The current logic of calculating sg_nents can fail
if data_offset % PAGE_SIZE is not zero.
For example -
PAGE_SIZE = 4096
data_len = 3072
data_offset = 3072
As per current logic
sg_nents = max(1UL, DIV_ROUND_UP(data_len, PAGE_SIZE));
sg_nents = max(1UL, DIV_ROUND_UP(3072, 4096));
sg_nents = 1
But as data_offset % PAGE_SIZE = 3072 we should skip 3072 bytes
skip = 3K
sg_nents = max(1UL, DIV_ROUND_UP(3K(skip) + 3K(data_len), 4K(PAGE_SIZE));
sg_nents = 2;
This patch fixes this issue by adding skip to data_len.
Signed-off-by: Varun Prakash <varun@xxxxxxxxxxx>
---
drivers/target/iscsi/cxgbit/cxgbit_target.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/target/iscsi/cxgbit/cxgbit_target.c b/drivers/target/iscsi/cxgbit/cxgbit_target.c
index dda13f1..514986b 100644
--- a/drivers/target/iscsi/cxgbit/cxgbit_target.c
+++ b/drivers/target/iscsi/cxgbit/cxgbit_target.c
@@ -827,7 +827,7 @@ cxgbit_put_login_tx(struct iscsi_conn *conn, struct iscsi_login *login,
static void
cxgbit_skb_copy_to_sg(struct sk_buff *skb, struct scatterlist *sg,
- unsigned int nents)
+ unsigned int nents, u32 skip)
{
struct skb_seq_state st;
const u8 *buf;
@@ -846,7 +846,7 @@ cxgbit_skb_copy_to_sg(struct sk_buff *skb, struct scatterlist *sg,
}
consumed += sg_pcopy_from_buffer(sg, nents, (void *)buf,
- buf_len, consumed);
+ buf_len, skip + consumed);
}
}
@@ -912,7 +912,7 @@ cxgbit_handle_immediate_data(struct iscsi_cmd *cmd, struct iscsi_scsi_req *hdr,
struct scatterlist *sg = &cmd->se_cmd.t_data_sg[0];
u32 sg_nents = max(1UL, DIV_ROUND_UP(pdu_cb->dlen, PAGE_SIZE));
- cxgbit_skb_copy_to_sg(csk->skb, sg, sg_nents);
+ cxgbit_skb_copy_to_sg(csk->skb, sg, sg_nents, 0);
}
cmd->write_data_done += pdu_cb->dlen;
@@ -1069,11 +1069,13 @@ static int cxgbit_handle_iscsi_dataout(struct cxgbit_sock *csk)
cmd->se_cmd.data_length);
if (!(pdu_cb->flags & PDUCBF_RX_DATA_DDPD)) {
+ u32 skip = data_offset % PAGE_SIZE;
+
sg_off = data_offset / PAGE_SIZE;
sg_start = &cmd->se_cmd.t_data_sg[sg_off];
- sg_nents = max(1UL, DIV_ROUND_UP(data_len, PAGE_SIZE));
+ sg_nents = max(1UL, DIV_ROUND_UP(skip + data_len, PAGE_SIZE));
- cxgbit_skb_copy_to_sg(csk->skb, sg_start, sg_nents);
+ cxgbit_skb_copy_to_sg(csk->skb, sg_start, sg_nents, skip);
}
check_payload:
--
2.0.2
--
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