[PATCH 08/23] nvmet: add context annotation for nvmet_ns::blksize_shift

[Nilay Shroff <nilay@linux.ibm.com>]

The nvmet_ns::blksize_shift field is protected by nvmet_subsys::lock.
Annotate it with __guarded_by(&subsys->lock) to allow the Clang context
analyzer to validate accesses to this field.

The I/O hotpath also accesses nvmet_ns::blksize_shift without holding
subsys->lock. This is safe because the namespace reference held by the
I/O request prevents the namespace from being modified while the I/O is
in flight.

Introduce nvmet_ns_blksize_shift(), annotated with __context_unsafe(),
to allow these lockless accesses without triggering context analyzer
warnings. Use this accessor at all relevant call sites that access
blksize_shift without holding subsys->lock, including the namespace
identify, block I/O, file I/O, ZNS, and common LBA/sector conversion
paths.

Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
---
 drivers/nvme/target/admin-cmd.c   |  4 ++--
 drivers/nvme/target/io-cmd-bdev.c |  4 ++--
 drivers/nvme/target/io-cmd-file.c | 12 +++++++-----
 drivers/nvme/target/nvmet.h       | 10 ++++++----
 drivers/nvme/target/zns.c         |  2 +-
 5 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
index 761caac84255..4302dba7c000 100644
--- a/drivers/nvme/target/admin-cmd.c
+++ b/drivers/nvme/target/admin-cmd.c
@@ -891,7 +891,7 @@ static void nvmet_execute_identify_ns(struct nvmet_req *req)
 	 * that out from the underlying device.
 	 */
 	id->ncap = id->nsze =
-		cpu_to_le64(req->ns->size >> req->ns->blksize_shift);
+		cpu_to_le64(req->ns->size >> nvmet_ns_blksize_shift(req->ns));
 	switch (req->port->ana_state[req->ns->anagrpid]) {
 	case NVME_ANA_INACCESSIBLE:
 	case NVME_ANA_PERSISTENT_LOSS:
@@ -935,7 +935,7 @@ static void nvmet_execute_identify_ns(struct nvmet_req *req)
 
 	memcpy(&id->nguid, &req->ns->nguid, sizeof(id->nguid));
 
-	id->lbaf[0].ds = req->ns->blksize_shift;
+	id->lbaf[0].ds = nvmet_ns_blksize_shift(req->ns);
 
 	if (req->sq->ctrl->pi_support && nvmet_ns_has_pi(req->ns)) {
 		id->dpc = NVME_NS_DPC_PI_FIRST | NVME_NS_DPC_PI_LAST |
diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index 7c263cb169a8..e950b442ffc6 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -393,7 +393,7 @@ static void nvmet_bdev_execute_discard(struct nvmet_req *req)
 			break;
 
 		nr_sects = (sector_t)le32_to_cpu(range.nlb) <<
-			   (ns->blksize_shift - 9);
+			   (nvmet_ns_blksize_shift(ns) - 9);
 		__blkdev_issue_discard(nvmet_ns_bdev(ns),
 				nvmet_lba_to_sect(ns, range.slba), nr_sects,
 				GFP_KERNEL, &bio);
@@ -442,7 +442,7 @@ static void nvmet_bdev_execute_write_zeroes(struct nvmet_req *req)
 
 	sector = nvmet_lba_to_sect(req->ns, write_zeroes->slba);
 	nr_sector = (((sector_t)le16_to_cpu(write_zeroes->length) + 1) <<
-		(req->ns->blksize_shift - 9));
+		(nvmet_ns_blksize_shift(req->ns) - 9));
 
 	ret = __blkdev_issue_zeroout(nvmet_ns_bdev(req->ns), sector, nr_sector,
 			GFP_KERNEL, &bio, 0);
diff --git a/drivers/nvme/target/io-cmd-file.c b/drivers/nvme/target/io-cmd-file.c
index 4307232c9160..90dbfbd16978 100644
--- a/drivers/nvme/target/io-cmd-file.c
+++ b/drivers/nvme/target/io-cmd-file.c
@@ -131,7 +131,7 @@ static bool nvmet_file_execute_io(struct nvmet_req *req, int ki_flags)
 	if (req->f.mpool_alloc && nr_bvec > NVMET_MAX_MPOOL_BVEC)
 		is_sync = true;
 
-	pos = le64_to_cpu(req->cmd->rw.slba) << req->ns->blksize_shift;
+	pos = le64_to_cpu(req->cmd->rw.slba) << nvmet_ns_blksize_shift(req->ns);
 	if (unlikely(pos + req->transfer_len > req->ns->size)) {
 		ret = -ENOSPC;
 		goto complete;
@@ -297,9 +297,10 @@ static void nvmet_file_execute_discard(struct nvmet_req *req)
 		if (status)
 			break;
 
