Btrfs: Separate finding-right-mirror and writing-to-target's process in scrub_handle_errored_block()

In corrent code, code of finding-right-mirror and writing-to-target
are mixed in logic, if we find a right mirror but failed in writing
to target, it will treat as "hadn't found right block", and fill the
target with sblock_bad.

Actually, "failed in writing to target" does not mean "source
block is wrong", this patch separate above two condition in logic,
and do some cleanup to make code clean.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 17 insertions, 27 deletions

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 68867b2e4620..c40ffbc9581f 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1114,35 +1114,21 @@ nodatasum_case:
                 success = 1;
                 for (page_num = 0; page_num < sblock_bad->page_count;
                      page_num++) {
-                        int sub_success;
+                        struct scrub_block *sblock_other = NULL;
 
-                        sub_success = 0;
                         for (mirror_index = 0;
                              mirror_index < BTRFS_MAX_MIRRORS &&
                              sblocks_for_recheck[mirror_index].page_count > 0;
                              mirror_index++) {
-                                struct scrub_block *sblock_other =
-                                        sblocks_for_recheck + mirror_index;
-                                struct scrub_page *page_other =
-                                        sblock_other->pagev[page_num];
-
-                                if (!page_other->io_error) {
-                                        ret = scrub_write_page_to_dev_replace(
-                                                        sblock_other, page_num);
-                                        if (ret == 0) {
-                                                /* succeeded for this page */
-                                                sub_success = 1;
-                                                break;
-                                        } else {
-                                                btrfs_dev_replace_stats_inc(
-                                                        &sctx->dev_root->
-                                                        fs_info->dev_replace.
-                                                        num_write_errors);
-                                        }
+                                if (!sblocks_for_recheck[mirror_index].
+                                    pagev[page_num]->io_error) {
+                                        sblock_other = sblocks_for_recheck +
+                                                       mirror_index;
+                                        break;
                                 }
                         }
 
-                        if (!sub_success) {
+                        if (!sblock_other) {
                                 /*
                                  * did not find a mirror to fetch the page
                                  * from. scrub_write_page_to_dev_replace()
@@ -1150,13 +1136,17 @@ nodatasum_case:
                                  * filling the block with zeros before
                                  * submitting the write request
                                  */
+                                sblock_other = sblock_bad;
+                                success = 0;
+                        }
+
+                        if (scrub_write_page_to_dev_replace(sblock_other,
+                                                            page_num) != 0) {
+                                btrfs_dev_replace_stats_inc(
+                                        &sctx->dev_root->
+                                        fs_info->dev_replace.
+                                        num_write_errors);
                                 success = 0;
-                                ret = scrub_write_page_to_dev_replace(
-                                                sblock_bad, page_num);
-                                if (ret)
-                                        btrfs_dev_replace_stats_inc(
-                                                &sctx->dev_root->fs_info->
-                                                dev_replace.num_write_errors);
                         }
                 }