[PATCH v8 10/11] scsi: scsi_debug: Map the region written by WRITE ATOMIC (16)

[Niklas Cassel <cassel@kernel.org>]

When logical block provisioning is enabled, every command that writes
user data calls map_region() so that GET LBA STATUS reports the region
as mapped. resp_atomic_write() does not, so GET LBA STATUS keeps
reporting a region as deallocated after a WRITE ATOMIC (16) has written
it.

Call map_region() the way resp_write_dt0() does, holding the zone
metadata write lock across the access. That lock is what serialises the
map against resp_unmap(), which does nothing unless logical block
provisioning is enabled.

Assisted-by: LLM
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: John Garry <john.garry@linux.dev>
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 v7: a comment above map_region() explains why its callers
may map more than was written, as John suggested.
---
 drivers/scsi/scsi_debug.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index c0bcf8155fc8..0ae0a6ac3baa 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -4876,6 +4876,11 @@ static unsigned int map_state(struct sdeb_store_info *sip, sector_t lba,
 	return mapped;
 }
 
+/*
+ * Callers may map the whole range of a write without checking how much of
+ * it was written. SBC-6 4.7.4.6.2 allows a deallocated LBA to become mapped
+ * at any time, and only requires an LBA that was written to be mapped.
+ */
 static void map_region(struct sdeb_store_info *sip, sector_t lba,
 		       unsigned int len)
 {
@@ -6203,6 +6208,7 @@ 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()) {
@@ -6251,7 +6257,15 @@ static int resp_atomic_write(struct scsi_cmnd *scp,
 	if (scsi_bufflen(scp) < len * sdebug_sector_size)
 		return DID_ERROR << 16;
 
+	if (lbp)
+		sdeb_meta_write_lock(sip);
+
 	ret = do_device_access(sip, scp, 0, lba, len, 0, true, true);
+	if (lbp) {
+		map_region(sip, lba, len);
+		sdeb_meta_write_unlock(sip);
+	}
+
 	if (unlikely(ret == -1))
 		return DID_ERROR << 16;
 	if (unlikely(ret != len * sdebug_sector_size))
-- 
2.55.0