From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id 0D1DA7F5A for ; Wed, 1 Apr 2015 10:07:22 -0500 (CDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay2.corp.sgi.com (Postfix) with ESMTP id 06177304043 for ; Wed, 1 Apr 2015 08:07:18 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) by cuda.sgi.com with ESMTP id Gdn379ZN4s1QBRAx (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Wed, 01 Apr 2015 08:07:13 -0700 (PDT) Date: Wed, 1 Apr 2015 17:07:09 +0200 From: Jan Kara Subject: Re: [PATCH 3/8] dax: expose __dax_fault for filesystems with locking constraints Message-ID: <20150401150709.GQ26339@quack.suse.cz> References: <1427194266-2885-1-git-send-email-david@fromorbit.com> <1427194266-2885-4-git-send-email-david@fromorbit.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1427194266-2885-4-git-send-email-david@fromorbit.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Dave Chinner Cc: linux-fsdevel@vger.kernel.org, willy@linux.intel.com, jack@suse.cz, xfs@oss.sgi.com On Tue 24-03-15 21:51:01, Dave Chinner wrote: > From: Dave Chinner > > Some filesystems cannot call dax_fault() directly because they have > different locking and/or allocation constraints in the page fault IO > path. To handle this, we need to follow the same model as the > generic block_page_mkwrite code, where the internals are exposed via > __block_page_mkwrite() so that filesystems can wrap the correct > locking and operations around the outside. > > This is loosely based on a patch originally from Matthew Willcox. > Unlike the original patch, it does not change ext4 code, error > returns or unwritten extent conversion handling. It also adds a > __dax_mkwrite() wrapper for .page_mkwrite implementations to do the > right thing, too. We will need a normal error return from __dax_mkwrite() for proper ENOSPC handling in ext4. You could do this when touching that code here if you feel like that but if not, I can do that as a separate patch. Anyway, feel free to add: Reviewed-by: Jan Kara Honza > > Signed-off-by: Dave Chinner > --- > fs/dax.c | 15 +++++++++++++-- > include/linux/fs.h | 5 ++++- > 2 files changed, 17 insertions(+), 3 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 431ec2b..0121f7d 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -313,7 +313,17 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh, > return error; > } > > -static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, > +/** > + * __dax_fault - handle a page fault on a DAX file > + * @vma: The virtual memory area where the fault occurred > + * @vmf: The description of the fault > + * @get_block: The filesystem method used to translate file offsets to blocks > + * > + * When a page fault occurs, filesystems may call this helper in their > + * fault handler for DAX files. __dax_fault() assumes the caller has done all > + * the necessary locking for the page fault to proceed successfully. > + */ > +int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, > get_block_t get_block, dax_iodone_t complete_unwritten) > { > struct file *file = vma->vm_file; > @@ -440,6 +450,7 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, > } > goto out; > } > +EXPORT_SYMBOL(__dax_fault); > > /** > * dax_fault - handle a page fault on a DAX file > @@ -460,7 +471,7 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, > sb_start_pagefault(sb); > file_update_time(vma->vm_file); > } > - result = do_dax_fault(vma, vmf, get_block, complete_unwritten); > + result = __dax_fault(vma, vmf, get_block, complete_unwritten); > if (vmf->flags & FAULT_FLAG_WRITE) > sb_end_pagefault(sb); > > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 82100ae..7e5a2d6 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -2606,7 +2606,10 @@ 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, > dax_iodone_t); > -#define dax_mkwrite(vma, vmf, gb, iod) dax_fault(vma, vmf, gb, iod) > +int __dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t, > + dax_iodone_t); > +#define dax_mkwrite(vma, vmf, gb, iod) dax_fault(vma, vmf, gb, iod) > +#define __dax_mkwrite(vma, vmf, gb, iod) __dax_fault(vma, vmf, gb, iod) > > #ifdef CONFIG_BLOCK > typedef void (dio_submit_t)(int rw, struct bio *bio, struct inode *inode, > -- > 2.0.0 > -- Jan Kara SUSE Labs, CR _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs