[v7,15/22] dax: set errors in mapping when writeback fails
diff mbox

Message ID 20170616193427.13955-16-jlayton@redhat.com
State New
Headers show

Commit Message

Jeff Layton June 16, 2017, 7:34 p.m. UTC
Jan Kara's description for this patch is much better than mine, so I'm
quoting it verbatim here:

DAX currently doesn't set errors in the mapping when cache flushing
fails in dax_writeback_mapping_range(). Since this function can get
called only from fsync(2) or sync(2), this is actually as good as it can
currently get since we correctly propagate the error up from
dax_writeback_mapping_range() to filemap_fdatawrite()

However, in the future better writeback error handling will enable us to
properly report these errors on fsync(2) even if there are multiple file
descriptors open against the file or if sync(2) gets called before
fsync(2). So convert DAX to using standard error reporting through the
mapping.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-and-Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 fs/dax.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Jeff Layton June 17, 2017, 12:39 p.m. UTC | #1
On Fri, 2017-06-16 at 15:34 -0400, Jeff Layton wrote:
> Jan Kara's description for this patch is much better than mine, so I'm
> quoting it verbatim here:
> 
> DAX currently doesn't set errors in the mapping when cache flushing
> fails in dax_writeback_mapping_range(). Since this function can get
> called only from fsync(2) or sync(2), this is actually as good as it can
> currently get since we correctly propagate the error up from
> dax_writeback_mapping_range() to filemap_fdatawrite()
> 
> However, in the future better writeback error handling will enable us to
> properly report these errors on fsync(2) even if there are multiple file
> descriptors open against the file or if sync(2) gets called before
> fsync(2). So convert DAX to using standard error reporting through the
> mapping.
> 
> Signed-off-by: Jeff Layton <jlayton@redhat.com>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-and-Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> ---
>  fs/dax.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index 9899f07acf72..c663e8cc2a76 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -856,8 +856,10 @@ int dax_writeback_mapping_range(struct address_space *mapping,
>  
>  			ret = dax_writeback_one(bdev, dax_dev, mapping,
>  					indices[i], pvec.pages[i]);
> -			if (ret < 0)
> +			if (ret < 0) {
> +				mapping_set_error(mapping, ret);
>  				goto out;
> +			}
>  		}
>  	}
>  out:

I should point out here that Ross had an issue with this patch in an
earlier set, that I addressed with a flag in the last set. The flag is
icky though.

In this set, patch #6 should make it unnecessary:

    mm: clear AS_EIO/AS_ENOSPC when writeback initiation fails

Ross, could you test that this set still works ok for you with dax? It
should apply reasonably cleanly on top of linux-next.

Thanks,
Ross Zwisler June 19, 2017, 5:48 p.m. UTC | #2
On Sat, Jun 17, 2017 at 08:39:53AM -0400, Jeff Layton wrote:
> On Fri, 2017-06-16 at 15:34 -0400, Jeff Layton wrote:
> > Jan Kara's description for this patch is much better than mine, so I'm
> > quoting it verbatim here:
> > 
> > DAX currently doesn't set errors in the mapping when cache flushing
> > fails in dax_writeback_mapping_range(). Since this function can get
> > called only from fsync(2) or sync(2), this is actually as good as it can
> > currently get since we correctly propagate the error up from
> > dax_writeback_mapping_range() to filemap_fdatawrite()
> > 
> > However, in the future better writeback error handling will enable us to
> > properly report these errors on fsync(2) even if there are multiple file
> > descriptors open against the file or if sync(2) gets called before
> > fsync(2). So convert DAX to using standard error reporting through the
> > mapping.
> > 
> > Signed-off-by: Jeff Layton <jlayton@redhat.com>
> > Reviewed-by: Jan Kara <jack@suse.cz>
> > Reviewed-by: Christoph Hellwig <hch@lst.de>
> > Reviewed-and-Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> > ---
> >  fs/dax.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/dax.c b/fs/dax.c
> > index 9899f07acf72..c663e8cc2a76 100644
> > --- a/fs/dax.c
> > +++ b/fs/dax.c
> > @@ -856,8 +856,10 @@ int dax_writeback_mapping_range(struct address_space *mapping,
> >  
> >  			ret = dax_writeback_one(bdev, dax_dev, mapping,
> >  					indices[i], pvec.pages[i]);
> > -			if (ret < 0)
> > +			if (ret < 0) {
> > +				mapping_set_error(mapping, ret);
> >  				goto out;
> > +			}
> >  		}
> >  	}
> >  out:
> 
> I should point out here that Ross had an issue with this patch in an
> earlier set, that I addressed with a flag in the last set. The flag is
> icky though.
> 
> In this set, patch #6 should make it unnecessary:
> 
>     mm: clear AS_EIO/AS_ENOSPC when writeback initiation fails
> 
> Ross, could you test that this set still works ok for you with dax? It
> should apply reasonably cleanly on top of linux-next.

Yep, v7 passes my DAX testing.

Patch
diff mbox

diff --git a/fs/dax.c b/fs/dax.c
index 9899f07acf72..c663e8cc2a76 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -856,8 +856,10 @@  int dax_writeback_mapping_range(struct address_space *mapping,
 
 			ret = dax_writeback_one(bdev, dax_dev, mapping,
 					indices[i], pvec.pages[i]);
-			if (ret < 0)
+			if (ret < 0) {
+				mapping_set_error(mapping, ret);
 				goto out;
+			}
 		}
 	}
 out: