[PATCH 3.14 33/33] target: Drop arbitrary maximum I/O size limit

Greg Kroah-Hartman
2015-02-03T23:28:12Z

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

commit 046ba64285a4389ae5e9a7dfa253c6bff3d7c341 upstream.

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>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/target/target_core_device.c | 8 ++++----
drivers/target/target_core_file.c | 11 ++++++++++-
drivers/target/target_core_iblock.c | 2 +-
drivers/target/target_core_sbc.c | 15 ---------------
drivers/target/target_core_spc.c | 5 +----
5 files changed, 16 insertions(+), 25 deletions(-)

--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -1153,10 +1153,10 @@ int se_dev_set_optimal_sectors(struct se
" changed for TCM/pSCSI\n", dev);
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;
}

@@ -1565,7 +1565,6 @@ struct se_device *target_alloc_device(st
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;
@@ -1606,6 +1605,7 @@ int target_configure_device(struct se_de
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();
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -620,7 +620,16 @@ fd_execute_rw(struct se_cmd *cmd, struct
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.
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -123,7 +123,7 @@ static int iblock_configure_device(struc
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;

/*
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -910,21 +910,6 @@ sbc_parse_cdb(struct se_cmd *cmd, struct
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;
- }
-
end_lba = dev->transport->get_blocks(dev) + 1;
if (cmd->t_task_lba + sectors > end_lba) {
pr_err("cmd exceeds last lba %llu "
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -503,7 +503,6 @@ 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;

@@ -537,9 +536,7 @@ spc_emulate_evpd_b0(struct se_cmd *cmd,
/*
* 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