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Update the documentation for read/write iovectors

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Ronnie Sahlberg
2012-11-25 18:56:33 -08:00
parent 718c71b7a3
commit cbfb086d40
1 changed files with 16 additions and 8 deletions
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24
include/iscsi.h
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@@ -929,25 +929,33 @@ iscsi_report_supported_opcodes_sync(struct iscsi_context *iscsi, int lun,
int return_timeouts, int maxsize);
/*
* This function is used when the application wants to specify its own buffers to read the data
* from the DATA-IN PDUs into.
* The main use is for SCSI read operations to have them write directly into the application buffers to
* avoid the two copies that would occur otherwise.
* First copy from the individual DATA-IN blobs to linearize the buffer and the second in the callback
* to copy the data from the linearized buffer into the application buffer.
* These functions are used when the application wants to specify its own buffers to read the data
* from the DATA-IN PDUs into, or write the data to DATA-OUT PDUs from.
* The main use is for SCSI READ10/12/16 WRITE10/12/16 operations to have them read/write directly from
* the applications buffer, avoiding coying the data.
*
* This also supports reading into a vector of buffers by calling this function multiple times.
* The individual buffers will be filled in the same order as they were created.
*
* Example:
* Example READ10:
* task = iscsi_read10_task( ( 2 512byte blocks into two buffers)
* scsi_task_add_data_in_buffer(task, first_buffer, 512
* scsi_task_add_data_in_buffer(task, second_buffer, 512
*
*
* If you use this function you can not use task->datain in the callback.
* If you use this function you can not use task->datain in the READ callback.
* task->datain.size will be 0 and
* task->datain.data will be NULL
*
* Example WRITE10: (write 2 blocks)
* static struct scsi_iovec iov[2];
*
* task = iscsi_write10_task(iscsi, lun, 0, NULL, 512, 512, 0, 0, 0, 0, 0, callback, private_data);
* iov[0].iov_base = first_buffer;
* iov[0].iov_len = 512;
* iov[1].iov_base = second_buffer;
* iov[1].iov_len = 512;
* scsi_task_set_iov_out(task, &iov[0], 2);
*/
EXTERN int scsi_task_add_data_in_buffer(struct scsi_task *task, int len, unsigned char *buf);
EXTERN int scsi_task_add_data_out_buffer(struct scsi_task *task, int len, unsigned char *buf);