null_blk: support read-only and offline zone conditions

In zoned mode, zones with write pointers can have conditions "read-only"
or "offline". In read-only condition, zones can not be written. In
offline condition, the zones can be neither written nor read. These
conditions are intended for zones with media failures, then it is
difficult to set those conditions to zones on real devices.

To test handling of zones in the conditions, add a feature to null_blk
to set up zones in read-only or offline condition. Add new configuration
attributes "zone_readonly" and "zone_offline". Write a sector to the
attribute files to specify the target zone to set the zone conditions.
For example, following command lines do it:

   echo 0 > nullb1/zone_readonly
   echo 524288 > nullb1/zone_offline

When the specified zones are already in read-only or offline condition,
normal empty condition is restored to the zones. These condition changes
can be done only after the null_blk device get powered, since status
area of each zone is not yet allocated before power-on.

Also improve zone condition checks to inhibit all commands for zones in
offline conditions. In same manner, inhibit write and zone management
commands for zones in read-only condition.

Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Link: https://lore.kernel.org/r/20221201061036.2342206-1-shinichiro.kawasaki@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index 94ff68052b1e..eb5972c50be8 100644
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -151,6 +151,8 @@ blk_status_t null_process_zoned_cmd(struct nullb_cmd *cmd, enum req_op op,
 				    sector_t sector, sector_t nr_sectors);
 size_t null_zone_valid_read_len(struct nullb *nullb,
 				sector_t sector, unsigned int len);
+ssize_t zone_cond_store(struct nullb_device *dev, const char *page,
+			size_t count, enum blk_zone_cond cond);
 #else
 static inline int null_init_zoned_dev(struct nullb_device *dev,
 				      struct request_queue *q)
@@ -174,6 +176,12 @@ static inline size_t null_zone_valid_read_len(struct nullb *nullb,
 {
 	return len;
 }
+static inline ssize_t zone_cond_store(struct nullb_device *dev,
+				      const char *page, size_t count,
+				      enum blk_zone_cond cond)
+{
+	return -EOPNOTSUPP;
+}
 #define null_report_zones	NULL
 #endif /* CONFIG_BLK_DEV_ZONED */
 #endif /* __NULL_BLK_H */