On Thu, May 03, 2018 at 10:46:59AM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > Add a new iomap_swapfile_activate function so that filesystems can > activate swap files without having to use the obsolete and slow bmap > function. This enables XFS to support fallocate'd swap files and > swap files on realtime devices. > Shouldn't we also prevent the extents of an active swapfile from becoming shared? If I swapon(a) and reflink(a, b), swapout to a now has to break the reflink or corrupt b! In my old Btrfs swapfile series [1] I just forbid all reflink operations on active swapfiles. One thing to note is that then this will need a matching ->swap_deactivate(), which currently isn't called if ->swap_activate() returned > 0. 1: https://github.com/osandov/linux/tree/btrfs-swap > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > --- > v3: catch null iomap addr, fix too-short extent detection > v2: document the swap file layout requirements, combine adjacent > real/unwritten extents, align reported swap extents to physical page > size boundaries, fix compiler errors when swap disabled
