[PATCH 3.14 59/92] target/file: Fix SG table for prot_buf initialization

Greg Kroah-Hartman
2015-05-02T20:13:33Z

From: Akinobu Mita <akinobu.mita@gmail.com>

commit c836777830428372074d5129ac513e1472c99791 upstream.

In fd_do_prot_rw(), it allocates prot_buf which is used to copy from
se_cmd->t_prot_sg by sbc_dif_copy_prot(). The SG table for prot_buf
is also initialized by allocating 'se_cmd->t_prot_nents' entries of
scatterlist and setting the data length of each entry to PAGE_SIZE
at most.

However if se_cmd->t_prot_sg contains a clustered entry (i.e.
sg->length > PAGE_SIZE), the SG table for prot_buf can't be
initialized correctly and sbc_dif_copy_prot() can't copy to prot_buf.
(This actually happened with TCM loopback fabric module)

As prot_buf is allocated by kzalloc() and it's physically contiguous,
we only need a single scatterlist entry.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/target/target_core_file.c | 21 ++++++---------------
1 file changed, 6 insertions(+), 15 deletions(-)

--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -263,11 +263,10 @@ static int fd_do_prot_rw(struct se_cmd *
struct se_device *se_dev = cmd->se_dev;
struct fd_dev *dev = FD_DEV(se_dev);
struct file *prot_fd = dev->fd_prot_file;
- struct scatterlist *sg;
loff_t pos = (cmd->t_task_lba * se_dev->prot_length);
unsigned char *buf;
- u32 prot_size, len, size;
- int rc, ret = 1, i;
+ u32 prot_size;
+ int rc, ret = 1;

prot_size = (cmd->data_length / se_dev->dev_attrib.block_size) *
se_dev->prot_length;
@@ -280,24 +279,16 @@ static int fd_do_prot_rw(struct se_cmd *
}
buf = fd_prot->prot_buf;

- fd_prot->prot_sg_nents = cmd->t_prot_nents;
- fd_prot->prot_sg = kzalloc(sizeof(struct scatterlist) *
- fd_prot->prot_sg_nents, GFP_KERNEL);
+ fd_prot->prot_sg_nents = 1;
+ fd_prot->prot_sg = kzalloc(sizeof(struct scatterlist),
+ GFP_KERNEL);
if (!fd_prot->prot_sg) {
pr_err("Unable to allocate fd_prot->prot_sg\n");
kfree(fd_prot->prot_buf);
return -ENOMEM;
}
sg_init_table(fd_prot->prot_sg, fd_prot->prot_sg_nents);
- size = prot_size;
-
- for_each_sg(fd_prot->prot_sg, sg, fd_prot->prot_sg_nents, i) {
-
- len = min_t(u32, PAGE_SIZE, size);
- sg_set_buf(sg, buf, len);
- size -= len;
- buf += len;
- }
+ sg_set_buf(fd_prot->prot_sg, buf, prot_size);
}

if (is_write) {