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iscsi-target: Fix sendpage breakage with proper padding+DataDigest iovec offsets 

This patch fixes a bug in the iscsit_fe_sendpage_sg() transmit codepath that
was originally introduced with the v3.1 iscsi-target merge that incorrectly
uses hardcoded cmd->iov_data_count values to determine cmd->iov_data[] offsets
for extra outgoing padding and DataDigest payload vectors.

This code is obviously incorrect for the DataDigest enabled case with sendpage
offload, and this fix ensures correct operation for padding + DataDigest,
padding only, and DataDigest only cases.  The bug was introduced during a
pre-merge change in iscsit_fe_sendpage_sg() to natively use struct scatterlist
instead of the legacy v3.0 struct se_mem logic.

Cc: Andy Grover <agrover@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Nicholas Bellinger 2011-09-16 16:55:47 -07:00
parent 2ff017f5b4
commit 40b054970a
1 changed files with 15 additions and 7 deletions
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22
drivers/target/iscsi/iscsi_target_util.c
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@ -1256,7 +1256,7 @@ int iscsit_fe_sendpage_sg(
struct kvec iov;
u32 tx_hdr_size, data_len;
u32 offset = cmd->first_data_sg_off;
int tx_sent;
int tx_sent, iov_off;
send_hdr:
tx_hdr_size = ISCSI_HDR_LEN;
@ -1276,9 +1276,19 @@ send_hdr:
}
data_len = cmd->tx_size - tx_hdr_size - cmd->padding;
if (conn->conn_ops->DataDigest)
/*
* Set iov_off used by padding and data digest tx_data() calls below
* in order to determine proper offset into cmd->iov_data[]
*/
if (conn->conn_ops->DataDigest) {
data_len -= ISCSI_CRC_LEN;
if (cmd->padding)
iov_off = (cmd->iov_data_count - 2);
else
iov_off = (cmd->iov_data_count - 1);
} else {
iov_off = (cmd->iov_data_count - 1);
}
/*
* Perform sendpage() for each page in the scatterlist
*/
@ -1307,8 +1317,7 @@ send_pg:
send_padding:
if (cmd->padding) {
struct kvec *iov_p =
&cmd->iov_data[cmd->iov_data_count-1];
struct kvec *iov_p = &cmd->iov_data[iov_off++];
tx_sent = tx_data(conn, iov_p, 1, cmd->padding);
if (cmd->padding != tx_sent) {
@ -1322,8 +1331,7 @@ send_padding:
send_datacrc:
if (conn->conn_ops->DataDigest) {
struct kvec *iov_d =
&cmd->iov_data[cmd->iov_data_count];
struct kvec *iov_d = &cmd->iov_data[iov_off];
tx_sent = tx_data(conn, iov_d, 1, ISCSI_CRC_LEN);
if (ISCSI_CRC_LEN != tx_sent) {