[PATCH v3 08/11] Btrfs, replace: write raid56 parity into the replace target device

[Miao Xie]

This function reused the code of parity scrub, and we just write
the right parity or corrected parity into the target device before
the parity scrub end.

Signed-off-by: Miao Xie <mi...@cn.fujitsu.com>
---
Changelog v1 -> v3:
- None.
---
 fs/btrfs/raid56.c | 23 +++++++++++++++++++++++
 fs/btrfs/scrub.c  |  2 +-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 6f82c1b..cfa449f 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -2311,7 +2311,9 @@ static void raid_write_parity_end_io(struct bio *bio, int 
err)
 static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio,
                                         int need_check)
 {
+       struct btrfs_bio *bbio = rbio->bbio;
        void *pointers[rbio->real_stripes];
+       DECLARE_BITMAP(pbitmap, rbio->stripe_npages);
        int nr_data = rbio->nr_data;
        int stripe;
        int pagenr;
@@ -2321,6 +2323,7 @@ static noinline void finish_parity_scrub(struct 
btrfs_raid_bio *rbio,
        struct page *q_page = NULL;
        struct bio_list bio_list;
        struct bio *bio;
+       int is_replace = 0;
        int ret;
 
        bio_list_init(&bio_list);
@@ -2334,6 +2337,11 @@ static noinline void finish_parity_scrub(struct 
btrfs_raid_bio *rbio,
                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
@@ -2422,6 +2430,21 @@ writeback:
                        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 */
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 7f95afc..0ae837f 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -2714,7 +2714,7 @@ static void scrub_parity_check_and_repair(struct 
scrub_parity *sparity)
                goto out;
 
        length = sparity->logic_end - sparity->logic_start + 1;
-       ret = btrfs_map_sblock(sctx->dev_root->fs_info, REQ_GET_READ_MIRRORS,
+       ret = btrfs_map_sblock(sctx->dev_root->fs_info, WRITE,
                               sparity->logic_start,
                               &length, &bbio, 0, &raid_map);
        if (ret || !bbio || !raid_map)
-- 
1.9.3

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