Re: [PATCH 3/3] md/raid10: fix wrong setting of max_corr_read_errors

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Hi,

在 2023/04/27 16:56, linan666@xxxxxxxxxxxxxxx 写道:
From: Li Nan <linan122@xxxxxxxxxx>

max_corr_read_errors should not be negative number. Change it to
unsigned int where use it.

Fixes: 1e50915fe0bb ("raid: improve MD/raid10 handling of correctable read errors.")
Signed-off-by: Li Nan <linan122@xxxxxxxxxx>
---
  drivers/md/md.c     | 2 +-
  drivers/md/raid10.c | 4 ++--
  2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index faffbd042925..a365ed122960 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4484,7 +4484,7 @@ __ATTR_PREALLOC(array_state, S_IRUGO|S_IWUSR, array_state_show, array_state_stor
static ssize_t
  max_corrected_read_errors_show(struct mddev *mddev, char *page) {
-	return sprintf(page, "%d\n",
+	return sprintf(page, "%u\n",
  		       atomic_read(&mddev->max_corr_read_errors));
  }
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 4fcfcb350d2b..28cdb2ae0e91 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2727,7 +2727,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
  	int sect = 0; /* Offset from r10_bio->sector */
  	int sectors = r10_bio->sectors;
  	struct md_rdev *rdev;
-	int max_read_errors = atomic_read(&mddev->max_corr_read_errors);
+	unsigned int max_read_errors = atomic_read(&mddev->max_corr_read_errors);

This line exceed 80 columns.
  	int d = r10_bio->devs[r10_bio->read_slot].devnum;
/* still own a reference to this rdev, so it cannot
@@ -2743,7 +2743,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
  	check_decay_read_errors(mddev, rdev);
  	atomic_inc(&rdev->read_errors);
  	if (atomic_read(&rdev->read_errors) > max_read_errors) {
-		pr_notice("md/raid10:%s: %pg: Raid device exceeded read_error threshold [cur %d:max %d]\n",
+		pr_notice("md/raid10:%s: %pg: Raid device exceeded read_error threshold [cur %u:max %u]\n",
  			  mdname(mddev), rdev->bdev,
  			  atomic_read(&rdev->read_errors), max_read_errors);
  		pr_notice("md/raid10:%s: %pg: Failing raid device\n",


This is not critical, but I think it's better do some cleanup to fold
above code into check_decay_read_errors(), and rename it to
check_read_error():

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 7135cfaf75db..633aabfea452 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2636,18 +2636,17 @@ static void recovery_request_write(struct mddev *mddev, struct r10bio *r10_bio)
  * since the last recorded read error.
  *
  */
-static void check_decay_read_errors(struct mddev *mddev, struct md_rdev *rdev)
+static bool check_read_errors(struct mddev *mddev, struct md_rdev *rdev)
 {
-       long cur_time_mon;
+       time64_t cur_time_mon = ktime_get_seconds();
        unsigned long hours_since_last;
-       unsigned int read_errors = atomic_read(&rdev->read_errors);
-
-       cur_time_mon = ktime_get_seconds();
+       unsigned int read_errors;
+       unsigned int max_read_errors;

        if (rdev->last_read_error == 0) {
                /* first time we've seen a read error */
                rdev->last_read_error = cur_time_mon;
-               return;
+               goto increase;
        }

        hours_since_last = (long)(cur_time_mon -
@@ -2660,10 +2659,26 @@ static void check_decay_read_errors(struct mddev *mddev, struct md_rdev *rdev)
         * just set read errors to 0. We do this to avoid
         * overflowing the shift of read_errors by hours_since_last.
         */
+       read_errors = atomic_read(&rdev->read_errors);
        if (hours_since_last >= 8 * sizeof(read_errors))
                atomic_set(&rdev->read_errors, 0);
        else
atomic_set(&rdev->read_errors, read_errors >> hours_since_last);
+
+increase:
+       max_read_errors = atomic_read(&mddev->max_corr_read_errors);
+       read_errors = atomic_inc_return(&rdev->read_errors);
+       if (read_errors > max_read_errors) {
+ pr_notice("md/raid10:%s: %pg: Raid device exceeded read_error threshold [cur %u:max %u]\n",
+                         mdname(mddev), rdev->bdev,
+                         read_errors, max_read_errors);
+               pr_notice("md/raid10:%s: %pg: Failing raid device\n",
+                         mdname(mddev), rdev->bdev);
+               md_error(mddev, rdev);
+               return true;
+       }
+
+       return false;
 }

 static int r10_sync_page_io(struct md_rdev *rdev, sector_t sector,
@@ -2703,7 +2718,6 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
        int sect = 0; /* Offset from r10_bio->sector */
        int sectors = r10_bio->sectors;
        struct md_rdev *rdev;
-       int max_read_errors = atomic_read(&mddev->max_corr_read_errors);
        int d = r10_bio->devs[r10_bio->read_slot].devnum;

        /* still own a reference to this rdev, so it cannot
@@ -2716,15 +2730,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
                   more fix_read_error() attempts */
                return;

-       check_decay_read_errors(mddev, rdev);
-       atomic_inc(&rdev->read_errors);
-       if (atomic_read(&rdev->read_errors) > max_read_errors) {
- pr_notice("md/raid10:%s: %pg: Raid device exceeded read_error threshold [cur %d:max %d]\n",
-                         mdname(mddev), rdev->bdev,
-                         atomic_read(&rdev->read_errors), max_read_errors);
-               pr_notice("md/raid10:%s: %pg: Failing raid device\n",
-                         mdname(mddev), rdev->bdev);
-               md_error(mddev, rdev);
+       if (check_read_errors(mddev, rdev)) {
                r10_bio->devs[r10_bio->read_slot].bio = IO_BLOCKED;
                return;
        }

Thanks,
Kuai





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