[PATCH 6/7] xfs: add configuration handlers for specific errors

[PATCH 6/7] xfs: add configuration handlers for specific errors

[Carlos Maiolino]

now most of the infrastructure is in place, we can start adding
support for configuring specific errors such as ENODEV, ENOSPC, EIO,
etc. Add these error configurations and configure them all to have
appropriate behaviours. That is, all will be configured to retry forever by
default, except for ENODEV, which is an unrecoverable error, so it will be
configured to not retry on error

Changelog:

V3:
	- Do not implement .fail_speed and .fail_at_unmount
	- .fail_at_unmount will be implemented in a different patch

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
---
 fs/xfs/xfs_mount.h |  3 +++
 fs/xfs/xfs_sysfs.c | 20 ++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 0382140..e3b3267 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -49,6 +49,9 @@ enum {
 };
 enum {
 	XFS_ERR_DEFAULT,
+	XFS_ERR_EIO,
+	XFS_ERR_ENOSPC,
+	XFS_ERR_ENODEV,
 	XFS_ERR_ERRNO_MAX,
 };
 
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index c881360..1ed9033 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -481,6 +481,17 @@ static const struct xfs_error_init xfs_error_meta_init[XFS_ERR_ERRNO_MAX] = {
 	  .max_retries = -1,
 	  .retry_timeout = 0,
 	},
+	{ .name = "EIO",
+	  .max_retries = -1,
+	  .retry_timeout = 0,
+	},
+	{ .name = "ENOSPC",
+	  .max_retries = -1,
+	  .retry_timeout = 0,
+	},
+	{ .name = "ENODEV",
+	  .max_retries = -1,
+	},
 };
 
 static int
@@ -578,6 +589,15 @@ xfs_error_get_cfg(
 	struct xfs_error_cfg	*cfg;
 
 	switch (error) {
+	case EIO:
+		cfg = &mp->m_error_cfg[error_class][XFS_ERR_EIO];
+		break;
+	case ENOSPC:
+		cfg = &mp->m_error_cfg[error_class][XFS_ERR_ENOSPC];
+		break;
+	case ENODEV:
+		cfg = &mp->m_error_cfg[error_class][XFS_ERR_ENODEV];
+		break;
 	default:
 		cfg = &mp->m_error_cfg[error_class][XFS_ERR_DEFAULT];
 		break;
-- 
2.4.11

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Re: [PATCH 6/7] xfs: add configuration handlers for specific errors

[Brian Foster]

On Wed, May 04, 2016 at 05:43:19PM +0200, Carlos Maiolino wrote:
> now most of the infrastructure is in place, we can start adding
> support for configuring specific errors such as ENODEV, ENOSPC, EIO,
> etc. Add these error configurations and configure them all to have
> appropriate behaviours. That is, all will be configured to retry forever by
> default, except for ENODEV, which is an unrecoverable error, so it will be
> configured to not retry on error
> 
> Changelog:
> 
> V3:
> 	- Do not implement .fail_speed and .fail_at_unmount
> 	- .fail_at_unmount will be implemented in a different patch
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> ---
>  fs/xfs/xfs_mount.h |  3 +++
>  fs/xfs/xfs_sysfs.c | 20 ++++++++++++++++++++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index 0382140..e3b3267 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -49,6 +49,9 @@ enum {
>  };
>  enum {
>  	XFS_ERR_DEFAULT,
> +	XFS_ERR_EIO,
> +	XFS_ERR_ENOSPC,
> +	XFS_ERR_ENODEV,
>  	XFS_ERR_ERRNO_MAX,
>  };
>  
> diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
> index c881360..1ed9033 100644
> --- a/fs/xfs/xfs_sysfs.c
> +++ b/fs/xfs/xfs_sysfs.c
> @@ -481,6 +481,17 @@ static const struct xfs_error_init xfs_error_meta_init[XFS_ERR_ERRNO_MAX] = {
>  	  .max_retries = -1,
>  	  .retry_timeout = 0,
>  	},
> +	{ .name = "EIO",
> +	  .max_retries = -1,
> +	  .retry_timeout = 0,
> +	},
> +	{ .name = "ENOSPC",
> +	  .max_retries = -1,
> +	  .retry_timeout = 0,
> +	},
> +	{ .name = "ENODEV",
> +	  .max_retries = -1,

Shouldn't this be 0?

Brian

> +	},
>  };
>  
>  static int
> @@ -578,6 +589,15 @@ xfs_error_get_cfg(
>  	struct xfs_error_cfg	*cfg;
>  
>  	switch (error) {
> +	case EIO:
> +		cfg = &mp->m_error_cfg[error_class][XFS_ERR_EIO];
> +		break;
> +	case ENOSPC:
> +		cfg = &mp->m_error_cfg[error_class][XFS_ERR_ENOSPC];
> +		break;
> +	case ENODEV:
> +		cfg = &mp->m_error_cfg[error_class][XFS_ERR_ENODEV];
> +		break;
>  	default:
>  		cfg = &mp->m_error_cfg[error_class][XFS_ERR_DEFAULT];
>  		break;
> -- 
> 2.4.11
> 
> _______________________________________________
> xfs mailing list
> xfs@oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs

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Re: [PATCH 6/7] xfs: add configuration handlers for specific errors

[Dave Chinner]

On Thu, May 05, 2016 at 10:11:02AM -0400, Brian Foster wrote:
> On Wed, May 04, 2016 at 05:43:19PM +0200, Carlos Maiolino wrote:
> > now most of the infrastructure is in place, we can start adding
> > support for configuring specific errors such as ENODEV, ENOSPC, EIO,
> > etc. Add these error configurations and configure them all to have
> > appropriate behaviours. That is, all will be configured to retry forever by
> > default, except for ENODEV, which is an unrecoverable error, so it will be
> > configured to not retry on error
> > 
> > Changelog:
> > 
> > V3:
> > 	- Do not implement .fail_speed and .fail_at_unmount
> > 	- .fail_at_unmount will be implemented in a different patch
> > 
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> > ---
> >  fs/xfs/xfs_mount.h |  3 +++
> >  fs/xfs/xfs_sysfs.c | 20 ++++++++++++++++++++
> >  2 files changed, 23 insertions(+)
> > 
> > diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> > index 0382140..e3b3267 100644
> > --- a/fs/xfs/xfs_mount.h
> > +++ b/fs/xfs/xfs_mount.h
> > @@ -49,6 +49,9 @@ enum {
> >  };
> >  enum {
> >  	XFS_ERR_DEFAULT,
> > +	XFS_ERR_EIO,
> > +	XFS_ERR_ENOSPC,
> > +	XFS_ERR_ENODEV,
> >  	XFS_ERR_ERRNO_MAX,
> >  };
> >  
> > diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
> > index c881360..1ed9033 100644
> > --- a/fs/xfs/xfs_sysfs.c
> > +++ b/fs/xfs/xfs_sysfs.c
> > @@ -481,6 +481,17 @@ static const struct xfs_error_init xfs_error_meta_init[XFS_ERR_ERRNO_MAX] = {
> >  	  .max_retries = -1,
> >  	  .retry_timeout = 0,
> >  	},
> > +	{ .name = "EIO",
> > +	  .max_retries = -1,
> > +	  .retry_timeout = 0,
> > +	},
> > +	{ .name = "ENOSPC",
> > +	  .max_retries = -1,
> > +	  .retry_timeout = 0,
> > +	},
> > +	{ .name = "ENODEV",
> > +	  .max_retries = -1,
> 
> Shouldn't this be 0?

If they are supposed to be "retry forever", they shoul dbe set to
the define I asked to be added in the last review. i.e.
XFS_ERR_RETRY_FOREVER. But if a device goes away, then we may as
well fail immediately as it will never come back as the same
device....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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[PATCH 0/7] Configurable error behavior [V4]

[Carlos Maiolino]

New revision ot the patchset according with comments for V3.

This patchset is aimed to implement a configurable error behavior in XFS, and,
most of the design has been done by Dave, so, I kept his signed-off.

Detailed changelog is written on each patch, but, major changes are:

	- make fail_at_unmount a global configuration option inside
	  ../xfs/<dev>/err/fail_at_unmount

Carlos Maiolino (7):
  xfs: configurable error behavior via sysfs
  xfs: introduce metadata IO error class
  xfs: add configurable error support to metadata buffers
  xfs: introduce table-based init for error behaviors
  xfs: add configuration of error failure speed
  xfs: add configuration handlers for specific errors
  xfs: add "fail at unmount" error handling configuration

 fs/xfs/xfs_buf.h      |  20 ++++
 fs/xfs/xfs_buf_item.c | 121 +++++++++++++--------
 fs/xfs/xfs_mount.c    |  22 +++-
 fs/xfs/xfs_mount.h    |  34 ++++++
 fs/xfs/xfs_sysfs.c    | 291 +++++++++++++++++++++++++++++++++++++++++++++++++-
 fs/xfs/xfs_sysfs.h    |   3 +
 fs/xfs/xfs_trace.h    |   1 -
 7 files changed, 446 insertions(+), 46 deletions(-)

-- 
2.4.11

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[PATCH 1/7] xfs: configurable error behavior via sysfs

[Carlos Maiolino]

We need to be able to change the way XFS behaviours in error
conditions depending on the type of underlying storage. This is
necessary for handling non-traditional block devices with extended
error cases, such as thin provisioned devices that can return ENOSPC
as an IO error.

Introduce the basic sysfs infrastructure needed to define and
configure error behaviours. This is done to be generic enough to
extend to configuring behaviour in other error conditions, such as
ENOMEM, which also has different desired behaviours according to
machine configuration.

