On Tue 27-08-19 21:51:18, Dave Chinner wrote: > On Tue, Aug 27, 2019 at 10:05:49AM +0800, Joseph Qi wrote: > > This patch set is trying to revert parallel dio reads feature at present > > since it causes significant performance regression in mixed random > > read/write scenario. > > > > Joseph Qi (3): > > Revert "ext4: remove EXT4_STATE_DIOREAD_LOCK flag" > > Revert "ext4: fix off-by-one error when writing back pages before dio > > read" > > Revert "ext4: Allow parallel DIO reads" > > > > fs/ext4/ext4.h | 17 +++++++++++++++++ > > fs/ext4/extents.c | 19 ++++++++++++++----- > > fs/ext4/inode.c | 47 +++++++++++++++++++++++++++++++---------------- > > fs/ext4/ioctl.c | 4 ++++ > > fs/ext4/move_extent.c | 4 ++++ > > fs/ext4/super.c | 12 +++++++----- > > 6 files changed, 77 insertions(+), 26 deletions(-) > > Before doing this, you might want to have a chat and co-ordinate > with the folks that are currently trying to port the ext4 direct IO > code to use the iomap infrastructure: > > https://lore.kernel.org/linux-ext4/20190827095221.GA1568@xxxxxxxxxxxxxxxxxxxxxx/T/#t > > That is going to need the shared locking on read and will work just > fine with shared locking on write, too (it's the code that XFS uses > for direct IO). So it might be best here if you work towards shared > locking on the write side rather than just revert the shared locking > on the read side.... Yeah, after converting ext4 DIO path to iomap infrastructure, using shared inode lock for all aligned non-extending DIO writes will be easy so I'd prefer if we didn't have to redo the iomap conversion patches due to these reverts. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
