LittleFS can't read last file created

[d-soliveira]

Hi there,

I created an filesystem image on Ubuntu as described in Littlefs-fuse, with a simple TXT file just for testing and flashed it at the correct uC's memory address.

For some reason, I cannot read the TXT file content. The function fs_open(&file, fname_txt, FS_O_READ) returns 0, which means it found the file, but the fs_read(&file, &buffer, sizeof(buffer)) returns 0 and the buffer array is empty.

However, if I create a second file I can read the first file but not the second file and so on. The new file could be empty.

I guess it could be some image's configuration, but I can't figure it out.
Someone have experience something similar?

Thank you!

[de-nordic]

Have you provided the lfs, when creating the image, with following parameters:
--block-size equal to flash device erase page size
--read_size
--prog_size
--block_cycles
--cache_size
--lookahead_size

according to your board DTS/Kconfig parameters?

[d-soliveira]

Hi @de-nordic !

I haven't configured the LFS parameters, probably that is the problem.
I'm using an STM32L4S5VI, which has 256 pages of 4 Kbytes and my DTS file is:

storage_partition: partition@fc000 {
			label = "storage";
			reg = <0x000fc000 0x0004000>;

I tried to format the LFS as you suggested, but now I'm getting another error when try to mount it on Linux host

littlefs/lfs.c:1070:error: Corrupted dir pair at {0x0, 0x1}
lfs_fuse.c:514:error: Invalid or incomplete multibyte or wide character

My steps were:

1. Create an image dd if=/dev/zero of=image bs=4096 count=4
2. Format the LFS image ./lfs --block_size=4096 --block_count=4 --read_size=4096 --prog_size=4096 --format /dev/loop12
3. Mount it on Ubuntu ./lfs /dev/loop12 mount and got the error.

If I understand, the block_size is each small page's block (4 Kb in my case) and the block_count are the number of 4Kb I need. Am I right?

The LFS's documentation states the

    // Size of an erasable block. This does not impact ram consumption and
    // may be larger than the physical erase size. However, non-inlined files
    // take up at minimum one block. Must be a multiple of the read
    // and program sizes.
    lfs_size_t block_size;

    // Number of erasable blocks on the device.
    lfs_size_t block_count;

Thank you

[de-nordic]

The default parameters are as follows:

as long as you do not use fstab, like the automount in samples/subsys/fs/littlefs does, these will be your defaults. The automount uses DTS overlay with the parameters.
The read_size and the write_size set granular size of the read/write operations within the block.
So the block size is fine (4k), the other need correction according to your setup.

[d-soliveira]

Hi @de-nordic

I have configured the parameters as your suggestion, and now I can read the file without any problem. Thank you!

For someone who could be facing the same problem, my steps were:

1. Removed the fstab option.
2. Adjusted the DTS file to storage_partition: partition@fc000 { label = "storage"; reg = <0x000fc000 0x0008000>; };
3. dd if=/dev/zero of=image_new.bin bs=4096 count=8
4. ./lfs --block_size=4096 --read_size=16 --prog_size=64 --block_cycles=512 --cache_size=64 --lookahead_size=32 --format /dev/loop12
5. ./lfs --block_size=4096 --read_size=16 --prog_size=64 --block_cycles=512 --cache_size=64 --lookahead_size=32 /dev/loop12 mount