Changelog:

V3:
	- Rebase patch on top of linux-xfs tree
	- Remove XFS_ERR_FAIL enums, once we are not using them
	  to control the fail speed, but base it on max_retries value
	- Get rid of xfs_error_cfg.fail_speed field. We will use only
	  .max_retries to control the failure speed for each error

V4:
	- Fix typo error in xfs_sysfs.c

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
---
 fs/xfs/xfs_mount.c | 10 +++++++++-
 fs/xfs/xfs_mount.h | 20 ++++++++++++++++++++
 fs/xfs/xfs_sysfs.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 fs/xfs/xfs_sysfs.h |  3 +++
 4 files changed, 84 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 654799f..eda3906 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -689,10 +689,15 @@ xfs_mountfs(
 	if (error)
 		goto out_remove_sysfs;
 
-	error = xfs_uuid_mount(mp);
+	error = xfs_error_sysfs_init(mp);
 	if (error)
 		goto out_del_stats;
 
+
+	error = xfs_uuid_mount(mp);
+	if (error)
+		goto out_remove_error_sysfs;
+
 	/*
 	 * Set the minimum read and write sizes
 	 */
@@ -967,6 +972,8 @@ xfs_mountfs(
 	xfs_da_unmount(mp);
  out_remove_uuid:
 	xfs_uuid_unmount(mp);
+ out_remove_error_sysfs:
+	xfs_error_sysfs_del(mp);
  out_del_stats:
 	xfs_sysfs_del(&mp->m_stats.xs_kobj);
  out_remove_sysfs:
@@ -1055,6 +1062,7 @@ xfs_unmountfs(
 #endif
 	xfs_free_perag(mp);
 
+	xfs_error_sysfs_del(mp);
 	xfs_sysfs_del(&mp->m_stats.xs_kobj);
 	xfs_sysfs_del(&mp->m_kobj);
 }
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index bac6b34..d639795 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -37,6 +37,24 @@ enum {
 	XFS_LOWSP_MAX,
 };
 
+/*
+ * Error Configuration
+ *
+ * Error classes define the subsystem the configuration belongs to.
+ * Error numbers define the errors that are configurable.
+ */
+enum {
+	XFS_ERR_CLASS_MAX,
+};
+enum {
+	XFS_ERR_ERRNO_MAX,
+};
+
+struct xfs_error_cfg {
+	struct xfs_kobj	kobj;
+	int		max_retries;
+};
+
 typedef struct xfs_mount {
 	struct super_block	*m_super;
 	xfs_tid_t		m_tid;		/* next unused tid for fs */
@@ -127,6 +145,8 @@ typedef struct xfs_mount {
 	int64_t			m_low_space[XFS_LOWSP_MAX];
 						/* low free space thresholds */
 	struct xfs_kobj		m_kobj;
+	struct xfs_kobj		m_error_kobj;
+	struct xfs_error_cfg	m_error_cfg[XFS_ERR_CLASS_MAX][XFS_ERR_ERRNO_MAX];
 	struct xstats		m_stats;	/* per-fs stats */
 
 	struct workqueue_struct *m_buf_workqueue;
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index 6ced4f1..74e3940 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -17,10 +17,11 @@
  */
 
 #include "xfs.h"
-#include "xfs_sysfs.h"
+#include "xfs_shared.h"
 #include "xfs_format.h"
 #include "xfs_log_format.h"
 #include "xfs_trans_resv.h"
+#include "xfs_sysfs.h"
 #include "xfs_log.h"
 #include "xfs_log_priv.h"
 #include "xfs_stats.h"
@@ -362,3 +363,53 @@ struct kobj_type xfs_log_ktype = {
 	.sysfs_ops = &xfs_sysfs_ops,
 	.default_attrs = xfs_log_attrs,
 };
+
+/*
+ * Metadata IO error configuration
+ *
+ * The sysfs structure here is:
+ *	...xfs/<dev>/error/<class>/<errno>/<error_attrs>
+ *
+ * where <class> allows us to discriminate between data IO and metadata IO,
+ * and any other future type of IO (e.g. special inode or directory error
+ * handling) we care to support.
+ */
+static struct attribute *xfs_error_attrs[] = {
+	NULL,
+};
+
+static inline struct xfs_error_cfg *
+to_error_cfg(struct kobject *kobject)
+{
+	struct xfs_kobj *kobj = to_kobj(kobject);
+	return container_of(kobj, struct xfs_error_cfg, kobj);
+}
+
+struct kobj_type xfs_error_cfg_ktype = {
+	.release = xfs_sysfs_release,
+	.sysfs_ops = &xfs_sysfs_ops,
+	.default_attrs = xfs_error_attrs,
+};
+
+struct kobj_type xfs_error_ktype = {
+	.release = xfs_sysfs_release,
+};
+
+int
+xfs_error_sysfs_init(
+	struct xfs_mount	*mp)
+{
+	int			error;
+
+	/* .../xfs/<dev>/error/ */
+	error = xfs_sysfs_init(&mp->m_error_kobj, &xfs_error_ktype,
+				&mp->m_kobj, "error");
+	return error;
+}
+
+void
+xfs_error_sysfs_del(
+	struct xfs_mount	*mp)
+{
+	xfs_sysfs_del(&mp->m_error_kobj);
+}
diff --git a/fs/xfs/xfs_sysfs.h b/fs/xfs/xfs_sysfs.h
index be692e5..d046371 100644
--- a/fs/xfs/xfs_sysfs.h
+++ b/fs/xfs/xfs_sysfs.h
@@ -58,4 +58,7 @@ xfs_sysfs_del(
 	wait_for_completion(&kobj->complete);
 }
 
+int	xfs_error_sysfs_init(struct xfs_mount *mp);
+void	xfs_error_sysfs_del(struct xfs_mount *mp);
+
 #endif	/* __XFS_SYSFS_H__ */
-- 
2.4.11

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[PATCH 2/7] xfs: introduce metadata IO error class

[Carlos Maiolino]

Now we have the basic infrastructure, add the first error class so
we can build up the infrastructure in a meaningful way. Add the
metadata async write IO error class and sysfs entry, and introduce a
default configuration that matches the existing "retry forever" behavior
for async write metadata buffers.

Changelog:

V3:
	- Use 'cfg->max_retries = -1' as the default configuration for the
	  "retry forever" behavior, instead of
	  cfg->fail_speed = XFS_ERR_FAIL_NEVER

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
---
 fs/xfs/xfs_mount.h |  3 +++
 fs/xfs/xfs_sysfs.c | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index d639795..352a5c8 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -44,9 +44,11 @@ enum {
  * Error numbers define the errors that are configurable.
  */
 enum {
+	XFS_ERR_METADATA,
 	XFS_ERR_CLASS_MAX,
 };
 enum {
+	XFS_ERR_DEFAULT,
 	XFS_ERR_ERRNO_MAX,
 };
 
@@ -146,6 +148,7 @@ typedef struct xfs_mount {
 						/* low free space thresholds */
 	struct xfs_kobj		m_kobj;
 	struct xfs_kobj		m_error_kobj;
+	struct xfs_kobj		m_error_meta_kobj;
 	struct xfs_error_cfg	m_error_cfg[XFS_ERR_CLASS_MAX][XFS_ERR_ERRNO_MAX];
 	struct xstats		m_stats;	/* per-fs stats */
 
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index 74e3940..07c9599 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -399,11 +399,34 @@ int
 xfs_error_sysfs_init(
 	struct xfs_mount	*mp)
 {
+	struct xfs_error_cfg	*cfg;
 	int			error;
 
 	/* .../xfs/<dev>/error/ */
 	error = xfs_sysfs_init(&mp->m_error_kobj, &xfs_error_ktype,
 				&mp->m_kobj, "error");
+	if (error)
+		return error;
+
+	/* .../xfs/<dev>/error/metadata/ */
+	error = xfs_sysfs_init(&mp->m_error_meta_kobj, &xfs_error_ktype,
+				&mp->m_error_kobj, "metadata");
+	if (error)
+		goto out_error;
+
+	cfg = &mp->m_error_cfg[XFS_ERR_METADATA][XFS_ERR_DEFAULT];
+	error = xfs_sysfs_init(&cfg->kobj, &xfs_error_cfg_ktype,
+				&mp->m_error_meta_kobj, "default");
+	if (error)
+		goto out_error_meta;
+	cfg->max_retries = -1;
+
+	return 0;
+
+out_error_meta:
+	xfs_sysfs_del(&mp->m_error_meta_kobj);
+out_error:
+	xfs_sysfs_del(&mp->m_error_kobj);
 	return error;
 }
 
@@ -411,5 +434,16 @@ void
 xfs_error_sysfs_del(
 	struct xfs_mount	*mp)
 {
+	struct xfs_error_cfg	*cfg;
+	int			i, j;
+
+	for (i = 0; i < XFS_ERR_CLASS_MAX; i++) {
+		for (j = 0; j < XFS_ERR_ERRNO_MAX; j++) {
+			cfg = &mp->m_error_cfg[i][j];
+
+			xfs_sysfs_del(&cfg->kobj);
+		}
+	}
+	xfs_sysfs_del(&mp->m_error_meta_kobj);
 	xfs_sysfs_del(&mp->m_error_kobj);
 }
-- 
2.4.11

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[PATCH 3/7] xfs: add configurable error support to metadata buffers

[Carlos Maiolino]

With the error configuration handle for async metadata write errors
in place, we can now add initial support to the IO error processing
in xfs_buf_iodone_error().

Add an infrastructure function to look up the configuration handle,
and rearrange the error handling to prepare the way for different
error handling conigurations to be used.

Changelog:

V3:
	- in xfs_buf_iodone_callbacks, use cfg->max_retries to
	  determine if the filesystem should fail or not, a zero value
	  means it should never retry.

