[U-Boot] [PATCH 2/2] ext2: Simplify partial sector access logic

Anton Staaf
2011-06-13T21:40:40Z

Previously reading or writing zero full sectors (reading the end of
one sector and the beginning of the next for example) was special
cased and involved stack allocating a second sector buffer. This
change uses the same code path for this case as well as when there
are a non-zero number of full sectors to access. The result is
easier to read and reduces the maximum stack used.

Signed-off-by: Anton Staaf <robotboy@chromium.org>
Cc: Andy Fleming <afleming@freescale.com>
---
fs/ext2/dev.c | 42 +++++++++++++++---------------------------
1 files changed, 15 insertions(+), 27 deletions(-)

diff --git a/fs/ext2/dev.c b/fs/ext2/dev.c
index 4365b3b..78851d0 100644
--- a/fs/ext2/dev.c
+++ b/fs/ext2/dev.c
@@ -53,7 +53,7 @@ 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];
- unsigned block_len;
+ unsigned sectors;

/*
* Check partition boundaries
@@ -98,35 +98,23 @@ int ext2fs_devread(int sector, int byte_offset, int byte_len, char *buf)
sector++;
}

- if (byte_len == 0)
- return 1;
-
/* read sector aligned part */
- block_len = byte_len & ~(SECTOR_SIZE - 1);
-
- if (block_len == 0) {
- u8 p[SECTOR_SIZE];
-
- block_len = SECTOR_SIZE;
- ext2fs_block_dev_desc->block_read(ext2fs_block_dev_desc->dev,
- part_info.start + sector,
- 1, (unsigned long *)p);
- memcpy(buf, p, byte_len);
- return 1;
- }
+ sectors = byte_len / SECTOR_SIZE;
+
+ if (sectors > 0) {
+ if (ext2fs_block_dev_desc->block_read(
+ ext2fs_block_dev_desc->dev,
+ part_info.start + sector,
+ sectors,
+ (unsigned long *) buf) != sectors) {
+ printf(" ** %s read error - block\n", __func__);
+ return 0;
+ }

- if (ext2fs_block_dev_desc->block_read(ext2fs_block_dev_desc->dev,
- part_info.start + sector,
- block_len / SECTOR_SIZE,
- (unsigned long *) buf) !=
- block_len / SECTOR_SIZE) {
- printf(" ** %s read error - block\n", __func__);
- return 0;
+ buf += sectors * SECTOR_SIZE;
+ byte_len -= sectors * SECTOR_SIZE;
+ sector += sectors;
}
- block_len = byte_len & ~(SECTOR_SIZE - 1);
- buf += block_len;
- byte_len -= block_len;
- sector += block_len / SECTOR_SIZE;

if (byte_len != 0) {
/* read rest of data which are not in whole sector */
--
1.7.3.1