null_blk: introduce badblocks_once parameter

When IO errors happen on real storage devices, the IOs repeated to the
same target range can success by virtue of recovery features by devices,
such as reserved block assignment. To simulate such IO errors and
recoveries, introduce the new parameter badblocks_once parameter. When
this parameter is set to 1, the specified badblocks are cleared after
the first IO error, so that the next IO to the blocks succeed.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://lore.kernel.org/r/20250226100613.1622564-3-shinichiro.kawasaki@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 0725d221cff49ea975e0c3b88f2d7dc6268454ec..2a060a6ea8c0b1c296067758103318c4854599f5 100644 (file)
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -473,6 +473,7 @@ NULLB_DEVICE_ATTR(shared_tags, bool, NULL);
 NULLB_DEVICE_ATTR(shared_tag_bitmap, bool, NULL);
 NULLB_DEVICE_ATTR(fua, bool, NULL);
 NULLB_DEVICE_ATTR(rotational, bool, NULL);
+NULLB_DEVICE_ATTR(badblocks_once, bool, NULL);
 
 static ssize_t nullb_device_power_show(struct config_item *item, char *page)
 {
@@ -593,6 +594,7 @@ CONFIGFS_ATTR_WO(nullb_device_, zone_offline);
 
 static struct configfs_attribute *nullb_device_attrs[] = {
        &nullb_device_attr_badblocks,
+       &nullb_device_attr_badblocks_once,
        &nullb_device_attr_blocking,
        &nullb_device_attr_blocksize,
        &nullb_device_attr_cache_size,
@@ -1315,10 +1317,13 @@ static inline blk_status_t null_handle_badblocks(struct nullb_cmd *cmd,
        sector_t first_bad;
        int bad_sectors;
 
-       if (badblocks_check(bb, sector, nr_sectors, &first_bad, &bad_sectors))
-               return BLK_STS_IOERR;
+       if (!badblocks_check(bb, sector, nr_sectors, &first_bad, &bad_sectors))
+               return BLK_STS_OK;
 
-       return BLK_STS_OK;
+       if (cmd->nq->dev->badblocks_once)
+               badblocks_clear(bb, first_bad, bad_sectors);
+
+       return BLK_STS_IOERR;
 }
 
 static inline blk_status_t null_handle_memory_backed(struct nullb_cmd *cmd,

diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index 6f9fe6171087045673633083db34ac0e3c7a8030..3c4c07f0418b06593a3074843316c249be3d05f8 100644 (file)
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -63,6 +63,7 @@ struct nullb_device {
        unsigned long flags; /* device flags */
        unsigned int curr_cache;
        struct badblocks badblocks;
+       bool badblocks_once;
 
        unsigned int nr_zones;
        unsigned int nr_zones_imp_open;