V4:
	- With the refactor of xfs_buf_iodone_callbacks, we don't need
	  xfs_buf_item_iodone trace anymore, once it already contains
	  item_iodone_async trace. Also, since it was the only caller from
	  this tracepoint, just remove its definition
	- Move xfs_error_get_cfg() call to just before the usage of cfg

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
---
 fs/xfs/xfs_buf.h      |   1 +
 fs/xfs/xfs_buf_item.c | 112 ++++++++++++++++++++++++++++++--------------------
 fs/xfs/xfs_mount.h    |   3 ++
 fs/xfs/xfs_sysfs.c    |  17 ++++++++
 fs/xfs/xfs_trace.h    |   1 -
 5 files changed, 88 insertions(+), 46 deletions(-)

diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 4eb89bd..adef116 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -183,6 +183,7 @@ typedef struct xfs_buf {
 	unsigned int		b_page_count;	/* size of page array */
 	unsigned int		b_offset;	/* page offset in first page */
 	int			b_error;	/* error code on I/O */
+	int			b_last_error;	/* previous async I/O error */
 	const struct xfs_buf_ops	*b_ops;
 
 #ifdef XFS_BUF_LOCK_TRACKING
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 99e91a0..b8d0cd4 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -1042,35 +1042,22 @@ xfs_buf_do_callbacks(
 	}
 }
 
-/*
- * This is the iodone() function for buffers which have had callbacks
- * attached to them by xfs_buf_attach_iodone().  It should remove each
- * log item from the buffer's list and call the callback of each in turn.
- * When done, the buffer's fsprivate field is set to NULL and the buffer
- * is unlocked with a call to iodone().
- */
-void
-xfs_buf_iodone_callbacks(
+static bool
+xfs_buf_iodone_callback_error(
 	struct xfs_buf		*bp)
 {
 	struct xfs_log_item	*lip = bp->b_fspriv;
 	struct xfs_mount	*mp = lip->li_mountp;
 	static ulong		lasttime;
 	static xfs_buftarg_t	*lasttarg;
-
-	if (likely(!bp->b_error))
-		goto do_callbacks;
+	struct xfs_error_cfg	*cfg;
 
 	/*
 	 * If we've already decided to shutdown the filesystem because of
 	 * I/O errors, there's no point in giving this a retry.
 	 */
-	if (XFS_FORCED_SHUTDOWN(mp)) {
-		xfs_buf_stale(bp);
-		bp->b_flags |= XBF_DONE;
-		trace_xfs_buf_item_iodone(bp, _RET_IP_);
-		goto do_callbacks;
-	}
+	if (XFS_FORCED_SHUTDOWN(mp))
+		goto out_stale;
 
 	if (bp->b_target != lasttarg ||
 	    time_after(jiffies, (lasttime + 5*HZ))) {
@@ -1079,45 +1066,80 @@ xfs_buf_iodone_callbacks(
 	}
 	lasttarg = bp->b_target;
 
+	/* synchronous writes will have callers process the error */
+	if (!(bp->b_flags & XBF_ASYNC))
+		goto out_stale;
+
+	trace_xfs_buf_item_iodone_async(bp, _RET_IP_);
+	ASSERT(bp->b_iodone != NULL);
+
 	/*
 	 * If the write was asynchronous then no one will be looking for the
-	 * error.  Clear the error state and write the buffer out again.
-	 *
-	 * XXX: This helps against transient write errors, but we need to find
-	 * a way to shut the filesystem down if the writes keep failing.
-	 *
-	 * In practice we'll shut the filesystem down soon as non-transient
-	 * errors tend to affect the whole device and a failing log write
-	 * will make us give up.  But we really ought to do better here.
+	 * error.  If this is the first failure of this type, clear the error
+	 * state and write the buffer out again. This means we always retry an
+	 * async write failure at least once, but we also need to set the buffer
+	 * up to behave correctly now for repeated failures.
 	 */
-	if (bp->b_flags & XBF_ASYNC) {
-		ASSERT(bp->b_iodone != NULL);
-
-		trace_xfs_buf_item_iodone_async(bp, _RET_IP_);
+	if (!(bp->b_flags & (XBF_STALE|XBF_WRITE_FAIL)) ||
+	     bp->b_last_error != bp->b_error) {
+		bp->b_flags |= (XBF_WRITE | XBF_ASYNC |
+			        XBF_DONE | XBF_WRITE_FAIL);
+		bp->b_last_error = bp->b_error;
+		xfs_buf_ioerror(bp, 0);
+		xfs_buf_submit(bp);
+		return true;
+	}
 
-		xfs_buf_ioerror(bp, 0); /* errno of 0 unsets the flag */
+	/*
+	 * Repeated failure on an async write. Take action according to the
+	 * error configuration we have been set up to use.
+	 */
+	cfg = xfs_error_get_cfg(mp, XFS_ERR_METADATA, bp->b_error);
+	if (!cfg->max_retries)
+		goto permanent_error;
 
-		if (!(bp->b_flags & (XBF_STALE|XBF_WRITE_FAIL))) {
-			bp->b_flags |= XBF_WRITE | XBF_ASYNC |
-				       XBF_DONE | XBF_WRITE_FAIL;
-			xfs_buf_submit(bp);
-		} else {
-			xfs_buf_relse(bp);
-		}
-
-		return;
-	}
+	/* still a transient error, higher layers will retry */
+	xfs_buf_ioerror(bp, 0);
+	xfs_buf_relse(bp);
+	return true;
 
 	/*
-	 * If the write of the buffer was synchronous, we want to make
-	 * sure to return the error to the caller of xfs_bwrite().
+	 * Permanent error - we need to trigger a shutdown if we haven't already
+	 * to indicate that inconsistency will result from this action.
 	 */
+permanent_error:
+	xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
+out_stale:
 	xfs_buf_stale(bp);
 	bp->b_flags |= XBF_DONE;
-
 	trace_xfs_buf_error_relse(bp, _RET_IP_);
+	return false;
+}
+
+/*
+ * This is the iodone() function for buffers which have had callbacks attached
+ * to them by xfs_buf_attach_iodone(). We need to iterate the items on the
+ * callback list, mark the buffer as having no more callbacks and then push the
+ * buffer through IO completion processing.
+ */
+void
+xfs_buf_iodone_callbacks(
+	struct xfs_buf		*bp)
+{
+	/*
+	 * If there is an error, process it. Some errors require us
+	 * to run callbacks after failure processing is done so we
+	 * detect that and take appropriate action.
+	 */
+	if (bp->b_error && xfs_buf_iodone_callback_error(bp))
+		return;
+
+	/*
+	 * Successful IO or permanent error. Either way, we can clear the
+	 * retry state here in preparation for the next error that may occur.
+	 */
+	bp->b_last_error = 0;
 
-do_callbacks:
 	xfs_buf_do_callbacks(bp);
 	bp->b_fspriv = NULL;
 	bp->b_iodone = NULL;
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 352a5c8..0c5a976 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -387,4 +387,7 @@ extern void	xfs_set_low_space_thresholds(struct xfs_mount *);
 int	xfs_zero_extent(struct xfs_inode *ip, xfs_fsblock_t start_fsb,
 			xfs_off_t count_fsb);
 
+struct xfs_error_cfg * xfs_error_get_cfg(struct xfs_mount *mp,
+		int error_class, int error);
+
 #endif	/* __XFS_MOUNT_H__ */
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index 07c9599..1cb5a85 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -447,3 +447,20 @@ xfs_error_sysfs_del(
 	xfs_sysfs_del(&mp->m_error_meta_kobj);
 	xfs_sysfs_del(&mp->m_error_kobj);
 }
+
+struct xfs_error_cfg *
+xfs_error_get_cfg(
+	struct xfs_mount	*mp,
+	int			error_class,
+	int			error)
+{
+	struct xfs_error_cfg	*cfg;
+
+	switch (error) {
+	default:
+		cfg = &mp->m_error_cfg[error_class][XFS_ERR_DEFAULT];
+		break;
+	}
+
+	return cfg;
+}
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 840d52e..ea94ee0 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -364,7 +364,6 @@ DEFINE_BUF_EVENT(xfs_buf_delwri_split);
 DEFINE_BUF_EVENT(xfs_buf_get_uncached);
 DEFINE_BUF_EVENT(xfs_bdstrat_shut);
 DEFINE_BUF_EVENT(xfs_buf_item_relse);
-DEFINE_BUF_EVENT(xfs_buf_item_iodone);
 DEFINE_BUF_EVENT(xfs_buf_item_iodone_async);
 DEFINE_BUF_EVENT(xfs_buf_error_relse);
 DEFINE_BUF_EVENT(xfs_buf_wait_buftarg);
-- 
2.4.11

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[PATCH 4/7] xfs: introduce table-based init for error behaviors

[Carlos Maiolino]

Before we start expanding the number of error classes and errors we
can configure behaviour for, we need a simple and clear way to
define the default behaviour that we initialized each mount with.
Introduce a table based method for keeping the initial configuration
in, and apply that to the existing initialization code.

Changelog:

V3:
	- Replace all .fail_speed fields by .max_retries, once the code will no
	  longer use .fail_speed to decide when it should fail
	- The "Default" attribute is also in lower-case (default). I don't
	  believe it's a good idea to have a mixed-case attribute names in sysfs.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
---
 fs/xfs/xfs_sysfs.c | 72 +++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 60 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index 1cb5a85..71046d9 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -395,11 +395,67 @@ struct kobj_type xfs_error_ktype = {
 	.release = xfs_sysfs_release,
 };
 
+/*
+ * Error initialization tables. These need to be ordered in the same
+ * order as the enums used to index the array. All class init tables need to
+ * define a "default" behaviour as the first entry, all other entries can be
+ * empty.
+ */
+struct xfs_error_init {
+	char		*name;
+	int		max_retries;
+};
+
+static const struct xfs_error_init xfs_error_meta_init[XFS_ERR_ERRNO_MAX] = {
+	{ .name = "default",
+	  .max_retries = -1,
+	},
+};
+
+static int
+xfs_error_sysfs_init_class(
+	struct xfs_mount	*mp,
+	int			class,
+	const char		*parent_name,
+	struct xfs_kobj		*parent_kobj,
+	const struct xfs_error_init init[])
+{
+	struct xfs_error_cfg	*cfg;
+	int			error;
+	int			i;
+
+	ASSERT(class < XFS_ERR_CLASS_MAX);
+
+	error = xfs_sysfs_init(parent_kobj, &xfs_error_ktype,
+				&mp->m_error_kobj, parent_name);
+	if (error)
+		return error;
+
+	for (i = 0; i < XFS_ERR_ERRNO_MAX; i++) {
+		cfg = &mp->m_error_cfg[class][i];
+		error = xfs_sysfs_init(&cfg->kobj, &xfs_error_cfg_ktype,
+					parent_kobj, init[i].name);
+		if (error)
+			goto out_error;
+
+		cfg->max_retries = init[i].max_retries;
+	}
+	return 0;
+
+out_error:
+	/* unwind the entries that succeeded */
+	for (i--; i >= 0; i--) {
+		cfg = &mp->m_error_cfg[class][i];
+		xfs_sysfs_del(&cfg->kobj);
+	}
+	xfs_sysfs_del(parent_kobj);
+	return error;
+}
+
 int
 xfs_error_sysfs_init(
 	struct xfs_mount	*mp)
 {
-	struct xfs_error_cfg	*cfg;
 	int			error;
 
