[$] Disabling an extent optimization

Post Syndicated from original https://lwn.net/Articles/898029/

In the final filesystem session at the
2022 Linux Storage,
Filesystem, Memory-management and BPF Summit
(LSFMM), David Howells led
a discussion on a filesystem optimization that is causing various kinds of
problems. Extent-based filesystems have data structures that sometimes do
not reflect the holes
that exist in files. Reads from holes in sparse files (i.e. files with
holes) must return zeroes, but filesystems are not obligated to maintain knowledge of
the holes beyond that, which leads to the problems.

This concludes our coverage of LSFMM 2022.