 == rbio->real_stripes) + return NULL; + return rbio_stripe_page(rbio, rbio->nr_data + 1, index); +} + +/* + * The first stripe in the table for a logical address + * has the lock. rbios are added in one of three ways: + * + * 1) Nobody has the stripe locked yet. The rbio is given + * the lock and 0 is returned. The caller must start the IO + * themselves. + * + * 2) Someone has the stripe locked, but we're able to merge + * with the lock owner. The rbio is freed and the IO will + * start automatically along with the existing rbio. 1 is returned. + * + * 3) Someone has the stripe locked, but we're not able to merge. + * The rbio is added to the lock owner's plug list, or merged into + * an rbio already on the plug list. When the lock owner unlocks, + * the next rbio on the list is run and the IO is started automatically. + * 1 is returned + * + * If we return 0, the caller still owns the rbio and must continue with + * IO submission. If we return 1, the caller must assume the rbio has + * already been freed. + */ +static noinline int lock_stripe_add(struct btrfs_raid_bio *rbio) +{ + int bucket = rbio_bucket(rbio); + struct btrfs_stripe_hash *h = rbio->fs_info->stripe_hash_table->table + bucket; + struct btrfs_raid_bio *cur; + struct btrfs_raid_bio *pending; + unsigned long flags; + struct btrfs_raid_bio *freeit = NULL; + struct btrfs_raid_bio *cache_drop = NULL; + int ret = 0; + + spin_lock_irqsave(&h->lock, flags); + list_for_each_entry(cur, &h->hash_list, hash_list) { + if (cur->bbio->raid_map[0] == rbio->bbio->raid_map[0]) { + spin_lock(&cur->bio_list_lock); + + /* can we steal this cached rbio's pages? */ + if (bio_list_empty(&cur->bio_list) && + list_empty(&cur->plug_list) && + test_bit(RBIO_CACHE_BIT, &cur->flags) && + !test_bit(RBIO_RMW_LOCKED_BIT, &cur->flags)) { + list_del_init(&cur->hash_list); + refcount_dec(&cur->refs); + + steal_rbio(cur, rbio); + cache_drop = cur; + spin_unlock(&cur->bio_list_lock); + + goto lockit; + } + + /* can we merge into the lock owner? */ + if (rbio_can_merge(cur, rbio)) { + merge_rbio(cur, rbio); + spin_unlock(&cur->bio_list_lock); + freeit = rbio; + ret = 1; + goto out; + } + + + /* + * we couldn't merge with the running + * rbio, see if we can merge with the + * pending ones. We don't have to + * check for rmw_locked because there + * is no way they are inside finish_rmw + * right now + */ + list_for_each_entry(pending, &cur->plug_list, + plug_list) { + if (rbio_can_merge(pending, rbio)) { + merge_rbio(pending, rbio); + spin_unlock(&cur->bio_list_lock); + freeit = rbio; + ret = 1; + goto out; + } + } + + /* no merging, put us on the tail of the plug list, + * our rbio will be started with the currently + * running rbio unlocks + */ + list_add_tail(&rbio->plug_list, &cur->plug_list); + spin_unlock(&cur->bio_list_lock); + ret = 1; + goto out; + } + } +lockit: + refcount_inc(&rbio->refs); + list_add(&rbio->hash_list, &h->hash_list); +out: + spin_unlock_irqrestore(&h->lock, flags); + if (cache_drop) + remove_rbio_from_cache(cache_drop); + if (freeit) + __free_raid_bio(freeit); + return ret; +} + +/* + * called as rmw or parity rebuild is completed. If the plug list has more + * rbios waiting for this stripe, the next one on the list will be started + */ +static noinline void unlock_stripe(struct btrfs_raid_bio *rbio) +{ + int bucket; + struct btrfs_stripe_hash *h; + unsigned long flags; + int keep_cache = 0; + + bucket = rbio_bucket(rbio); + h = rbio->fs_info->stripe_hash_table->table + bucket; + + if (list_empty(&rbio->plug_list)) + cache_rbio(rbio); + + spin_lock_irqsave(&h->lock, flags); + spin_lock(&rbio->bio_list_lock); + + if (!list_empty(&rbio->hash_list)) { + /* + * if we're still cached and there is no other IO + * to perform, just leave this rbio here for others + * to steal from later + */ + if (list_empty(&rbio->plug_list) && + test_bit(RBIO_CACHE_BIT, &rbio->flags)) { + keep_cache = 1; + clear_bit(RBIO_RMW_LOCKED_BIT, &rbio->flags); + BUG_ON(!bio_list_empty(&rbio->bio_list)); + goto done; + } + + list_del_init(&rbio->hash_list); + refcount_dec(&rbio->refs); + + /* + * we use the plug list to hold all the rbios + * waiting for the chance to lock this stripe. + * hand the lock over to one of them. + */ + if (!list_empty(&rbio->plug_list)) { + struct btrfs_raid_bio *next; + struct list_head *head = rbio->plug_list.next; + + next = list_entry(head, struct btrfs_raid_bio, + plug_list); + + list_del_init(&rbio->plug_list); + + list_add(&next->hash_list, &h->hash_list); + refcount_inc(&next->refs); + spin_unlock(&rbio->bio_list_lock); + spin_unlock_irqrestore(&h->lock, flags); + + if (next->operation == BTRFS_RBIO_READ_REBUILD) + start_async_work(next, read_rebuild_work); + else if (next->operation == BTRFS_RBIO_REBUILD_MISSING) { + steal_rbio(rbio, next); + start_async_work(next, read_rebuild_work); + } else if (next->operation == BTRFS_RBIO_WRITE) { + steal_rbio(rbio, next); + start_async_work(next, rmw_work); + } else if (next->operation == BTRFS_RBIO_PARITY_SCRUB) { + steal_rbio(rbio, next); + start_async_work(next, scrub_parity_work); + } + + goto done_nolock; + } + } +done: + spin_unlock(&rbio->bio_list_lock); + spin_unlock_irqrestore(&h->lock, flags); + +done_nolock: + if (!keep_cache) + remove_rbio_from_cache(rbio); +} + +static void __free_raid_bio(struct btrfs_raid_bio *rbio) +{ + int i; + + if (!refcount_dec_and_test(&rbio->refs)) + return; + + WARN_ON(!list_empty(&rbio->stripe_cache)); + WARN_ON(!list_empty(&rbio->hash_list)); + WARN_ON(!bio_list_empty(&rbio->bio_list)); + + for (i = 0; i < rbio->nr_pages; i++) { + if (rbio->stripe_pages[i]) { + __free_page(rbio->stripe_pages[i]); + rbio->stripe_pages[i] = NULL; + } + } + + btrfs_put_bbio(rbio->bbio); + kfree(rbio); +} + +static void rbio_endio_bio_list(struct bio *cur, blk_status_t err) +{ + struct bio *next; + + while (cur) { + next = cur->bi_next; + cur->bi_next = NULL; + cur->bi_status = err; + bio_endio(cur); + cur = next; + } +} + +/* + * this frees the rbio and runs through all the bios in the + * bio_list and calls end_io on them + */ +static void rbio_orig_end_io(struct btrfs_raid_bio *rbio, blk_status_t err) +{ + struct bio *cur = bio_list_get(&rbio->bio_list); + struct bio *extra; + + if (rbio->generic_bio_cnt) + btrfs_bio_counter_sub(rbio->fs_info, rbio->generic_bio_cnt); + + /* + * At this moment, rbio->bio_list is empty, however since rbio does not + * always have RBIO_RMW_LOCKED_BIT set and rbio is still linked on the + * hash list, rbio may be merged with others so that rbio->bio_list + * becomes non-empty. + * Once unlock_stripe() is done, rbio->bio_list will not be updated any + * more and we can call bio_endio() on all queued bios. + */ + unlock_stripe(rbio); + extra = bio_list_get(&rbio->bio_list); + __free_raid_bio(rbio); + + rbio_endio_bio_list(cur, err); + if (extra) + rbio_endio_bio_list(extra, err); +} + +/* + * end io function used by finish_rmw. When we finally + * get here, we've written a full stripe + */ +static void raid_write_end_io(struct bio *bio) +{ + struct btrfs_raid_bio *rbio = bio->bi_private; + blk_status_t err = bio->bi_status; + int max_errors; + + if (err) + fail_bio_stripe(rbio, bio); + + bio_put(bio); + + if (!atomic_dec_and_test(&rbio->stripes_pending)) + return; + + err = BLK_STS_OK; + + /* OK, we have read all the stripes we need to. */ + max_errors = (rbio->operation == BTRFS_RBIO_PARITY_SCRUB) ? + 0 : rbio->bbio->max_errors; + if (atomic_read(&rbio->error) > max_errors) + err = BLK_STS_IOERR; + + rbio_orig_end_io(rbio, err); +} + +/* + * the read/modify/write code wants to use the original bio for + * any pages it included, and then use the rbio for everything + * else. This function decides if a given index (stripe number) + * and page number in that stripe fall inside the original bio + * or the rbio. + * + * if you set bio_list_only, you'll get a NULL back for any ranges + * that are outside the bio_list + * + * This doesn't take any refs on anything, you get a bare page pointer + * and the caller must bump refs as required. + * + * You must call index_rbio_pages once before you can trust + * the answers from this function. + */ +static struct page *page_in_rbio(struct btrfs_raid_bio *rbio, + int index, int pagenr, int bio_list_only) +{ + int chunk_page; + struct page *p = NULL; + + chunk_page = index * (rbio->stripe_len >> PAGE_SHIFT) + pagenr; + + spin_lock_irq(&rbio->bio_list_lock); + p = rbio->bio_pages[chunk_page]; + spin_unlock_irq(&rbio->bio_list_lock); + + if (p || bio_list_only) + return p; + + return rbio->stripe_pages[chunk_page]; +} + +/* + * number of pages we need for the entire stripe across all the + * drives + */ +static unsigned long rbio_nr_pages(unsigned long stripe_len, int nr_stripes) +{ + return DIV_ROUND_UP(stripe_len, PAGE_SIZE) * nr_stripes; +} + +/* + * allocation and initial setup for the btrfs_raid_bio. Not + * this does not allocate any pages for rbio->pages. + */ +static struct btrfs_raid_bio *alloc_rbio(struct btrfs_fs_info *fs_info, + struct btrfs_bio *bbio, + u64 stripe_len) +{ + struct btrfs_raid_bio *rbio; + int nr_data = 0; + int real_stripes = bbio->num_stripes - bbio->num_tgtdevs; + int num_pages = rbio_nr_pages(stripe_len, real_stripes); + int stripe_npages = DIV_ROUND_UP(stripe_len, PAGE_SIZE); + void *p; + + rbio = kzalloc(sizeof(*rbio) + + sizeof(*rbio->stripe_pages) * num_pages + + sizeof(*rbio->bio_pages) * num_pages + + sizeof(*rbio->finish_pointers) * real_stripes + + sizeof(*rbio->dbitmap) * BITS_TO_LONGS(stripe_npages) + + sizeof(*rbio->finish_pbitmap) * + BITS_TO_LONGS(stripe_npages), + GFP_NOFS); + if (!rbio) + return ERR_PTR(-ENOMEM); + + bio_list_init(&rbio->bio_list); + INIT_LIST_HEAD(&rbio->plug_list); + spin_lock_init(&rbio->bio_list_lock); + INIT_LIST_HEAD(&rbio->stripe_cache); + INIT_LIST_HEAD(&rbio->hash_list); + rbio->bbio = bbio; + rbio->fs_info = fs_info; + rbio->stripe_len = stripe_len; + rbio->nr_pages = num_pages; + rbio->real_stripes = real_stripes; + rbio->stripe_npages = stripe_npages; + rbio->faila = -1; + rbio->failb = -1; + refcount_set(&rbio->refs, 1); + atomic_set(&rbio->error, 0); + atomic_set(&rbio->stripes_pending, 0); + + /* + * the stripe_pages, bio_pages, etc arrays point to the extra + * memory we allocated past the end of the rbio + */ + p = rbio + 1; +#define CONSUME_ALLOC(ptr, count) do { \ + ptr = p; \ + p = (unsigned char *)p + sizeof(*(ptr)) * (count); \ + } while (0) + CONSUME_ALLOC(rbio->stripe_pages, num_pages); + CONSUME_ALLOC(rbio->bio_pages, num_pages); + CONSUME_ALLOC(rbio->finish_pointers, real_stripes); + CONSUME_ALLOC(rbio->dbitmap, BITS_TO_LONGS(stripe_npages)); + CONSUME_ALLOC(rbio->finish_pbitmap, BITS_TO_LONGS(stripe_npages)); +#undef CONSUME_ALLOC + + if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID5) + nr_data = real_stripes - 1; + else if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID6) + nr_data = real_stripes - 2; + else + BUG(); + + rbio->nr_data = nr_data; + return rbio; +} + +/* allocate pages for all the stripes in the bio, including parity */ +static int alloc_rbio_pages(struct btrfs_raid_bio *rbio) +{ + int i; + struct page *page; + + for (i = 0; i < rbio->nr_pages; i++) { + if (rbio->stripe_pages[i]) + continue; + page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); + if (!page) + return -ENOMEM; + rbio->stripe_pages[i] = page; + } + return 0; +} + +/* only allocate pages for p/q stripes */ +static int alloc_rbio_parity_pages(struct btrfs_raid_bio *rbio) +{ + int i; + struct page *page; + + i = rbio_stripe_page_index(rbio, rbio->nr_data, 0); + + for (; i < rbio->nr_pages; i++) { + if (rbio->stripe_pages[i]) + continue; + page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); + if (!page) + return -ENOMEM; + rbio->stripe_pages[i] = page; + } + return 0; +} + +/* + * add a single page from a specific stripe into our list of bios for IO + * this will try to merge into existing bios if possible, and returns + * zero if all went well. + */ +static int rbio_add_io_page(struct btrfs_raid_bio *rbio, + struct bio_list *bio_list, + struct page *page, + int stripe_nr, + unsigned long page_index, + unsigned long bio_max_len) +{ + struct bio *last = bio_list->tail; + u64 last_end = 0; + int ret; + struct bio *bio; + struct btrfs_bio_stripe *stripe; + u64 disk_start; + + stripe = &rbio->bbio->stripes[stripe_nr]; + disk_start = stripe->physical + (page_index << PAGE_SHIFT); + + /* if the device is missing, just fail this stripe */ + if (!stripe->dev->bdev) + return fail_rbio_index(rbio, stripe_nr); + + /* see if we can add this page onto our existing bio */ + if (last) { + last_end = (u64)last->bi_iter.bi_sector << 9; + last_end += last->bi_iter.bi_size; + + /* + * we can't merge these if they are from different + * devices or if they are not contiguous + */ + if (last_end == disk_start && stripe->dev->bdev && + !last->bi_status && + last->bi_disk == stripe->dev->bdev->bd_disk && + last->bi_partno == stripe->dev->bdev->bd_partno) { + ret = bio_add_page(last, page, PAGE_SIZE, 0); + if (ret == PAGE_SIZE) + return 0; + } + } + + /* put a new bio on the list */ + bio = btrfs_io_bio_alloc(bio_max_len >> PAGE_SHIFT ?: 1); + bio->bi_iter.bi_size = 0; + bio_set_dev(bio, stripe->dev->bdev); + bio->bi_iter.bi_sector = disk_start >> 9; + + bio_add_page(bio, page, PAGE_SIZE, 0); + bio_list_add(bio_list, bio); + return 0; +} + +/* + * while we're doing the read/modify/write cycle, we could + * have errors in reading