v4.19.13 snapshot.
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
new file mode 100644
index 0000000..df41d70
--- /dev/null
+++ b/fs/btrfs/raid56.c
@@ -0,0 +1,2744 @@
+// 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;
+ int p_stripe = -1;
+ int q_stripe = -1;
+ struct bio_list bio_list;
+ struct bio *bio;
+ int ret;
+
+ bio_list_init(&bio_list);
+
+ if (rbio->real_stripes - rbio->nr_data == 1) {
+ p_stripe = rbio->real_stripes - 1;
+ } else if (rbio->real_stripes - rbio->nr_data == 2) {
+ p_stripe = rbio->real_stripes - 2;
+ q_stripe = rbio->real_stripes - 1;
+ } 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 (q_stripe != -1) {
+
+ /*
+ * 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;
+ int p_stripe = -1;
+ int q_stripe = -1;
+ 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) {
+ p_stripe = rbio->real_stripes - 1;
+ } else if (rbio->real_stripes - rbio->nr_data == 2) {
+ p_stripe = rbio->real_stripes - 2;
+ q_stripe = rbio->real_stripes - 1;
+ } 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 (q_stripe != -1) {
+ q_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+ if (!q_page) {
+ __free_page(p_page);
+ goto cleanup;
+ }
+ SetPageUptodate(q_page);
+ }
+
+ atomic_set(&rbio->error, 0);
+
+ 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);
+ }
+
+ /* then add the parity stripe */
+ pointers[stripe++] = kmap(p_page);
+
+ if (q_stripe != -1) {
+
+ /*
+ * raid6, add the qstripe and call the
+ * library function to fill in our p/q
+ */
+ pointers[stripe++] = kmap(q_page);
+
+ 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 < rbio->real_stripes; stripe++)
+ kunmap(page_in_rbio(rbio, stripe, pagenr, 0));
+ }
+
+ __free_page(p_page);
+ if (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);
+}