[PATCH v2] ext2: fix sleeping in atomic bugs on error

[PATCH v2] ext2: fix sleeping in atomic bugs on error

[Dan Carpenter]

The ext2_error() function syncs the filesystem so it sleeps.  The caller
is holding a spinlock so it's not allowed to sleep.

   ext2_statfs() <- disables preempt
   -> ext2_count_free_blocks()
      -> ext2_get_group_desc()

Fix this by using WARN() to print an error message and a stack trace
instead of using ext2_error().

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
v2: The first version disabled the sync in ext2_error()

 fs/ext2/balloc.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index 1f3f4326bf3c..c17ccc19b938 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -48,10 +48,9 @@ struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
 	struct ext2_sb_info *sbi = EXT2_SB(sb);
 
 	if (block_group >= sbi->s_groups_count) {
-		ext2_error (sb, "ext2_get_group_desc",
-			    "block_group >= groups_count - "
-			    "block_group = %d, groups_count = %lu",
-			    block_group, sbi->s_groups_count);
+		WARN(1, "block_group >= groups_count - "
+		     "block_group = %d, groups_count = %lu",
+		     block_group, sbi->s_groups_count);
 
 		return NULL;
 	}
@@ -59,10 +58,9 @@ struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
 	group_desc = block_group >> EXT2_DESC_PER_BLOCK_BITS(sb);
 	offset = block_group & (EXT2_DESC_PER_BLOCK(sb) - 1);
 	if (!sbi->s_group_desc[group_desc]) {
-		ext2_error (sb, "ext2_get_group_desc",
-			    "Group descriptor not loaded - "
-			    "block_group = %d, group_desc = %lu, desc = %lu",
-			     block_group, group_desc, offset);
+		WARN(1, "Group descriptor not loaded - "
+		     "block_group = %d, group_desc = %lu, desc = %lu",
+		      block_group, group_desc, offset);
 		return NULL;
 	}
 
-- 
2.20.1

Re: [PATCH v2] ext2: fix sleeping in atomic bugs on error

[Jan Kara]

On Tue 21-09-21 23:32:33, Dan Carpenter wrote:
> The ext2_error() function syncs the filesystem so it sleeps.  The caller
> is holding a spinlock so it's not allowed to sleep.
> 
>    ext2_statfs() <- disables preempt
>    -> ext2_count_free_blocks()
>       -> ext2_get_group_desc()
> 
> Fix this by using WARN() to print an error message and a stack trace
> instead of using ext2_error().
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Thanks! I've added the patch to my tree.

								Honza

> ---
> v2: The first version disabled the sync in ext2_error()
> 
>  fs/ext2/balloc.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
> index 1f3f4326bf3c..c17ccc19b938 100644
> --- a/fs/ext2/balloc.c
> +++ b/fs/ext2/balloc.c
> @@ -48,10 +48,9 @@ struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
>  	struct ext2_sb_info *sbi = EXT2_SB(sb);
>  
>  	if (block_group >= sbi->s_groups_count) {
> -		ext2_error (sb, "ext2_get_group_desc",
> -			    "block_group >= groups_count - "
> -			    "block_group = %d, groups_count = %lu",
> -			    block_group, sbi->s_groups_count);
> +		WARN(1, "block_group >= groups_count - "
> +		     "block_group = %d, groups_count = %lu",
> +		     block_group, sbi->s_groups_count);
>  
>  		return NULL;
>  	}
> @@ -59,10 +58,9 @@ struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
>  	group_desc = block_group >> EXT2_DESC_PER_BLOCK_BITS(sb);
>  	offset = block_group & (EXT2_DESC_PER_BLOCK(sb) - 1);
>  	if (!sbi->s_group_desc[group_desc]) {
> -		ext2_error (sb, "ext2_get_group_desc",
> -			    "Group descriptor not loaded - "
> -			    "block_group = %d, group_desc = %lu, desc = %lu",
> -			     block_group, group_desc, offset);
> +		WARN(1, "Group descriptor not loaded - "
> +		     "block_group = %d, group_desc = %lu, desc = %lu",
> +		      block_group, group_desc, offset);
>  		return NULL;
>  	}
>  
> -- 
> 2.20.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR