[patch 08/19] ext3 sequential read regression fix

[Greg KH <gregkh@suse.de>]

[-- Attachment #1: ext3-sequential-read-regression-fix.patch --]
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-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Badari Pulavarty <pbadari@us.ibm.com>

ext3-get-blocks support caused ~20% degrade in Sequential read
performance (tiobench). Problem is with marking the buffer boundary
so IO can be submitted right away. Here is the patch to fix it.

2.6.18-rc6:
-----------
# ./iotest
1048576+0 records in
1048576+0 records out
4294967296 bytes (4.3 GB) copied, 75.2726 seconds, 57.1 MB/s

real    1m15.285s
user    0m0.276s
sys     0m3.884s


2.6.18-rc6 + fix:
-----------------
[root@elm3a241 ~]# ./iotest
1048576+0 records in
1048576+0 records out
4294967296 bytes (4.3 GB) copied, 62.9356 seconds, 68.2 MB/s


The boundary block check in ext3_get_blocks_handle needs to be adjusted
against the count of blocks mapped in this call, now that it can map
more than one block.

Signed-off-by: Suparna Bhattacharya <suparna@in.ibm.com>
Tested-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>


---
 fs/ext3/inode.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- linux-2.6.17.13.orig/fs/ext3/inode.c
+++ linux-2.6.17.13/fs/ext3/inode.c
@@ -926,7 +926,7 @@ int ext3_get_blocks_handle(handle_t *han
 	set_buffer_new(bh_result);
 got_it:
 	map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
-	if (blocks_to_boundary == 0)
+	if (count > blocks_to_boundary)
 		set_buffer_boundary(bh_result);
 	err = count;
 	/* Clean up and exit */

--