target: Drop arbitrary maximum I/O size limit

This patch drops the arbitrary maximum I/O size limit in sbc_parse_cdb(),
which currently for fabric_max_sectors is hardcoded to 8192 (4 MB for 512
byte sector devices), and for hw_max_sectors is a backend driver dependent
value.

This limit is problematic because Linux initiators have only recently
started to honor block limits MAXIMUM TRANSFER LENGTH, and other non-Linux
based initiators (eg: MSFT Fibre Channel) can also generate I/Os larger
than 4 MB in size.

Currently when this happens, the following message will appear on the
target resulting in I/Os being returned with non recoverable status:

  SCSI OP 28h with too big sectors 16384 exceeds fabric_max_sectors: 8192

Instead, drop both [fabric,hw]_max_sector checks in sbc_parse_cdb(),
and convert the existing hw_max_sectors into a purely informational
attribute used to represent the granuality that backend driver and/or
subsystem code is splitting I/Os upon.

Also, update FILEIO with an explicit FD_MAX_BYTES check in fd_execute_rw()
to deal with the one special iovec limitiation case.

v2 changes:
  - Drop hw_max_sectors check in sbc_parse_cdb()

Reported-by: Lance Gropper <lance.gropper@qosserver.com>
Reported-by: Stefan Priebe <s.priebe@profihost.ag>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Roland Dreier <roland@purestorage.com>
Cc: stable@vger.kernel.org # 3.4
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

5 files changed, 16 insertions, 25 deletions

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 7653cfb027a2..ee4b89fb8841 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -1156,10 +1156,10 @@ int se_dev_set_optimal_sectors(struct se_device *dev, u32 optimal_sectors)
                         dev, dev->export_count);
                 return -EINVAL;
         }
-        if (optimal_sectors > dev->dev_attrib.fabric_max_sectors) {
+        if (optimal_sectors > dev->dev_attrib.hw_max_sectors) {
                 pr_err("dev[%p]: Passed optimal_sectors %u cannot be"
-                        " greater than fabric_max_sectors: %u\n", dev,
-                        optimal_sectors, dev->dev_attrib.fabric_max_sectors);
+                        " greater than hw_max_sectors: %u\n", dev,
+                        optimal_sectors, dev->dev_attrib.hw_max_sectors);
                 return -EINVAL;
         }
 
@@ -1554,7 +1554,6 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
                                 DA_UNMAP_GRANULARITY_ALIGNMENT_DEFAULT;
         dev->dev_attrib.max_write_same_len = DA_MAX_WRITE_SAME_LEN;
         dev->dev_attrib.fabric_max_sectors = DA_FABRIC_MAX_SECTORS;
-        dev->dev_attrib.optimal_sectors = DA_FABRIC_MAX_SECTORS;
 
         xcopy_lun = &dev->xcopy_lun;
         xcopy_lun->lun_se_dev = dev;
@@ -1595,6 +1594,7 @@ int target_configure_device(struct se_device *dev)
         dev->dev_attrib.hw_max_sectors =
                 se_dev_align_max_sectors(dev->dev_attrib.hw_max_sectors,
                                          dev->dev_attrib.hw_block_size);
+        dev->dev_attrib.optimal_sectors = dev->dev_attrib.hw_max_sectors;
 
         dev->dev_index = scsi_get_new_index(SCSI_DEVICE_INDEX);
         dev->creation_time = get_jiffies_64();
diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index c2aea099ea4a..b09021135c3b 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -621,7 +621,16 @@ fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
         struct fd_prot fd_prot;
         sense_reason_t rc;
         int ret = 0;
-
+        /*
+         * We are currently limited by the number of iovecs (2048) per
+         * single vfs_[writev,readv] call.
+         */
+        if (cmd->data_length > FD_MAX_BYTES) {
+                pr_err("FILEIO: Not able to process I/O of %u bytes due to"
+                       "FD_MAX_BYTES: %u iovec count limitiation\n",
+                        cmd->data_length, FD_MAX_BYTES);
+                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+        }
         /*
          * Call vectorized fileio functions to map struct scatterlist
          * physical memory addresses to struct iovec virtual memory.
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 3efff94fbd97..5795cd8ab5d9 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -124,7 +124,7 @@ static int iblock_configure_device(struct se_device *dev)
         q = bdev_get_queue(bd);
 
         dev->dev_attrib.hw_block_size = bdev_logical_block_size(bd);
-        dev->dev_attrib.hw_max_sectors = UINT_MAX;
+        dev->dev_attrib.hw_max_sectors = queue_max_hw_sectors(q);
         dev->dev_attrib.hw_queue_depth = q->nr_requests;
 
         /*
diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
index 11bea1952435..cd4bed7b2757 100644
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -953,21 +953,6 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
 
         if (cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) {
                 unsigned long long end_lba;
-
-                if (sectors > dev->dev_attrib.fabric_max_sectors) {
-                        printk_ratelimited(KERN_ERR "SCSI OP %02xh with too"
-                                " big sectors %u exceeds fabric_max_sectors:"
-                                " %u\n", cdb[0], sectors,
-                                dev->dev_attrib.fabric_max_sectors);
-                        return TCM_INVALID_CDB_FIELD;
-                }
-                if (sectors > dev->dev_attrib.hw_max_sectors) {
-                        printk_ratelimited(KERN_ERR "SCSI OP %02xh with too"
-                                " big sectors %u exceeds backend hw_max_sectors:"
-                                " %u\n", cdb[0], sectors,
-                                dev->dev_attrib.hw_max_sectors);
-                        return TCM_INVALID_CDB_FIELD;
-                }
 check_lba:
                 end_lba = dev->transport->get_blocks(dev) + 1;
                 if (cmd->t_task_lba + sectors > end_lba) {
diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index 1307600fe726..4c71657da56a 100644
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -505,7 +505,6 @@ static sense_reason_t
 spc_emulate_evpd_b0(struct se_cmd *cmd, unsigned char *buf)
 {
         struct se_device *dev = cmd->se_dev;
-        u32 max_sectors;
         int have_tp = 0;
         int opt, min;
 
@@ -539,9 +538,7 @@ spc_emulate_evpd_b0(struct se_cmd *cmd, unsigned char *buf)
         /*
          * Set MAXIMUM TRANSFER LENGTH
          */
-        max_sectors = min(dev->dev_attrib.fabric_max_sectors,
-                          dev->dev_attrib.hw_max_sectors);
-        put_unaligned_be32(max_sectors, &buf[8]);
+        put_unaligned_be32(dev->dev_attrib.hw_max_sectors, &buf[8]);
 
         /*
          * Set OPTIMAL TRANSFER LENGTH