Fix comments style (use kernel-doc style) and content to clarify some
functions. Also fix some functions signature indentation and remove a
useless blank line in sd_zbc_read_zones().
No functional change is introduced by this patch.
Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
drivers/scsi/scsi_lib.c | 5 ++-
drivers/scsi/sd_zbc.c | 117 +++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 104 insertions(+), 18 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 9cf6a80fe297..c72b97a74906 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1752,7 +1752,10 @@ static void scsi_done(struct scsi_cmnd *cmd)
*
* Returns: Nothing
*
- * Lock status: IO request lock assumed to be held when called.
+ * Lock status: request queue lock assumed to be held when called.
+ *
+ * Note: See sd_zbc.c sd_zbc_write_lock_zone() for write order
+ * protection for ZBC disks.
*/
static void scsi_request_fn(struct request_queue *q)
__releases(q->queue_lock)
diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
index 692c8cbc7ed8..023f705ae235 100644
--- a/drivers/scsi/sd_zbc.c
+++ b/drivers/scsi/sd_zbc.c
@@ -32,10 +32,14 @@
#include "sd.h"
/**
- * Convert a zone descriptor to a zone struct.
+ * sd_zbc_parse_report - Convert a zone descriptor to a struct blk_zone,
+ * @sdkp: The disk the report originated from
+ * @buf: Address of the report zone descriptor
+ * @zone: the destination zone structure
+ *
+ * All LBA sized values are converted to 512B sectors unit.
*/
-static void sd_zbc_parse_report(struct scsi_disk *sdkp,
- u8 *buf,
+static void sd_zbc_parse_report(struct scsi_disk *sdkp, u8 *buf,
struct blk_zone *zone)
{
struct scsi_device *sdp = sdkp->device;
@@ -58,7 +62,13 @@ static void sd_zbc_parse_report(struct scsi_disk *sdkp,
}
/**
- * Issue a REPORT ZONES scsi command.
+ * sd_zbc_report_zones - Issue a REPORT ZONES scsi command.
+ * @sdkp: The target disk
+ * @buf: Buffer to use for the reply
+ * @buflen: the buffer size
+ * @lba: Start LBA of the report
+ *
+ * For internal use during device validation.
*/
static int sd_zbc_report_zones(struct scsi_disk *sdkp, unsigned char *buf,
unsigned int buflen, sector_t lba)
@@ -99,6 +109,12 @@ static int sd_zbc_report_zones(struct scsi_disk *sdkp, unsigned char *buf,
return 0;
}
+/**
+ * sd_zbc_setup_report_cmnd - Prepare a REPORT ZONES scsi command
+ * @cmd: The command to setup
+ *
+ * Call in sd_init_command() for a REQ_OP_ZONE_REPORT request.
+ */
int sd_zbc_setup_report_cmnd(struct scsi_cmnd *cmd)
{
struct request *rq = cmd->request;
@@ -141,6 +157,14 @@ int sd_zbc_setup_report_cmnd(struct scsi_cmnd *cmd)
return BLKPREP_OK;
}
+/**
+ * sd_zbc_report_zones_complete - Process a REPORT ZONES scsi command reply.
+ * @scmd: The completed report zones command
+ * @good_bytes: reply size in bytes
+ *
+ * Convert all reported zone descriptors to struct blk_zone. The conversion
+ * is done in-place, directly in the request specified sg buffer.
+ */
static void sd_zbc_report_zones_complete(struct scsi_cmnd *scmd,
unsigned int good_bytes)
{
@@ -196,17 +220,32 @@ static void sd_zbc_report_zones_complete(struct scsi_cmnd *scmd,
local_irq_restore(flags);
}
+/**
+ * sd_zbc_zone_sectors - Get the device zone size in number of 512B sectors.
+ * @sdkp: The target disk
+ */
static inline sector_t sd_zbc_zone_sectors(struct scsi_disk *sdkp)
{
return logical_to_sectors(sdkp->device, sdkp->zone_blocks);
}
+/**
+ * sd_zbc_zone_no - Get the number of the zone conataining a sector.
+ * @sdkp: The target disk
+ * @sector: 512B sector address contained in the zone
+ */
static inline unsigned int sd_zbc_zone_no(struct scsi_disk *sdkp,
sector_t sector)
{
return sectors_to_logical(sdkp->device, sector) >> sdkp->zone_shift;
}
+/**
+ * sd_zbc_setup_reset_cmnd - Prepare a RESET WRITE POINTER scsi command.
+ * @cmd: the command to setup
+ *
+ * Called from sd_init_command() for a REQ_OP_ZONE_RESET request.
+ */
int sd_zbc_setup_reset_cmnd(struct scsi_cmnd *cmd)
{
struct request *rq = cmd->request;
@@ -239,6 +278,23 @@ int sd_zbc_setup_reset_cmnd(struct scsi_cmnd *cmd)
return BLKPREP_OK;
}
+/**
+ * sd_zbc_write_lock_zone - Write lock a sequential zone.
