Re: [PATCH 1/4] bdi: add check for bdi_debug_root

[weiping zhang]

On Mon, Oct 30, 2017 at 02:00:28PM +0100, Jan Kara wrote:
> On Fri 27-10-17 01:35:36, weiping zhang wrote:
> > this patch add a check for bdi_debug_root and do error handle for it.
> > we should make sure it was created success, otherwise when add new
> > block device's bdi folder(eg, 8:0) will be create a debugfs root directory.
> > 
> > Signed-off-by: weiping zhang 
> > ---
> >  mm/backing-dev.c | 17 ++---
> >  1 file changed, 14 insertions(+), 3 deletions(-)
> 
> These functions get called only on system boot - ENOMEM in those cases is
> generally considered fatal and oopsing is acceptable result. So I don't
> think this patch is needed.
> 
OK, I drop this patch.

Thanks a ton.

Re: [PATCH 1/4] bdi: add check for bdi_debug_root

[Jan Kara]

On Fri 27-10-17 01:35:36, weiping zhang wrote:
> this patch add a check for bdi_debug_root and do error handle for it.
> we should make sure it was created success, otherwise when add new
> block device's bdi folder(eg, 8:0) will be create a debugfs root directory.
> 
> Signed-off-by: weiping zhang 
> ---
>  mm/backing-dev.c | 17 ++---
>  1 file changed, 14 insertions(+), 3 deletions(-)

These functions get called only on system boot - ENOMEM in those cases is
generally considered fatal and oopsing is acceptable result. So I don't
think this patch is needed.

Honza

> 
> diff --git a/mm/backing-dev.c b/mm/backing-dev.c
> index 74b52dfd5852..5072be19d9b2 100644
> --- a/mm/backing-dev.c
> +++ b/mm/backing-dev.c
> @@ -36,9 +36,12 @@ struct workqueue_struct *bdi_wq;
>  
>  static struct dentry *bdi_debug_root;
>  
> -static void bdi_debug_init(void)
> +static int bdi_debug_init(void)
>  {
>   bdi_debug_root = debugfs_create_dir("bdi", NULL);
> + if (!bdi_debug_root)
> + return -ENOMEM;
> + return 0;
>  }
>  
>  static int bdi_debug_stats_show(struct seq_file *m, void *v)
> @@ -126,8 +129,9 @@ static void bdi_debug_unregister(struct backing_dev_info 
> *bdi)
>   debugfs_remove(bdi->debug_dir);
>  }
>  #else
> -static inline void bdi_debug_init(void)
> +static inline int bdi_debug_init(void)
>  {
> + return 0;
>  }
>  static inline void bdi_debug_register(struct backing_dev_info *bdi,
> const char *name)
> @@ -229,12 +233,19 @@ ATTRIBUTE_GROUPS(bdi_dev);
>  
>  static __init int bdi_class_init(void)
>  {
> + int ret;
> +
>   bdi_class = class_create(THIS_MODULE, "bdi");
>   if (IS_ERR(bdi_class))
>   return PTR_ERR(bdi_class);
>  
>   bdi_class->dev_groups = bdi_dev_groups;
> - bdi_debug_init();
> + ret = bdi_debug_init();
> + if (ret) {
> + class_destroy(bdi_class);
> + bdi_class = NULL;
> + return ret;
> + }
>  
>   return 0;
>  }
> -- 
> 2.14.2
> 
-- 
Jan Kara 
SUSE Labs, CR

[PATCH 1/4] bdi: add check for bdi_debug_root

[weiping zhang]

this patch add a check for bdi_debug_root and do error handle for it.
we should make sure it was created success, otherwise when add new
block device's bdi folder(eg, 8:0) will be create a debugfs root directory.

Signed-off-by: weiping zhang 
---
 mm/backing-dev.c | 17 ++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 74b52dfd5852..5072be19d9b2 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -36,9 +36,12 @@ struct workqueue_struct *bdi_wq;
 
 static struct dentry *bdi_debug_root;
 
-static void bdi_debug_init(void)
+static int bdi_debug_init(void)
 {
bdi_debug_root = debugfs_create_dir("bdi", NULL);
+   if (!bdi_debug_root)
+   return -ENOMEM;
+   return 0;
 }
 
 static int bdi_debug_stats_show(struct seq_file *m, void *v)
@@ -126,8 +129,9 @@ static void bdi_debug_unregister(struct backing_dev_info 
*bdi)
debugfs_remove(bdi->debug_dir);
 }
 #else
-static inline void bdi_debug_init(void)
+static inline int bdi_debug_init(void)
 {
+   return 0;
 }
 static inline void bdi_debug_register(struct backing_dev_info *bdi,
  const char *name)
@@ -229,12 +233,19 @@ ATTRIBUTE_GROUPS(bdi_dev);
 
 static __init int bdi_class_init(void)
 {
+   int ret;
+
bdi_class = class_create(THIS_MODULE, "bdi");
if (IS_ERR(bdi_class))
return PTR_ERR(bdi_class);
 
bdi_class->dev_groups = bdi_dev_groups;
-   bdi_debug_init();
+   ret = bdi_debug_init();
+   if (ret) {
+   class_destroy(bdi_class);
+   bdi_class = NULL;
+   return ret;
+   }
 
return 0;
 }
-- 
2.14.2