[3.8.y.z extended stable] Patch "target/file: Update hw_max_sectors based on current block_size" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    target/file: Update hw_max_sectors based on current block_size

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.16.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 4089250f23f3be09f20b999784389b97e94d8e91 Mon Sep 17 00:00:00 2001
From: Nicholas Bellinger <nab at linux-iscsi.org>
Date: Thu, 12 Dec 2013 12:24:11 -0800
Subject: target/file: Update hw_max_sectors based on current block_size

commit 95cadace8f3959282e76ebf8b382bd0930807d2c upstream.

This patch allows FILEIO to update hw_max_sectors based on the current
max_bytes_per_io.  This is required because vfs_[writev,readv]() can accept
a maximum of 2048 iovecs per call, so the enforced hw_max_sectors really
needs to be calculated based on block_size.

This addresses a >= v3.5 bug where block_size=512 was rejecting > 1M
sized I/O requests, because FD_MAX_SECTORS was hardcoded to 2048 for
the block_size=4096 case.

(v2: Use max_bytes_per_io instead of ->update_hw_max_sectors)

Reported-by: Henrik Goldman <hg at x-formation.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
[ kamal: backport to 3.8 (context) ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/target/target_core_device.c | 5 +++++
 drivers/target/target_core_file.c   | 8 ++++----
 drivers/target/target_core_file.h   | 5 ++++-
 include/target/target_core_base.h   | 1 +
 4 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 96f4981..c461180 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -1048,6 +1048,11 @@ int se_dev_set_block_size(struct se_device *dev, u32 block_size)
 	dev->dev_attrib.block_size = block_size;
 	pr_debug("dev[%p]: SE Device block_size changed to %u\n",
 			dev, block_size);
+
+	if (dev->dev_attrib.max_bytes_per_io)
+		dev->dev_attrib.hw_max_sectors =
+			dev->dev_attrib.max_bytes_per_io / block_size;
+
 	return 0;
 }

diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index 89aa3b2a..9bfe625 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -64,9 +64,8 @@ static int fd_attach_hba(struct se_hba *hba, u32 host_id)
 	pr_debug("CORE_HBA[%d] - TCM FILEIO HBA Driver %s on Generic"
 		" Target Core Stack %s\n", hba->hba_id, FD_VERSION,
 		TARGET_CORE_MOD_VERSION);
-	pr_debug("CORE_HBA[%d] - Attached FILEIO HBA: %u to Generic"
-		" MaxSectors: %u\n",
-		hba->hba_id, fd_host->fd_host_id, FD_MAX_SECTORS);
+	pr_debug("CORE_HBA[%d] - Attached FILEIO HBA: %u to Generic\n",
+		hba->hba_id, fd_host->fd_host_id);

 	return 0;
 }
@@ -174,7 +173,8 @@ static int fd_configure_device(struct se_device *dev)
 	fd_dev->fd_block_size = dev->dev_attrib.hw_block_size;

 	dev->dev_attrib.hw_block_size = FD_BLOCKSIZE;
-	dev->dev_attrib.hw_max_sectors = FD_MAX_SECTORS;
+	dev->dev_attrib.max_bytes_per_io = FD_MAX_BYTES;
+	dev->dev_attrib.hw_max_sectors = FD_MAX_BYTES / fd_dev->fd_block_size;
 	dev->dev_attrib.hw_queue_depth = FD_MAX_DEVICE_QUEUE_DEPTH;

 	if (fd_dev->fbd_flags & FDBD_HAS_BUFFERED_IO_WCE) {
diff --git a/drivers/target/target_core_file.h b/drivers/target/target_core_file.h
index 37ffc5b..d7772c1 100644
--- a/drivers/target/target_core_file.h
+++ b/drivers/target/target_core_file.h
@@ -7,7 +7,10 @@
 #define FD_DEVICE_QUEUE_DEPTH	32
 #define FD_MAX_DEVICE_QUEUE_DEPTH 128
 #define FD_BLOCKSIZE		512
-#define FD_MAX_SECTORS		2048
+/*
+ * Limited by the number of iovecs (2048) per vfs_[writev,readv] call
+ */
+#define FD_MAX_BYTES		8388608

 #define RRF_EMULATE_CDB		0x01
 #define RRF_GOT_LBA		0x02
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 663e34a..55bf359 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -615,6 +615,7 @@ struct se_dev_attrib {
 	u32		unmap_granularity;
 	u32		unmap_granularity_alignment;
 	u32		max_write_same_len;
+	u32		max_bytes_per_io;
 	struct se_device *da_dev;
 	struct config_group da_group;
 };
--
1.8.3.2