null_blk: Fix zoned command handling

For write operations issued to a null_blk device with zoned mode
enabled, the state and write pointer position of the zone targeted by
the command should be checked before badblocks and memory backing
are handled as the write may be first failed due to, for instance, a
sector position not aligned with the zone write pointer. This order of
checking for errors reflects more accuratly the behavior of physical
zoned devices.

Furthermore, the write pointer position of the target zone should be
incremented only and only if no errors are reported by badblocks and
memory backing handling.

To fix this, introduce the small helper function null_process_cmd()
which execute null_handle_badblocks() and null_handle_memory_backed()
and use this function in null_zone_write() to correctly handle write
requests to zoned null devices depending on the type and state of the
write target zone. Also call this function in null_handle_zoned() to
process read requests to zoned null devices.

null_process_cmd() is called directly from null_handle_cmd() for
regular null devices, resulting in no functional change for these type
of devices. To have symmetric names, the function null_handle_zoned()
is renamed to null_process_zoned_cmd().

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 24 insertions, 11 deletions

diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
index 4e1c0712278e..8335e2b04aac 100644
--- a/drivers/block/null_blk_main.c
+++ b/drivers/block/null_blk_main.c
@@ -1276,6 +1276,25 @@ static inline void nullb_complete_cmd(struct nullb_cmd *cmd)
 	}
 }
 
+blk_status_t null_process_cmd(struct nullb_cmd *cmd,
+			      enum req_opf op, sector_t sector,
+			      unsigned int nr_sectors)
+{
+	struct nullb_device *dev = cmd->nq->dev;
+	blk_status_t ret;
+
+	if (dev->badblocks.shift != -1) {
+		ret = null_handle_badblocks(cmd, sector, nr_sectors);
+		if (ret != BLK_STS_OK)
+			return ret;
+	}
+
+	if (dev->memory_backed)
+		return null_handle_memory_backed(cmd, op);
+
+	return BLK_STS_OK;
+}
+
 static blk_status_t null_handle_cmd(struct nullb_cmd *cmd, sector_t sector,
 				    sector_t nr_sectors, enum req_opf op)
 {
@@ -1294,17 +1313,11 @@ static blk_status_t null_handle_cmd(struct nullb_cmd *cmd, sector_t sector,
 		goto out;
 	}
 
-	if (nullb->dev->badblocks.shift != -1) {
-		cmd->error = null_handle_badblocks(cmd, sector, nr_sectors);
-		if (cmd->error != BLK_STS_OK)
-			goto out;
-	}
-
-	if (dev->memory_backed)
-		cmd->error = null_handle_memory_backed(cmd, op);
-
-	if (!cmd->error && dev->zoned)
-		cmd->error = null_handle_zoned(cmd, op, sector, nr_sectors);
+	if (dev->zoned)
+		cmd->error = null_process_zoned_cmd(cmd, op,
+						    sector, nr_sectors);
+	else
+		cmd->error = null_process_cmd(cmd, op, sector, nr_sectors);
 
 out:
 	nullb_complete_cmd(cmd);