ext4: cache-align buffers so the invalidation works

DMA buffer cache invalidation requires that buffers have cache-aligned
buffer locations and sizes. Use memalign() and ALLOC_CACHE_ALIGN_BUFFER()
to ensure this.

On Tegra at least, without this fix, the following fail commands fail in
u-boot-master/ext4, but succeeded at the branch's branch point in
u-boot/master. With this fix, the commands work again:

ext2ls mmc 0:1 /
ext2load mmc 0:1 /boot/zImage

Cc: Uma Shankar <uma.shankar@samsung.com>
Cc: Manjunatha C Achar <a.manjunatha@samsung.com>
Cc: Iqbal Shareef <iqbal.ams@samsung.com>
Cc: Hakgoo Lee <goodguy.lee@samsung.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Tom Rini <trini@ti.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>

fs/ext4/dev.c

@@ -62,7 +62,7 @@ int ext4fs_set_blk_dev(block_dev_desc_t *rbdd, int part)
 
 int ext4fs_devread(int sector, int byte_offset, int byte_len, char *buf)
 {
-	char sec_buf[SECTOR_SIZE];
+	ALLOC_CACHE_ALIGN_BUFFER(char, sec_buf, SECTOR_SIZE);
 	unsigned block_len;
 
 	/* Check partition boundaries */
@@ -107,7 +107,7 @@ int ext4fs_devread(int sector, int byte_offset, int byte_len, char *buf)
 	block_len = byte_len & ~(SECTOR_SIZE - 1);
 
 	if (block_len == 0) {
-		u8 p[SECTOR_SIZE];
+		ALLOC_CACHE_ALIGN_BUFFER(u8, p, SECTOR_SIZE);
 
 		block_len = SECTOR_SIZE;
 		ext4fs_block_dev_desc->block_read(ext4fs_block_dev_desc->dev,

fs/ext4/ext4_common.c

@@ -71,7 +71,7 @@ void put_ext4(uint64_t off, void *buf, uint32_t size)
 	uint64_t startblock;
 	uint64_t remainder;
 	unsigned char *temp_ptr = NULL;
-	unsigned char sec_buf[SECTOR_SIZE];
+	ALLOC_CACHE_ALIGN_BUFFER(unsigned char, sec_buf, SECTOR_SIZE);
 	struct ext_filesystem *fs = get_fs();
 
 	startblock = off / (uint64_t)SECTOR_SIZE;

fs/ext4/ext4_common.h

@@ -55,7 +55,12 @@
 #define SUPERBLOCK_SIZE	1024
 #define F_FILE			1
 
-#define zalloc(size) calloc(1, size)
+static inline void *zalloc(size_t size)
+{
+	void *p = memalign(ARCH_DMA_MINALIGN, size);
+	memset(p, 0, size);
+	return p;
+}
 
 extern unsigned long part_offset;
 int ext4fs_read_inode(struct ext2_data *data, int ino,