From: Zhao Lei <zhao...@cn.fujitsu.com>
The code are similar, combine them to make code clean and easy to maintenance.
Some lost condition are also completed with benefit of this combination.
Signed-off-by: Zhao Lei <zhao...@cn.fujitsu.com>
Signed-off-by: Miao Xie <mi...@cn.fujitsu.com>
---
fs/btrfs/scrub.c | 110 ++++++++++++++++++++++++++++---------------------------
1 file changed, 57 insertions(+), 53 deletions(-)
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index d1d681f..000fa59 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1099,19 +1099,47 @@ nodatasum_case:
}
}
+ /*
+ * In case of I/O errors in the area that is supposed to be
+ * repaired, continue by picking good copies of those pages.
+ * Select the good pages from mirrors to rewrite bad pages from
+ * the area to fix. Afterwards verify the checksum of the block
+ * that is supposed to be repaired. This verification step is
+ * only done for the purpose of statistic counting and for the
+ * final scrub report, whether errors remain.
+ * A perfect algorithm could make use of the checksum and try
+ * all possible combinations of pages from the different mirrors
+ * until the checksum verification succeeds. For example, when
+ * the 2nd page of mirror #1 faces I/O errors, and the 2nd page
+ * of mirror #2 is readable but the final checksum test fails,
+ * then the 2nd page of mirror #3 could be tried, whether now
+ * the final checksum succeedes. But this would be a rare
+ * exception and is therefore not implemented. At least it is
+ * avoided that the good copy is overwritten.
+ * A more useful improvement would be to pick the sectors
+ * without I/O error based on sector sizes (512 bytes on legacy
+ * disks) instead of on PAGE_SIZE. Then maybe 512 byte of one
+ * mirror could be repaired by taking 512 byte of a different
+ * mirror, even if other 512 byte sectors in the same PAGE_SIZE
+ * area are unreadable.
+ */
+
/* can only fix I/O errors from here on */
if (sblock_bad->no_io_error_seen)
goto did_not_correct_error;
- /*
- * for dev_replace, pick good pages and write to the target device.
- */
- if (sctx->is_dev_replace) {
- success = 1;
- for (page_num = 0; page_num < sblock_bad->page_count;
- page_num++) {
- struct scrub_block *sblock_other = NULL;
+ success = 1;
+ for (page_num = 0; page_num < sblock_bad->page_count;
+ page_num++) {
+ struct scrub_page *page_bad = sblock_bad->pagev[page_num];
+ struct scrub_block *sblock_other = NULL;
+ /* skip no-io-error page in scrub */
+ if (!page_bad->io_error && !sctx->is_dev_replace)
+ continue;
+
+ /* try to find no-io-error page in mirrors */
+ if (page_bad->io_error) {
for (mirror_index = 0;
mirror_index < BTRFS_MAX_MIRRORS &&
sblocks_for_recheck[mirror_index].page_count > 0;
@@ -1123,18 +1151,20 @@ nodatasum_case:
break;
}
}
+ if (!sblock_other)
+ success = 0;
+ }
- if (!sblock_other) {
- /*
- * did not find a mirror to fetch the page
- * from. scrub_write_page_to_dev_replace()
- * handles this case (page->io_error), by
- * filling the block with zeros before
- * submitting the write request
- */
+ if (sctx->is_dev_replace) {
+ /*
+ * did not find a mirror to fetch the page
+ * from. scrub_write_page_to_dev_replace()
+ * handles this case (page->io_error), by
+ * filling the block with zeros before
+ * submitting the write request
+ */
+ if (!sblock_other)
sblock_other = sblock_bad;
- success = 0;
- }
if (scrub_write_page_to_dev_replace(sblock_other,
page_num) != 0) {
@@ -1144,9 +1174,15 @@ nodatasum_case:
num_write_errors);
success = 0;
}
+ } else if (sblock_other) {
+ ret = scrub_repair_page_from_good_copy(sblock_bad,
+ sblock_other,
+ page_num, 0);
+ if (0 == ret)
+ page_bad->io_error = 0;
+ else
+ success = 0;
}
-
- goto out;
}
/*
@@ -1175,39 +1211,7 @@ nodatasum_case:
* area are unreadable.
*/
- success = 1;
- for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
- struct scrub_page *page_bad = sblock_bad->pagev[page_num];
-
- if (!page_bad->io_error)
- continue;
-
- 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_repair_page_from_good_copy(
- sblock_bad, sblock_other, page_num, 0);
- if (0 == ret) {
- page_bad->io_error = 0;
- break; /* succeeded for this page */
- }
- }
- }
-
- if (page_bad->io_error) {
- /* did not find a mirror to copy the page from */
- success = 0;
- }
- }
-
- if (success) {
+ if (success && !sctx->is_dev_replace) {
if (is_metadata || have_csum) {
/*
* need to verify the checksum now that all
--
1.8.5.1
--
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