On Fri, Apr 01, 2022 at 03:29:37PM +0800, Qu Wenruo wrote: > [BUG] > For a 4K sector sized btrfs with v1 cache enabled and only mounted on > systems with 4K page size, if it's mounted on subpage (64K page size) > systems, it can cause the following warning on v1 space cache: > > BTRFS error (device dm-1): csum mismatch on free space cache > BTRFS warning (device dm-1): failed to load free space cache for block group 84082688, rebuilding it now > > Although not a big deal, as kernel can rebuild it without problem, such > warning will bother end users, especially if they want to switch the > same btrfs seamlessly between different page sized systems. > > [CAUSE] > V1 free space cache is still using fixed PAGE_SIZE for various bitmap, > like BITS_PER_BITMAP. > > Such hard-coded PAGE_SIZE usage will cause various mismatch, from v1 > cache size to checksum. > > Thus kernel will always reject v1 cache with a different PAGE_SIZE with > csum mismatch. > > [FIX] > Although we should fix v1 cache, it's already going to be marked > deprecated soon. > > And we have v2 cache based on metadata (which is already fully subpage > compatible), and it has almost everything superior than v1 cache. > > So just force subpage mount to use v2 cache on mount. > > Reported-by: Matt Corallo <blnxfsl@xxxxxxxxxxx> > CC: stable@xxxxxxxxxxxxxxx # 5.15+ > Link: https://lore.kernel.org/linux-btrfs/61aa27d1-30fc-c1a9-f0f4-9df544395ec3@xxxxxxxxxxx/ > Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> Thanks, Josef
