[PATCH] fs: fat: Handle 'FAT sector size mismatch'
Tom Rini
trini at konsulko.com
Tue Nov 19 16:44:36 CET 2024
On Tue, Nov 19, 2024 at 01:00:48PM +0530, Varadarajan Narayanan wrote:
> Do FAT read and write based on the device sector size
> instead of the size recorded in the FAT meta data. This
> helps to overcome the 'FAT sector size mismatch' error
> and enables U-Boot to read/write those partitions.
>
> Signed-off-by: Varadarajan Narayanan <quic_varada at quicinc.com>
> ---
> fs/fat/fat.c | 227 ++++++++++++++++++++++++++++++++++++++++++---
> fs/fat/fat_write.c | 19 ----
> 2 files changed, 214 insertions(+), 32 deletions(-)
>
> diff --git a/fs/fat/fat.c b/fs/fat/fat.c
> index e2570e8167..f4bad99335 100644
> --- a/fs/fat/fat.c
> +++ b/fs/fat/fat.c
> @@ -44,24 +44,223 @@ static void downcase(char *str, size_t len)
>
> static struct blk_desc *cur_dev;
> static struct disk_partition cur_part_info;
> +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++;
> + } 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, 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 +774,8 @@ 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 +846,12 @@ 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
With this patch, we now have
https://patchwork.ozlabs.org/project/uboot/patch/20241113044956.1836896-1-caleb.connolly@linaro.org/
and
https://patchwork.ozlabs.org/project/uboot/patch/20230730111516.v2.1.Ia13846500fab3d5a1d5573db11a040d233994fa6@changeid/
for seemingly the same issue. Can you please try these other two
patches and report which ones do / don't handle your use case as well?
Thanks!
--
Tom
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