mm: have filemap_check_and_advance_wb_err clear AS_EIO/AS_ENOSPC

Message ID 20170922133331.28812-1-jlayton@kernel.org
State New
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Series
  • mm: have filemap_check_and_advance_wb_err clear AS_EIO/AS_ENOSPC
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Commit Message

Jeff Layton Sept. 22, 2017, 1:33 p.m.
From: Jeff Layton <jlayton@redhat.com>

Eryu noticed that he could sometimes get a leftover error reported when
it shouldn't be on fsync with ext2 and non-journalled ext4. The problem
is that writeback_single_inode still uses filemap_fdatawait. That picks
up a previously set AS_EIO flag, which would ordinarily have been
cleared before.

Since we're mostly using this function as a replacement for
filemap_check_errors, have filemap_check_and_advance_wb_err clear AS_EIO
and AS_ENOSPC when reporting an error. That should allow the new
function to better emulate the behavior of the old with respect to these
flags.

Reported-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 mm/filemap.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Jan Kara Sept. 25, 2017, 8:17 a.m. | #1
On Fri 22-09-17 09:33:31, Jeff Layton wrote:
> From: Jeff Layton <jlayton@redhat.com>
> 
> Eryu noticed that he could sometimes get a leftover error reported when
> it shouldn't be on fsync with ext2 and non-journalled ext4. The problem
> is that writeback_single_inode still uses filemap_fdatawait. That picks
> up a previously set AS_EIO flag, which would ordinarily have been
> cleared before.
> 
> Since we're mostly using this function as a replacement for
> filemap_check_errors, have filemap_check_and_advance_wb_err clear AS_EIO
> and AS_ENOSPC when reporting an error. That should allow the new
> function to better emulate the behavior of the old with respect to these
> flags.
> 
> Reported-by: Eryu Guan <eguan@redhat.com>
> Signed-off-by: Jeff Layton <jlayton@redhat.com>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  mm/filemap.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 870971e20967..404722ea0fdd 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -620,6 +620,14 @@ int file_check_and_advance_wb_err(struct file *file)
>  		trace_file_check_and_advance_wb_err(file, old);
>  		spin_unlock(&file->f_lock);
>  	}
> +
> +	/*
> +	 * We're mostly using this function as a drop in replacement for
> +	 * filemap_check_errors. Clear AS_EIO/AS_ENOSPC to emulate the effect
> +	 * that the legacy code would have had on these flags.
> +	 */
> +	clear_bit(AS_EIO, &mapping->flags);
> +	clear_bit(AS_ENOSPC, &mapping->flags);
>  	return err;
>  }
>  EXPORT_SYMBOL(file_check_and_advance_wb_err);
> -- 
> 2.13.5
>
Jeff Layton Sept. 25, 2017, 7:53 p.m. | #2
On Fri, 2017-09-22 at 09:33 -0400, Jeff Layton wrote:
> From: Jeff Layton <jlayton@redhat.com>
> 
> Eryu noticed that he could sometimes get a leftover error reported when
> it shouldn't be on fsync with ext2 and non-journalled ext4. The problem
> is that writeback_single_inode still uses filemap_fdatawait. That picks
> up a previously set AS_EIO flag, which would ordinarily have been
> cleared before.
> 
> Since we're mostly using this function as a replacement for
> filemap_check_errors, have filemap_check_and_advance_wb_err clear AS_EIO
> and AS_ENOSPC when reporting an error. That should allow the new
> function to better emulate the behavior of the old with respect to these
> flags.
> 
> Reported-by: Eryu Guan <eguan@redhat.com>
> Signed-off-by: Jeff Layton <jlayton@redhat.com>
> ---
>  mm/filemap.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 870971e20967..404722ea0fdd 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -620,6 +620,14 @@ int file_check_and_advance_wb_err(struct file *file)
>  		trace_file_check_and_advance_wb_err(file, old);
>  		spin_unlock(&file->f_lock);
>  	}
> +
> +	/*
> +	 * We're mostly using this function as a drop in replacement for
> +	 * filemap_check_errors. Clear AS_EIO/AS_ENOSPC to emulate the effect
> +	 * that the legacy code would have had on these flags.
> +	 */
> +	clear_bit(AS_EIO, &mapping->flags);
> +	clear_bit(AS_ENOSPC, &mapping->flags);
>  	return err;
>  }
>  EXPORT_SYMBOL(file_check_and_advance_wb_err);

Andrew, would you mind picking this patch up? It seems to work fine for
me, but it wouldn't hurt to let it stew in linux-next for a bit.

Thanks,

Patch

diff --git a/mm/filemap.c b/mm/filemap.c
index 870971e20967..404722ea0fdd 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -620,6 +620,14 @@  int file_check_and_advance_wb_err(struct file *file)
 		trace_file_check_and_advance_wb_err(file, old);
 		spin_unlock(&file->f_lock);
 	}
+
+	/*
+	 * We're mostly using this function as a drop in replacement for
+	 * filemap_check_errors. Clear AS_EIO/AS_ENOSPC to emulate the effect
+	 * that the legacy code would have had on these flags.
+	 */
+	clear_bit(AS_EIO, &mapping->flags);
+	clear_bit(AS_ENOSPC, &mapping->flags);
 	return err;
 }
 EXPORT_SYMBOL(file_check_and_advance_wb_err);