From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: [PATCH 3/3] DAX: use pfn_mkwrite to update c/mtime Date: Wed, 4 Mar 2015 18:19:35 +0100 Message-ID: <20150304171935.GA5443@quack.suse.cz> References: <54F733BD.7060807@plexistor.com> <54F73746.5020300@plexistor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Dave Chinner , Matthew Wilcox , Andrew Morton , "Kirill A. Shutemov" , Jan Kara , Hugh Dickins , Mel Gorman , linux-mm@kvack.org, linux-nvdimm , linux-fsdevel To: Boaz Harrosh Return-path: Received: from cantor2.suse.de ([195.135.220.15]:39337 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758854AbbCDRTn (ORCPT ); Wed, 4 Mar 2015 12:19:43 -0500 Content-Disposition: inline In-Reply-To: <54F73746.5020300@plexistor.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed 04-03-15 18:48:06, Boaz Harrosh wrote: > From: Yigal Korman > > Without this patch, c/mtime is not updated correctly when mmap'ed page is > first read from and then written to. > > A new xfstest is submitted for testing this (generic/080) > > Signed-off-by: Yigal Korman > Signed-off-by: Boaz Harrosh > --- > fs/dax.c | 13 +++++++++++++ > fs/ext2/file.c | 1 + > fs/ext4/file.c | 1 + > include/linux/fs.h | 1 + > 4 files changed, 16 insertions(+) > > diff --git a/fs/dax.c b/fs/dax.c > index ed1619e..cd63adc 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -464,6 +464,19 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, > EXPORT_SYMBOL_GPL(dax_fault); > > /** > + * dax_pfn_mkwrite - handle first write to DAX page > + * @vma: The virtual memory area where the fault occurred > + * @vmf: The description of the fault > + * > + */ > +int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) > +{ > + file_update_time(vma->vm_file); > + return VM_FAULT_NOPAGE; > +} > +EXPORT_SYMBOL_GPL(dax_pfn_mkwrite); Hum, you likely want a freeze protection in there as well (sb_start_pagefault() and sb_end_pagefault()). Don't you? Otherwise user could start writing to the page while filesystem is frozen. That's another bug you could mention in your description. Honza > + > +/** > * dax_zero_page_range - zero a range within a page of a DAX file > * @inode: The file being truncated > * @from: The file offset that is being truncated to > diff --git a/fs/ext2/file.c b/fs/ext2/file.c > index e317017..866a3ce 100644 > --- a/fs/ext2/file.c > +++ b/fs/ext2/file.c > @@ -39,6 +39,7 @@ static int ext2_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) > static const struct vm_operations_struct ext2_dax_vm_ops = { > .fault = ext2_dax_fault, > .page_mkwrite = ext2_dax_mkwrite, > + .pfn_mkwrite = dax_pfn_mkwrite, > }; > > static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma) > diff --git a/fs/ext4/file.c b/fs/ext4/file.c > index 33a09da..b43a7a6 100644 > --- a/fs/ext4/file.c > +++ b/fs/ext4/file.c > @@ -206,6 +206,7 @@ static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) > static const struct vm_operations_struct ext4_dax_vm_ops = { > .fault = ext4_dax_fault, > .page_mkwrite = ext4_dax_mkwrite, > + .pfn_mkwrite = dax_pfn_mkwrite, > }; > #else > #define ext4_dax_vm_ops ext4_file_vm_ops > diff --git a/include/linux/fs.h b/include/linux/fs.h > index b4d71b5..24af817 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -2597,6 +2597,7 @@ int dax_clear_blocks(struct inode *, sector_t block, long size); > int dax_zero_page_range(struct inode *, loff_t from, unsigned len, get_block_t); > int dax_truncate_page(struct inode *, loff_t from, get_block_t); > int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t); > +int dax_pfn_mkwrite(struct vm_area_struct *, struct vm_fault *); > #define dax_mkwrite(vma, vmf, gb) dax_fault(vma, vmf, gb) > > #ifdef CONFIG_BLOCK > -- > 1.9.3 > > -- Jan Kara SUSE Labs, CR