Re: [PATCH v2 3/4] md/raid10: fix wrong setting of max_corr_read_errors

From: Yu Kuai
Date: Fri May 12 2023 - 22:21:54 EST


在 2023/05/13 9:08, Song Liu 写道:
On Fri, May 5, 2023 at 7:02 PM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:


在 2023/05/06 9:23, 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.

Looks good, feel free to add:

Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>

Fixes: 1e50915fe0bb ("raid: improve MD/raid10 handling of correctable read errors.")
Signed-off-by: Li Nan <linan122@xxxxxxxxxx>

Hmm.. Does the current code break in any cases?

The problem is that somewhere use unsigned value, and somewhere use
signed value, and I thinsk the only functional change is in
fix_read_error(), if max_read_errors is negative, the judgement will
always pass before this patch:

if (atomic_read(&rdev->read_errors) > max_read_errors)



drivers/md/md.c | 2 +-
drivers/md/raid10.c | 5 +++--
2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index fd5c3babcd6d..4a1e566d6bdc 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4486,7 +4486,7 @@ __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",

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 4fcfcb350d2b..4d615fcc6a50 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2727,7 +2727,8 @@ 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);
int d = r10_bio->devs[r10_bio->read_slot].devnum;

/* still own a reference to this rdev, so it cannot
@@ -2743,7 +2744,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
check_decay_read_errors(mddev, rdev);
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",