Assertion on minimum block size < 128 bytes

[jnz86]

There is an assertion that prevents the blocksize from being set lower than 128 bytes.

I have reasons, but I was trying to set a block size lower than that.

lfs: littlefs/lfs.c:4186: lfs_init: Assertion lfs->cfg->block_size >= 128' failed.`

Does LittleFS have that same limitation?

[geky]

Hi @jnz86,

You're welcome to comment out that line, but the filesystem may break in unexpected ways.

You may also need to comment out the following assert which checks the CTZ skip-list related limit explicitly: here.

The 128 byte limit was chosen as it's the maximum number of pointers in a single-block in our CTZ skip-list data structure (more info here). littlefs doesn't check if this overflows, so if you create a large enough file, ~2GiB, with small blocks, this can break.

I would also be a bit concerned with metadata fitting with such small blocks. If there isn't enough space for global-state + tail-pointers in an mdir the filesystem might break in unexpected ways in hard to reach cases.

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Out of curiosity what is the motivation for such small blocks? I'm assuming this is RAM/NVRAM/EEPROM?