On Mon, May 14, 2018 at 1:56 AM, Eric Whitney <enwlinux@xxxxxxxxx> wrote: > The goals of this patch series are to solve the specific bugs > described in bugzilla #151491 and to arrive at a correct solution > for delayed allocated cluster accounting for bigalloc file systems > generally. Under some circumstances, ext4 currently makes gross > overestimates of the number of reserved clusters required to handle > bigalloc write requests under delayed allocation. In addition to > premature ENOSPC and quota limit failures, these overestimates tend > to persist over time and in some cases even persist across umounts > and remounts of an affected file system. > > This patch series is a work in progress. Although it does appear to > correct all known delayed cluster accounting deficiencies, and > produces no regressions for all xfstest-bld test cases, it currently > contains a significant bug that adversely affects ext4's direct I/O > code. The next and hopefully final step is to address that bug. > These patches are being posted now to show the work in progress and > to solicit comments on its general approach and implementation. > > All of the patches in the series must be applied as a unit to obtain > a correct solution to the problem. The individual fixes in this > series have not been submitted separately because they can cause > new failures or misbehavior to appear. The effect is to make matters > even worse for the use case described in bugzilla #151491 until all > the fixes have been applied together. > > This patch series is based on 4.17-rc3. 4.17-rc4 has exhibited a > number of undiagnosed xfstest-bldtest test failures that appear to be > unrelated to ext4 and which make comparisons with a regression > baseline troublesome. 4.17-rc3 is free of those failures. > FYI, I'm going thru the whole patch set, the first two patches look good to me. thanks, liubo > Eric Whitney (5): > ext4: fix reserved cluster accounting at delayed write time > ext4: reduce reserved cluster count by number of allocated clusters > ext4: adjust reserved cluster count when removing extents > ext4: release delayed allocated clusters when removing block ranges > ext4: don't release delalloc clusters when invalidating page > > fs/ext4/ext4.h | 11 + > fs/ext4/extents.c | 661 ++++++++++++++++++++++++++++------------------- > fs/ext4/extents_status.c | 303 ++++++++++++++++++++++ > fs/ext4/extents_status.h | 20 ++ > fs/ext4/inode.c | 113 ++++---- > fs/ext4/mballoc.c | 11 +- > 6 files changed, 798 insertions(+), 321 deletions(-) > > -- > 2.11.0 >
