[PATCH v5 09/10] scsi: scsi_debug: Map the region written by WRITE ATOMIC (16)

[Niklas Cassel <cassel@kernel.org>]

When logical block provisioning is enabled, a command that writes user
data marks the region that it wrote in the provisioning map, so that
GET LBA STATUS reports the region as mapped. resp_write_dt0(),
resp_write_scat() and resp_write_same() all call map_region() for that.

resp_atomic_write() does not, so a WRITE ATOMIC (16) leaves the
provisioning map untouched, and GET LBA STATUS keeps reporting the
region as deallocated after it has been written. map_state(), which
GET LBA STATUS uses, is the only reader of the map, so that is the whole
of the effect.

Call map_region() the way resp_write_dt0() does, and take the zone
metadata write lock across the access as it does when logical block
provisioning is enabled. That lock is what serialises the provisioning
map against resp_unmap(), which holds it while unmap_region() clears map
bits and zeroes the data that they cover. resp_unmap() does nothing
unless logical block provisioning is enabled, so the lock is only needed
in that case.

Assisted-by: LLM
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Fixes: 84f3a3c01d70 ("scsi: scsi_debug: Atomic write support")
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
Tested with:

  modprobe scsi_debug sector_size=512 physblk_exp=3 dev_size_mb=128 \
      atomic_wr=1 lbpu=1

GET LBA STATUS reports a region that has never been written as
deallocated, and reports it as mapped after a WRITE ATOMIC (16) of eight
blocks. Only an ordinary WRITE did so before this patch.
---

Changes since v4: the meta_data_locked variable is gone, as suggested.
 drivers/scsi/scsi_debug.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index d07f6f891951..2e1a02c383a3 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -6202,6 +6202,7 @@ static int resp_atomic_write(struct scsi_cmnd *scp,
 	u8 *cmd = scp->cmnd;
 	u16 boundary, len;
 	u64 lba, lba_tmp;
+	bool lbp = scsi_debug_lbp();
 	int ret;
 
 	if (!scsi_debug_atomic_write()) {
@@ -6246,7 +6247,16 @@ static int resp_atomic_write(struct scsi_cmnd *scp,
 		}
 	}
 
+	if (lbp)
+		sdeb_meta_write_lock(sip);
+
 	ret = do_device_access(sip, scp, 0, lba, len, 0, true, true);
+	if (unlikely(lbp))
+		map_region(sip, lba, len);
+
+	if (lbp)
+		sdeb_meta_write_unlock(sip);
+
 	if (unlikely(ret == -1))
 		return DID_ERROR << 16;
 	if (unlikely(ret != len * sdebug_sector_size))
-- 
2.55.0