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target/rd: Don't pass incomplete scatterlist entries to sbc_dif_verify_* 

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 problem can be fixed by chaining protection information scatterlist
at creation time.  For the architectures which don't support sg chaining
(i.e. !CONFIG_ARCH_HAS_SG_CHAIN), fix it by allocating temporary
scatterlist if needed.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: Sagi Grimberg <sagig@dev.mellanox.co.il>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: target-devel@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Akinobu Mita 2015-04-11 13:17:31 +09:00 committed by Nicholas Bellinger
parent 054922bb35
commit bfd9a53e01
1 changed files with 64 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

67
drivers/target/target_core_rd.c
View File

@ -139,10 +139,22 @@ static int rd_allocate_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *
unsigned char *p;
while (total_sg_needed) {
unsigned int chain_entry = 0;
sg_per_table = (total_sg_needed > max_sg_per_table) ?
max_sg_per_table : total_sg_needed;
sg = kzalloc(sg_per_table * sizeof(struct scatterlist),
#ifdef CONFIG_ARCH_HAS_SG_CHAIN
/*
* Reserve extra element for chain entry
*/
if (sg_per_table < total_sg_needed)
chain_entry = 1;
#endif /* CONFIG_ARCH_HAS_SG_CHAIN */
sg = kcalloc(sg_per_table + chain_entry, sizeof(*sg),
GFP_KERNEL);
if (!sg) {
pr_err("Unable to allocate scatterlist array"
@ -150,7 +162,16 @@ static int rd_allocate_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *
return -ENOMEM;
}
sg_init_table(sg, sg_per_table);
sg_init_table(sg, sg_per_table + chain_entry);
#ifdef CONFIG_ARCH_HAS_SG_CHAIN
if (i > 0) {
sg_chain(sg_table[i - 1].sg_table,
max_sg_per_table + 1, sg);
}
#endif /* CONFIG_ARCH_HAS_SG_CHAIN */
sg_table[i].sg_table = sg;
sg_table[i].rd_sg_count = sg_per_table;
@ -390,11 +411,13 @@ static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, dif_verify dif_verify)
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_npages __maybe_unused;
u64 tmp;
sense_reason_t rc;
sense_reason_t rc = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
tmp = cmd->t_task_lba * se_dev->prot_length;
prot_offset = do_div(tmp, PAGE_SIZE);
@ -407,7 +430,45 @@ static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, dif_verify dif_verify)
prot_sg = &prot_table->sg_table[prot_page -
prot_table->page_start_offset];
#ifndef CONFIG_ARCH_HAS_SG_CHAIN
prot_npages = DIV_ROUND_UP(prot_offset + sectors * se_dev->prot_length,
PAGE_SIZE);
/*
* Allocate temporaly contiguous scatterlist entries if 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) {
kfree(prot_sg);
return rc;
}
sg_unmark_end(&prot_sg[i - 1]);
}
prot_sg[i] = prot_table->sg_table[prot_page + i -
prot_table->page_start_offset];
}
}
#endif /* !CONFIG_ARCH_HAS_SG_CHAIN */
rc = dif_verify(cmd, cmd->t_task_lba, sectors, 0, prot_sg, prot_offset);
if (need_to_release)
kfree(prot_sg);
return rc;
}