Superblock expansion is an irreversible operation. In an effort to prevent superblock expansion from claiming valuable scratch space (important for small, <~8 block filesystems), littlefs prevents superblock expansion when the disk is "mostly full".
In true computer-scientist fashion, this "mostly full" threshold was set to ~50%.
As pointed out by @gbolgradov and @rojer, >~50% utilization is not uncommon, and it can lead to a situation where superblock expansion does not occur in a relatively healthy filesystem, causing focused wear at the root.
To remedy this, the threshold is now increased to ~88% (7/8) full.
This may change in the future and should probably be eventually user configurable.
geky-bot
commented
6 months ago
Superblock expansion is an irreversible operation. In an effort to prevent superblock expansion from claiming valuable scratch space (important for small, <~8 block filesystems), littlefs prevents superblock expansion when the disk is "mostly full".
In true computer-scientist fashion, this "mostly full" threshold was set to ~50%.
As pointed out by @gbolgradov and @rojer, >~50% utilization is not uncommon, and it can lead to a situation where superblock expansion does not occur in a relatively healthy filesystem, causing focused wear at the root.
To remedy this, the threshold is now increased to ~88% (7/8) full.
This may change in the future and should probably be eventually user configurable.
See https://github.com/littlefs-project/littlefs/issues/901 for more info.