pages off the disk. This checks + * for errors and if we're not able to read the page it'll + * trigger parity reconstruction. The rmw will be finished + * after we've reconstructed the failed stripes + */ +static void validate_rbio_for_rmw(struct btrfs_raid_bio *rbio) +{ + if (rbio->faila >= 0 || rbio->failb >= 0) { + BUG_ON(rbio->faila == rbio->real_stripes - 1); + __raid56_parity_recover(rbio); + } else { + finish_rmw(rbio); + } +} + +/* + * helper function to walk our bio list and populate the bio_pages array with + * the result. This seems expensive, but it is faster than constantly + * searching through the bio list as we setup the IO in finish_rmw or stripe + * reconstruction. + * + * This must be called before you trust the answers from page_in_rbio + */ +static void index_rbio_pages(struct btrfs_raid_bio *rbio) +{ + struct bio *bio; + u64 start; + unsigned long stripe_offset; + unsigned long page_index; + + spin_lock_irq(&rbio->bio_list_lock); + bio_list_for_each(bio, &rbio->bio_list) { + struct bio_vec bvec; + struct bvec_iter iter; + int i = 0; + + start = (u64)bio->bi_iter.bi_sector << 9; + stripe_offset = start - rbio->bbio->raid_map[0]; + page_index = stripe_offset >> PAGE_SHIFT; + + if (bio_flagged(bio, BIO_CLONED)) + bio->bi_iter = btrfs_io_bio(bio)->iter; + + bio_for_each_segment(bvec, bio, iter) { + rbio->bio_pages[page_index + i] = bvec.bv_page; + i++; + } + } + spin_unlock_irq(&rbio->bio_list_lock); +} + +/* + * this is called from one of two situations. We either + * have a full stripe from the higher layers, or we've read all + * the missing bits off disk. + * + * This will calculate the parity and then send down any + * changed blocks. + */ +static noinline void finish_rmw(struct btrfs_raid_bio *rbio) +{ + struct btrfs_bio *bbio = rbio->bbio; + void **pointers = rbio->finish_pointers; + int nr_data = rbio->nr_data; + int stripe; + int pagenr; + bool has_qstripe; + struct bio_list bio_list; + struct bio *bio; + int ret; + + bio_list_init(&bio_list); + + if (rbio->real_stripes - rbio->nr_data == 1) + has_qstripe = false; + else if (rbio->real_stripes - rbio->nr_data == 2) + has_qstripe = true; + else + BUG(); + + /* at this point we either have a full stripe, + * or we've read the full stripe from the drive. + * recalculate the parity and write the new results. + * + * We're not allowed to add any new bios to the + * bio list here, anyone else that wants to + * change this stripe needs to do their own rmw. + */ + spin_lock_irq(&rbio->bio_list_lock); + set_bit(RBIO_RMW_LOCKED_BIT, &rbio->flags); + spin_unlock_irq(&rbio->bio_list_lock); + + atomic_set(&rbio->error, 0); + + /* + * now that we've set rmw_locked, run through the + * bio list one last time and map the page pointers + * + * We don't cache full rbios because we're assuming + * the higher layers are unlikely to use this area of + * the disk again soon. If they do use it again, + * hopefully they will send another full bio. + */ + index_rbio_pages(rbio); + if (!rbio_is_full(rbio)) + cache_rbio_pages(rbio); + else + clear_bit(RBIO_CACHE_READY_BIT, &rbio->flags); + + for (pagenr = 0; pagenr < rbio->stripe_npages; pagenr++) { + struct page *p; + /* first collect one page from each data stripe */ + for (stripe = 0; stripe < nr_data; stripe++) { + p = page_in_rbio(rbio, stripe, pagenr, 0); + pointers[stripe] = kmap(p); + } + + /* then add the parity stripe */ + p = rbio_pstripe_page(rbio, pagenr); + SetPageUptodate(p); + pointers[stripe++] = kmap(p); + + if (has_qstripe) { + + /* + * raid6, add the qstripe and call the + * library function to fill in our p/q + */ + p = rbio_qstripe_page(rbio, pagenr); + SetPageUptodate(p); + pointers[stripe++] = kmap(p); + + raid6_call.gen_syndrome(rbio->real_stripes, PAGE_SIZE, + pointers); + } else { + /* raid5 */ + copy_page(pointers[nr_data], pointers[0]); + run_xor(pointers + 1, nr_data - 1, PAGE_SIZE); + } + + + for (stripe = 0; stripe < rbio->real_stripes; stripe++) + kunmap(page_in_rbio(rbio, stripe, pagenr, 0)); + } + + /* + * time to start writing. Make bios for everything from the + * higher layers (the bio_list in our rbio) and our p/q. Ignore + * everything else. + */ + for (stripe = 0; stripe < rbio->real_stripes; stripe++) { + for (pagenr = 0; pagenr < rbio->stripe_npages; pagenr++) { + struct page *page; + if (stripe < rbio->nr_data) { + page = page_in_rbio(rbio, stripe, pagenr, 1); + if (!page) + continue; + } else { + page = rbio_stripe_page(rbio, stripe, pagenr); + } + + ret = rbio_add_io_page(rbio, &bio_list, + page, stripe, pagenr, rbio->stripe_len); + if (ret) + goto cleanup; + } + } + + if (likely(!bbio->num_tgtdevs)) + goto write_data; + + for (stripe = 0; stripe < rbio->real_stripes; stripe++) { + if (!bbio->tgtdev_map[stripe]) + continue; + + for (pagenr = 0; pagenr < rbio->stripe_npages; pagenr++) { + struct page *page; + if (stripe < rbio->nr_data) { + page = page_in_rbio(rbio, stripe, pagenr, 1); + if (!page) + continue; + } else { + page = rbio_stripe_page(rbio, stripe, pagenr); + } + + ret = rbio_add_io_page(rbio, &bio_list, page, + rbio->bbio->tgtdev_map[stripe], + pagenr, rbio->stripe_len); + if (ret) + goto cleanup; + } + } + +write_data: + atomic_set(&rbio->stripes_pending, bio_list_size(&bio_list)); + BUG_ON(atomic_read(&rbio->stripes_pending) == 0); + + while (1) { + bio = bio_list_pop(&bio_list); + if (!bio) + break; + + bio->bi_private = rbio; + bio->bi_end_io = raid_write_end_io; + bio->bi_opf = REQ_OP_WRITE; + + submit_bio(bio); + } + return; + +cleanup: + rbio_orig_end_io(rbio, BLK_STS_IOERR); + + while ((bio = bio_list_pop(&bio_list))) + bio_put(bio); +} + +/* + * helper to find the stripe number for a given bio. Used to figure out which + * stripe has failed. This expects the bio to correspond to a physical disk, + * so it looks up based on physical sector numbers. + */ +static int find_bio_stripe(struct btrfs_raid_bio *rbio, + struct bio *bio) +{ + u64 physical = bio->bi_iter.bi_sector; + u64 stripe_start; + int i; + struct btrfs_bio_stripe *stripe; + + physical <<= 9; + + for (i = 0; i < rbio->bbio->num_stripes; i++) { + stripe = &rbio->bbio->stripes[i]; + stripe_start = stripe->physical; + if (physical >= stripe_start && + physical < stripe_start + rbio->stripe_len && + stripe->dev->bdev && + bio->bi_disk == stripe->dev->bdev->bd_disk && + bio->bi_partno == stripe->dev->bdev->bd_partno) { + return i; + } + } + return -1; +} + +/* + * helper to find the stripe number for a given + * bio (before mapping). Used to figure out which stripe has + * failed. This looks up based on logical block numbers. + */ +static int find_logical_bio_stripe(struct btrfs_raid_bio *rbio, + struct bio *bio) +{ + u64 logical = bio->bi_iter.bi_sector; + u64 