 	/* .../xfs/<dev>/error/ */
@@ -409,22 +465,14 @@ xfs_error_sysfs_init(
 		return error;
 
 	/* .../xfs/<dev>/error/metadata/ */
-	error = xfs_sysfs_init(&mp->m_error_meta_kobj, &xfs_error_ktype,
-				&mp->m_error_kobj, "metadata");
+	error = xfs_error_sysfs_init_class(mp, XFS_ERR_METADATA,
+				"metadata", &mp->m_error_meta_kobj,
+				xfs_error_meta_init);
 	if (error)
 		goto out_error;
 
-	cfg = &mp->m_error_cfg[XFS_ERR_METADATA][XFS_ERR_DEFAULT];
-	error = xfs_sysfs_init(&cfg->kobj, &xfs_error_cfg_ktype,
-				&mp->m_error_meta_kobj, "default");
-	if (error)
-		goto out_error_meta;
-	cfg->max_retries = -1;
-
 	return 0;
 
-out_error_meta:
-	xfs_sysfs_del(&mp->m_error_meta_kobj);
 out_error:
 	xfs_sysfs_del(&mp->m_error_kobj);
 	return error;
-- 
2.4.11

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[PATCH 5/7] xfs: add configuration of error failure speed

[Carlos Maiolino]

On reception of an error, we can fail immediately, perform some
bound amount of retries or retry indefinitely. The current behaviour
we have is to retry forever.

However, we'd like the ability to choose how long the filesystem should try
after an error, it can either fail immediately, retry a few times, or retry
forever. This is implemented by using max_retries sysfs attribute, to hold the
amount of times we allow the filesystem to retry after an error. Being -1 a
special case where the filesystem will retry indefinitely.

Add both a maximum retry count and a retry timeout so that we can bound by
time and/or physical IO attempts.

Finally, plumb these into xfs_buf_iodone error processing so that
the error behaviour follows the selected configuration.

Changelog:

V3:
	- In xfs_buf_iodone_callback_error, use max_retries to decide how long
	  the filesystem should retry on errors instead of XFS_ERR_FAIL enums
	  and fail_speed

	- Remove all code implementing fail_speed attribute from the original
	  patch
		-- failure_speed_show/store attributes function implementation
		-- max_retries_store() now accepts values from -1 up to INT_MAX

	- retry_timeout_seconds_show() print fixed:
		-- jiffies_to_msecs() should be divided by MSEC_PER_SEC
		-- trailing whitespace removed

V4:
	- Add XFS_ERR_RETRY_FOREVER flag, to avoid a -1 magic number
	- Reword xfs_buf comment according Brian's suggestion
	- Remove pointless check for val > INT_MAX


Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
---
 fs/xfs/xfs_buf.h      | 21 ++++++++++++-
 fs/xfs/xfs_buf_item.c | 13 +++++++--
 fs/xfs/xfs_mount.h    |  3 ++
 fs/xfs/xfs_sysfs.c    | 81 ++++++++++++++++++++++++++++++++++++++++++++++++---
 4 files changed, 111 insertions(+), 7 deletions(-)

diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index adef116..8bfb974 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -183,7 +183,26 @@ typedef struct xfs_buf {
 	unsigned int		b_page_count;	/* size of page array */
 	unsigned int		b_offset;	/* page offset in first page */
 	int			b_error;	/* error code on I/O */
-	int			b_last_error;	/* previous async I/O error */
+
+	/*
+	 * async write failure retry count. Initialised to zero on the first
+	 * failure, then when it exceeds the maximum configured without a
+	 * success the write is considered to be failed permanently and the
+	 * iodone handler will take appropriate action.
+	 *
+	 * For retry timeouts, we record the jiffie of the first failure. This
+	 * means that we can change the retry timeout for buffers already under
+	 * I/O and thus avoid getting stuck in a retry loop with a long timeout.
+	 *
+	 * last_error is used to ensure that we are getting repeated errors, not
+	 * different errors. e.g. a block device might change ENOSPC to EIO when
+	 * a failure timeout occurs, so we want to re-initialise the error
+	 * retry behaviour appropriately when that happens.
+	 */
+	int			b_retries;
+	unsigned long		b_first_retry_time; /* in jiffies */
+	int			b_last_error;
+
 	const struct xfs_buf_ops	*b_ops;
 
 #ifdef XFS_BUF_LOCK_TRACKING
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index b8d0cd4..0d95c59 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -1085,6 +1085,9 @@ xfs_buf_iodone_callback_error(
 		bp->b_flags |= (XBF_WRITE | XBF_ASYNC |
 			        XBF_DONE | XBF_WRITE_FAIL);
 		bp->b_last_error = bp->b_error;
+		bp->b_retries = 0;
+		bp->b_first_retry_time = jiffies;
+
 		xfs_buf_ioerror(bp, 0);
 		xfs_buf_submit(bp);
 		return true;
@@ -1095,8 +1098,13 @@ xfs_buf_iodone_callback_error(
 	 * error configuration we have been set up to use.
 	 */
 	cfg = xfs_error_get_cfg(mp, XFS_ERR_METADATA, bp->b_error);
-	if (!cfg->max_retries)
-		goto permanent_error;
+
+	if (cfg->max_retries != XFS_ERR_RETRY_FOREVER &&
+	    ++bp->b_retries > cfg->max_retries)
+			goto permanent_error;
+	if (cfg->retry_timeout &&
+	    time_after(jiffies, cfg->retry_timeout + bp->b_first_retry_time))
+			goto permanent_error;
 
 	/* still a transient error, higher layers will retry */
 	xfs_buf_ioerror(bp, 0);
@@ -1139,6 +1147,7 @@ xfs_buf_iodone_callbacks(
 	 * retry state here in preparation for the next error that may occur.
 	 */
 	bp->b_last_error = 0;
+	bp->b_retries = 0;
 
 	xfs_buf_do_callbacks(bp);
 	bp->b_fspriv = NULL;
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 0c5a976..2fafa94 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -52,9 +52,12 @@ enum {
 	XFS_ERR_ERRNO_MAX,
 };
 
+#define XFS_ERR_RETRY_FOREVER	-1
+
 struct xfs_error_cfg {
 	struct xfs_kobj	kobj;
 	int		max_retries;
+	unsigned long	retry_timeout;	/* in jiffies, 0 = no timeout */
 };
 
 typedef struct xfs_mount {
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index 71046d9..918d144 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -374,10 +374,6 @@ struct kobj_type xfs_log_ktype = {
  * and any other future type of IO (e.g. special inode or directory error
  * handling) we care to support.
  */
-static struct attribute *xfs_error_attrs[] = {
-	NULL,
-};
-
 static inline struct xfs_error_cfg *
 to_error_cfg(struct kobject *kobject)
 {
@@ -385,6 +381,79 @@ to_error_cfg(struct kobject *kobject)
 	return container_of(kobj, struct xfs_error_cfg, kobj);
 }
 
+static ssize_t
+max_retries_show(
+	struct kobject	*kobject,
+	char		*buf)
+{
+	struct xfs_error_cfg *cfg = to_error_cfg(kobject);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", cfg->max_retries);
+}
+
+static ssize_t
+max_retries_store(
+	struct kobject	*kobject,
+	const char	*buf,
+	size_t		count)
+{
+	struct xfs_error_cfg *cfg = to_error_cfg(kobject);
+	int		ret;
+	int		val;
+
+	ret = kstrtoint(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	if (val < -1)
+		return -EINVAL;
+
+	cfg->max_retries = val;
+	return count;
+}
+XFS_SYSFS_ATTR_RW(max_retries);
+
+static ssize_t
+retry_timeout_seconds_show(
+	struct kobject	*kobject,
+	char		*buf)
+{
+	struct xfs_error_cfg *cfg = to_error_cfg(kobject);
+
+	return snprintf(buf, PAGE_SIZE, "%ld\n",
+			jiffies_to_msecs(cfg->retry_timeout) / MSEC_PER_SEC);
+}
+
+static ssize_t
+retry_timeout_seconds_store(
+	struct kobject	*kobject,
+	const char	*buf,
+	size_t		count)
+{
+	struct xfs_error_cfg *cfg = to_error_cfg(kobject);
+	int		ret;
+	int		val;
+
+	ret = kstrtoint(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	/* 1 day timeout maximum */
+	if (val < 0 || val > 86400)
+		return -EINVAL;
+
+	cfg->retry_timeout = msecs_to_jiffies(val * MSEC_PER_SEC);
+	return count;
+}
+XFS_SYSFS_ATTR_RW(retry_timeout_seconds);
+
+static struct attribute *xfs_error_attrs[] = {
+	ATTR_LIST(max_retries),
+	ATTR_LIST(retry_timeout_seconds),
+	NULL,
+};
+
+
 struct kobj_type xfs_error_cfg_ktype = {
 	.release = xfs_sysfs_release,
 	.sysfs_ops = &xfs_sysfs_ops,
@@ -404,11 +473,13 @@ struct kobj_type xfs_error_ktype = {
 struct xfs_error_init {
 	char		*name;
 	int		max_retries;
+	int		retry_timeout;	/* in seconds */
 };
 
 static const struct xfs_error_init xfs_error_meta_init[XFS_ERR_ERRNO_MAX] = {
 	{ .name = "default",
 	  .max_retries = -1,
+	  .retry_timeout = 0,
 	},
 };
 
@@ -439,6 +510,8 @@ xfs_error_sysfs_init_class(
 			goto out_error;
 
 		cfg->max_retries = init[i].max_retries;
+		cfg->retry_timeout = msecs_to_jiffies(
+					init[i].retry_timeout * MSEC_PER_SEC);
 	}
 	return 0;
 
-- 
2.4.11

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[PATCH 6/7] xfs: add configuration handlers for specific errors

[Carlos Maiolino]

now most of the infrastructure is in place, we can start adding
support for configuring specific errors such as ENODEV, ENOSPC, EIO,
etc. Add these error configurations and configure them all to have
appropriate behaviours. That is, all will be configured to retry forever by
default, except for ENODEV, which is an unrecoverable error, so it will be
configured to not retry on error

