On Fri 20-05-22 11:36:41, Stefan Roesch wrote:
> This introduces the S_PENDING_TIME flag. If an async buffered write
> needs to update the time, it cannot be processed in the fast path of
> io-uring. When a time update is pending this flag is set for async
> buffered writes. Other concurrent async buffered writes for the same
> file do not need to wait while this time update is pending.
>
> This reduces the number of async buffered writes that need to get punted
> to the io-workers in io-uring.
>
> Signed-off-by: Stefan Roesch <shr@xxxxxx>
...
> @@ -2184,10 +2184,17 @@ int file_modified_async(struct file *file, int flags)
> ret = file_needs_update_time(inode, file, &now);
> if (ret <= 0)
> return ret;
> - if (flags & IOCB_NOWAIT)
> + if (flags & IOCB_NOWAIT) {
> + if (IS_PENDING_TIME(inode))
> + return 0;
> +
> + inode->i_flags |= S_PENDING_TIME;
> return -EAGAIN;
> + }
>
> - return __file_update_time(inode, file, &now, ret);
> + ret = __file_update_time(inode, file, &now, ret);
> + inode->i_flags &= ~S_PENDING_TIME;
> + return ret;
> }
> EXPORT_SYMBOL(file_modified_async);
You still didn't address my concern that i_flags is modified without the
protection of i_rwsem here. That can lead to corruption of i_flags value
and rather nasty (and hard to debug) consequences. You can use
inode_set_flags() here to make things kinda safe. The whole inode->i_flags
handling is a mess but not yours to resolve ;)
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
