| Message ID | 20170308162934.21989-7-jlayton@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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. -- Trond Myklebust Linux NFS client maintainer, PrimaryData trond.myklebust@primarydata.com
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? 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. Thanks,
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
On Thu, Mar 09 2017, 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. > In that case, would 'ret' be ERESTARTSYS or EAGAIN or similar? Should mapping_set_error() ignore those? Thanks, NeilBrown > -- > Trond Myklebust > Linux NFS client maintainer, PrimaryData > trond.myklebust@primarydata.com
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; } /**
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(-)