[U-Boot] [PATCH] ext2: Cache line aligned partial sector bounce buffer

[Anton Staaf]

Currently, if a device read request is done that does not begin or end
on a sector boundary a stack allocated bounce buffer is used to perform
the read, and then just the part of the sector that is needed is copied
into the users buffer.  This stack allocation can mean that the bounce
buffer will not be aligned to the dcache line size.  This is a problem
when caches are enabled because unaligned cache invalidates are not
safe.

This patch allocates a cache line size aligned sector sized bounce
buffer the first time that ext2fs_devread is called.

Signed-off-by: Anton Staaf <robotboy at chromium.org>
Cc: Lukasz Majewski <l.majewski at samsung.com>
Cc: Mike Frysinger <vapier at gentoo.org>
Cc: Dave Liu <r63238 at freescale.com>
Cc: Andy Fleming <afleming at gmail.com>
Cc: Albert ARIBAUD <albert.u.boot at aribaud.net>
---

This patch depends on Lukasz Majewski's dcache line size patch sent to the
list in: http://patchwork.ozlabs.org/patch/110501/

 fs/ext2/dev.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/fs/ext2/dev.c b/fs/ext2/dev.c
index 78851d0..4b2aeef 100644
--- a/fs/ext2/dev.c
+++ b/fs/ext2/dev.c
@@ -26,6 +26,7 @@
 
 #include <common.h>
 #include <config.h>
+#include <malloc.h>
 #include <ext2fs.h>
 
 static block_dev_desc_t *ext2fs_block_dev_desc;
@@ -52,9 +53,15 @@ int ext2fs_set_blk_dev(block_dev_desc_t *rbdd, int part)
 
 int ext2fs_devread(int sector, int byte_offset, int byte_len, char *buf)
 {
-	char sec_buf[SECTOR_SIZE];
+	static char *sec_buf;
 	unsigned sectors;
 
+	if (sec_buf == NULL)
+		sec_buf = memalign(get_dcache_line_size(), SECTOR_SIZE);
+
+	if (sec_buf == NULL)
+		return 0; //-ENOMEM
+
 	/*
 	 *  Check partition boundaries
 	 */
-- 
1.7.3.1