From: Trond Myklebust <trondmy@primarydata.com>
To: "viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
"jlayton@redhat.com" <jlayton@redhat.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Cc: "linux-nilfs@vger.kernel.org" <linux-nilfs@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"neilb@suse.com" <neilb@suse.com>,
"konishi.ryusuke@lab.ntt.co.jp" <konishi.ryusuke@lab.ntt.co.jp>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"adilger@dilger.ca" <adilger@dilger.ca>,
"James.Bottomley@HansenPartnership.com"
<James.Bottomley@HansenPartnership.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH v2 6/9] mm: set mapping error when launder_pages fails
Date: Wed, 8 Mar 2017 19:16:32 +0000 [thread overview]
Message-ID: <1489000588.3098.8.camel@primarydata.com> (raw)
In-Reply-To: <1488998288.2802.25.camel@redhat.com>
On Wed, 2017-03-08 at 13:38 -0500, Jeff Layton wrote:
> On Wed, 2017-03-08 at 18:01 +0000, Trond Myklebust wrote:
> > On Wed, 2017-03-08 at 11:29 -0500, Jeff Layton wrote:
> > > If launder_page fails, then we hit a problem writing back some
> > > inode
> > > data. Ensure that we communicate that fact in a subsequent fsync
> > > since
> > > another task could still have it open for write.
> > >
> > > Signed-off-by: Jeff Layton <jlayton@redhat.com>
> > > ---
> > > mm/truncate.c | 6 +++++-
> > > 1 file changed, 5 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/mm/truncate.c b/mm/truncate.c
> > > index 6263affdef88..29ae420a5bf9 100644
> > > --- a/mm/truncate.c
> > > +++ b/mm/truncate.c
> > > @@ -594,11 +594,15 @@ invalidate_complete_page2(struct
> > > address_space
> > > *mapping, struct page *page)
> > >
> > > static int do_launder_page(struct address_space *mapping, struct
> > > page *page)
> > > {
> > > + int ret;
> > > +
> > > if (!PageDirty(page))
> > > return 0;
> > > if (page->mapping != mapping || mapping->a_ops-
> > > >launder_page
> > > == NULL)
> > > return 0;
> > > - return mapping->a_ops->launder_page(page);
> > > + ret = mapping->a_ops->launder_page(page);
> > > + mapping_set_error(mapping, ret);
> > > + return ret;
> > > }
> > >
> > > /**
> >
> > No. At that layer, you don't know that this is a page error. In the
> > NFS
> > case, it could, for instance, just as well be a fatal signal.
> >
>
> Ok...don't we have the same problem with writepage then? Most of the
> writepage callers will set an error in the mapping if writepage
> returns
> any sort of error? A fatal signal in that codepath could cause the
> same
> problem, it seems. We don't dip into direct reclaim so much anymore,
> so
> maybe signals aren't an issue there?
If writepage() fails due to a signal, then it has the option of marking
the page as dirty and returning AOP_WRITEPAGE_ACTIVATE. That's not
possible for launder_page().
> The alternative here would be to push this down into the callers. I
> worry a bit though about getting this right across filesystems
> though.
> It'd be preferable it if we could keep the mapping_set_error call in
> generic VFS code instead, but if not then I'll just plan to do that.
>
--
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@primarydata.com
next prev parent reply other threads:[~2017-03-08 19:20 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-08 16:29 [PATCH v2 0/9] mm/fs: get PG_error out of the writeback reporting business Jeff Layton
2017-03-08 16:29 ` [PATCH v2 1/9] mm: fix mapping_set_error call in me_pagecache_dirty Jeff Layton
2017-03-10 0:06 ` Ross Zwisler
2017-03-08 16:29 ` [PATCH v2 2/9] mm: drop "wait" parameter from write_one_page Jeff Layton
2017-03-10 0:07 ` Ross Zwisler
2017-03-08 16:29 ` [PATCH v2 3/9] mm: clear any AS_* errors when returning error on any fsync or close Jeff Layton
2017-03-08 21:23 ` NeilBrown
2017-03-09 0:10 ` Jeff Layton
2017-03-10 0:09 ` Ross Zwisler
2017-03-10 3:08 ` Jeff Layton
2017-03-08 16:29 ` [PATCH v2 4/9] nilfs2: set the mapping error when calling SetPageError on writeback Jeff Layton
2017-03-08 16:29 ` [PATCH v2 5/9] dax: set error in mapping when writeback fails Jeff Layton
2017-03-10 0:21 ` Ross Zwisler
2017-03-08 16:29 ` [PATCH v2 6/9] mm: set mapping error when launder_pages fails Jeff Layton
2017-03-08 18:01 ` Trond Myklebust
2017-03-08 18:38 ` Jeff Layton
2017-03-08 19:16 ` Trond Myklebust [this message]
2017-03-08 21:28 ` NeilBrown
2017-03-08 16:29 ` [PATCH v2 7/9] mm: ensure that we set mapping error if writeout() fails Jeff Layton
2017-03-08 16:29 ` [PATCH v2 8/9] mm: don't TestClearPageError in __filemap_fdatawait_range Jeff Layton
2017-03-08 16:29 ` [PATCH v2 9/9] Documentation: document what to do on a writeback error Jeff Layton
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