Commit Graph

2 Commits

Author SHA1 Message Date
Christopher Haster
daa6577060 Renamed all prefixes to include the major version
This is needed to allow compilation of multiple versions in the same
binary. Also note that the FUSE testing was removed because of related
name issues.

./scripts/prefix.py lfs1
2019-01-30 14:03:16 -06:00
Christopher Haster
2936514b5e Added atomic move using dirty tag in entry type
The "move problem" has been present in littlefs for a while, but I haven't
come across a solution worth implementing for various reasons.

The problem is simple: how do we move directory entries across
directories atomically? Since multiple directory entries are involved,
we can't rely entirely on the atomic block updates. It ends up being
a bit of a puzzle.

To make the problem more complicated, any directory block update can
fail due to wear, and cause the directory block to need to be relocated.
This happens rarely, but brings a large number of corner cases.

---

The solution in this patch is simple:
1. Mark source as "moving"
2. Copy source to destination
3. Remove source

If littlefs ever runs into a "moving" entry, that means a power loss
occured during a move. Either the destination entry exists or it
doesn't. In this case we just search the entire filesystem for the
destination entry.

This is expensive, however the chance of a power loss during a move
is relatively low.
2017-10-10 06:18:46 -05:00