On 12/1/20 10:18 AM, Brian Foster wrote: > On Mon, Nov 30, 2020 at 07:37:31PM -0800, Darrick J. Wong wrote: >> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx> >> >> Define an incompat feature flag to indicate that the filesystem needs to >> be repaired. While libxfs will recognize this feature, the kernel will >> refuse to mount if the feature flag is set, and only xfs_repair will be >> able to clear the flag. The goal here is to force the admin to run >> xfs_repair to completion after upgrading the filesystem, or if we >> otherwise detect anomalies. >> >> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> >> --- > IIUC, we're using an incompat bit to intentionally ensure the filesystem > cannot mount, even on kernels that predate this particular "needs > repair" feature. The only difference is that an older kernel would > complain about an unknown feature and return a different error code. > Right? > > That seems reasonable, but out of curiousity is there a need/reason for > using an incompat bit over an ro_compat bit? I'm a fan of a straight-up incompat, because we don't really know what format changes in the future might require this flag to be set; nothing guarantees that future changes will be ro-compat-safe, right? -Eric
