From: Matthew Bobrowski <mbobrowski@mbobrowski.org>
To: Ritesh Harjani <riteshh@linux.ibm.com>
Cc: tytso@mit.edu, jack@suse.cz, adilger.kernel@dilger.ca,
linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
david@fromorbit.com, hch@infradead.org, darrick.wong@oracle.com
Subject: Re: [PATCH v2 5/6] ext4: introduce direct IO write path using iomap infrastructure
Date: Wed, 11 Sep 2019 22:39:05 +1000 [thread overview]
Message-ID: <20190911123905.GA26735@bobrowski> (raw)
In-Reply-To: <20190911080853.43B954C04E@d06av22.portsmouth.uk.ibm.com>
On Wed, Sep 11, 2019 at 01:38:52PM +0530, Ritesh Harjani wrote:
> On 9/9/19 2:56 PM, Ritesh Harjani wrote:
> > On 9/9/19 4:49 AM, Matthew Bobrowski wrote:
> > > @@ -217,6 +218,14 @@ static ssize_t ext4_write_checks(struct kiocb
> > > *iocb, struct iov_iter *from)
> > > if (ret <= 0)
> > > return ret;
> > >
> > > + ret = file_remove_privs(iocb->ki_filp);
> > > + if (ret)
> > > + return 0;
> > > +
> > > + ret = file_update_time(iocb->ki_filp);
> > > + if (ret)
> > > + return 0;
> > > +
> > > if (unlikely(IS_IMMUTABLE(inode)))
> > > return -EPERM;
>
> Maybe we can move this up. If file is IMMUTABLE no point in
> calling for above actions (file_remove_privs/file_updatetime).
Yep, sure could do this. In fact, I think we could put this above
generic_write_checks().
> Also why not use file_modified() API which does the same.
Ah, nice. Indeed we can, thanks for simplifying it.
> > > @@ -234,6 +243,34 @@ static ssize_t ext4_write_checks(struct kiocb
> > > *iocb, struct iov_iter *from)
> > > return iov_iter_count(from);
> > > }
> > >
> > > +static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
> > > + struct iov_iter *from)
> > > +{
> > > + ssize_t ret;
> > > + struct inode *inode = file_inode(iocb->ki_filp);
> > > +
> > > + if (iocb->ki_flags & IOCB_NOWAIT)
> > > + return -EOPNOTSUPP;
> > > +
> > > + if (!inode_trylock(inode))
> > > + inode_lock(inode);
>
> Is it really needed to check for trylock first?
> we can directly call for inode_lock() here.
You're right, no need to do this dance. We can call inode_lock() directly.
> > > +
> > > + ret = ext4_write_checks(iocb, from);
> > > + if (ret <= 0)
> > > + goto out;
> > > +
> > > + current->backing_dev_info = inode_to_bdi(inode);
> > > + ret = generic_perform_write(iocb->ki_filp, from, iocb->ki_pos);
> > > + current->backing_dev_info = NULL;
> > > +out:
> > > + inode_unlock(inode);
> > > + if (likely(ret > 0)) {
> > > + iocb->ki_pos += ret;
> > > + ret = generic_write_sync(iocb, ret);
> > > + }
> > > + return ret;
> > > +}
> > > +
> > > + if (!ext4_dio_checks(inode)) {
> > > + inode_unlock(inode);
> > > + /*
> > > + * Fallback to buffered IO if the operation on the
> > > + * inode is not supported by direct IO.
> > > + */
> > > + return ext4_buffered_write_iter(iocb, from);
> > > + }
> > > +
> > > + ret = ext4_write_checks(iocb, from);
> This can modify the count in iov_iter *from.
Good point. We'll recalculate the iter 'count' again.
Thank you for the review/suggestions, highly appreciated.
--<M>--
next prev parent reply other threads:[~2019-09-11 12:39 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-08 23:18 [PATCH v2 0/6] ext4: port direct IO to iomap infrastructure Matthew Bobrowski
2019-09-08 23:18 ` [PATCH v2 1/6] ext4: introduce direct IO read path using " Matthew Bobrowski
2019-09-09 7:48 ` Ritesh Harjani
2019-09-08 23:19 ` [PATCH v2 2/6] ext4: move inode extension/truncate code out from ext4_iomap_end() Matthew Bobrowski
2019-09-09 8:17 ` Ritesh Harjani
2019-09-10 10:26 ` Matthew Bobrowski
2019-09-10 11:16 ` Ritesh Harjani
2019-09-08 23:19 ` [PATCH v2 3/6] iomap: modify ->end_io() calling convention Matthew Bobrowski
2019-09-08 23:32 ` Matthew Bobrowski
2019-09-08 23:19 ` [PATCH v2 4/6] ext4: reorder map.m_flags checks in ext4_iomap_begin() Matthew Bobrowski
2019-09-09 8:30 ` Ritesh Harjani
2019-09-08 23:19 ` [PATCH v2 5/6] ext4: introduce direct IO write path using iomap infrastructure Matthew Bobrowski
2019-09-09 9:20 ` Ritesh Harjani
2019-09-09 9:26 ` Ritesh Harjani
2019-09-09 14:32 ` Ritesh Harjani
2019-09-10 11:20 ` Matthew Bobrowski
2019-09-10 10:31 ` Matthew Bobrowski
2019-09-11 8:08 ` Ritesh Harjani
2019-09-11 12:39 ` Matthew Bobrowski [this message]
2019-09-08 23:20 ` [PATCH v2 6/6] ext4: cleanup legacy buffer_head direct IO code Matthew Bobrowski
2019-09-09 9:36 ` Ritesh Harjani
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