On Thu, Apr 09, 2020 at 11:29:47AM +0300, Konstantin Khlebnikov wrote: > Stacked filesystems like overlayfs has no own writeback, but they have to > forward syncfs() requests to backend for keeping data integrity. > > During global sync() each overlayfs instance calls method ->sync_fs() > for backend although it itself is in global list of superblocks too. > As a result one syscall sync() could write one superblock several times > and send multiple disk barriers. > > This patch adds flag SB_I_SKIP_SYNC into sb->sb_iflags to avoid that. Why wouldn't you just remove the ->sync_fs method from overlay? I mean, if you don't need the filesystem to do anything special for one specific data integrity sync_fs call, you don't need it for any of them, yes? -Dave. -- Dave Chinner david@xxxxxxxxxxxxx
