Do FAT read and write based on the device sector size
instead of the size recorded in the FAT meta data.
FAT code issues i/o in terms of the sector size. Convert that to
device sector size before doing the actual i/o. Additionally,
handle leading/trailing blocks when the meta data based block
no and i/o size is not an exact multiple of the device sector
size or vice versa.
Tested on UFS device with sector size 4096 and meta data recorded
sector size 512.
Signed-off-by: Varadarajan Narayanan <quic_var...@quicinc.com>
---
fs/fat/fat.c | 218 ++++++++++++++++++++++++++++++++++++++++++---
fs/fat/fat_write.c | 19 ----
2 files changed, 205 insertions(+), 32 deletions(-)
diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index e2570e8167..efbf892c7a 100644
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -44,24 +44,214 @@ static void downcase(char *str, size_t len)
static struct blk_desc *cur_dev;
static struct disk_partition cur_part_info;
+static int fat_sect_size;
#define DOS_BOOT_MAGIC_OFFSET 0x1fe
#define DOS_FS_TYPE_OFFSET 0x36
#define DOS_FS32_TYPE_OFFSET 0x52
-static int disk_read(__u32 block, __u32 nr_blocks, void *buf)
+inline __u32 sect_to_block(__u32 sect, __u32 *off)
{
- ulong ret;
+ *off = 0;
+ if (fat_sect_size && fat_sect_size < cur_part_info.blksz) {
+ int div = cur_part_info.blksz / fat_sect_size;
+
+ *off = sect % div;
+ return sect / div;
+ } else if (fat_sect_size && (fat_sect_size > cur_part_info.blksz)) {
+ return sect * (fat_sect_size / cur_part_info.blksz);
+ }
- if (!cur_dev)
- return -1;
+ return sect;
+}
- ret = blk_dread(cur_dev, cur_part_info.start + block, nr_blocks, buf);
+inline __u32 size_to_blocks(__u32 size)
+{
+ return (size + (cur_part_info.blksz - 1)) / cur_part_info.blksz;
+}
- if (ret != nr_blocks)
- return -1;
+static int disk_read(__u32 sect, __u32 nr_sect, void *buf)
+{
+ int ret;
+ __u8 *block = NULL;
+ __u32 rem, size;
+ __u32 s, n;
- return ret;
+ rem = nr_sect * fat_sect_size;
+ /*
+ * block N block N + 1 block N + 2
+ * +-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | | | | |s|e|c|t|o|r| | |s|e|c|t|o|r| | |s|e|c|t|o|r| | | | |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * . . . | | | | . . .
+ * ------+---------------+---------------+---------------+------
+ * |<--- FAT reads in sectors --->|
+ *
+ * | part 1 | part 2 | part 3 |
+ *
+ */
+
+ /* Do part 1 */
+ if (fat_sect_size) {
+ __u32 offset;
+
+ /* Read one block and copy out the leading sectors */
+ block = malloc_cache_aligned(cur_dev->blksz);
+ if (!block) {
+ printf("Error: allocating block: %lu\n",
cur_dev->blksz);
+ return -1;
+ }
+
+ s = sect_to_block(sect, &offset);
+ offset = offset * fat_sect_size;
+
+ ret = blk_dread(cur_dev, cur_part_info.start + s, 1, block);
+ if (ret != 1) {
+ ret = -1;
+ goto exit;
+ }
+
+ if (rem > (cur_part_info.blksz - offset))
+ size = cur_part_info.blksz - offset;
+ else
+ size = rem;
+
+ memcpy(buf, block + offset, size);
+ rem -= size;
+ buf += size;
+ s++;
+ } else {
+ /*
+ * fat_sect_size not being set implies, this is the first read
+ * to partition. The first sector is being read to get the
+ * FS meta data. The FAT sector size is got from this meta data.
+ */
+ ret = blk_dread(cur_dev, cur_part_info.start + s, 1, buf);
+ if (ret != 1)
+ return -1;
+ }
+
+ /* Do part 2, read directly into the given buffer */
+ if (rem > cur_part_info.blksz) {
+ n = rem / cur_part_info.blksz;
+ ret = blk_dread(cur_dev, cur_part_info.start + s, n, buf);
+ if (ret != n) {
+ ret = -1;
+ goto exit;
+ }
+ buf += n * cur_part_info.blksz;
+ rem = rem % cur_part_info.blksz;
+ s += n;
+ }
+
+ /* Do part 3, read a block and copy the trailing sectors */
+ if (rem) {
+ ret = blk_dread(cur_dev, cur_part_info.start + s, 1, block);
+ if (ret != 1) {
+ ret = -1;
+ goto exit;
+ } else {
+ memcpy(buf, block, rem);
+ }
+ }
+exit:
+ if (block)
+ free(block);
+
+ return (ret == -1) ? -1 : nr_sect;
+}
+
+int disk_write(__u32 sect, __u32 nr_sect, void *buf)
+{
+ int ret;
+ __u8 *block = NULL;
+ __u32 rem, size;
+ __u32 s, n;
+
+ rem = nr_sect * fat_sect_size;
+ /*
+ * block N block N + 1 block N + 2
+ * +-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | | | | |s|e|c|t|o|r| | |s|e|c|t|o|r| | |s|e|c|t|o|r| | | | |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * . . . | | | | . . .
+ * ------+---------------+---------------+---------------+------
+ * |<--- FAT reads in sectors --->|
+ *
+ * | part 1 | part 2 | part 3 |
+ *
+ */
+
+ /* Do part 1 */
+ if (fat_sect_size) {
+ __u32 offset;
+
+ /* Read one block and overwrite the leading sectors */
+ block = malloc_cache_aligned(cur_dev->blksz);
+ if (!block) {
+ printf("Error: allocating block: %lu\n",
cur_dev->blksz);
+ return -1;
+ }
+
+ s = sect_to_block(sect, &offset);
+ offset = offset * fat_sect_size;
+
+ ret = blk_dread(cur_dev, cur_part_info.start + s, 1, block);
+ if (ret != 1) {
+ ret = -1;
+ goto exit;
+ }
+
+ if (rem > (cur_part_info.blksz - offset))
+ size = cur_part_info.blksz - offset;
+ else
+ size = rem;
+
+ memcpy(block + offset, buf, size);
+ ret = blk_dwrite(cur_dev, cur_part_info.start + s, 1, block);
+ if (ret != 1) {
+ ret = -1;
+ goto exit;
+ }
+
+ rem -= size;
+ buf += size;
+ s++;
+ }
+
+ /* Do part 2, write directly from the given buffer */
+ if (rem > cur_part_info.blksz) {
+ n = rem / cur_part_info.blksz;
+ ret = blk_dwrite(cur_dev, cur_part_info.start + s, n, buf);
+ if (ret != n) {
+ ret = -1;
+ goto exit;
+ }
+ buf += n * cur_part_info.blksz;
+ rem = rem % cur_part_info.blksz;
+ s += n;
+ }
+
+ /* Do part 3, read a block and copy the trailing sectors */
+ if (rem) {
+ ret = blk_dread(cur_dev, cur_part_info.start + s, 1, block);
+ if (ret != 1) {
+ ret = -1;
+ goto exit;
+ } else {
+ memcpy(block, buf, rem);
+ }
+ ret = blk_dwrite(cur_dev, cur_part_info.start + s, 1, block);
+ if (ret != 1) {
+ ret = -1;
+ goto exit;
+ }
+ }
+exit:
+ if (block)
+ free(block);
+
+ return (ret == -1) ? -1 : nr_sect;
}
int fat_set_blk_dev(struct blk_desc *dev_desc, struct disk_partition *info)
@@ -575,6 +765,8 @@ read_bootsectandvi(boot_sector *bs, volume_info *volinfo,
int *fatsize)
return -1;
}
+ fat_sect_size = 0;
+
if (disk_read(0, 1, block) < 0) {
debug("Error: reading block\n");
ret = -1;
@@ -645,12 +837,12 @@ static int get_fs_info(fsdata *mydata)
mydata->rootdir_sect = mydata->fat_sect + mydata->fatlength * bs.fats;
mydata->sect_size = get_unaligned_le16(bs.sector_size);
+ fat_sect_size = mydata->sect_size;
mydata->clust_size = bs.cluster_size;
- if (mydata->sect_size != cur_part_info.blksz) {
- log_err("FAT sector size mismatch (fs=%u, dev=%lu)\n",
- mydata->sect_size, cur_part_info.blksz);
- return -1;
- }
+ if (mydata->sect_size != cur_part_info.blksz)
+ log_info("FAT sector size mismatch (fs=%u, dev=%lu)\n",
+ mydata->sect_size, cur_part_info.blksz);
+
if (mydata->clust_size == 0) {
log_err("FAT cluster size not set\n");
return -1;
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index ea877ee917..f7a210d790 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -192,25 +192,6 @@ out:
}
static int total_sector;
-static int disk_write(__u32 block, __u32 nr_blocks, void *buf)
-{
- ulong ret;
-
- if (!cur_dev)
- return -1;
-
- if (cur_part_info.start + block + nr_blocks >
- cur_part_info.start + total_sector) {
- printf("error: overflow occurs\n");
- return -1;
- }
-
- ret = blk_dwrite(cur_dev, cur_part_info.start + block, nr_blocks, buf);
- if (nr_blocks && ret == 0)
- return -1;
-
- return ret;
-}
/*
* Write fat buffer into block device
--
2.34.1
