On 4/4/2015 3:24 PM, Akinobu Mita wrote:
The scatterlist for protection information which is passed to
sbc_dif_verify_read() or sbc_dif_verify_write() requires that
neighboring scatterlist entries are contiguous or chained so that they
can be iterated by sg_next().
However, the protection information for RD-MCP backends could be located
in the multiple scatterlist arrays when the ramdisk space is too large.
So if the read/write request straddles this boundary, sbc_dif_verify_read()
or sbc_dif_verify_write() can't iterate all scatterlist entries.
This fixes it by allocating temporary scatterlist if it is needed.
Signed-off-by: Akinobu Mita <[email protected]>
Cc: Nicholas Bellinger <[email protected]>
Cc: Asias He <[email protected]>
Cc: "Martin K. Petersen" <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Cc: [email protected]
Cc: [email protected]
---
drivers/target/target_core_rd.c | 39 +++++++++++++++++++++++++++++++++++----
1 file changed, 35 insertions(+), 4 deletions(-)
diff --git a/drivers/target/target_core_rd.c b/drivers/target/target_core_rd.c
index 4d614c9..19c893d 100644
--- a/drivers/target/target_core_rd.c
+++ b/drivers/target/target_core_rd.c
@@ -387,11 +387,12 @@ static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd,
bool is_write)
struct se_device *se_dev = cmd->se_dev;
struct rd_dev *dev = RD_DEV(se_dev);
struct rd_dev_sg_table *prot_table;
+ bool need_to_release = false;
struct scatterlist *prot_sg;
u32 sectors = cmd->data_length / se_dev->dev_attrib.block_size;
- u32 prot_offset, prot_page;
+ u32 prot_offset, prot_page, prot_npages;
u64 tmp;
- sense_reason_t rc;
+ sense_reason_t rc = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
sense_reason_t (*dif_verify)(struct se_cmd *, sector_t, unsigned int,
unsigned int, struct scatterlist *, int) =
is_write ? sbc_dif_verify_write : sbc_dif_verify_read;
@@ -404,10 +405,40 @@ static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd,
bool is_write)
if (!prot_table)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
- prot_sg = &prot_table->sg_table[prot_page -
- prot_table->page_start_offset];
+ prot_npages = DIV_ROUND_UP(prot_offset + sectors * se_dev->prot_length,
+ PAGE_SIZE);
+
+ /* prot pages straddles multiple scatterlist tables */
+ if (prot_table->page_end_offset < prot_page + prot_npages - 1) {
+ int i;
+
+ prot_sg = kcalloc(prot_npages, sizeof(*prot_sg), GFP_KERNEL);
+ if (!prot_sg)
+ return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+
+ need_to_release = true;
+ sg_init_table(prot_sg, prot_npages);
+
+ for (i = 0; i < prot_npages; i++) {
+ if (prot_page + i > prot_table->page_end_offset) {
+ prot_table = rd_get_prot_table(dev,
+ prot_page + i);
+ if (!prot_table)
+ goto out;
+ sg_unmark_end(&prot_sg[i - 1]);
+ }
+ prot_sg[i] = prot_table->sg_table[prot_page + i -
+ prot_table->page_start_offset];
+ }
+ } else {
+ prot_sg = &prot_table->sg_table[prot_page -
+ prot_table->page_start_offset];
+ }
rc = dif_verify(cmd, cmd->t_task_lba, sectors, 0, prot_sg, prot_offset);
+out:
+ if (need_to_release)
+ kfree(prot_sg);
I think it is safe to free prot_sg if you just make sure to initialize
it to NULL at declaration time, no need for 'need_to_release'.
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