Author: trasz
Date: Sun May 4 15:35:04 2014
New Revision: 265323
URL: http://svnweb.freebsd.org/changeset/base/265323
Log:
Provide better descriptions for 'struct ctl_scsiio' fields; based mostly
on emails from ken@.
Modified:
head/sys/cam/ctl/ctl_io.h
Modified: head/sys/cam/ctl/ctl_io.h
==============================================================================
--- head/sys/cam/ctl/ctl_io.h Sun May 4 15:05:53 2014 (r265322)
+++ head/sys/cam/ctl/ctl_io.h Sun May 4 15:35:04 2014 (r265323)
@@ -293,21 +293,60 @@ union ctl_io;
*/
struct ctl_scsiio {
struct ctl_io_hdr io_hdr; /* common to all I/O types */
+
+ /*
+ * The ext_* fields are generally intended for frontend use; CTL itself
+ * doesn't modify or use them.
+ */
uint32_t ext_sg_entries; /* 0 = no S/G list, > 0 = num entries */
uint8_t *ext_data_ptr; /* data buffer or S/G list */
uint32_t ext_data_len; /* Data transfer length */
uint32_t ext_data_filled; /* Amount of data filled so far */
- uint32_t kern_sg_entries; /* 0 = no S/G list, > 0 = num entries */
- uint32_t rem_sg_entries; /* 0 = no S/G list, > 0 = num entries */
- uint8_t *kern_data_ptr; /* data buffer or S/G list */
- uint32_t kern_data_len; /* Length of this S/G list/buffer */
- uint32_t kern_total_len; /* Total length of this transaction */
- uint32_t kern_data_resid; /* Length left to transfer after this*/
- uint32_t kern_rel_offset; /* Byte Offset of this transfer */
+
+ /*
+ * The number of scatter/gather entries in the list pointed to
+ * by kern_data_ptr. 0 means there is no list, just a data pointer.
+ */
+ uint32_t kern_sg_entries;
+
+ uint32_t rem_sg_entries; /* Unused. */
+
+ /*
+ * The data pointer or a pointer to the scatter/gather list.
+ */
+ uint8_t *kern_data_ptr;
+
+ /*
+ * Length of the data buffer or scatter/gather list. It's also
+ * the length of this particular piece of the data transfer,
+ * ie. number of bytes expected to be transferred by the current
+ * invocation of frontend's datamove() callback. It's always
+ * less than or equal to kern_total_len.
+ */
+ uint32_t kern_data_len;
+
+ /*
+ * Total length of data to be transferred during this particular
+ * SCSI command, as decoded from SCSI CDB.
+ */
+ uint32_t kern_total_len;
+
+ /*
+ * Amount of data left after the current data transfer.
+ */
+ uint32_t kern_data_resid;
+
+ /*
+ * Byte offset of this transfer, equal to the amount of data
+ * already transferred for this SCSI command during previous
+ * datamove() invocations.
+ */
+ uint32_t kern_rel_offset;
+
struct scsi_sense_data sense_data; /* sense data */
uint8_t sense_len; /* Returned sense length */
uint8_t scsi_status; /* SCSI status byte */
- uint8_t sense_residual; /* sense residual length */
+ uint8_t sense_residual; /* Unused. */
uint32_t residual; /* data residual length */
uint32_t tag_num; /* tag number */
ctl_tag_type tag_type; /* simple, ordered, head of queue,etc.*/
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