Changelog:

V3:
	- Do not implement .fail_speed and .fail_at_unmount
	- .fail_at_unmount will be implemented in a different patch

V4:
	- ENODEV should fail immediately by default
	- Use XFS_ERR_RETRY_FOREVER flag, instead of -1 directly

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
---
 fs/xfs/xfs_mount.h |  3 +++
 fs/xfs/xfs_sysfs.c | 22 +++++++++++++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 2fafa94..72ec3e3 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -49,6 +49,9 @@ enum {
 };
 enum {
 	XFS_ERR_DEFAULT,
+	XFS_ERR_EIO,
+	XFS_ERR_ENOSPC,
+	XFS_ERR_ENODEV,
 	XFS_ERR_ERRNO_MAX,
 };
 
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index 918d144..084a606 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -478,9 +478,20 @@ struct xfs_error_init {
 
 static const struct xfs_error_init xfs_error_meta_init[XFS_ERR_ERRNO_MAX] = {
 	{ .name = "default",
-	  .max_retries = -1,
+	  .max_retries = XFS_ERR_RETRY_FOREVER,
 	  .retry_timeout = 0,
 	},
+	{ .name = "EIO",
+	  .max_retries = XFS_ERR_RETRY_FOREVER,
+	  .retry_timeout = 0,
+	},
+	{ .name = "ENOSPC",
+	  .max_retries = XFS_ERR_RETRY_FOREVER,
+	  .retry_timeout = 0,
+	},
+	{ .name = "ENODEV",
+	  .max_retries = 0,
+	},
 };
 
 static int
@@ -578,6 +589,15 @@ xfs_error_get_cfg(
 	struct xfs_error_cfg	*cfg;
 
 	switch (error) {
+	case EIO:
+		cfg = &mp->m_error_cfg[error_class][XFS_ERR_EIO];
+		break;
+	case ENOSPC:
+		cfg = &mp->m_error_cfg[error_class][XFS_ERR_ENOSPC];
+		break;
+	case ENODEV:
+		cfg = &mp->m_error_cfg[error_class][XFS_ERR_ENODEV];
+		break;
 	default:
 		cfg = &mp->m_error_cfg[error_class][XFS_ERR_DEFAULT];
 		break;
-- 
2.4.11

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[PATCH 7/7] xfs: add "fail at unmount" error handling configuration

[Carlos Maiolino]

If we take "retry forever" literally on metadata IO errors, we can
hang at unmount, once it retries those writes forever. This is the
default behavior, unfortunately.

Add an error configuration option for this behavior and default it to "fail" so
that an unmount will trigger actuall errors, a shutdown and allow the unmount to
succeed. It will be noisy, though, as it will log the errors and shutdown that
occurs.

To fix this, we need to mark the filesystem as being in the process of
unmounting. Do this with a mount flag that is added at the appropriate time
(i.e. before the blocking AIL sync). We also need to add this flag if mount
fails after the initial phase of log recovery has been run.

Changelog:

V3:
	- No major changes have been done to this patch, only the ones needed to
	  accomodate it on top of the remaining patches
V4:
	- Make fail_at_unmount a global configuration option into
	  ../xfs/<dev>/error directory
	- Add m_fail_unmount boolean to xfs_mount, to keep track of unmount
	  error behavior
	- Create err_to_mp() helper, to translate a kobject, from m_error_kobj
	  into its xfs_mount

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
---
 fs/xfs/xfs_buf_item.c |  4 ++++
 fs/xfs/xfs_mount.c    | 12 ++++++++++++
 fs/xfs/xfs_mount.h    |  2 ++
 fs/xfs/xfs_sysfs.c    | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 64 insertions(+)

diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 0d95c59..3425799 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -1106,6 +1106,10 @@ xfs_buf_iodone_callback_error(
 	    time_after(jiffies, cfg->retry_timeout + bp->b_first_retry_time))
 			goto permanent_error;
 
+	/* At unmount we may treat errors differently */
+	if ((mp->m_flags & XFS_MOUNT_UNMOUNTING) && mp->m_fail_unmount)
+		goto permanent_error;
+
 	/* still a transient error, higher layers will retry */
 	xfs_buf_ioerror(bp, 0);
 	xfs_buf_relse(bp);
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index eda3906..1bcee7e 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -680,6 +680,9 @@ xfs_mountfs(
 
 	xfs_set_maxicount(mp);
 
+	/* enable fail_at_unmount as default */
+	mp->m_fail_unmount = 1;
+
 	error = xfs_sysfs_init(&mp->m_kobj, &xfs_mp_ktype, NULL, mp->m_fsname);
 	if (error)
 		goto out;
@@ -961,6 +964,7 @@ xfs_mountfs(
 	cancel_delayed_work_sync(&mp->m_reclaim_work);
 	xfs_reclaim_inodes(mp, SYNC_WAIT);
  out_log_dealloc:
+	mp->m_flags |= XFS_MOUNT_UNMOUNTING;
 	xfs_log_mount_cancel(mp);
  out_fail_wait:
 	if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp)
@@ -1012,6 +1016,14 @@ xfs_unmountfs(
 	xfs_log_force(mp, XFS_LOG_SYNC);
 
 	/*
+	 * We now need to tell the world we are unmounting. This will allow
+	 * us to detect that the filesystem is going away and we should error
+	 * out anything that we have been retrying in the background. This will
+	 * prevent neverending retries iin AIL pushing from hanging the unmount.
+	 */
+	mp->m_flags |= XFS_MOUNT_UNMOUNTING;
+
+	/*
 	 * Flush all pending changes from the AIL.
 	 */
 	xfs_ail_push_all_sync(mp->m_ail);
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 72ec3e3..9063a9c 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -177,6 +177,7 @@ typedef struct xfs_mount {
 	 */
 	__uint32_t		m_generation;
 
+	bool			m_fail_unmount;
 #ifdef DEBUG
 	/*
 	 * DEBUG mode instrumentation to test and/or trigger delayed allocation
@@ -195,6 +196,7 @@ typedef struct xfs_mount {
 #define XFS_MOUNT_WSYNC		(1ULL << 0)	/* for nfs - all metadata ops
 						   must be synchronous except
 						   for space allocations */
+#define XFS_MOUNT_UNMOUNTING	(1ULL << 1)	/* filesystem is unmounting */
 #define XFS_MOUNT_WAS_CLEAN	(1ULL << 3)
 #define XFS_MOUNT_FS_SHUTDOWN	(1ULL << 4)	/* atomic stop of all filesystem
 						   operations, typically for
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index 084a606..4c2c550 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -381,6 +381,13 @@ to_error_cfg(struct kobject *kobject)
 	return container_of(kobj, struct xfs_error_cfg, kobj);
 }
 
+static inline struct xfs_mount *
+err_to_mp(struct kobject *kobject)
+{
+	struct xfs_kobj *kobj = to_kobj(kobject);
+	return container_of(kobj, struct xfs_mount, m_error_kobj);
+}
+
 static ssize_t
 max_retries_show(
 	struct kobject	*kobject,
@@ -447,6 +454,38 @@ retry_timeout_seconds_store(
 }
 XFS_SYSFS_ATTR_RW(retry_timeout_seconds);
 
+static ssize_t
+fail_at_unmount_show(
+	struct kobject	*kobject,
+	char		*buf)
+{
+	struct xfs_mount	*mp = err_to_mp(kobject);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", mp->m_fail_unmount);
+}
+
+static ssize_t
+fail_at_unmount_store(
+	struct kobject	*kobject,
+	const char	*buf,
+	size_t		count)
+{
+	struct xfs_mount	*mp = err_to_mp(kobject);
+	int		ret;
+	int		val;
+
+	ret = kstrtoint(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	if (val < 0 || val > 1)
+		return -EINVAL;
+
+	mp->m_fail_unmount = val;
+	return count;
+}
+XFS_SYSFS_ATTR_RW(fail_at_unmount);
+
 static struct attribute *xfs_error_attrs[] = {
 	ATTR_LIST(max_retries),
 	ATTR_LIST(retry_timeout_seconds),
@@ -462,6 +501,7 @@ struct kobj_type xfs_error_cfg_ktype = {
 
 struct kobj_type xfs_error_ktype = {
 	.release = xfs_sysfs_release,
+	.sysfs_ops = &xfs_sysfs_ops,
 };
 
 /*
@@ -548,6 +588,12 @@ xfs_error_sysfs_init(
 	if (error)
 		return error;
 
+	error = sysfs_create_file(&mp->m_error_kobj.kobject,
+				  ATTR_LIST(fail_at_unmount));
+
+	if (error)
+		goto out_error;
+
 	/* .../xfs/<dev>/error/metadata/ */
 	error = xfs_error_sysfs_init_class(mp, XFS_ERR_METADATA,
 				"metadata", &mp->m_error_meta_kobj,
-- 
2.4.11

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Re: [PATCH 3/7] xfs: add configurable error support to metadata buffers

[Brian Foster]