stripe_start; + int i; + + logical <<= 9; + + for (i = 0; i < rbio->nr_data; i++) { + stripe_start = rbio->bbio->raid_map[i]; + if (logical >= stripe_start && + logical < stripe_start + rbio->stripe_len) { + return i; + } + } + return -1; +} + +/* + * returns -EIO if we had too many failures + */ +static int fail_rbio_index(struct btrfs_raid_bio *rbio, int failed) +{ + unsigned long flags; + int ret = 0; + + spin_lock_irqsave(&rbio->bio_list_lock, flags); + + /* we already know this stripe is bad, move on */ + if (rbio->faila == failed || rbio->failb == failed) + goto out; + + if (rbio->faila == -1) { + /* first failure on this rbio */ + rbio->faila = failed; + atomic_inc(&rbio->error); + } else if (rbio->failb == -1) { + /* second failure on this rbio */ + rbio->failb = failed; + atomic_inc(&rbio->error); + } else { + ret = -EIO; + } +out: + spin_unlock_irqrestore(&rbio->bio_list_lock, flags); + + return ret; +} + +/* + * helper to fail a stripe based on a physical disk + * bio. + */ +static int fail_bio_stripe(struct btrfs_raid_bio *rbio, + struct bio *bio) +{ + int failed = find_bio_stripe(rbio, bio); + + if (failed < 0) + return -EIO; + + return fail_rbio_index(rbio, failed); +} + +/* + * this sets each page in the bio uptodate. It should only be used on private + * rbio pages, nothing that comes in from the higher layers + */ +static void set_bio_pages_uptodate(struct bio *bio) +{ + struct bio_vec *bvec; + int i; + + ASSERT(!bio_flagged(bio, BIO_CLONED)); + + bio_for_each_segment_all(bvec, bio, i) + SetPageUptodate(bvec->bv_page); +} + +/* + * end io for the read phase of the rmw cycle. All the bios here are physical + * stripe bios we've read from the disk so we can recalculate the parity of the + * stripe. + * + * This will usually kick off finish_rmw once all the bios are read in, but it + * may trigger parity reconstruction if we had any errors along the way + */ +static void raid_rmw_end_io(struct bio *bio) +{ + struct btrfs_raid_bio *rbio = bio->bi_private; + + if (bio->bi_status) + fail_bio_stripe(rbio, bio); + else + set_bio_pages_uptodate(bio); + + bio_put(bio); + + if (!atomic_dec_and_test(&rbio->stripes_pending)) + return; + + if (atomic_read(&rbio->error) > rbio->bbio->max_errors) + goto cleanup; + + /* + * this will normally call finish_rmw to start our write + * but if there are any failed stripes we'll reconstruct + * from parity first + */ + validate_rbio_for_rmw(rbio); + return; + +cleanup: + + rbio_orig_end_io(rbio, BLK_STS_IOERR); +} + +/* + * the stripe must be locked by the caller. It will + * unlock after all the writes are done + */ +static int raid56_rmw_stripe(struct btrfs_raid_bio *rbio) +{ + int bios_to_read = 0; + struct bio_list bio_list; + int ret; + int pagenr; + int stripe; + struct bio *bio; + + bio_list_init(&bio_list); + + ret = alloc_rbio_pages(rbio); + if (ret) + goto cleanup; + + index_rbio_pages(rbio); + + atomic_set(&rbio->error, 0); + /* + * build a list of bios to read all the missing parts of this + * stripe + */ + for (stripe = 0; stripe < rbio->nr_data; stripe++) { + for (pagenr = 0; pagenr < rbio->stripe_npages; pagenr++) { + struct page *page; + /* + * we want to find all the pages missing from + * the rbio and read them from the disk. If + * page_in_rbio finds a page in the bio list + * we don't need to read it off the stripe. + */ + page = page_in_rbio(rbio, stripe, pagenr, 1); + if (page) + continue; + + page = rbio_stripe_page(rbio, stripe, pagenr); + /* + * the bio cache may have handed us an uptodate + * page. If so, be happy and use it + */ + if (PageUptodate(page)) + continue; + + ret = rbio_add_io_page(rbio, &bio_list, page, + stripe, pagenr, rbio->stripe_len); + if (ret) + goto cleanup; + } + } + + bios_to_read = bio_list_size(&bio_list); + if (!bios_to_read) { + /* + * this can happen if others have merged with + * us, it means there is nothing left to read. + * But if there are missing devices it may not be + * safe to do the full stripe write yet. + */ + goto finish; + } + + /* + * the bbio may be freed once we submit the last bio. Make sure + * not to touch it after that + */ + atomic_set(&rbio->stripes_pending, bios_to_read); + while (1) { + bio = bio_list_pop(&bio_list); + if (!bio) + break; + + bio->bi_private = rbio; + bio->bi_end_io = raid_rmw_end_io; + bio->bi_opf = REQ_OP_READ; + + btrfs_bio_wq_end_io(rbio->fs_info, bio, BTRFS_WQ_ENDIO_RAID56); + + submit_bio(bio); + } + /* the actual write will happen once the reads are done */ + return 0; + +cleanup: + rbio_orig_end_io(rbio, BLK_STS_IOERR); + + while ((bio = bio_list_pop(&bio_list))) + bio_put(bio); + + return -EIO; + +finish: + validate_rbio_for_rmw(rbio); + return 0; +} + +/* + * if the upper layers pass in a full stripe, we thank them by only allocating + * enough pages to hold the parity, and sending it all down quickly. + */ +static int full_stripe_write(struct btrfs_raid_bio *rbio) +{ + int ret; + + ret = alloc_rbio_parity_pages(rbio); + if (ret) { + __free_raid_bio(rbio); + return ret; + } + + ret = lock_stripe_add(rbio); + if (ret == 0) + finish_rmw(rbio); + return 0; +} + +/* + * partial stripe writes get handed over to async helpers. + * We're really hoping to merge a few more writes into this + * rbio before calculating new parity + */ +static int partial_stripe_write(struct btrfs_raid_bio *rbio) +{ + int ret; + + ret = lock_stripe_add(rbio); + if (ret == 0) + start_async_work(rbio, rmw_work); + return 0; +} + +/* + * sometimes while we were reading from the drive to + * recalculate parity, enough new bios come into create + * a full stripe. So we do a check here to see if we can + * go directly to finish_rmw + */ +static int __raid56_parity_write(struct btrfs_raid_bio *rbio) +{ + /* head off into rmw land if we don't have a full stripe */ + if (!rbio_is_full(rbio)) + return partial_stripe_write(rbio); + return full_stripe_write(rbio); +} + +/* + * We use plugging call backs to collect full stripes. + * Any time we get a partial stripe write while plugged + * we collect it into a list. When the unplug comes down, + * we sort the list by logical block number and merge + * everything we can into the same rbios + */ +struct btrfs_plug_cb { + struct blk_plug_cb cb; + struct btrfs_fs_info *info; + struct list_head rbio_list; + struct btrfs_work work; +}; + +/* + * rbios on the plug list are sorted for easier merging. + */ +static int plug_cmp(void *priv, struct list_head *a, struct list_head *b) +{ + struct btrfs_raid_bio *ra = container_of(a, struct btrfs_raid_bio, + plug_list); + struct btrfs_raid_bio *rb = container_of(b, struct btrfs_raid_bio, + plug_list); + u64 a_sector = ra->bio_list.head->bi_iter.bi_sector; + u64 b_sector = rb->bio_list.head->bi_iter.bi_sector; + + if (a_sector < b_sector) + return -1; + if (a_sector > b_sector) + return 1; + return 0; +} + +static void run_plug(struct btrfs_plug_cb *plug) +{ + struct btrfs_raid_bio *cur; + struct btrfs_raid_bio *last = NULL; + + /* + * sort our plug list then try to merge + * everything we can in hopes of creating full + * stripes. + */ + list_sort(NULL, &plug->rbio_list, plug_cmp); + while (!list_empty(&plug->rbio_list)) { + cur = list_entry(plug->rbio_list.next, + struct btrfs_raid_bio, plug_list); + list_del_init(&cur->plug_list); + + if (rbio_is_full(cur)) { + int ret; + + /* we have a full stripe, send it down */ + ret = full_stripe_write(cur); + BUG_ON(ret); + continue; + } + if (last) { + if (rbio_can_merge(last, cur)) { + merge_rbio(last, cur); + __free_raid_bio(cur); + continue; + + } + __raid56_parity_write(last); + } + last = cur; + } + if (last) { + __raid56_parity_write(last); + } + kfree(plug); +} + +/* + * if the unplug comes from schedule, we have to push the + * work off to a helper thread + */ +static void unplug_work(struct btrfs_work *work) +{ + struct btrfs_plug_cb *plug; + plug = container_of(work, struct btrfs_plug_cb, work); + run_plug(plug); +} + +static void btrfs_raid_unplug(struct blk_plug_cb *cb, bool from_schedule) +{ + struct btrfs_plug_cb *plug; + plug = container_of(cb, struct btrfs_plug_cb, cb); + + if (from_schedule) { + btrfs_init_work(&plug->work, btrfs_rmw_helper, + unplug_work, NULL, NULL); + btrfs_queue_work(plug->info->rmw_workers, + &plug->work); + return; + } + run_plug(plug); +} + +/* + * our main entry point for writes from the rest of the FS. + */ +int raid56_parity_write(struct btrfs_fs_info *fs_info, struct bio *bio, + struct btrfs_bio *bbio, u64 stripe_len) +{ + struct btrfs_raid_bio *rbio; + struct btrfs_plug_cb *plug = NULL; + struct blk_plug_cb *cb; + int ret; + + rbio = alloc_rbio(fs_info, bbio, stripe_len); + if (IS_ERR(rbio)) { + btrfs_put_bbio(bbio); + return PTR_ERR(rbio); + } + bio_list_add(&rbio->bio_list, bio); + rbio->bio_list_bytes = bio->bi_iter.bi_size; + rbio->operation = BTRFS_RBIO_WRITE; + + btrfs_bio_counter_inc_noblocked(fs_info); + rbio->generic_bio_cnt = 1; + + /* + * don't plug on full rbios, just get them out the door + * as quickly as we can + */ + if (rbio_is_full(rbio)) { + ret = full_stripe_write(rbio); + if (ret) + btrfs_bio_counter_dec(fs_info); + return ret; + } + + cb = blk_check_plugged(btrfs_raid_unplug, fs_info, sizeof(*plug)); + if (cb) { + plug = container_of(cb, struct btrfs_plug_cb, cb); + if (!plug->info) { + plug->info = fs_info; + INIT_LIST_HEAD(&plug->rbio_list); + } + list_add_tail(&rbio->plug_list, &plug->rbio_list); + ret = 0; + } else { + ret = __raid56_parity_write(rbio); + if (ret) + btrfs_bio_counter_dec(fs_info); + } + return ret; +} + +/* + * all parity reconstruction happens here. We've read in everything + * we can find from the drives and this does the heavy lifting of + * sorting the good from the bad. + */ +static void __raid_recover_end_io(struct btrfs_raid_bio *rbio) +{ + int pagenr, stripe; + void **pointers; + int faila = -1, failb = -1; + struct page *page; + blk_status_t err; + int i; + + pointers = kcalloc(rbio->real_stripes, sizeof(void *), GFP_NOFS); + if (!pointers) { + err = BLK_STS_RESOURCE; + goto cleanup_io; + } + + faila = rbio->faila; + failb = rbio->failb; + + if (rbio->operation == BTRFS_RBIO_READ_REBUILD || + rbio->operation == BTRFS_RBIO_REBUILD_MISSING) { + spin_lock_irq(&rbio->bio_list_lock); + set_bit(RBIO_RMW_LOCKED_BIT, &rbio->flags); + spin_unlock_irq(&rbio->bio_list_lock); + } + + index_rbio_pages(rbio); + + for (pagenr = 0; pagenr < rbio->stripe_npages; pagenr++) { + /* + * Now we just use bitmap to mark the horizontal stripes in + * which we have data when doing parity scrub. + */ + if (rbio->operation == BTRFS_RBIO_PARITY_SCRUB && + !test_bit(pagenr, rbio->dbitmap)) + continue; + + /* setup our array of pointers with pages + * from each stripe + */ + for (stripe = 0; stripe < rbio->real_stripes; stripe++) { + /* + * if we're rebuilding a read, we have to use + * pages from the bio list + */ + if ((rbio->operation == BTRFS_RBIO_READ_REBUILD || + rbio->operation == BTRFS_RBIO_REBUILD_MISSING) && + (stripe == faila || stripe == failb)) { + page = page_in_rbio(rbio, stripe, pagenr, 0); + } else { + page = rbio_stripe_page(rbio, stripe, pagenr); + } + pointers[stripe] = kmap(page); + } + + /* all raid6 handling here */ + if (rbio->bbio->map_type & BTRFS_BLOCK_GROUP_RAID6) { + /* + * single failure, rebuild from parity raid5 + * style + */ + if (failb < 0) { + if (faila == rbio->nr_data) { + /* + * Just the P stripe has failed, without + * a bad data or Q stripe. + * TODO, we should redo the xor here. + */ + err = BLK_STS_IOERR; + goto cleanup; + } + /* + * a single failure in raid6 is rebuilt + * in the pstripe code below + */ + goto pstripe; + } + + /* make sure our ps and qs are in order */ + if (faila > failb) { + int tmp = failb; + failb = faila; + faila = tmp; + } + + /* if the q stripe is failed, do a pstripe reconstruction + * from the xors. + * If both the q stripe and the P stripe are failed, we're + * here due to a crc mismatch and we can't give them the + * data they want + */ + if (rbio->bbio->raid_map[failb] == RAID6_Q_STRIPE) { + if (rbio->bbio->raid_map[faila] == + RAID5_P_STRIPE) { + err = BLK_STS_IOERR; + goto cleanup; + } + /* + * otherwise we have one bad data stripe and + * a good P stripe. raid5! + */ + goto pstripe; + } + + if (rbio->bbio->raid_map[failb] == RAID5_P_STRIPE) { + raid6_datap_recov(rbio->real_stripes, + PAGE_SIZE, faila, pointers); + } else { + raid6_2data_recov(rbio->real_stripes, + PAGE_SIZE, faila, failb, + pointers); + } + } else { + void *p; + + /* rebuild from P stripe here (raid5 or raid6) */ + BUG_ON(failb != -1); +pstripe: + /* Copy parity block into failed block to start with */ + copy_page(pointers[faila], pointers[rbio->nr_data]); + + /* rearrange the pointer array */ + p = pointers[faila]; + for (stripe = faila; stripe < rbio->nr_data - 1; stripe++) + pointers[stripe] = pointers[stripe + 1]; + pointers[rbio->nr_data - 1] = p; + + /* xor in the rest */ + run_xor(pointers, rbio->nr_data - 1, PAGE_SIZE); + } + /* if we're doing this rebuild as part of an rmw, go through + * and set all of our private rbio pages in the + * failed stripes as uptodate. This way finish_rmw will + * know they can be trusted. If this was a read reconstruction, + * other endio functions will fiddle the uptodate bits + */ + if (rbio->operation == BTRFS_RBIO_WRITE) { + for (i = 0; i < rbio->stripe_npages; i++) { + if (faila != -1) { + page = rbio_stripe_page(rbio, faila, i); + SetPageUptodate(page); + } + if (failb != -1) { + page = rbio_stripe_page(rbio, failb, i); + SetPageUptodate(page); + } + } + } + for (stripe = 0; stripe < rbio->real_stripes; stripe++) { + /* + * if we're rebuilding a read, we have to use + * pages from the bio list + */ + if ((rbio->operation == BTRFS_RBIO_READ_REBUILD || + rbio->operation == BTRFS_RBIO_REBUILD_MISSING) && + (stripe == faila || stripe == failb)) { + page = page_in_rbio(rbio, stripe, pagenr, 0); + } else { + page = rbio_stripe_page(rbio, stripe, pagenr); + } + kunmap(page); + } + } + + err = BLK_STS_OK; +cleanup: + kfree(pointers); + +cleanup_io: + /* + * Similar to READ_REBUILD, REBUILD_MISSING at this point also has a + * valid rbio which is consistent with ondisk content, thus such a + * valid rbio can be cached to avoid further disk reads. + */ + if (rbio->operation == BTRFS_RBIO_READ_REBUILD || + rbio->operation == BTRFS_RBIO_REBUILD_MISSING) { + /* + * - In case of two failures, where rbio->failb != -1: + * + * Do not cache this rbio since the above read reconstruction + * (raid6_datap_recov() or raid6_2data_recov()) may have + * changed some content of stripes which are not identical to + * on-disk content any more, otherwise, a later write/recover + * may steal stripe_pages from this rbio and end up with + * corruptions or rebuild failures. + * + * - In case of single failure, where rbio->failb == -1: + * + * Cache this rbio iff the above read reconstruction is + * excuted without problems. + */ + if (err == BLK_STS_OK && rbio->failb < 0) + cache_rbio_pages(rbio); + else + clear_bit(RBIO_CACHE_READY_BIT, &rbio->flags); + + rbio_orig_end_io(rbio, err); + } else if (err == BLK_STS_OK) { + rbio->faila = -1; + rbio->failb = -1; + + if (rbio->operation == BTRFS_RBIO_WRITE) + finish_rmw(rbio); + else if (rbio->operation == BTRFS_RBIO_PARITY_SCRUB) + finish_parity_scrub(rbio, 0); + else + BUG(); + } else { + rbio_orig_end_io(rbio, err); + } +} + +/* + * This is called only for stripes we've read from disk to + * reconstruct the parity. + */ +static void raid_recover_end_io(struct bio *bio) +{ + struct btrfs_raid_bio *rbio = bio->bi_private; + + /* + * we only read stripe pages off the disk, set them + * up to date if there were no errors + */ + if (bio->bi_status) + fail_bio_stripe(rbio, bio); + else + set_bio_pages_uptodate(bio); + bio_put(bio); + + if (!atomic_dec_and_test(&rbio->stripes_pending)) + return; + + if (atomic_read(&rbio->error) > rbio->bbio->max_errors) + rbio_orig_end_io(rbio, BLK_STS_IOERR); + else + __raid_recover_end_io(rbio); +} + +/* + * reads everything we need off the disk to reconstruct + * the parity. endio handlers trigger final reconstruction + * when the IO is done. + * + * This is used both for reads from the higher layers and for + * parity construction required to finish a rmw cycle. + */ +static int __raid56_parity_recover(struct btrfs_raid_bio *rbio) +{ + int bios_to_read = 0; + struct bio_list bio_list; + int ret; + int pagenr; + int stripe; + struct bio *bio; + + bio_list_init(&bio_list); + + ret = alloc_rbio_pages(rbio); + if (ret) + goto cleanup; + + atomic_set(&rbio->error, 0); + + /* + * read everything that hasn't failed. Thanks to the + * stripe cache, it is possible that some or all of these + * pages are going to be uptodate. + */ + for (stripe = 0; stripe < rbio->real_stripes; stripe++) { + if (rbio->faila == stripe || rbio->failb == stripe) { + atomic_inc(&rbio->error); + continue; + } + + for (pagenr = 0; pagenr < rbio->stripe_npages; pagenr++) { + struct page *p; + + /* + * the rmw code may have already read this + * page in + */ + p = rbio_stripe_page(rbio, stripe, pagenr); + if (PageUptodate(p)) + continue; + + ret = rbio_add_io_page(rbio, &bio_list, + rbio_stripe_page(rbio, stripe, pagenr), + stripe, pagenr, rbio->stripe_len); + if (ret < 0) + goto cleanup; + } + } + + bios_to_read = bio_list_size(&bio_list); + if (!bios_to_read) { + /* + * we might have no bios to read just because the pages + * were up to date, or we might have no bios to read because + * the devices were gone. + */ + if (atomic_read(&rbio->error) <= rbio->bbio->max_errors) { + __raid_recover_end_io(rbio); + goto out; + } else { + goto cleanup; + } + } + + /* + * the bbio may be freed once we submit the last bio. Make sure + * not to touch it after that + */ + atomic_set(&rbio->stripes_pending, bios_to_read); + while (1) { + bio = bio_list_pop(&bio_list); + if (!bio) + break; + + bio->bi_private = rbio; + bio->bi_end_io = raid_recover_end_io; + bio->bi_opf = REQ_OP_READ; + + btrfs_bio_wq_end_io(rbio->fs_info, bio, BTRFS_WQ_ENDIO_RAID56); + + submit_bio(bio); + } +out: + return 0; + +cleanup: + if (rbio->operation == BTRFS_RBIO_READ_REBUILD || + rbio->operation == BTRFS_RBIO_REBUILD_MISSING) + rbio_orig_end_io(rbio, BLK_STS_IOERR); + + while ((bio = bio_list_pop(&bio_list))) + bio_put(bio); + + return -EIO; +} + +/* + * the main entry point for reads from the higher layers. This + * is really only called when the normal read path had a failure, + * so we assume the bio they send down corresponds to a failed part + * of the drive. + */ +int raid56_parity_recover(struct btrfs_fs_info *fs_info, struct bio *bio, + struct btrfs_bio *bbio, u64 stripe_len, + int mirror_num, int generic_io) +{ + struct btrfs_raid_bio *rbio; + int ret; + + if (generic_io) { + ASSERT(bbio->mirror_num == mirror_num); + btrfs_io_bio(bio)->mirror_num = mirror_num; + } + + rbio = alloc_rbio(fs_info, bbio, stripe_len); + if (IS_ERR(rbio)) { + if (generic_io) + btrfs_put_bbio(bbio); + return PTR_ERR(rbio); + } + + rbio->operation = BTRFS_RBIO_READ_REBUILD; + bio_list_add(&rbio->bio_list, bio); + rbio->bio_list_bytes = bio->bi_iter.bi_size; + + rbio->faila = find_logical_bio_stripe(rbio, bio); + if (rbio->faila == -1) { + btrfs_warn(fs_info, + "%s could not find the bad stripe in raid56 so that we cannot recover any more (bio has logical %llu len %llu, bbio has map_type %llu)", + __func__, (u64)bio->bi_iter.bi_sector << 9, + (u64)bio->bi_iter.bi_size, bbio->map_type); + if (generic_io) + btrfs_put_bbio(bbio); + kfree(rbio); + return -EIO; + } + + if (generic_io) { + btrfs_bio_counter_inc_noblocked(fs_info); + rbio->generic_bio_cnt = 1; + } else { + btrfs_get_bbio(bbio); + } + + /* + * Loop retry: + * for 'mirror == 2', reconstruct from all other stripes. + * for 'mirror_num > 2', select a stripe to fail on every retry. + */ + if (mirror_num > 2) { + /* + * 'mirror == 3' is to fail the p stripe and + * reconstruct from the q stripe. 