[PATCH 3.19 055/177] target: Fix PR_APTPL_BUF_LEN buffer size limitation

Greg Kroah-Hartman
2015-03-16T14:13:33Z

From: Nicholas Bellinger <nab@linux-iscsi.org>

commit f161d4b44d7cc1dc66b53365215227db356378b1 upstream.

This patch addresses the original PR_APTPL_BUF_LEN = 8k limitiation
for write-out of PR APTPL metadata that Martin has recently been
running into.

It changes core_scsi3_update_and_write_aptpl() to use vzalloc'ed
memory instead of kzalloc, and increases the default hardcoded
length to 256k.

It also adds logic in core_scsi3_update_and_write_aptpl() to double
the original length upon core_scsi3_update_aptpl_buf() failure, and
retries until the vzalloc'ed buffer is large enough to accommodate
the outgoing APTPL metadata.

Reported-by: Martin Svec <martin.svec@zoner.cz>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/target/target_core_pr.c | 25 +++++++++++++------------
include/target/target_core_base.h | 2 +-
2 files changed, 14 insertions(+), 13 deletions(-)

--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c
@@ -1874,8 +1874,8 @@ static int core_scsi3_update_aptpl_buf(
}

if ((len + strlen(tmp) >= pr_aptpl_buf_len)) {
- pr_err("Unable to update renaming"
- " APTPL metadata\n");
+ pr_err("Unable to update renaming APTPL metadata,"
+ " reallocating larger buffer\n");
ret = -EMSGSIZE;
goto out;
}
@@ -1892,8 +1892,8 @@ static int core_scsi3_update_aptpl_buf(
lun->lun_sep->sep_rtpi, lun->unpacked_lun, reg_count);

if ((len + strlen(tmp) >= pr_aptpl_buf_len)) {
- pr_err("Unable to update renaming"
- " APTPL metadata\n");
+ pr_err("Unable to update renaming APTPL metadata,"
+ " reallocating larger buffer\n");
ret = -EMSGSIZE;
goto out;
}
@@ -1956,7 +1956,7 @@ static int __core_scsi3_write_aptpl_to_f
static sense_reason_t core_scsi3_update_and_write_aptpl(struct se_device *dev, bool aptpl)
{
unsigned char *buf;
- int rc;
+ int rc, len = PR_APTPL_BUF_LEN;

if (!aptpl) {
char *null_buf = "No Registrations or Reservations\n";
@@ -1970,25 +1970,26 @@ static sense_reason_t core_scsi3_update_

return 0;
}
-
- buf = kzalloc(PR_APTPL_BUF_LEN, GFP_KERNEL);
+retry:
+ buf = vzalloc(len);
if (!buf)
return TCM_OUT_OF_RESOURCES;

- rc = core_scsi3_update_aptpl_buf(dev, buf, PR_APTPL_BUF_LEN);
+ rc = core_scsi3_update_aptpl_buf(dev, buf, len);
if (rc < 0) {
- kfree(buf);
- return TCM_OUT_OF_RESOURCES;
+ vfree(buf);
+ len *= 2;
+ goto retry;
}

rc = __core_scsi3_write_aptpl_to_file(dev, buf);
if (rc != 0) {
pr_err("SPC-3 PR: Could not update APTPL\n");
- kfree(buf);
+ vfree(buf);
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}
dev->t10_pr.pr_aptpl_active = 1;
- kfree(buf);
+ vfree(buf);
pr_debug("SPC-3 PR: Set APTPL Bit Activated\n");
return 0;
}
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -407,7 +407,7 @@ struct t10_reservation {
/* Activate Persistence across Target Power Loss enabled
* for SCSI device */
int pr_aptpl_active;
-#define PR_APTPL_BUF_LEN 8192
+#define PR_APTPL_BUF_LEN 262144
u32 pr_generation;
spinlock_t registration_lock;
spinlock_t aptpl_reg_lock;