On Wed, Aug 14, 2013 at 11:10:54AM +0200, Jan Kara wrote:
> this is second iteration of patches to fix handling of O_SYNC AIO DIO.
> Since previous version I've addressed Dave's comments:
> - slightly expanded changelog of the first patch
> - workqueue is now created with parameters allowing paralelism
> - workqueue name contains sb->s_id
> - workqueue is created on demand (I decided to do this to reduce the overhead
> in unnecessary cases)
> The patchset survives xfstests run for ext4 & xfs so it should be sane. Since
> this touches several filesystems (although only ext4 & xfs are non-trivial),
> the question is who should carry these patches. Maybe Al? But since xfs and
> ext4 changes are non-trivial, I'd like to have a review from their
Looks sane, except that I'd probably put destroying the queue after
evict_inodes(), next to ->put_super() call.
Said that, there's another interesting problem in the code affected by that
sucker: generic_file_aio_write() might very well sync the wrong range.
Consider O_APPEND case; __generic_file_aio_write() will call
generic_write_checks(), which will update its copy of pos, and proceed to
write starting from there. All right and proper, but then we return into
generic_file_aio_write() and sync the range of the right length, starting
at the *original* value of pos...