On Tue, May 10, 2016 at 02:16:17PM +0200, Carlos Maiolino wrote:
> With the error configuration handle for async metadata write errors
> in place, we can now add initial support to the IO error processing
> in xfs_buf_iodone_error().
> 
> Add an infrastructure function to look up the configuration handle,
> and rearrange the error handling to prepare the way for different
> error handling conigurations to be used.
> 
> Changelog:
> 
> V3:
> 	- in xfs_buf_iodone_callbacks, use cfg->max_retries to
> 	  determine if the filesystem should fail or not, a zero value
> 	  means it should never retry.
> 
> V4:
> 	- With the refactor of xfs_buf_iodone_callbacks, we don't need
> 	  xfs_buf_item_iodone trace anymore, once it already contains
> 	  item_iodone_async trace. Also, since it was the only caller from
> 	  this tracepoint, just remove its definition
> 	- Move xfs_error_get_cfg() call to just before the usage of cfg
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/xfs_buf.h      |   1 +
>  fs/xfs/xfs_buf_item.c | 112 ++++++++++++++++++++++++++++++--------------------
>  fs/xfs/xfs_mount.h    |   3 ++
>  fs/xfs/xfs_sysfs.c    |  17 ++++++++
>  fs/xfs/xfs_trace.h    |   1 -
>  5 files changed, 88 insertions(+), 46 deletions(-)
> 
> diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
> index 4eb89bd..adef116 100644
> --- a/fs/xfs/xfs_buf.h
> +++ b/fs/xfs/xfs_buf.h
> @@ -183,6 +183,7 @@ typedef struct xfs_buf {
>  	unsigned int		b_page_count;	/* size of page array */
>  	unsigned int		b_offset;	/* page offset in first page */
>  	int			b_error;	/* error code on I/O */
> +	int			b_last_error;	/* previous async I/O error */
>  	const struct xfs_buf_ops	*b_ops;
>  
>  #ifdef XFS_BUF_LOCK_TRACKING
> diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
> index 99e91a0..b8d0cd4 100644
> --- a/fs/xfs/xfs_buf_item.c
> +++ b/fs/xfs/xfs_buf_item.c
> @@ -1042,35 +1042,22 @@ xfs_buf_do_callbacks(
>  	}
>  }
>  
> -/*
> - * This is the iodone() function for buffers which have had callbacks
> - * attached to them by xfs_buf_attach_iodone().  It should remove each
> - * log item from the buffer's list and call the callback of each in turn.
> - * When done, the buffer's fsprivate field is set to NULL and the buffer
> - * is unlocked with a call to iodone().
> - */
> -void
> -xfs_buf_iodone_callbacks(
> +static bool
> +xfs_buf_iodone_callback_error(
>  	struct xfs_buf		*bp)
>  {
>  	struct xfs_log_item	*lip = bp->b_fspriv;
>  	struct xfs_mount	*mp = lip->li_mountp;
>  	static ulong		lasttime;
>  	static xfs_buftarg_t	*lasttarg;
> -
> -	if (likely(!bp->b_error))
> -		goto do_callbacks;
> +	struct xfs_error_cfg	*cfg;
>  
>  	/*
>  	 * If we've already decided to shutdown the filesystem because of
>  	 * I/O errors, there's no point in giving this a retry.
>  	 */
> -	if (XFS_FORCED_SHUTDOWN(mp)) {
> -		xfs_buf_stale(bp);
> -		bp->b_flags |= XBF_DONE;
> -		trace_xfs_buf_item_iodone(bp, _RET_IP_);
> -		goto do_callbacks;
> -	}
> +	if (XFS_FORCED_SHUTDOWN(mp))
> +		goto out_stale;
>  
>  	if (bp->b_target != lasttarg ||
>  	    time_after(jiffies, (lasttime + 5*HZ))) {
> @@ -1079,45 +1066,80 @@ xfs_buf_iodone_callbacks(
>  	}
>  	lasttarg = bp->b_target;
>  
> +	/* synchronous writes will have callers process the error */
> +	if (!(bp->b_flags & XBF_ASYNC))
> +		goto out_stale;
> +
> +	trace_xfs_buf_item_iodone_async(bp, _RET_IP_);
> +	ASSERT(bp->b_iodone != NULL);
> +
>  	/*
>  	 * If the write was asynchronous then no one will be looking for the
> -	 * error.  Clear the error state and write the buffer out again.
> -	 *
> -	 * XXX: This helps against transient write errors, but we need to find
> -	 * a way to shut the filesystem down if the writes keep failing.
> -	 *
> -	 * In practice we'll shut the filesystem down soon as non-transient
> -	 * errors tend to affect the whole device and a failing log write
> -	 * will make us give up.  But we really ought to do better here.
> +	 * error.  If this is the first failure of this type, clear the error
> +	 * state and write the buffer out again. This means we always retry an
> +	 * async write failure at least once, but we also need to set the buffer
> +	 * up to behave correctly now for repeated failures.
>  	 */
> -	if (bp->b_flags & XBF_ASYNC) {
> -		ASSERT(bp->b_iodone != NULL);
> -
> -		trace_xfs_buf_item_iodone_async(bp, _RET_IP_);
> +	if (!(bp->b_flags & (XBF_STALE|XBF_WRITE_FAIL)) ||
> +	     bp->b_last_error != bp->b_error) {
> +		bp->b_flags |= (XBF_WRITE | XBF_ASYNC |
> +			        XBF_DONE | XBF_WRITE_FAIL);
> +		bp->b_last_error = bp->b_error;
> +		xfs_buf_ioerror(bp, 0);
> +		xfs_buf_submit(bp);
> +		return true;
> +	}
>  
> -		xfs_buf_ioerror(bp, 0); /* errno of 0 unsets the flag */
> +	/*
> +	 * Repeated failure on an async write. Take action according to the
> +	 * error configuration we have been set up to use.
> +	 */
> +	cfg = xfs_error_get_cfg(mp, XFS_ERR_METADATA, bp->b_error);
> +	if (!cfg->max_retries)
> +		goto permanent_error;
>  
> -		if (!(bp->b_flags & (XBF_STALE|XBF_WRITE_FAIL))) {
> -			bp->b_flags |= XBF_WRITE | XBF_ASYNC |
> -				       XBF_DONE | XBF_WRITE_FAIL;
> -			xfs_buf_submit(bp);
> -		} else {
> -			xfs_buf_relse(bp);
> -		}
> -
> -		return;
> -	}
> +	/* still a transient error, higher layers will retry */
> +	xfs_buf_ioerror(bp, 0);
> +	xfs_buf_relse(bp);
> +	return true;
>  
>  	/*
> -	 * If the write of the buffer was synchronous, we want to make
> -	 * sure to return the error to the caller of xfs_bwrite().
> +	 * Permanent error - we need to trigger a shutdown if we haven't already
> +	 * to indicate that inconsistency will result from this action.
>  	 */
> +permanent_error:
> +	xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
> +out_stale:
>  	xfs_buf_stale(bp);
>  	bp->b_flags |= XBF_DONE;
> -
>  	trace_xfs_buf_error_relse(bp, _RET_IP_);
> +	return false;
> +}
> +
> +/*
> + * This is the iodone() function for buffers which have had callbacks attached
> + * to them by xfs_buf_attach_iodone(). We need to iterate the items on the
> + * callback list, mark the buffer as having no more callbacks and then push the
> + * buffer through IO completion processing.
> + */
> +void
> +xfs_buf_iodone_callbacks(
> +	struct xfs_buf		*bp)
> +{
> +	/*
> +	 * If there is an error, process it. Some errors require us
> +	 * to run callbacks after failure processing is done so we
> +	 * detect that and take appropriate action.
> +	 */
> +	if (bp->b_error && xfs_buf_iodone_callback_error(bp))
> +		return;
> +
> +	/*
> +	 * Successful IO or permanent error. Either way, we can clear the
> +	 * retry state here in preparation for the next error that may occur.
> +	 */
> +	bp->b_last_error = 0;
>  
> -do_callbacks:
>  	xfs_buf_do_callbacks(bp);
>  	bp->b_fspriv = NULL;
>  	bp->b_iodone = NULL;
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index 352a5c8..0c5a976 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -387,4 +387,7 @@ extern void	xfs_set_low_space_thresholds(struct xfs_mount *);
>  int	xfs_zero_extent(struct xfs_inode *ip, xfs_fsblock_t start_fsb,
>  			xfs_off_t count_fsb);
>  
> +struct xfs_error_cfg * xfs_error_get_cfg(struct xfs_mount *mp,
> +		int error_class, int error);
> +
>  #endif	/* __XFS_MOUNT_H__ */
> diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
> index 07c9599..1cb5a85 100644
> --- a/fs/xfs/xfs_sysfs.c
> +++ b/fs/xfs/xfs_sysfs.c
> @@ -447,3 +447,20 @@ xfs_error_sysfs_del(
>  	xfs_sysfs_del(&mp->m_error_meta_kobj);
>  	xfs_sysfs_del(&mp->m_error_kobj);
>  }
> +
> +struct xfs_error_cfg *
> +xfs_error_get_cfg(
> +	struct xfs_mount	*mp,
> +	int			error_class,
> +	int			error)
> +{
> +	struct xfs_error_cfg	*cfg;
> +
> +	switch (error) {
> +	default:
> +		cfg = &mp->m_error_cfg[error_class][XFS_ERR_DEFAULT];
> +		break;
> +	}
> +
> +	return cfg;
> +}
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 840d52e..ea94ee0 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -364,7 +364,6 @@ DEFINE_BUF_EVENT(xfs_buf_delwri_split);
>  DEFINE_BUF_EVENT(xfs_buf_get_uncached);
>  DEFINE_BUF_EVENT(xfs_bdstrat_shut);
>  DEFINE_BUF_EVENT(xfs_buf_item_relse);
> -DEFINE_BUF_EVENT(xfs_buf_item_iodone);
>  DEFINE_BUF_EVENT(xfs_buf_item_iodone_async);
>  DEFINE_BUF_EVENT(xfs_buf_error_relse);
>  DEFINE_BUF_EVENT(xfs_buf_wait_buftarg);
> -- 
> 2.4.11
> 
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> http://oss.sgi.com/mailman/listinfo/xfs

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Re: [PATCH 6/7] xfs: add configuration handlers for specific errors

[Brian Foster]

