From 1f2cedce37842a2b6b14b01662f04a19e8b64a42 Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche@acm.org>
Date: Thu, 11 Nov 2010 09:26:44 +0000
Subject: [PATCH] Merged scripts directory from ibmvstgt-port branch (svn merge
 -r2369:2654
 https://scst.svn.sourceforge.net/svnroot/scst/branches/ibmvstgt-port/scripts).

git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@2661 d57e44dd-8a1f-0410-8b47-8ef2f437770f
---
 scripts/generate-kernel-patch | 101 ++++++++++++++++++++++++++++------
 1 file changed, 85 insertions(+), 16 deletions(-)

diff --git a/scripts/generate-kernel-patch b/scripts/generate-kernel-patch
index 9054c6be2..608c3dccd 100755
--- a/scripts/generate-kernel-patch
+++ b/scripts/generate-kernel-patch
@@ -395,9 +395,9 @@ done \
 
   add_file "fcst/Makefile_in-tree" \
            "drivers/scst/fcst/Makefile"
-  
+
   add_file "fcst/Kconfig" "drivers/scst/fcst/Kconfig"
-  
+
   for f in $(ls fcst/*.[ch] 2>/dev/null)
   do
     add_file "${f}" "drivers/scst/fcst/${f#fcst/}"
@@ -556,26 +556,95 @@ fi
       cat <<EOF
 [SCSI] ibmvstgt: Port from tgt to SCST
 
-The current ibmvstgt and libsrp kernel modules are based on the tgt
-infrastructure. Both modules need the scsi_tgt kernel module and the tgtd user
-space process in order to function properly. This patch modifies the ibmvstgt
-and libsrp kernel modules such that both use the SCST storage target framework
-instead of tgt. Porting ibmvstgt to SCST is required for upstream acceptance
-of SCST.
+The ibmvstgt and libsrp kernel modules as included in the 2.6.37 kernel are
+based on the tgt SCSI target framework. Both kernel modules need the scsi_tgt
+kernel module and the tgtd user space process in order to function
+properly. This patch modifies the ibmvstgt and libsrp kernel modules such that
+both use the SCST storage target framework instead of tgt. As a result,
+neither the scsi_tgt kernel module nor the tgtd user space process are any
+more necessary when using the ibmvstgt driver.
 
 This patch introduces one backwards-incompatible change, namely that the path
 of the ibmvstgt sysfs attributes is modified. This change is unavoidable
-because this patch dissociates ibmvstgt SRP sessions from a SCSI host instance.
+because this patch dissociates ibmvstgt SRP sessions from a SCSI host
+instance.  Since the user space STGT driver ibmvio was the only user of
+these attributes, that shouldn't be an issue.
 
-Notes:
-- ibmvstgt is the only user of libsrp.
-- A 2.6.35 kernel tree with this patch applied does compile cleanly on the
-systems supported by the ibmvstgt kernel module, the patch itself is checkpatch
-clean and does not introduce any new sparse warnings. This patch has not been
-tested in any other way however. The primary purpose of this patch is to invite
-feedback about the chosen approach.
+Functional changes in ibmvstgt compared to the patch posted on October 2, 2010:
+- The format of a SCSI INQUIRY response is now in the format expected by AIX.
+- Added support for persistent reservations.
+- Increased maximum data size for a single SRP command from 128 KB to 64 MB.
+- The maximum RDMA transfer size supported by a single H_COPY_RDMA call is
+  queried at driver initiatlization time from the open firmware tree / larger
+  transfers than 128 KB are now supported too.
+- If DMA mapping fails while handling a READ or WRITE command, the offending
+  command is retried until the associated data has been transferred instead of
+  reporting to the ibmvscsi client that the SCSI command failed.
+- Aborting a SCSI command does no longer trigger an SRP credit leak.
+- VSCSI command/response queue: one element has been reserved for management
+  datagrams since these fall outside the SRP credit mechanism. Added a compile-
+  time check whether the size of this queue is a power of two.
+- Fixed a race condition which in theory could have caused the VSCSI receive
+  queue to overflow: srp_iu_put() is now invoked before a response is sent back
+  to the initiator instead of after.
+- The flag SRP_RSP_FLAG_SNSVALID in an SRP_RSP information unit is now only
+  set when a response contains sense data and not when e.g. the response status
+  is BUSY and no sense data is sent back to the initiator.
+- In ibmvstgt_init(), get_system_info() is now invoked before registering the
+  sysfs attributes that export the queried values.
+- Avoid that ibmvstgt_release() triggers a NULL-pointer dereference when
+  invoked before a client has logged in.
+- The second and subsequent SRP_LOGIN received from a client does no longer
+  trigger a BUG_ON() in process_login().
+- Moved enum iue_flags from libsrp to ibmvstgt because it is ibmvstgt-specific.
+- Removed a variable that was modified but never read from ibmvstgt_rdma().
+- ibmvstgt_probe(): changed the datatype of the variable "dma" from
+  unsigned * into const unsigned * such that a cast could be removed.
+- Fixed all compiler and sparse warnings (C=2 CF=-D__CHECK_ENDIAN__).
+
+Functional changes in libsrp compared to the patch posted on October 2, 2010:
+- Renamed vscsis_data_length() into srp_data_length() and exported
+  this function.
+- All error messages reported via printk() do now have prefix KERN_ERR.
+- modified srp_target_alloc() and srp_target_free() such that the
+  driver-private data reflects whether or not target data has been allocated.
+  This change was necessary to avoid that ibmvstgt_remove() triggers a
+  NULL-pointer dereference if ibmvstgt_probe() failed.
+- srp_transfer_data(): All three return statements related to DMA mapping
+  failure do now return -ENOMEM instead of 0, -EIO and -ENOMEM.
+- srp_direct_data(): Removed the ext_desc argument since not used.
+- srp_direct_data() and srp_indirect_data(): Use the data length from
+  the SCSI CDB instead of the length from the SRP_CMD data descriptors. Also,
+  compute the correct data length even if dma_map == 0.
+- srp_direct_data() and srp_indirect_data(): Use DMA_TO/FROM_DEVICE
+  instead of DMA_BIDIRECTIONAL for the buffers mapped for transferring data
+  via DMA.
+- struct srp_target: eliminated the information unit linked list and also the
+  V_FLYING flag since both were duplicating information managed by the SCST
+  core.
+- Fixed all compiler and sparse warnings (C=2 CF=-D__CHECK_ENDIAN__).
+
+Note: ibmvstgt is the only user of libsrp.
+
+Tests performed on a backport to kernel version 2.6.18 of this driver:
+- Verified that the kernel module ibmvstgt loads and initializes successfully
+  and also that the client connected after loading.
+- Verified that virtual disks configured in scst_vdisk were discovered by
+  the client.
+- Performed IO stress testing on the device.
+- Performed basic I/O performance testing. With a RAM disk as target linear
+  direct I/O throughput was above 2 GB/s and a 4 KB random I/O test resulted
+  in more than 10000 IOPS (without any caching of DMA mappings in the target).
+  Both initiator and target were a dual core POWER6 LPAR.
+- Verified that after unloading and reloading ibmvstgt and after client
+  recovery that the initiator devices were functioning normally.
+- Verified that after a client reboot ibmvscsic reconnected with the target
+  and that the target devices were again usable.
 
 Signed-off-by: Bart Van Assche <bvanassche@acm.org>
+Cc: Fujita Tomonori <fujita.tomonori@lab.ntt.co.jp>
+Cc: Brian King <brking@linux.vnet.ibm.com>
+Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
 
 EOF
     fi