On Sat, Aug 17, 2024 at 9:04 PM Harshad Shirwadkar <harshadshirwadkar@xxxxxxxxx> wrote: > > V7 Cover Letter > --------------- > > This is the V7 of the patch series. This patch series contains fixes to > review comments by Jan Kara (<jack@xxxxxxx>). The main changes are as > follows: > > - As discussed in V6 review, I have dropped "ext4: add nolock mode to > ext4_map_blocks()" patch given that we now ensure that i_data_sem is > always grabbed before ext4_mark_inode_dirty() is called. > > - I have also dropped "ext4: introduce selective flushing in fast commit" > given that correctly implementing that would require more changes, and I > think they would be best done outside of this series. > > - I added "ext4: introduce selective flushing in fast commit" as the last > patch in the series. While testing log group tests I found a few failures > which get fixed due to this patch. Sorry that was a copy paste error. I meant to say I have added a new patch - "ext4: hold s_fc_lock while during fast commit" (which is the last patch in the series). - Harshad > > V6 Cover Letter > --------------- > > This is the V6 of the patch series. This patch series contains fixes to a > bunch of kernel build warnings reported by Kernel Test Robot > (lkp@xxxxxxxxx) and Dan Carpenter (dan.carpenter@xxxxxxxxxx). Thank you! > > V5 Cover Letter > --------------- > > This patch series supersedes the patch series "ext4: remove journal barrier > during fast commit" sent in July 2022[1]. Except following three patches > all the other patches are newly introduced in this series. > > * ext4: convert i_fc_lock to spinlock > * ext4: for committing inode, make ext4_fc_track_inode wait > * ext4: drop i_fc_updates from inode fc info > > This patchset does not introduce any on-disk format and / or user visible > API change. This patchset reworks fast-commit's commit path improve overall > performance of the commit path. Following optimizations have been added in > this series: > > * Avoid having to lock the journal throughout the fast commit. > * Remove tracking of open handles per inode. > * Avoid issuing cache flushes when fast commits are contained within a > single FUA writes and there is no data that needs flushing. > * Temporarily lift committing thread's priority to match that of the > journal thread to reduce scheduling delays. > > With the changes introduced in this patch series, now the commit path for > fast commits is as follows: > > 1. Lock the journal by calling jbd2_journal_lock_updates_no_rsv(). This > ensures that all the exsiting handles finish and no new handles can > start. > 2. Mark all the fast commit eligible inodes as undergoing fast commit by > setting "EXT4_STATE_FC_COMMITTING" state. > 3. Unlock the journal by calling jbd2_journal_unlock_updates. This allows > starting of new handles. If new handles try to start an update on any of > the inodes that are being committed, ext4_fc_track_inode() will block > until those inodes have finished the fast commit. > 4. Submit data buffers of all the committing inodes. > 5. Wait for [4] to complete. > 6. Commit all the directory entry updates in the fast commit space. > 7. Commit all the changed inodes in the fast commit space and clear > "EXT4_STATE_FC_COMMITTING" for all the inodes. > 8. Write tail tag to ensure atomicity of commits. > > (The above flow has been documented in the code as well) > > I verified that the patch series introduces no regressions in "log" groups > when "fast_commit" feature is enabled. > > Also, we have a paper on fast commits in USENIX ATC 2024 this year which > should become available on the website[2] in a few months. > > [1] https://lwn.net/Articles/902022/ > [2] https://www.usenix.org/conference/atc24 > > Harshad Shirwadkar (9): > ext4: convert i_fc_lock to spinlock > ext4: for committing inode, make ext4_fc_track_inode wait > ext4: mark inode dirty before grabbing i_data_sem in ext4_setattr > ext4: rework fast commit commit path > ext4: drop i_fc_updates from inode fc info > ext4: update code documentation > ext4: temporarily elevate commit thread priority > ext4: make fast commit ineligible on ext4_reserve_inode_write failure > ext4: hold s_fc_lock while during fast commit > > fs/ext4/ext4.h | 18 +- > fs/ext4/fast_commit.c | 339 ++++++++++++++++++------------------ > fs/ext4/fast_commit.h | 1 + > fs/ext4/inline.c | 3 + > fs/ext4/inode.c | 38 ++-- > fs/ext4/super.c | 9 +- > fs/jbd2/journal.c | 2 - > include/trace/events/ext4.h | 7 +- > 8 files changed, 214 insertions(+), 203 deletions(-) > > -- > 2.46.0.184.g6999bdac58-goog >