On Tue, May 10, 2016 at 02:16:20PM +0200, Carlos Maiolino wrote:
> now most of the infrastructure is in place, we can start adding
> support for configuring specific errors such as ENODEV, ENOSPC, EIO,
> etc. Add these error configurations and configure them all to have
> appropriate behaviours. That is, all will be configured to retry forever by
> default, except for ENODEV, which is an unrecoverable error, so it will be
> configured to not retry on error
> 
> Changelog:
> 
> V3:
> 	- Do not implement .fail_speed and .fail_at_unmount
> 	- .fail_at_unmount will be implemented in a different patch
> 
> V4:
> 	- ENODEV should fail immediately by default
> 	- Use XFS_ERR_RETRY_FOREVER flag, instead of -1 directly
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/xfs_mount.h |  3 +++
>  fs/xfs/xfs_sysfs.c | 22 +++++++++++++++++++++-
>  2 files changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index 2fafa94..72ec3e3 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -49,6 +49,9 @@ enum {
>  };
>  enum {
>  	XFS_ERR_DEFAULT,
> +	XFS_ERR_EIO,
> +	XFS_ERR_ENOSPC,
> +	XFS_ERR_ENODEV,
>  	XFS_ERR_ERRNO_MAX,
>  };
>  
> diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
> index 918d144..084a606 100644
> --- a/fs/xfs/xfs_sysfs.c
> +++ b/fs/xfs/xfs_sysfs.c
> @@ -478,9 +478,20 @@ struct xfs_error_init {
>  
>  static const struct xfs_error_init xfs_error_meta_init[XFS_ERR_ERRNO_MAX] = {
>  	{ .name = "default",
> -	  .max_retries = -1,
> +	  .max_retries = XFS_ERR_RETRY_FOREVER,
>  	  .retry_timeout = 0,
>  	},
> +	{ .name = "EIO",
> +	  .max_retries = XFS_ERR_RETRY_FOREVER,
> +	  .retry_timeout = 0,
> +	},
> +	{ .name = "ENOSPC",
> +	  .max_retries = XFS_ERR_RETRY_FOREVER,
> +	  .retry_timeout = 0,
> +	},
> +	{ .name = "ENODEV",
> +	  .max_retries = 0,
> +	},
>  };
>  
>  static int
> @@ -578,6 +589,15 @@ xfs_error_get_cfg(
>  	struct xfs_error_cfg	*cfg;
>  
>  	switch (error) {
> +	case EIO:
> +		cfg = &mp->m_error_cfg[error_class][XFS_ERR_EIO];
> +		break;
> +	case ENOSPC:
> +		cfg = &mp->m_error_cfg[error_class][XFS_ERR_ENOSPC];
> +		break;
> +	case ENODEV:
> +		cfg = &mp->m_error_cfg[error_class][XFS_ERR_ENODEV];
> +		break;
>  	default:
>  		cfg = &mp->m_error_cfg[error_class][XFS_ERR_DEFAULT];
>  		break;
> -- 
> 2.4.11
> 
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Re: [PATCH 7/7] xfs: add "fail at unmount" error handling configuration

[Brian Foster]

On Tue, May 10, 2016 at 02:16:21PM +0200, Carlos Maiolino wrote:
> If we take "retry forever" literally on metadata IO errors, we can
> hang at unmount, once it retries those writes forever. This is the
> default behavior, unfortunately.
> 
> Add an error configuration option for this behavior and default it to "fail" so
> that an unmount will trigger actuall errors, a shutdown and allow the unmount to
> succeed. It will be noisy, though, as it will log the errors and shutdown that
> occurs.
> 
> To fix this, we need to mark the filesystem as being in the process of
> unmounting. Do this with a mount flag that is added at the appropriate time
> (i.e. before the blocking AIL sync). We also need to add this flag if mount
> fails after the initial phase of log recovery has been run.
> 
> Changelog:
> 
> V3:
> 	- No major changes have been done to this patch, only the ones needed to
> 	  accomodate it on top of the remaining patches
> V4:
> 	- Make fail_at_unmount a global configuration option into
> 	  ../xfs/<dev>/error directory
> 	- Add m_fail_unmount boolean to xfs_mount, to keep track of unmount
> 	  error behavior
> 	- Create err_to_mp() helper, to translate a kobject, from m_error_kobj
> 	  into its xfs_mount
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> ---
>  fs/xfs/xfs_buf_item.c |  4 ++++
>  fs/xfs/xfs_mount.c    | 12 ++++++++++++
>  fs/xfs/xfs_mount.h    |  2 ++
>  fs/xfs/xfs_sysfs.c    | 46 ++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 64 insertions(+)
> 
...
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index eda3906..1bcee7e 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
...
> @@ -1012,6 +1016,14 @@ xfs_unmountfs(
>  	xfs_log_force(mp, XFS_LOG_SYNC);
>  
>  	/*
> +	 * We now need to tell the world we are unmounting. This will allow
> +	 * us to detect that the filesystem is going away and we should error
> +	 * out anything that we have been retrying in the background. This will
> +	 * prevent neverending retries iin AIL pushing from hanging the unmount.

Spelling:			       in

Otherwise looks good:

Reviewed-by: Brian Foster <bfoster@redhat.com>

> +	 */
> +	mp->m_flags |= XFS_MOUNT_UNMOUNTING;
> +
> +	/*
>  	 * Flush all pending changes from the AIL.
>  	 */
>  	xfs_ail_push_all_sync(mp->m_ail);
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index 72ec3e3..9063a9c 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -177,6 +177,7 @@ typedef struct xfs_mount {
>  	 */
>  	__uint32_t		m_generation;
>  
> +	bool			m_fail_unmount;
>  #ifdef DEBUG
>  	/*
>  	 * DEBUG mode instrumentation to test and/or trigger delayed allocation
> @@ -195,6 +196,7 @@ typedef struct xfs_mount {
>  #define XFS_MOUNT_WSYNC		(1ULL << 0)	/* for nfs - all metadata ops
>  						   must be synchronous except
>  						   for space allocations */
> +#define XFS_MOUNT_UNMOUNTING	(1ULL << 1)	/* filesystem is unmounting */
>  #define XFS_MOUNT_WAS_CLEAN	(1ULL << 3)
>  #define XFS_MOUNT_FS_SHUTDOWN	(1ULL << 4)	/* atomic stop of all filesystem
>  						   operations, typically for
> diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
> index 084a606..4c2c550 100644
> --- a/fs/xfs/xfs_sysfs.c
> +++ b/fs/xfs/xfs_sysfs.c
> @@ -381,6 +381,13 @@ to_error_cfg(struct kobject *kobject)
>  	return container_of(kobj, struct xfs_error_cfg, kobj);
>  }
>  
> +static inline struct xfs_mount *
> +err_to_mp(struct kobject *kobject)
> +{
> +	struct xfs_kobj *kobj = to_kobj(kobject);
> +	return container_of(kobj, struct xfs_mount, m_error_kobj);
> +}
> +
>  static ssize_t
>  max_retries_show(
>  	struct kobject	*kobject,
> @@ -447,6 +454,38 @@ retry_timeout_seconds_store(
>  }
>  XFS_SYSFS_ATTR_RW(retry_timeout_seconds);
>  
> +static ssize_t
> +fail_at_unmount_show(
> +	struct kobject	*kobject,
> +	char		*buf)
> +{
> +	struct xfs_mount	*mp = err_to_mp(kobject);
> +
> +	return snprintf(buf, PAGE_SIZE, "%d\n", mp->m_fail_unmount);
> +}
> +
> +static ssize_t
> +fail_at_unmount_store(
> +	struct kobject	*kobject,
> +	const char	*buf,
> +	size_t		count)
> +{
> +	struct xfs_mount	*mp = err_to_mp(kobject);
> +	int		ret;
> +	int		val;
> +
> +	ret = kstrtoint(buf, 0, &val);
> +	if (ret)
> +		return ret;
> +
> +	if (val < 0 || val > 1)
> +		return -EINVAL;
> +
> +	mp->m_fail_unmount = val;
> +	return count;
> +}
> +XFS_SYSFS_ATTR_RW(fail_at_unmount);
> +
>  static struct attribute *xfs_error_attrs[] = {
>  	ATTR_LIST(max_retries),
>  	ATTR_LIST(retry_timeout_seconds),
> @@ -462,6 +501,7 @@ struct kobj_type xfs_error_cfg_ktype = {
>  
>  struct kobj_type xfs_error_ktype = {
>  	.release = xfs_sysfs_release,
> +	.sysfs_ops = &xfs_sysfs_ops,
>  };
>  
>  /*
> @@ -548,6 +588,12 @@ xfs_error_sysfs_init(
>  	if (error)
>  		return error;
>  
> +	error = sysfs_create_file(&mp->m_error_kobj.kobject,
> +				  ATTR_LIST(fail_at_unmount));
> +
> +	if (error)
> +		goto out_error;
> +
>  	/* .../xfs/<dev>/error/metadata/ */
>  	error = xfs_error_sysfs_init_class(mp, XFS_ERR_METADATA,
>  				"metadata", &mp->m_error_meta_kobj,
> -- 
> 2.4.11
> 
> _______________________________________________
> xfs mailing list
> xfs@oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs

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Re: [PATCH 0/7] Configurable error behavior [V4]

[Brian Foster]

On Tue, May 10, 2016 at 02:16:14PM +0200, Carlos Maiolino wrote:
> New revision ot the patchset according with comments for V3.
> 
> This patchset is aimed to implement a configurable error behavior in XFS, and,
> most of the design has been done by Dave, so, I kept his signed-off.
> 
> Detailed changelog is written on each patch, but, major changes are:
> 
> 	- make fail_at_unmount a global configuration option inside
> 	  ../xfs/<dev>/err/fail_at_unmount
> 

Any reason you didn't carry the reviewed-by tags from v3?

