Re: [PATCH] Fix regression in O_DIRECT|O_SYNC writes to blockdevices

From: Jan Kara
Date: Thu Apr 15 2010 - 09:34:34 EST


On Thu 15-04-10 12:42:24, Christoph Hellwig wrote:
> On Thu, Apr 15, 2010 at 02:40:39PM +1000, Anton Blanchard wrote:
> > int blkdev_fsync(struct file *filp, struct dentry *dentry, int datasync)
> > {
> > - struct block_device *bdev = I_BDEV(filp->f_mapping->host);
> > + struct inode *bd_inode = filp->f_mapping->host;
> > + struct block_device *bdev = I_BDEV(bd_inode);
> > int error;
> >
> > + mutex_unlock(&bd_inode->i_mutex);
> > +
> > error = sync_blockdev(bdev);
>
> Actually you can just drop this call entirely. sync_blockdev is an
> overcomplicated alias for filemap_write_and_wait on the block device
> inode, which is exactl what we did just before calling into ->fsync
>
> It might be worth to still drop i_mutex for the cache flush, though.
Yeah, that's a good point... Anton, just remove sync_blockdev() from
blkdev_fsync completely please.

Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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