+ * @cmd: write command
+ *
+ * Called from sd_init_cmd() for write requests (standard write, write same or
+ * write zeroes operations). If the request target zone is not already locked,
+ * the zone is locked and BLKPREP_OK returned, allowing the request to proceed
+ * through dispatch in scsi_request_fn(). Otherwise, BLKPREP_DEFER is returned,
+ * forcing the request to wait for the zone to be unlocked, that is, for the
+ * previously issued write request targeting the same zone to complete.
+ *
+ * This is called from blk_peek_request() context with the queue lock held and
+ * before the request is removed from the scheduler. As a result, multiple
+ * contexts executing concurrently scsi_request_fn() cannot result in write
+ * sequence reordering as only a single write request per zone is allowed to
+ * proceed.
+ */
int sd_zbc_write_lock_zone(struct scsi_cmnd *cmd)
{
struct request *rq = cmd->request;
@@ -261,10 +317,7 @@ int sd_zbc_write_lock_zone(struct scsi_cmnd *cmd)
* Do not issue more than one write at a time per
* zone. This solves write ordering problems due to
* the unlocking of the request queue in the dispatch
- * path in the non scsi-mq case. For scsi-mq, this
- * also avoids potential write reordering when multiple
- * threads running on different CPUs write to the same
- * zone (with a synchronized sequential pattern).
+ * path in the non scsi-mq case.
*/
if (sdkp->zones_wlock &&
test_and_set_bit(zno, sdkp->zones_wlock))
@@ -276,6 +329,13 @@ int sd_zbc_write_lock_zone(struct scsi_cmnd *cmd)
return BLKPREP_OK;
}
+/**
+ * sd_zbc_write_unlock_zone - Write unlock a sequential zone.
+ * @cmd: write command
+ *
+ * Called from sd_uninit_cmd(). Unlocking the request target zone will allow
+ * dispatching the next write request for the zone.
+ */
void sd_zbc_write_unlock_zone(struct scsi_cmnd *cmd)
{
struct request *rq = cmd->request;
@@ -290,8 +350,16 @@ void sd_zbc_write_unlock_zone(struct scsi_cmnd *cmd)
}
}
-void sd_zbc_complete(struct scsi_cmnd *cmd,
- unsigned int good_bytes,
+/**
+ * sd_zbc_complete - ZBC command post processing.
+ * @cmd: Completed command
+ * @good_bytes: Command reply bytes
+ * @sshdr: command sense header
+ *
+ * Called from sd_done(). Process report zones reply and handle reset zone
+ * and write commands errors.
+ */
+void sd_zbc_complete(struct scsi_cmnd *cmd, unsigned int good_bytes,
struct scsi_sense_hdr *sshdr)
{
int result = cmd->result;
@@ -336,7 +404,11 @@ void sd_zbc_complete(struct scsi_cmnd *cmd,
}
/**
- * Read zoned block device characteristics (VPD page B6).
+ * sd_zbc_read_zoned_characteristics - Read zoned block device characteristics
+ * @sdkp: Target disk
+ * @buf: Buffer where to store the VPD page data
+ *
+ * Read VPD page B6.
*/
static int sd_zbc_read_zoned_characteristics(struct scsi_disk *sdkp,
unsigned char *buf)
@@ -366,10 +438,16 @@ static int sd_zbc_read_zoned_characteristics(struct scsi_disk *sdkp,
}
/**
- * Check reported capacity.
+ * sd_zbc_check_capacity - Check reported capacity.
+ * @sdkp: Target disk
+ * @buf: Buffer to use for commands
+ *
+ * ZBC drive may report only the capacity of the first conventional zones at
+ * LBA 0. This is indicated by the RC_BASIS field of the read capacity reply.
+ * Check this here. If the disk reported only its conventional zones capacity,
+ * get the total capacity by doing a report zones.
*/
-static int sd_zbc_check_capacity(struct scsi_disk *sdkp,
- unsigned char *buf)
+static int sd_zbc_check_capacity(struct scsi_disk *sdkp, unsigned char *buf)
{
sector_t lba;
int ret;
@@ -399,6 +477,13 @@ static int sd_zbc_check_capacity(struct scsi_disk *sdkp,
#define SD_ZBC_BUF_SIZE 131072
+/**
+ * sd_zbc_check_zone_size - Check the device zone sizes
+ * @sdkp: Target disk
+ *
+ * Check that all zones of the device are equal. The last zone can however
+ * be smaller. The zone size must also be a power of two number of LBAs.
+ */
static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)
{
u64 zone_blocks;
@@ -525,8 +610,7 @@ static int sd_zbc_setup(struct scsi_disk *sdkp)
return 0;
}
-int sd_zbc_read_zones(struct scsi_disk *sdkp,
- unsigned char *buf)
+int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned char *buf)
{
int ret;
@@ -537,7 +621,6 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp,
*/
return 0;
-
/* Get zoned block device characteristics */
ret = sd_zbc_read_zoned_characteristics(sdkp, buf);
if (ret)
--
2.13.6