-		offset = le64_to_cpu(range.slba) << req->ns->blksize_shift;
+		offset = le64_to_cpu(range.slba) <<
+				nvmet_ns_blksize_shift(req->ns);
 		len = le32_to_cpu(range.nlb);
-		len <<= req->ns->blksize_shift;
+		len <<= nvmet_ns_blksize_shift(req->ns);
 		if (offset + len > req->ns->size) {
 			req->error_slba = le64_to_cpu(range.slba);
 			status = errno_to_nvme_status(req, -ENOSPC);
@@ -351,9 +352,10 @@ static void nvmet_file_write_zeroes_work(struct work_struct *w)
 	loff_t len;
 	int ret;
 
-	offset = le64_to_cpu(write_zeroes->slba) << req->ns->blksize_shift;
+	offset = le64_to_cpu(write_zeroes->slba) <<
+			nvmet_ns_blksize_shift(req->ns);
 	len = (((sector_t)le16_to_cpu(write_zeroes->length) + 1) <<
-			req->ns->blksize_shift);
+			nvmet_ns_blksize_shift(req->ns));
 
 	if (unlikely(offset + len > req->ns->size)) {
 		nvmet_req_complete(req, errno_to_nvme_status(req, -ENOSPC));
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index d03e059d6d16..1ea0566b8eea 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -159,7 +159,8 @@ struct nvmet_ns {
 		__guarded_by(&subsys->lock);
 	u32			nsid
 		__guarded_by(&subsys->lock);
-	u32			blksize_shift;
+	u32			blksize_shift
+		__guarded_by(&subsys->lock);
 	loff_t			size;
 	u8			nguid[16];
 	uuid_t			uuid;
@@ -207,6 +208,7 @@ static inline _type nvmet_ns_##_name(struct nvmet_ns *ns)		    \
 NVMET_NS_ACCESSOR(struct block_device *, bdev)
 NVMET_NS_ACCESSOR(struct file *, file)
 NVMET_NS_ACCESSOR(u32, nsid)
+NVMET_NS_ACCESSOR(u32, blksize_shift)
 
 /*
  * These accessors use data_race() and READ_ONCE() to allow lockless access to
@@ -807,7 +809,7 @@ void nvmet_bdev_execute_zone_append(struct nvmet_req *req);
 static inline u32 nvmet_rw_data_len(struct nvmet_req *req)
 {
 	return ((u32)le16_to_cpu(req->cmd->rw.length) + 1) <<
-			req->ns->blksize_shift;
+			nvmet_ns_blksize_shift(req->ns);
 }
 
 static inline u32 nvmet_rw_metadata_len(struct nvmet_req *req)
@@ -1000,12 +1002,12 @@ static inline bool nvmet_ns_has_pi(struct nvmet_ns *ns)
 
 static inline __le64 nvmet_sect_to_lba(struct nvmet_ns *ns, sector_t sect)
 {
-	return cpu_to_le64(sect >> (ns->blksize_shift - SECTOR_SHIFT));
+	return cpu_to_le64(sect >> (nvmet_ns_blksize_shift(ns) - SECTOR_SHIFT));
 }
 
 static inline sector_t nvmet_lba_to_sect(struct nvmet_ns *ns, __le64 lba)
 {
-	return le64_to_cpu(lba) << (ns->blksize_shift - SECTOR_SHIFT);
+	return le64_to_cpu(lba) << (nvmet_ns_blksize_shift(ns) - SECTOR_SHIFT);
 }
 
 static inline bool nvmet_use_inline_bvec(struct nvmet_req *req)
diff --git a/drivers/nvme/target/zns.c b/drivers/nvme/target/zns.c
index ce5309453668..9afea37862ef 100644
--- a/drivers/nvme/target/zns.c
+++ b/drivers/nvme/target/zns.c
@@ -122,7 +122,7 @@ void nvmet_execute_identify_ns_zns(struct nvmet_req *req)
 	}
 
 	zsze = (bdev_zone_sectors(nvmet_ns_bdev(req->ns)) << 9) >>
-					req->ns->blksize_shift;
+					nvmet_ns_blksize_shift(req->ns);
 	id_zns->lbafe[0].zsze = cpu_to_le64(zsze);
 
 	mor = bdev_max_open_zones(nvmet_ns_bdev(req->ns));
-- 
2.53.0