scsi: sd: sd_zbc: Improve source code documentation

Add several kernel-doc headers. Declare input arrays const. Specify the
array size in function declarations.

Link: https://lore.kernel.org/r/20220421183023.3462291-2-bvanassche@acm.orgReviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/sd.h

@@ -222,7 +222,7 @@ static inline int sd_is_zoned(struct scsi_disk *sdkp)
 #ifdef CONFIG_BLK_DEV_ZONED
 
 void sd_zbc_release_disk(struct scsi_disk *sdkp);
-int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned char *buffer);
+int sd_zbc_read_zones(struct scsi_disk *sdkp, u8 buf[SD_BUF_SIZE]);
 int sd_zbc_revalidate_zones(struct scsi_disk *sdkp);
 blk_status_t sd_zbc_setup_zone_mgmt_cmnd(struct scsi_cmnd *cmd,
 					 unsigned char op, bool all);
@@ -238,8 +238,7 @@ blk_status_t sd_zbc_prepare_zone_append(struct scsi_cmnd *cmd, sector_t *lba,
 
 static inline void sd_zbc_release_disk(struct scsi_disk *sdkp) {}
 
-static inline int sd_zbc_read_zones(struct scsi_disk *sdkp,
-				    unsigned char *buf)
+static inline int sd_zbc_read_zones(struct scsi_disk *sdkp, u8 buf[SD_BUF_SIZE])
 {
 	return 0;
 }

drivers/scsi/sd_zbc.c

@@ -20,6 +20,12 @@
 
 #include "sd.h"
 
+/**
+ * sd_zbc_get_zone_wp_offset - Get zone write pointer offset.
+ * @zone: Zone for which to return the write pointer offset.
+ *
+ * Return: offset of the write pointer from the start of the zone.
+ */
 static unsigned int sd_zbc_get_zone_wp_offset(struct blk_zone *zone)
 {
 	if (zone->type == ZBC_ZONE_TYPE_CONV)
@@ -44,7 +50,21 @@ static unsigned int sd_zbc_get_zone_wp_offset(struct blk_zone *zone)
 	}
 }
 
-static int sd_zbc_parse_report(struct scsi_disk *sdkp, u8 *buf,
+/**
+ * sd_zbc_parse_report - Parse a SCSI zone descriptor
+ * @sdkp: SCSI disk pointer.
+ * @buf: SCSI zone descriptor.
+ * @idx: Index of the zone relative to the first zone reported by the current
+ *	sd_zbc_report_zones() call.
+ * @cb: Callback function pointer.
+ * @data: Second argument passed to @cb.
+ *
+ * Return: Value returned by @cb.
+ *
+ * Convert a SCSI zone descriptor into struct blk_zone format. Additionally,
+ * call @cb(blk_zone, @data).
+ */
+static int sd_zbc_parse_report(struct scsi_disk *sdkp, const u8 buf[64],
 			       unsigned int idx, report_zones_cb cb, void *data)
 {
 	struct scsi_device *sdp = sdkp->device;
@@ -189,6 +209,17 @@ static inline sector_t sd_zbc_zone_sectors(struct scsi_disk *sdkp)
 	return logical_to_sectors(sdkp->device, sdkp->zone_blocks);
 }
 
+/**
+ * sd_zbc_report_zones - SCSI .report_zones() callback.
+ * @disk: Disk to report zones for.
+ * @sector: Start sector.
+ * @nr_zones: Maximum number of zones to report.
+ * @cb: Callback function called to report zone information.
+ * @data: Second argument passed to @cb.
+ *
+ * Called by the block layer to iterate over zone information. See also the
+ * disk->fops->report_zones() calls in block/blk-zoned.c.
+ */
 int sd_zbc_report_zones(struct gendisk *disk, sector_t sector,
 			unsigned int nr_zones, report_zones_cb cb, void *data)
 {
@@ -276,6 +307,10 @@ static int sd_zbc_update_wp_offset_cb(struct blk_zone *zone, unsigned int idx,
 	return 0;
 }
 
+/*
+ * An attempt to append a zone triggered an invalid write pointer error.
+ * Reread the write pointer of the zone(s) in which the append failed.
+ */
 static void sd_zbc_update_wp_offset_workfn(struct work_struct *work)
 {
 	struct scsi_disk *sdkp;
@@ -585,7 +620,7 @@ static int sd_zbc_check_zoned_characteristics(struct scsi_disk *sdkp,
  * sd_zbc_check_capacity - Check the device capacity
  * @sdkp: Target disk
  * @buf: command buffer
- * @zblocks: zone size in number of blocks
+ * @zblocks: zone size in logical blocks
  *
  * Get the device zone size and check that the device capacity as reported
  * by READ CAPACITY matches the max_lba value (plus one) of the report zones
@@ -696,6 +731,11 @@ static void sd_zbc_revalidate_zones_cb(struct gendisk *disk)
 	swap(sdkp->zones_wp_offset, sdkp->rev_wp_offset);
 }
 
+/*
+ * Call blk_revalidate_disk_zones() if any of the zoned disk properties have
+ * changed that make it necessary to call that function. Called by
+ * sd_revalidate_disk() after the gendisk capacity has been set.
+ */
 int sd_zbc_revalidate_zones(struct scsi_disk *sdkp)
 {
 	struct gendisk *disk = sdkp->disk;
@@ -774,7 +814,16 @@ int sd_zbc_revalidate_zones(struct scsi_disk *sdkp)
 	return ret;
 }
 
-int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned char *buf)
+/**
+ * sd_zbc_read_zones - Read zone information and update the request queue
+ * @sdkp: SCSI disk pointer.
+ * @buf: 512 byte buffer used for storing SCSI command output.
+ *
+ * Read zone information and update the request queue zone characteristics and
+ * also the zoned device information in *sdkp. Called by sd_revalidate_disk()
+ * before the gendisk capacity has been set.
+ */
+int sd_zbc_read_zones(struct scsi_disk *sdkp, u8 buf[SD_BUF_SIZE])
 {
 	struct gendisk *disk = sdkp->disk;
 	struct request_queue *q = disk->queue;