[PATCH v3 0/8] speculative preallocation inode tracking

[Brian Foster]

Hi all,

This is v3 of the speculative preallocation inode tracking patchset. This
functionality tracks inodes with post-EOF speculative preallocation for the
purpose of background and on-demand trimming.

Background scanning occurs on a longish interval (5 minutes by default) and in
a best-effort mode (i.e., inodes are skipped due to lock contention or dirty
cache). The intent is to clear up post-EOF blocks on inodes that might have
allocations hanging around due to open-write-close sequences (NFS).

On demand scanning is provided via a new ioctl and supports various parameters
such as scan mode, filtering by quota id and minimum file size. A pending use
case for on demand scanning is for accurate quota accounting via the gluster
scale out filesystem (i.e., to free up preallocated space when near a usage
limit).

Brian

P.S., I've rebased and run this through xfstests a couple times. I'll probably
run at least once more with a low background scan interval just for sanity sake.
Also, Dave previously mentioned this conflicts with the xfssyncd patchset. I can
rebase on top of that if there is any preference in terms of order.

v3:
- Pushed dirty cache check up into patch 5 (minor clean up).
- Reworked xfs_can_free_eofblocks() in patch 3 as per Dave C.'s review.
- Rebased from linus' tree to the XFS tree.

v2:
- Remove unnecessary inode flag clear helper.
- Condense eofblocks set/clear tag functions.
- Move clear tag call into xfs_free_eofblocks().
- Modify AG walk infrastructure to support tag-based walk and utilize this
  functionality for the eofblocks scan (as opposed to the previous code
  duplicated from reclaim scanning).
- Improve ioctl functionality: new data structure fields/flags, validate quota
  is enabled.
- Increase default background scanning interval to 5 minutes, add tunable.

Brian Foster (8):
  xfs: add EOFBLOCKS inode tagging/untagging
  xfs: support a tag-based inode_ag_iterator
  xfs: create helper to check whether to free eofblocks on inode
  xfs: export xfs_free_eofblocks() and return EAGAIN on trylock failure
  xfs: create function to scan and clear EOFBLOCKS inodes
  xfs: add XFS_IOC_FREE_EOFBLOCKS ioctl
  xfs: add enhanced filtering to EOFBLOCKS scan
  xfs: add background scanning to clear EOFBLOCKS inodes

 fs/xfs/xfs_ag.h          |    1 +
 fs/xfs/xfs_fs.h          |   23 +++++
 fs/xfs/xfs_globals.c     |    1 +
 fs/xfs/xfs_ioctl.c       |   20 ++++
 fs/xfs/xfs_iomap.c       |    7 ++
 fs/xfs/xfs_iops.c        |    3 +
 fs/xfs/xfs_linux.h       |    1 +
 fs/xfs/xfs_mount.h       |    2 +
 fs/xfs/xfs_qm_syscalls.c |    5 +-
 fs/xfs/xfs_sync.c        |  215 ++++++++++++++++++++++++++++++++++++++++++++--
 fs/xfs/xfs_sync.h        |   11 ++-
 fs/xfs/xfs_sysctl.c      |    9 ++
 fs/xfs/xfs_sysctl.h      |    1 +
 fs/xfs/xfs_trace.h       |    6 ++
 fs/xfs/xfs_vnodeops.c    |   27 +++---
 fs/xfs/xfs_vnodeops.h    |   41 +++++++++-
 16 files changed, 344 insertions(+), 29 deletions(-)

-- 
1.7.7.6