| Message ID | cover.1535754957.git.osandov@fb.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Btrfs: implement swap file support | expand |
On Fri, Aug 31, 2018 at 03:36:35PM -0700, Omar Sandoval wrote: > This series implements swap file support for Btrfs. > > Changes since v4 [1]: > > - Added a kernel doc for btrfs_get_chunk_map() > - Got rid of "Btrfs: push EXCL_OP set into btrfs_rm_device()" > - Made activate error messages more clear and consistent > - Changed clear vs unlock order in activate error case > - Added "mm: export add_swap_extent()" as a separate patch > - Added a btrfs_wait_ordered_range() at the beginning of > btrfs_swap_activate() to catch newly created files > - Added some Reviewed-bys from Nikolay > > I took a stab at adding support for balance when a swap file is active, > but it's a major pain: we need to mark block groups which contain swap > file extents, check the block group counter in relocate/scrub, then > unmark the block groups when the swap file is deactivated, which gets > really messy because the file can grow while it is an active swap file. > If this is a deal breaker, I can work something out, but I don't think > it's worth the trouble. I'm afraid it is a deal breaker. Unlike dev-replace or resize, balance is used more often so switching off the swap file for the duration of the operation is administration pain. If it's possible to constrain the swap file further, like no growing that you mention, or mandatory preallocation or similar, then I hope it would make it possible to implement in a sane way.
On Thu, Sep 06, 2018 at 01:59:54PM +0200, David Sterba wrote: > On Fri, Aug 31, 2018 at 03:36:35PM -0700, Omar Sandoval wrote: > > This series implements swap file support for Btrfs. > > > > Changes since v4 [1]: > > > > - Added a kernel doc for btrfs_get_chunk_map() > > - Got rid of "Btrfs: push EXCL_OP set into btrfs_rm_device()" > > - Made activate error messages more clear and consistent > > - Changed clear vs unlock order in activate error case > > - Added "mm: export add_swap_extent()" as a separate patch > > - Added a btrfs_wait_ordered_range() at the beginning of > > btrfs_swap_activate() to catch newly created files > > - Added some Reviewed-bys from Nikolay > > > > I took a stab at adding support for balance when a swap file is active, > > but it's a major pain: we need to mark block groups which contain swap > > file extents, check the block group counter in relocate/scrub, then > > unmark the block groups when the swap file is deactivated, which gets > > really messy because the file can grow while it is an active swap file. > > If this is a deal breaker, I can work something out, but I don't think > > it's worth the trouble. > > I'm afraid it is a deal breaker. Unlike dev-replace or resize, balance > is used more often so switching off the swap file for the duration of > the operation is administration pain. > > If it's possible to constrain the swap file further, like no growing > that you mention, or mandatory preallocation or similar, then I hope it > would make it possible to implement in a sane way. Alright, I'll have another go.
From: Omar Sandoval <osandov@fb.com> Hi, This series implements swap file support for Btrfs. Changes since v4 [1]: - Added a kernel doc for btrfs_get_chunk_map() - Got rid of "Btrfs: push EXCL_OP set into btrfs_rm_device()" - Made activate error messages more clear and consistent - Changed clear vs unlock order in activate error case - Added "mm: export add_swap_extent()" as a separate patch - Added a btrfs_wait_ordered_range() at the beginning of btrfs_swap_activate() to catch newly created files - Added some Reviewed-bys from Nikolay I took a stab at adding support for balance when a swap file is active, but it's a major pain: we need to mark block groups which contain swap file extents, check the block group counter in relocate/scrub, then unmark the block groups when the swap file is deactivated, which gets really messy because the file can grow while it is an active swap file. If this is a deal breaker, I can work something out, but I don't think it's worth the trouble. This was tested with the swap tests in xfstests plus my new tests here [2]. Additionally, I used my swapme test program [3] and ran a few memory-intensive workloads (e.g., a highly parallel kernel build), verifying that swap was being used. All of this was done with lockdep enabled. This series is based on v4.19-rc1. Please take a look. Thanks! 1: https://www.spinics.net/lists/linux-btrfs/msg78731.html 2: https://github.com/osandov/xfstests/tree/btrfs-swap 3: https://github.com/osandov/osandov-linux/blob/master/scripts/swapme.c Omar Sandoval (6): mm: split SWP_FILE into SWP_ACTIVATED and SWP_FS mm: export add_swap_extent() vfs: update swap_{,de}activate documentation Btrfs: prevent ioctls from interfering with a swap file Btrfs: rename get_chunk_map() and make it non-static Btrfs: support swap files Documentation/filesystems/Locking | 17 +-- Documentation/filesystems/vfs.txt | 12 +- fs/btrfs/ctree.h | 6 + fs/btrfs/disk-io.c | 3 + fs/btrfs/inode.c | 232 ++++++++++++++++++++++++++++++ fs/btrfs/ioctl.c | 51 ++++++- fs/btrfs/volumes.c | 28 ++-- fs/btrfs/volumes.h | 9 ++ include/linux/swap.h | 13 +- mm/page_io.c | 6 +- mm/swapfile.c | 14 +- 11 files changed, 348 insertions(+), 43 deletions(-)