btrfs scrub: added unverified_errors

In normal operation, scrub is reading data sequentially in large portions.
In case of an i/o error, we try to find the corrupted area(s) by issuing
page sized read requests. With this commit we increment the
unverified_errors counter if all of the small size requests succeed.

Userland patches carrying such conspicous events to the administrator should
already be around.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

1 files changed, 26 insertions, 11 deletions

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index a8d03d5efb5d..35099fa97d56 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -201,18 +201,25 @@ nomem:
  * recheck_error gets called for every page in the bio, even though only
  * one may be bad
  */
-static void scrub_recheck_error(struct scrub_bio *sbio, int ix)
+static int scrub_recheck_error(struct scrub_bio *sbio, int ix)
 {
+        struct scrub_dev *sdev = sbio->sdev;
+        u64 sector = (sbio->physical + ix * PAGE_SIZE) >> 9;
+
         if (sbio->err) {
-                if (scrub_fixup_io(READ, sbio->sdev->dev->bdev,
-                                   (sbio->physical + ix * PAGE_SIZE) >> 9,
+                if (scrub_fixup_io(READ, sbio->sdev->dev->bdev, sector,
                                    sbio->bio->bi_io_vec[ix].bv_page) == 0) {
                         if (scrub_fixup_check(sbio, ix) == 0)
-                                return;
+                                return 0;
                 }
         }
 
+        spin_lock(&sdev->stat_lock);
+        ++sdev->stat.read_errors;
+        spin_unlock(&sdev->stat_lock);
+
         scrub_fixup(sbio, ix);
+        return 1;
 }
 
 static int scrub_fixup_check(struct scrub_bio *sbio, int ix)
@@ -382,8 +389,14 @@ static void scrub_checksum(struct btrfs_work *work)
         int ret;
 
         if (sbio->err) {
+                ret = 0;
                 for (i = 0; i < sbio->count; ++i)
-                        scrub_recheck_error(sbio, i);
+                        ret |= scrub_recheck_error(sbio, i);
+                if (!ret) {
+                        spin_lock(&sdev->stat_lock);
+                        ++sdev->stat.unverified_errors;
+                        spin_unlock(&sdev->stat_lock);
+                }
 
                 sbio->bio->bi_flags &= ~(BIO_POOL_MASK - 1);
                 sbio->bio->bi_flags |= 1 << BIO_UPTODATE;
@@ -396,10 +409,6 @@ static void scrub_checksum(struct btrfs_work *work)
                         bi->bv_offset = 0;
                         bi->bv_len = PAGE_SIZE;
                 }
-
-                spin_lock(&sdev->stat_lock);
-                ++sdev->stat.read_errors;
-                spin_unlock(&sdev->stat_lock);
                 goto out;
         }
         for (i = 0; i < sbio->count; ++i) {
@@ -420,8 +429,14 @@ static void scrub_checksum(struct btrfs_work *work)
                         WARN_ON(1);
                 }
                 kunmap_atomic(buffer, KM_USER0);
-                if (ret)
-                        scrub_recheck_error(sbio, i);
+                if (ret) {
+                        ret = scrub_recheck_error(sbio, i);
+                        if (!ret) {
+                                spin_lock(&sdev->stat_lock);
+                                ++sdev->stat.unverified_errors;
+                                spin_unlock(&sdev->stat_lock);
+                        }
+                }
         }
 
 out: