From 0bb8a456dd447090b5e9043b6604e240f93da15d Mon Sep 17 00:00:00 2001
From: Vladislav Bolkhovitin <vst@vlnb.net>
Date: Mon, 8 Jun 2009 17:01:04 +0000
Subject: [PATCH] readahead patches added. See
 http://sourceforge.net/mailarchive/forum.php?thread_name=a0272b440906030714g67eabc5k8f847fb1e538cc62%40mail.gma
 il.com&forum_name=scst-devel for more details.

git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@896 d57e44dd-8a1f-0410-8b47-8ef2f437770f
---
 scst/README                        |  5 +++++
 scst/kernel/readahead-2.6.25.patch | 13 +++++++++++++
 scst/kernel/readahead-2.6.26.patch | 13 +++++++++++++
 scst/kernel/readahead-2.6.27.patch | 13 +++++++++++++
 scst/kernel/readahead-2.6.28.patch | 13 +++++++++++++
 scst/kernel/readahead-2.6.29.patch | 13 +++++++++++++
 6 files changed, 70 insertions(+)
 create mode 100644 scst/kernel/readahead-2.6.25.patch
 create mode 100644 scst/kernel/readahead-2.6.26.patch
 create mode 100644 scst/kernel/readahead-2.6.27.patch
 create mode 100644 scst/kernel/readahead-2.6.28.patch
 create mode 100644 scst/kernel/readahead-2.6.29.patch

diff --git a/scst/README b/scst/README
index 8fc5ba960..e8b49abf9 100644
--- a/scst/README
+++ b/scst/README
@@ -79,6 +79,11 @@ using a pool of IO threads. It is considerably better for performance
 IO context. This patch allows that. If you don't apply this patch, you
 will loose this performance benefit.
 
+3. readahead-2.6.X.patch. This patch fixes problem in Linux readahead
+subsystem and greatly improves performance for software RAIDs. See
+http://sourceforge.net/mailarchive/forum.php?thread_name=a0272b440906030714g67eabc5k8f847fb1e538cc62%40mail.gmail.com&forum_name=scst-devel
+thread for more details.
+
 Then, to compile SCST type 'make scst'. It will build SCST itself and its
 device handlers. To install them type 'make scst_install'. The driver
 modules will be installed in '/lib/modules/`you_kernel_version`/extra'.
diff --git a/scst/kernel/readahead-2.6.25.patch b/scst/kernel/readahead-2.6.25.patch
new file mode 100644
index 000000000..87ab0bfac
--- /dev/null
+++ b/scst/kernel/readahead-2.6.25.patch
@@ -0,0 +1,13 @@
+diff --git a/mm/readahead.c b/mm/readahead.c
+index 133b6d5..fd3df66 100644
+--- a/mm/readahead.c
++++ b/mm/readahead.c
+@@ -473,5 +473,8 @@ page_cache_async_readahead(struct address_space *mapping,
+ 
+ 	/* do read-ahead */
+ 	ondemand_readahead(mapping, ra, filp, true, offset, req_size);
++
++	if (PageUptodate(page))
++		blk_run_backing_dev(mapping->backing_dev_info, NULL);		
+ }
+ EXPORT_SYMBOL_GPL(page_cache_async_readahead);
diff --git a/scst/kernel/readahead-2.6.26.patch b/scst/kernel/readahead-2.6.26.patch
new file mode 100644
index 000000000..c62905a3f
--- /dev/null
+++ b/scst/kernel/readahead-2.6.26.patch
@@ -0,0 +1,13 @@
+diff --git a/mm/readahead.c b/mm/readahead.c
+index 133b6d5..fd3df66 100644
+--- a/mm/readahead.c
++++ b/mm/readahead.c
+@@ -479,5 +479,8 @@ page_cache_async_readahead(struct address_space *mapping,
+ 
+ 	/* do read-ahead */
+ 	ondemand_readahead(mapping, ra, filp, true, offset, req_size);
++
++	if (PageUptodate(page))
++		blk_run_backing_dev(mapping->backing_dev_info, NULL);		
+ }
+ EXPORT_SYMBOL_GPL(page_cache_async_readahead);
diff --git a/scst/kernel/readahead-2.6.27.patch b/scst/kernel/readahead-2.6.27.patch
new file mode 100644
index 000000000..c62905a3f
--- /dev/null
+++ b/scst/kernel/readahead-2.6.27.patch
@@ -0,0 +1,13 @@
+diff --git a/mm/readahead.c b/mm/readahead.c
+index 133b6d5..fd3df66 100644
+--- a/mm/readahead.c
++++ b/mm/readahead.c
+@@ -479,5 +479,8 @@ page_cache_async_readahead(struct address_space *mapping,
+ 
+ 	/* do read-ahead */
+ 	ondemand_readahead(mapping, ra, filp, true, offset, req_size);
++
++	if (PageUptodate(page))
++		blk_run_backing_dev(mapping->backing_dev_info, NULL);		
+ }
+ EXPORT_SYMBOL_GPL(page_cache_async_readahead);
diff --git a/scst/kernel/readahead-2.6.28.patch b/scst/kernel/readahead-2.6.28.patch
new file mode 100644
index 000000000..c62905a3f
--- /dev/null
+++ b/scst/kernel/readahead-2.6.28.patch
@@ -0,0 +1,13 @@
+diff --git a/mm/readahead.c b/mm/readahead.c
+index 133b6d5..fd3df66 100644
+--- a/mm/readahead.c
++++ b/mm/readahead.c
+@@ -479,5 +479,8 @@ page_cache_async_readahead(struct address_space *mapping,
+ 
+ 	/* do read-ahead */
+ 	ondemand_readahead(mapping, ra, filp, true, offset, req_size);
++
++	if (PageUptodate(page))
++		blk_run_backing_dev(mapping->backing_dev_info, NULL);		
+ }
+ EXPORT_SYMBOL_GPL(page_cache_async_readahead);
diff --git a/scst/kernel/readahead-2.6.29.patch b/scst/kernel/readahead-2.6.29.patch
new file mode 100644
index 000000000..c62905a3f
--- /dev/null
+++ b/scst/kernel/readahead-2.6.29.patch
@@ -0,0 +1,13 @@
+diff --git a/mm/readahead.c b/mm/readahead.c
+index 133b6d5..fd3df66 100644
+--- a/mm/readahead.c
++++ b/mm/readahead.c
+@@ -479,5 +479,8 @@ page_cache_async_readahead(struct address_space *mapping,
+ 
+ 	/* do read-ahead */
+ 	ondemand_readahead(mapping, ra, filp, true, offset, req_size);
++
++	if (PageUptodate(page))
++		blk_run_backing_dev(mapping->backing_dev_info, NULL);		
+ }
+ EXPORT_SYMBOL_GPL(page_cache_async_readahead);