[PATCH] md: count corrected read errors per drive

Store this total in superblock (As appropriate), and make it available to
userspace via sysfs.

Signed-off-by: Neil Brown <neilb@suse.de>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

7 files changed, 57 insertions, 4 deletions

diff --git a/Documentation/md.txt b/Documentation/md.txt
index fd43fd2cad2f..a3eadf8e1701 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -222,6 +222,17 @@ Each directory contains:
                          of being recoverred to
         This list make grow in future.
 
+      errors
+        An approximate count of read errors that have been detected on
+        this device but have not caused the device to be evicted from
+        the array (either because they were corrected or because they
+        happened while the array was read-only).  When using version-1
+        metadata, this value persists across restarts of the array.
+
+        This value can be written while assembling an array thus
+        providing an ongoing count for arrays with metadata managed by
+        userspace.
+
 
 An active md device will also contain and entry for each active device
 in the array.  These are named
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 594d8c312e6a..32a4e2311e43 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1000,6 +1000,7 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
         }
         rdev->preferred_minor = 0xffff;
         rdev->data_offset = le64_to_cpu(sb->data_offset);
+        atomic_set(&rdev->corrected_errors, le32_to_cpu(sb->cnt_corrected_read));
 
         rdev->sb_size = le32_to_cpu(sb->max_dev) * 2 + 256;
         bmask = queue_hardsect_size(rdev->bdev->bd_disk->queue)-1;
@@ -1139,6 +1140,8 @@ static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev)
         else
                 sb->resync_offset = cpu_to_le64(0);
 
+        sb->cnt_corrected_read = atomic_read(&rdev->corrected_errors);
+
         if (mddev->bitmap && mddev->bitmap_file == NULL) {
                 sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_offset);
                 sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);
@@ -1592,9 +1595,30 @@ super_show(mdk_rdev_t *rdev, char *page)
 }
 static struct rdev_sysfs_entry rdev_super = __ATTR_RO(super);
 
+static ssize_t
+errors_show(mdk_rdev_t *rdev, char *page)
+{
+        return sprintf(page, "%d\n", atomic_read(&rdev->corrected_errors));
+}
+
+static ssize_t
+errors_store(mdk_rdev_t *rdev, const char *buf, size_t len)
+{
+        char *e;
+        unsigned long n = simple_strtoul(buf, &e, 10);
+        if (*buf && (*e == 0 || *e == '\n')) {
+                atomic_set(&rdev->corrected_errors, n);
+                return len;
+        }
+        return -EINVAL;
+}
+static struct rdev_sysfs_entry rdev_errors =
+__ATTR(errors, 0644, errors_show, errors_store);
+
 static struct attribute *rdev_default_attrs[] = {
         &rdev_state.attr,
         &rdev_super.attr,
+        &rdev_errors.attr,
         NULL,
 };
 static ssize_t
@@ -1674,6 +1698,7 @@ static mdk_rdev_t *md_import_device(dev_t newdev, int super_format, int super_mi
         rdev->data_offset = 0;
         atomic_set(&rdev->nr_pending, 0);
         atomic_set(&rdev->read_errors, 0);
+        atomic_set(&rdev->corrected_errors, 0);
 
         size = rdev->bdev->bd_inode->i_size >> BLOCK_SIZE_BITS;
         if (!size) {
@@ -4729,7 +4754,7 @@ static int set_ro(const char *val, struct kernel_param *kp)
         int num = simple_strtoul(val, &e, 10);
         if (*val && (*e == '\0' || *e == '\n')) {
                 start_readonly = num;
-                return 0;;
+                return 0;
         }
         return -EINVAL;
 }
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 181c9616d5f1..a06ff91f27e2 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1265,6 +1265,7 @@ static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio)
                                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
                                                 continue;
                                         rdev = conf->mirrors[d].rdev;
+                                        atomic_add(s, &rdev->corrected_errors);
                                         if (sync_page_io(rdev->bdev,
                                                          sect + rdev->data_offset,
                                                          s<<9,
@@ -1463,6 +1464,7 @@ static void raid1d(mddev_t *mddev)
                                                         d = conf->raid_disks;
                                                 d--;
                                                 rdev = conf->mirrors[d].rdev;
+                                                atomic_add(s, &rdev->corrected_errors);
                                                 if (rdev &&
                                                     test_bit(In_sync, &rdev->flags)) {
                                                         if (sync_page_io(rdev->bdev,
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 201dc7168a5f..9e658e519a27 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1122,9 +1122,13 @@ static int end_sync_read(struct bio *bio, unsigned int bytes_done, int error)
 
         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
                 set_bit(R10BIO_Uptodate, &r10_bio->state);
-        else if (!test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
-                md_error(r10_bio->mddev,
-                         conf->mirrors[d].rdev);
+        else {
+                atomic_add(r10_bio->sectors,
+                           &conf->mirrors[d].rdev->corrected_errors);
+                if (!test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
+                        md_error(r10_bio->mddev,
+                                 conf->mirrors[d].rdev);
+        }
 
         /* for reconstruct, we always reschedule after a read.
          * for resync, only after all reads
@@ -1430,6 +1434,7 @@ static void raid10d(mddev_t *mddev)
                                                 sl--;
                                                 d = r10_bio->devs[sl].devnum;
                                                 rdev = conf->mirrors[d].rdev;
+                                                atomic_add(s, &rdev->corrected_errors);
                                                 if (rdev &&
                                                     test_bit(In_sync, &rdev->flags)) {
                                                         if (sync_page_io(rdev->bdev,
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 9cc844f455bf..54f4a9847e38 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1400,6 +1400,9 @@ static void handle_stripe(struct stripe_head *sh)
                         bi->bi_io_vec[0].bv_offset = 0;
                         bi->bi_size = STRIPE_SIZE;
                         bi->bi_next = NULL;
+                        if (rw == WRITE &&
+                            test_bit(R5_ReWrite, &sh->dev[i].flags))
+                                atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
                         generic_make_request(bi);
                 } else {
                         if (rw == 1)
diff --git a/drivers/md/raid6main.c b/drivers/md/raid6main.c
index 84dd875bb2f6..8c823d686a60 100644
--- a/drivers/md/raid6main.c
+++ b/drivers/md/raid6main.c
@@ -1562,6 +1562,9 @@ static void handle_stripe(struct stripe_head *sh, struct page *tmp_page)
                         bi->bi_io_vec[0].bv_offset = 0;
                         bi->bi_size = STRIPE_SIZE;
                         bi->bi_next = NULL;
+                        if (rw == WRITE &&
+                            test_bit(R5_ReWrite, &sh->dev[i].flags))
+                                atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
                         generic_make_request(bi);
                 } else {
                         if (rw == 1)
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index 686463115438..68b929c079ab 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -95,6 +95,10 @@ struct mdk_rdev_s
         atomic_t        read_errors;    /* number of consecutive read errors that
                                          * we have tried to ignore.
                                          */
+        atomic_t        corrected_errors; /* number of corrected read errors,
+                                           * for reporting to userspace and storing
+                                           * in superblock.
+                                           */
 };
 
 struct mddev_s