Increase threshold for superblock expansion from ~50% -> ~88% full #910
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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. Found by gbolgradov and rojer
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Tests passed ✓, Code: 16828 B (+0.0%), Stack: 1448 B (+0.0%), Structs: 800 B (+0.0%)
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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 #901 for more info.