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Message-ID: <20090825131941.GF405@duck.novell.com> Date: Tue, 25 Aug 2009 15:19:41 +0200 From: Jan Kara <jack@...e.cz> To: Theodore Tso <tytso@....edu> Cc: Jan Kara <jack@...e.cz>, Mingming <cmm@...ibm.com>, linux-ext4@...r.kernel.org, Eric Sandeen <sandeen@...hat.com> Subject: Re: [PATCH 1/2 V2] Direct IO for holes and fallocate: add end_io callback On Mon 24-08-09 15:11:38, Theodore Tso wrote: > On Wed, Aug 19, 2009 at 04:15:57PM +0200, Jan Kara wrote: > > > +static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset, > > > + ssize_t size, void *private) > > > +{ > > > + ext4_io_end_t *io_end = iocb->private; > > > + struct workqueue_struct *wq; > > > + > > > + /* if not hole or unwritten extents, just simple return */ > > > + if (!io_end || !size) > > > + return; > > > + io_end->offset = offset; > > > + io_end->size = size; > > > + wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq; > > > + > > > + /* We need to convert unwritten extents to written */ > > > + queue_work(wq, &io_end->work); > > > + > > > + if (is_sync_kiocb(iocb)) > > > + flush_workqueue(wq); > > I don't think you can flush_workqueue here. end_io is called from > > interrupt context and flush_workqueue blocks for a long time... > > The wait should be done in ext4_direct_IO IMHO... > > I don't see a problem here? This is a direct_io end_io callback, not > a bio callback; so it's only called from an interrupt context in the > async I/O case, and we only call flush_workqueue() when the kiocb is > synchronous. Ah, right, I didn't realize that DIO end_io callback gets called from an interrupt context only for async IO. That also explains why XFS is fine doing the same thing. Thanks for the explanation. Honza -- Jan Kara <jack@...e.cz> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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