target: Fix PR_APTPL_BUF_LEN buffer size limitation

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>
Cc: stable@vger.kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c
index d56f2aaba9af9a6bb4b89d5c1080d426cba84e63..67fb3bf240cd8e52df911224d3faf2ba8179690c 100644 (file)
--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c
@@ -1862,8 +1862,8 @@ 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;
                }
@@ -1880,8 +1880,8 @@ 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;
                }
@@ -1944,7 +1944,7 @@ static int __core_scsi3_write_aptpl_to_file(
 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";
@@ -1958,25 +1958,26 @@ static sense_reason_t core_scsi3_update_and_write_aptpl(struct se_device *dev, b
 
                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;
 }

diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 397fb635766a96faa94c5b91788ad24fca0d2a34..eec07656eb03b2a1cc7cdd3648cdfdf8e23430f8 100644 (file)
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -409,7 +409,7 @@ 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;