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. 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
