* [PATCH] xfs: ensure we capture IO errors correctly
@ 2013-03-08 2:01 Dave Chinner
2013-03-08 13:06 ` Hans-Peter Jansen
2013-03-11 14:00 ` Mark Tinguely
0 siblings, 2 replies; 4+ messages in thread
From: Dave Chinner @ 2013-03-08 2:01 UTC (permalink / raw)
To: xfs
From: Dave Chinner <dchinner@redhat.com>
Failed buffer readahead can leave the buffer in the cache marked
with an error. Most callers that then issue a subsequent read on the
buffer do not zero the b_error field out, and so we may incorectly
detect an error during IO completion due to the stale error value
left on the buffer.
Avoid this problem by zeroing the error before IO submission. This
ensures that the only IO errors that are detected those captured
from are those captured from bio submission or completion.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_buf.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 50eb603..82b70bd 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1336,6 +1336,12 @@ _xfs_buf_ioapply(
int size;
int i;
+ /*
+ * Make sure we capture only current IO errors rather than stale errors
+ * left over from previous use of the buffer (e.g. failed readahead).
+ */
+ bp->b_error = 0;
+
if (bp->b_flags & XBF_WRITE) {
if (bp->b_flags & XBF_SYNCIO)
rw = WRITE_SYNC;
--
1.7.10.4
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] xfs: ensure we capture IO errors correctly
2013-03-08 2:01 [PATCH] xfs: ensure we capture IO errors correctly Dave Chinner
@ 2013-03-08 13:06 ` Hans-Peter Jansen
2013-03-11 2:00 ` Dave Chinner
2013-03-11 14:00 ` Mark Tinguely
1 sibling, 1 reply; 4+ messages in thread
From: Hans-Peter Jansen @ 2013-03-08 13:06 UTC (permalink / raw)
To: xfs
Hi,
this sounds like stable material after a little simmering..
Cheers,
Pete
Am Freitag, 8. März 2013, 13:01:14 schrieb Dave Chinner:
> From: Dave Chinner <dchinner@redhat.com>
>
> Failed buffer readahead can leave the buffer in the cache marked
> with an error. Most callers that then issue a subsequent read on the
> buffer do not zero the b_error field out, and so we may incorectly
> detect an error during IO completion due to the stale error value
> left on the buffer.
>
> Avoid this problem by zeroing the error before IO submission. This
> ensures that the only IO errors that are detected those captured
> from are those captured from bio submission or completion.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
> fs/xfs/xfs_buf.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index 50eb603..82b70bd 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -1336,6 +1336,12 @@ _xfs_buf_ioapply(
> int size;
> int i;
>
> + /*
> + * Make sure we capture only current IO errors rather than stale errors
> + * left over from previous use of the buffer (e.g. failed readahead).
> + */
> + bp->b_error = 0;
> +
> if (bp->b_flags & XBF_WRITE) {
> if (bp->b_flags & XBF_SYNCIO)
> rw = WRITE_SYNC;
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] xfs: ensure we capture IO errors correctly
2013-03-08 13:06 ` Hans-Peter Jansen
@ 2013-03-11 2:00 ` Dave Chinner
0 siblings, 0 replies; 4+ messages in thread
From: Dave Chinner @ 2013-03-11 2:00 UTC (permalink / raw)
To: Hans-Peter Jansen; +Cc: xfs
On Fri, Mar 08, 2013 at 02:06:52PM +0100, Hans-Peter Jansen wrote:
> Hi,
>
> this sounds like stable material after a little simmering..
Yes, it probably is a candidate for 3.8.x
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] xfs: ensure we capture IO errors correctly
2013-03-08 2:01 [PATCH] xfs: ensure we capture IO errors correctly Dave Chinner
2013-03-08 13:06 ` Hans-Peter Jansen
@ 2013-03-11 14:00 ` Mark Tinguely
1 sibling, 0 replies; 4+ messages in thread
From: Mark Tinguely @ 2013-03-11 14:00 UTC (permalink / raw)
To: Dave Chinner; +Cc: xfs
On 03/07/13 20:01, Dave Chinner wrote:
> From: Dave Chinner<dchinner@redhat.com>
>
> Failed buffer readahead can leave the buffer in the cache marked
> with an error. Most callers that then issue a subsequent read on the
> buffer do not zero the b_error field out, and so we may incorectly
> detect an error during IO completion due to the stale error value
> left on the buffer.
>
> Avoid this problem by zeroing the error before IO submission. This
> ensures that the only IO errors that are detected those captured
> from are those captured from bio submission or completion.
>
> Signed-off-by: Dave Chinner<dchinner@redhat.com>
> ---
Looks good.
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
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2013-03-08 2:01 [PATCH] xfs: ensure we capture IO errors correctly Dave Chinner
2013-03-08 13:06 ` Hans-Peter Jansen
2013-03-11 2:00 ` Dave Chinner
2013-03-11 14:00 ` Mark Tinguely
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