'mirror > 3' is to + * fail a data stripe and reconstruct from p+q stripe. + */ + rbio->failb = rbio->real_stripes - (mirror_num - 1); + ASSERT(rbio->failb > 0); + if (rbio->failb <= rbio->faila) + rbio->failb--; + } + + ret = lock_stripe_add(rbio); + + /* + * __raid56_parity_recover will end the bio with + * any errors it hits. We don't want to return + * its error value up the stack because our caller + * will end up calling bio_endio with any nonzero + * return + */ + if (ret == 0) + __raid56_parity_recover(rbio); + /* + * our rbio has been added to the list of + * rbios that will be handled after the + * currently lock owner is done + */ + return 0; + +} + +static void rmw_work(struct btrfs_work *work) +{ + struct btrfs_raid_bio *rbio; + + rbio = container_of(work, struct btrfs_raid_bio, work); + raid56_rmw_stripe(rbio); +} + +static void read_rebuild_work(struct btrfs_work *work) +{ + struct btrfs_raid_bio *rbio; + + rbio = container_of(work, struct btrfs_raid_bio, work); + __raid56_parity_recover(rbio); +} + +/* + * The following code is used to scrub/replace the parity stripe + * + * Caller must have already increased bio_counter for getting @bbio. + * + * Note: We need make sure all the pages that add into the scrub/replace + * raid bio are correct and not be changed during the scrub/replace. That + * is those pages just hold metadata or file data with checksum. + */ + +struct btrfs_raid_bio * +raid56_parity_alloc_scrub_rbio(struct btrfs_fs_info *fs_info, struct bio *bio, + struct btrfs_bio *bbio, u64 stripe_len, + struct btrfs_device *scrub_dev, + unsigned long *dbitmap, int stripe_nsectors) +{ + struct btrfs_raid_bio *rbio; + int i; + + rbio = alloc_rbio(fs_info, bbio, stripe_len); + if (IS_ERR(rbio)) + return NULL; + bio_list_add(&rbio->bio_list, bio); + /* + * This is a special bio which is used to hold the completion handler + * and make the scrub rbio is similar to the other types + */ + ASSERT(!bio->bi_iter.bi_size); + rbio->operation = BTRFS_RBIO_PARITY_SCRUB; + + /* + * After mapping bbio with BTRFS_MAP_WRITE, parities have been sorted + * to the end position, so this search can start from the first parity + * stripe. + */ + for (i = rbio->nr_data; i < rbio->real_stripes; i++) { + if (bbio->stripes[i].dev == scrub_dev) { + rbio->scrubp = i; + break; + } + } + ASSERT(i < rbio->real_stripes); + + /* Now we just support the sectorsize equals to page size */ + ASSERT(fs_info->sectorsize == PAGE_SIZE); + ASSERT(rbio->stripe_npages == stripe_nsectors); + bitmap_copy(rbio->dbitmap, dbitmap, stripe_nsectors); + + /* + * We have already increased bio_counter when getting bbio, record it + * so we can free it at rbio_orig_end_io(). + */ + rbio->generic_bio_cnt = 1; + + return rbio; +} + +/* Used for both parity scrub and missing. */ +void raid56_add_scrub_pages(struct btrfs_raid_bio *rbio, struct page *page, + u64 logical) +{ + int stripe_offset; + int index; + + ASSERT(logical >= rbio->bbio->raid_map[0]); + ASSERT(logical + PAGE_SIZE <= rbio->bbio->raid_map[0] + + rbio->stripe_len * rbio->nr_data); + stripe_offset = (int)(logical - rbio->bbio->raid_map[0]); + index = stripe_offset >> PAGE_SHIFT; + rbio->bio_pages[index] = page; +} + +/* + * We just scrub the parity that we have correct data on the same horizontal, + * so we needn't allocate all pages for all the stripes. + */ +static int alloc_rbio_essential_pages(struct btrfs_raid_bio *rbio) +{ + int i; + int bit; + int index; + struct page *page; + + for_each_set_bit(bit, rbio->dbitmap, rbio->stripe_npages) { + for (i = 0; i < rbio->real_stripes; i++) { + index = i * rbio->stripe_npages + bit; + if (rbio->stripe_pages[index]) + continue; + + page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); + if (!page) + return -ENOMEM; + rbio->stripe_pages[index] = page; + } + } + return 0; +} + +static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio, + int need_check) +{ + struct btrfs_bio *bbio = rbio->bbio; + void **pointers = rbio->finish_pointers; + unsigned long *pbitmap = rbio->finish_pbitmap; + int nr_data = rbio->nr_data; + int stripe; + int pagenr; + bool has_qstripe; + struct page *p_page = NULL; + struct page *q_page = NULL; + struct bio_list bio_list; + struct bio *bio; + int is_replace = 0; + int ret; + + bio_list_init(&bio_list); + + if (rbio->real_stripes - rbio->nr_data == 1) + has_qstripe = false; + else if (rbio->real_stripes - rbio->nr_data == 2) + has_qstripe = true; + else + BUG(); + + if (bbio->num_tgtdevs && bbio->tgtdev_map[rbio->scrubp]) { + is_replace = 1; + bitmap_copy(pbitmap, rbio->dbitmap, rbio->stripe_npages); + } + + /* + * Because the higher layers(scrubber) are unlikely to + * use this area of the disk again soon, so don't cache + * it. + */ + clear_bit(RBIO_CACHE_READY_BIT, &rbio->flags); + + if (!need_check) + goto writeback; + + p_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); + if (!p_page) + goto cleanup; + SetPageUptodate(p_page); + + if (has_qstripe) { + /* RAID6, allocate and map temp space for the Q stripe */ + q_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); + if (!q_page) { + __free_page(p_page); + goto cleanup; + } + SetPageUptodate(q_page); + pointers[rbio->real_stripes - 1] = kmap(q_page); + } + + atomic_set(&rbio->error, 0); + + /* Map the parity stripe just once */ + pointers[nr_data] = kmap(p_page); + + for_each_set_bit(pagenr, rbio->dbitmap, rbio->stripe_npages) { + struct page *p; + void *parity; + /* first collect one page from each data stripe */ + for (stripe = 0; stripe < nr_data; stripe++) { + p = page_in_rbio(rbio, stripe, pagenr, 0); + pointers[stripe] = kmap(p); + } + + if (has_qstripe) { + /* RAID6, call the library function to fill in our P/Q */ + raid6_call.gen_syndrome(rbio->real_stripes, PAGE_SIZE, + pointers); + } else { + /* raid5 */ + copy_page(pointers[nr_data], pointers[0]); + run_xor(pointers + 1, nr_data - 1, PAGE_SIZE); + } + + /* Check scrubbing parity and repair it */ + p = rbio_stripe_page(rbio, rbio->scrubp, pagenr); + parity = kmap(p); + if (memcmp(parity, pointers[rbio->scrubp], PAGE_SIZE)) + copy_page(parity, pointers[rbio->scrubp]); + else + /* Parity is right, needn't writeback */ + bitmap_clear(rbio->dbitmap, pagenr, 1); + kunmap(p); + + for (stripe = 0; stripe < nr_data; stripe++) + kunmap(page_in_rbio(rbio, stripe, pagenr, 0)); + } + + kunmap(p_page); + __free_page(p_page); + if (q_page) { + kunmap(q_page); + __free_page(q_page); + } + +writeback: + /* + * time to start writing. Make bios for everything from the + * higher layers (the bio_list in our rbio) and our p/q. Ignore + * everything else. + */ + for_each_set_bit(pagenr, rbio->dbitmap, rbio->stripe_npages) { + struct page *page; + + page = rbio_stripe_page(rbio, rbio->scrubp, pagenr); + ret = rbio_add_io_page(rbio, &bio_list, + page, rbio->scrubp, pagenr, rbio->stripe_len); + if (ret) + goto cleanup; + } + + if (!is_replace) + goto submit_write; + + for_each_set_bit(pagenr, pbitmap, rbio->stripe_npages) { + struct page *page; + + page = rbio_stripe_page(rbio, rbio->scrubp, pagenr); + ret = rbio_add_io_page(rbio, &bio_list, page, + bbio->tgtdev_map[rbio->scrubp], + pagenr, rbio->stripe_len); + if (ret) + goto cleanup; + } + +submit_write: + nr_data = bio_list_size(&bio_list); + if (!nr_data) { + /* Every parity is right */ + rbio_orig_end_io(rbio, BLK_STS_OK); + return; + } + + atomic_set(&rbio->stripes_pending, nr_data); + + while (1) { + bio = bio_list_pop(&bio_list); + if (!bio) + break; + + bio->bi_private = rbio; + bio->bi_end_io = raid_write_end_io; + bio->bi_opf = REQ_OP_WRITE; + + submit_bio(bio); + } + return; + +cleanup: + rbio_orig_end_io(rbio, BLK_STS_IOERR); + + while ((bio = bio_list_pop(&bio_list))) + bio_put(bio); +} + +static inline int is_data_stripe(struct btrfs_raid_bio *rbio, int stripe) +{ + if (stripe >= 0 && stripe < rbio->nr_data) + return 1; + return 0; +} + +/* + * While we're doing the parity check and repair, we could have errors + * in reading pages off the disk. This checks for errors and if we're + * not able to read the page it'll trigger parity reconstruction. The + * parity scrub will be finished after we've reconstructed the failed + * stripes + */ +static void validate_rbio_for_parity_scrub(struct btrfs_raid_bio *rbio) +{ + if (atomic_read(&rbio->error) > rbio->bbio->max_errors) + goto cleanup; + + if (rbio->faila >= 0 || rbio->failb >= 0) { + int dfail = 0, failp = -1; + + if (is_data_stripe(rbio, rbio->faila)) + dfail++; + else if (is_parity_stripe(rbio->faila)) + failp = rbio->faila; + + if (is_data_stripe(rbio, rbio->failb)) + dfail++; + else if (is_parity_stripe(rbio->failb)) + failp = rbio->failb; + + /* + * Because we can not use a scrubbing parity to repair + * the data, so the capability of the repair is declined. + * (In the case of RAID5, we can not repair anything) + */ + if (dfail > rbio->bbio->max_errors - 1) + goto cleanup; + + /* + * If all data is good, only parity is correctly, just + * repair the parity. + */ + if (dfail == 0) { + finish_parity_scrub(rbio, 0); + return; + } + + /* + * Here means we got one corrupted data stripe and one + * corrupted parity on RAID6, if the corrupted parity + * is scrubbing parity, luckily, use the other one to repair + * the data, or we can not repair the data stripe. + */ + if (failp != rbio->scrubp) + goto cleanup; + + __raid_recover_end_io(rbio); + } else { + finish_parity_scrub(rbio, 1); + } + return; + +cleanup: + rbio_orig_end_io(rbio, BLK_STS_IOERR); +} + +/* + * end io for the read phase of the rmw cycle. All the bios here are physical + * stripe bios we've read from the disk so we can recalculate the parity of the + * stripe. + * + * This will usually kick off finish_rmw once all the bios are read in, but it + * may trigger parity reconstruction if we had any errors along the way + */ +static void raid56_parity_scrub_end_io(struct bio *bio) +{ + struct btrfs_raid_bio *rbio = bio->bi_private; + + if (bio->bi_status) + fail_bio_stripe(rbio, bio); + else + set_bio_pages_uptodate(bio); + + bio_put(bio); + + if (!atomic_dec_and_test(&rbio->stripes_pending)) + return; + + /* + * this will normally call finish_rmw to start our write + * but if there are any failed stripes we'll reconstruct + * from parity first + */ + validate_rbio_for_parity_scrub(rbio); +} + +static void raid56_parity_scrub_stripe(struct btrfs_raid_bio *rbio) +{ + int bios_to_read = 0; + struct bio_list bio_list; + int ret; + int pagenr; + int stripe; + struct bio *bio; + + bio_list_init(&bio_list); + + ret = alloc_rbio_essential_pages(rbio); + if (ret) + goto cleanup; + + atomic_set(&rbio->error, 0); + /* + * build a list of bios to read all the missing parts of this + * stripe + */ + for (stripe = 0; stripe < rbio->real_stripes; stripe++) { + for_each_set_bit(pagenr, rbio->dbitmap, rbio->stripe_npages) { + struct page *page; + /* + * we want to find all the pages missing from + * the rbio and read them from the disk. If + * page_in_rbio finds a page in the bio list + * we don't need to read it off the stripe. + */ + page = page_in_rbio(rbio, stripe, pagenr, 1); + if (page) + continue; + + page = rbio_stripe_page(rbio, stripe, pagenr); + /* + * the bio cache may have handed us an uptodate + * page. If so, be happy and use it + */ + if (PageUptodate(page)) + continue; + + ret = rbio_add_io_page(rbio, &bio_list, page, + stripe, pagenr, rbio->stripe_len); + if (ret) + goto cleanup; + } + } + + bios_to_read = bio_list_size(&bio_list); + if (!bios_to_read) { + /* + * this can happen if others have merged with + * us, it means there is nothing left to read. + * But if there are missing devices it may not be + * safe to do the full stripe write yet. + */ + goto finish; + } + + /* + * the bbio may be freed once we submit the last bio. Make sure + * not to touch it after that + */ + atomic_set(&rbio->stripes_pending, bios_to_read); + while (1) { + bio = bio_list_pop(&bio_list); + if (!bio) + break; + + bio->bi_private = rbio; + bio->bi_end_io = raid56_parity_scrub_end_io; + bio->bi_opf = REQ_OP_READ; + + btrfs_bio_wq_end_io(rbio->fs_info, bio, BTRFS_WQ_ENDIO_RAID56); + + submit_bio(bio); + } + /* the actual write will happen once the reads are done */ + return; + +cleanup: + rbio_orig_end_io(rbio, BLK_STS_IOERR); + + while ((bio = bio_list_pop(&bio_list))) + bio_put(bio); + + return; + +finish: + validate_rbio_for_parity_scrub(rbio); +} + +static void scrub_parity_work(struct btrfs_work *work) +{ + struct btrfs_raid_bio *rbio; + + rbio = container_of(work, struct btrfs_raid_bio, work); + raid56_parity_scrub_stripe(rbio); +} + +void raid56_parity_submit_scrub_rbio(struct btrfs_raid_bio *rbio) +{ + if (!lock_stripe_add(rbio)) + start_async_work(rbio, scrub_parity_work); +} + +/* The following code is used for dev replace of a missing RAID 5/6 device. */ + +struct btrfs_raid_bio * +raid56_alloc_missing_rbio(struct btrfs_fs_info *fs_info, struct bio *bio, + struct btrfs_bio *bbio, u64 length) +{ + struct btrfs_raid_bio *rbio; + + rbio = alloc_rbio(fs_info, bbio, length); + if (IS_ERR(rbio)) + return NULL; + + rbio->operation = BTRFS_RBIO_REBUILD_MISSING; + bio_list_add(&rbio->bio_list, bio); + /* + * This is a special bio which is used to hold the completion handler + * and make the scrub rbio is similar to the other types + */ + ASSERT(!bio->bi_iter.bi_size); + + rbio->faila = find_logical_bio_stripe(rbio, bio); + if (rbio->faila == -1) { + BUG(); + kfree(rbio); + return NULL; + } + + /* + * When we get bbio, we have already increased bio_counter, record it + * so we can free it at rbio_orig_end_io() + */ + rbio->generic_bio_cnt = 1; + + return rbio; +} + +void raid56_submit_missing_rbio(struct btrfs_raid_bio *rbio) +{ + if (!lock_stripe_add(rbio)) + start_async_work(rbio, read_rebuild_work); +} |