For Dave's convenience (and based on the reviews of v3 and v4), for the
series:

Reviewed-by: Brian Foster <bfoster@redhat.com>

> Carlos Maiolino (7):
>   xfs: configurable error behavior via sysfs
>   xfs: introduce metadata IO error class
>   xfs: add configurable error support to metadata buffers
>   xfs: introduce table-based init for error behaviors
>   xfs: add configuration of error failure speed
>   xfs: add configuration handlers for specific errors
>   xfs: add "fail at unmount" error handling configuration
> 
>  fs/xfs/xfs_buf.h      |  20 ++++
>  fs/xfs/xfs_buf_item.c | 121 +++++++++++++--------
>  fs/xfs/xfs_mount.c    |  22 +++-
>  fs/xfs/xfs_mount.h    |  34 ++++++
>  fs/xfs/xfs_sysfs.c    | 291 +++++++++++++++++++++++++++++++++++++++++++++++++-
>  fs/xfs/xfs_sysfs.h    |   3 +
>  fs/xfs/xfs_trace.h    |   1 -
>  7 files changed, 446 insertions(+), 46 deletions(-)
> 
> -- 
> 2.4.11
> 
> _______________________________________________
> xfs mailing list
> xfs@oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs

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Re: [PATCH 7/7] xfs: add "fail at unmount" error handling configuration

[Carlos Maiolino]

On Wed, May 11, 2016 at 10:15:51AM -0400, Brian Foster wrote:
> On Tue, May 10, 2016 at 02:16:21PM +0200, Carlos Maiolino wrote:
> > If we take "retry forever" literally on metadata IO errors, we can
> > hang at unmount, once it retries those writes forever. This is the
> > default behavior, unfortunately.
> > 
> > Add an error configuration option for this behavior and default it to "fail" so
> > that an unmount will trigger actuall errors, a shutdown and allow the unmount to
> > succeed. It will be noisy, though, as it will log the errors and shutdown that
> > occurs.
> > 
> > To fix this, we need to mark the filesystem as being in the process of
> > unmounting. Do this with a mount flag that is added at the appropriate time
> > (i.e. before the blocking AIL sync). We also need to add this flag if mount
> > fails after the initial phase of log recovery has been run.
> > 
> > Changelog:
> > 
> > V3:
> > 	- No major changes have been done to this patch, only the ones needed to
> > 	  accomodate it on top of the remaining patches
> > V4:
> > 	- Make fail_at_unmount a global configuration option into
> > 	  ../xfs/<dev>/error directory
> > 	- Add m_fail_unmount boolean to xfs_mount, to keep track of unmount
> > 	  error behavior
> > 	- Create err_to_mp() helper, to translate a kobject, from m_error_kobj
> > 	  into its xfs_mount
> > 
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> > ---
> >  fs/xfs/xfs_buf_item.c |  4 ++++
> >  fs/xfs/xfs_mount.c    | 12 ++++++++++++
> >  fs/xfs/xfs_mount.h    |  2 ++
> >  fs/xfs/xfs_sysfs.c    | 46 ++++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 64 insertions(+)
> > 
> ...
> > diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> > index eda3906..1bcee7e 100644
> > --- a/fs/xfs/xfs_mount.c
> > +++ b/fs/xfs/xfs_mount.c
> ...
> > @@ -1012,6 +1016,14 @@ xfs_unmountfs(
> >  	xfs_log_force(mp, XFS_LOG_SYNC);
> >  
> >  	/*
> > +	 * We now need to tell the world we are unmounting. This will allow
> > +	 * us to detect that the filesystem is going away and we should error
> > +	 * out anything that we have been retrying in the background. This will
> > +	 * prevent neverending retries iin AIL pushing from hanging the unmount.
> 
> Spelling:			       in
> 

Dave, would you be able to fix it or do you want me to re-send this patch again?

> Otherwise looks good:
> 
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> 
> > +	 */
> > +	mp->m_flags |= XFS_MOUNT_UNMOUNTING;
> > +
> > +	/*
> >  	 * Flush all pending changes from the AIL.
> >  	 */
> >  	xfs_ail_push_all_sync(mp->m_ail);
> > diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> > index 72ec3e3..9063a9c 100644
> > --- a/fs/xfs/xfs_mount.h
> > +++ b/fs/xfs/xfs_mount.h
> > @@ -177,6 +177,7 @@ typedef struct xfs_mount {
> >  	 */
> >  	__uint32_t		m_generation;
> >  
> > +	bool			m_fail_unmount;
> >  #ifdef DEBUG
> >  	/*
> >  	 * DEBUG mode instrumentation to test and/or trigger delayed allocation
> > @@ -195,6 +196,7 @@ typedef struct xfs_mount {
> >  #define XFS_MOUNT_WSYNC		(1ULL << 0)	/* for nfs - all metadata ops
> >  						   must be synchronous except
> >  						   for space allocations */
> > +#define XFS_MOUNT_UNMOUNTING	(1ULL << 1)	/* filesystem is unmounting */
> >  #define XFS_MOUNT_WAS_CLEAN	(1ULL << 3)
> >  #define XFS_MOUNT_FS_SHUTDOWN	(1ULL << 4)	/* atomic stop of all filesystem
> >  						   operations, typically for
> > diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
> > index 084a606..4c2c550 100644
> > --- a/fs/xfs/xfs_sysfs.c
> > +++ b/fs/xfs/xfs_sysfs.c
> > @@ -381,6 +381,13 @@ to_error_cfg(struct kobject *kobject)
> >  	return container_of(kobj, struct xfs_error_cfg, kobj);
> >  }
> >  
> > +static inline struct xfs_mount *
> > +err_to_mp(struct kobject *kobject)
> > +{
> > +	struct xfs_kobj *kobj = to_kobj(kobject);
> > +	return container_of(kobj, struct xfs_mount, m_error_kobj);
> > +}
> > +
> >  static ssize_t
> >  max_retries_show(
> >  	struct kobject	*kobject,
> > @@ -447,6 +454,38 @@ retry_timeout_seconds_store(
> >  }
> >  XFS_SYSFS_ATTR_RW(retry_timeout_seconds);
> >  
> > +static ssize_t
> > +fail_at_unmount_show(
> > +	struct kobject	*kobject,
> > +	char		*buf)
> > +{
> > +	struct xfs_mount	*mp = err_to_mp(kobject);
> > +
> > +	return snprintf(buf, PAGE_SIZE, "%d\n", mp->m_fail_unmount);
> > +}
> > +
> > +static ssize_t
> > +fail_at_unmount_store(
> > +	struct kobject	*kobject,
> > +	const char	*buf,
> > +	size_t		count)
> > +{
> > +	struct xfs_mount	*mp = err_to_mp(kobject);
> > +	int		ret;
> > +	int		val;
> > +
> > +	ret = kstrtoint(buf, 0, &val);
> > +	if (ret)
> > +		return ret;
> > +
> > +	if (val < 0 || val > 1)
> > +		return -EINVAL;
> > +
> > +	mp->m_fail_unmount = val;
> > +	return count;
> > +}
> > +XFS_SYSFS_ATTR_RW(fail_at_unmount);
> > +
> >  static struct attribute *xfs_error_attrs[] = {
> >  	ATTR_LIST(max_retries),
> >  	ATTR_LIST(retry_timeout_seconds),
> > @@ -462,6 +501,7 @@ struct kobj_type xfs_error_cfg_ktype = {
> >  
> >  struct kobj_type xfs_error_ktype = {
> >  	.release = xfs_sysfs_release,
> > +	.sysfs_ops = &xfs_sysfs_ops,
> >  };
> >  
> >  /*
> > @@ -548,6 +588,12 @@ xfs_error_sysfs_init(
> >  	if (error)
> >  		return error;
> >  
> > +	error = sysfs_create_file(&mp->m_error_kobj.kobject,
> > +				  ATTR_LIST(fail_at_unmount));
> > +
> > +	if (error)
> > +		goto out_error;
> > +
> >  	/* .../xfs/<dev>/error/metadata/ */
> >  	error = xfs_error_sysfs_init_class(mp, XFS_ERR_METADATA,
> >  				"metadata", &mp->m_error_meta_kobj,
> > -- 
> > 2.4.11
> > 
> > _______________________________________________
> > xfs mailing list
> > xfs@oss.sgi.com
> > http://oss.sgi.com/mailman/listinfo/xfs

-- 
Carlos

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Re: [PATCH 0/7] Configurable error behavior [V4]

[Carlos Maiolino]

On Wed, May 11, 2016 at 10:15:59AM -0400, Brian Foster wrote:
> On Tue, May 10, 2016 at 02:16:14PM +0200, Carlos Maiolino wrote:
> > New revision ot the patchset according with comments for V3.
> > 
> > This patchset is aimed to implement a configurable error behavior in XFS, and,
> > most of the design has been done by Dave, so, I kept his signed-off.
> > 
> > Detailed changelog is written on each patch, but, major changes are:
> > 
> > 	- make fail_at_unmount a global configuration option inside
> > 	  ../xfs/<dev>/err/fail_at_unmount
> > 
> 
> Any reason you didn't carry the reviewed-by tags from v3?

No reason Brian, I just completely forgot to carry the tags to the new version,
sorry for the extra work.

> 
> For Dave's convenience (and based on the reviews of v3 and v4), for the
> series:
> 
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> 
> > Carlos Maiolino (7):
> >   xfs: configurable error behavior via sysfs
> >   xfs: introduce metadata IO error class
> >   xfs: add configurable error support to metadata buffers
> >   xfs: introduce table-based init for error behaviors
> >   xfs: add configuration of error failure speed
> >   xfs: add configuration handlers for specific errors
> >   xfs: add "fail at unmount" error handling configuration
> > 
> >  fs/xfs/xfs_buf.h      |  20 ++++
> >  fs/xfs/xfs_buf_item.c | 121 +++++++++++++--------
> >  fs/xfs/xfs_mount.c    |  22 +++-
> >  fs/xfs/xfs_mount.h    |  34 ++++++
> >  fs/xfs/xfs_sysfs.c    | 291 +++++++++++++++++++++++++++++++++++++++++++++++++-
> >  fs/xfs/xfs_sysfs.h    |   3 +
> >  fs/xfs/xfs_trace.h    |   1 -
> >  7 files changed, 446 insertions(+), 46 deletions(-)
> > 
> > -- 
> > 2.4.11
> > 
> > _______________________________________________
> > xfs mailing list
> > xfs@oss.sgi.com
> > http://oss.sgi.com/mailman/listinfo/xfs

-- 
Carlos

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Re: [PATCH 0/7] Configurable error behavior [V4]

[Dave Chinner]

On Wed, May 11, 2016 at 10:15:59AM -0400, Brian Foster wrote:
> On Tue, May 10, 2016 at 02:16:14PM +0200, Carlos Maiolino wrote:
> > New revision ot the patchset according with comments for V3.
> > 
> > This patchset is aimed to implement a configurable error behavior in XFS, and,
> > most of the design has been done by Dave, so, I kept his signed-off.
> > 
> > Detailed changelog is written on each patch, but, major changes are:
> > 
> > 	- make fail_at_unmount a global configuration option inside
> > 	  ../xfs/<dev>/err/fail_at_unmount
> > 
> 
> Any reason you didn't carry the reviewed-by tags from v3?
> 
> For Dave's convenience (and based on the reviews of v3 and v4), for the
> series:
> 
> Reviewed-by: Brian Foster <bfoster@redhat.com>

Thanks, Brian.

Carlos, no need to resend, I'll fix the typos up on merge.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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