From d961c188b205bb821c16d8d9b932456d2fb79211 Mon Sep 17 00:00:00 2001 From: Anton Staaf Date: Mon, 13 Jun 2011 11:40:40 +0000 Subject: [PATCH] ext2: Simplify partial sector access logic 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 Cc: Andy Fleming Acked-by: Detlev Zundel --- fs/ext2/dev.c | 42 +++++++++++++++--------------------------- 1 file changed, 15 insertions(+), 27 deletions(-) diff --git a/fs/ext2/dev.c b/fs/ext2/dev.c index 4365b3b882..78851d0a5d 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 */ -- 2.25.1