Hi all, Congratulations! You have made it to the final patchset of the main online fsck feature! This patchset fixes some stalling behavior that I observed when running FITRIM against large flash-based filesystems with very heavily fragmented free space data. In summary -- the current fstrim implementation optimizes for trimming the largest free extents first, and holds the AGF lock for the duration of the operation. This is great if fstrim is being run as a foreground process by a sysadmin. For xfs_scrub, however, this isn't so good -- we don't really want to block on one huge kernel call while reporting no progress information. We don't want to hold the AGF so long that background processes stall. These problems are easily fixable by issuing smaller FITRIM calls, but there's still the problem of walking the entire cntbt. To solve that second problem, we introduce a new sub-AG FITRIM implementation. To solve the first problem, make it relax the AGF periodically. If you're going to start using this code, I strongly recommend pulling from my git trees, which are linked below. This has been running on the djcloud for months with no problems. Enjoy! Comments and questions are, as always, welcome. --D kernel git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=discard-relax-locks --- Commits in this patchset: * xfs: fix severe performance problems when fstrimming a subset of an AG --- fs/xfs/xfs_discard.c | 172 +++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 169 insertions(+), 3 deletions(-)
