[PATCH 1/3] Btrfs: fix possible memory leak in find_parent_nodes()

[PATCH 1/3] Btrfs: fix possible memory leak in find_parent_nodes()

[Wang Shilong]

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
---
 fs/btrfs/backref.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index cb73a12..54e7610 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -911,7 +911,6 @@ again:
 
 	while (!list_empty(&prefs)) {
 		ref = list_first_entry(&prefs, struct __prelim_ref, list);
-		list_del(&ref->list);
 		WARN_ON(ref->count < 0);
 		if (ref->count && ref->root_id && ref->parent == 0) {
 			/* no parent == root of tree */
@@ -954,6 +953,7 @@ again:
 				eie->next = ref->inode_list;
 			}
 		}
+		list_del(&ref->list);
 		kfree(ref);
 	}
 
-- 
1.8.0.1

[PATCH 2/3] Btrfs: catch error return value from find_extent_in_eb()

[Wang Shilong]

find_extent_in_eb() may return ENOMEM, catch this error return value.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
---
 fs/btrfs/backref.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 54e7610..f7781e6 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -934,6 +934,10 @@ again:
 				}
 				ret = find_extent_in_eb(eb, bytenr,
 							*extent_item_pos, &eie);
+				if (ret) {
+					free_extent_buffer(eb);
+					goto out;
+				}
 				ref->inode_list = eie;
 				free_extent_buffer(eb);
 			}
-- 
1.8.0.1

[PATCH 3/3] Btrfs: allocate prelim_ref with a slab allocater

[Wang Shilong]

struct __prelim_ref is allocated and freed frequently when
walking backref tree, using slab allocater can not only
speed up allocating but also detect memory leaks.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
---
 fs/btrfs/backref.c | 30 +++++++++++++++++++++++++-----
 fs/btrfs/backref.h |  2 ++
 fs/btrfs/super.c   |  8 ++++++++
 3 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index f7781e6..916e4f1 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -119,6 +119,26 @@ struct __prelim_ref {
 	u64 wanted_disk_byte;
 };
 
+static struct kmem_cache *prelim_ref_cache;
+
+int __init btrfs_prelim_ref_init(void)
+{
+	prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
+					sizeof(struct __prelim_ref),
+					0,
+					SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
+					NULL);
+	if (!prelim_ref_cache)
+		return -ENOMEM;
+	return 0;
+}
+
+void btrfs_prelim_ref_exit(void)
+{
+	if (prelim_ref_cache)
+		kmem_cache_destroy(prelim_ref_cache);
+}
+
 /*
  * the rules for all callers of this function are:
  * - obtaining the parent is the goal
@@ -165,7 +185,7 @@ static int __add_prelim_ref(struct list_head *head, u64 root_id,
 {
 	struct __prelim_ref *ref;
 
-	ref = kmalloc(sizeof(*ref), gfp_mask);
+	ref = kmem_cache_alloc(prelim_ref_cache, gfp_mask);
 	if (!ref)
 		return -ENOMEM;
 
@@ -493,7 +513,7 @@ static void __merge_refs(struct list_head *head, int mode)
 			ref1->count += ref2->count;
 
 			list_del(&ref2->list);
-			kfree(ref2);
+			kmem_cache_free(prelim_ref_cache, ref2);
 		}
 
 	}
@@ -958,7 +978,7 @@ again:
 			}
 		}
 		list_del(&ref->list);
-		kfree(ref);
+		kmem_cache_free(prelim_ref_cache, ref);
 	}
 
 out:
@@ -966,13 +986,13 @@ out:
 	while (!list_empty(&prefs)) {
 		ref = list_first_entry(&prefs, struct __prelim_ref, list);
 		list_del(&ref->list);
-		kfree(ref);
+		kmem_cache_free(prelim_ref_cache, ref);
 	}
 	while (!list_empty(&prefs_delayed)) {
 		ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
 				       list);
 		list_del(&ref->list);
-		kfree(ref);
+		kmem_cache_free(prelim_ref_cache, ref);
 	}
 
 	return ret;
diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
index 8f2e767..a910b27 100644
--- a/fs/btrfs/backref.h
+++ b/fs/btrfs/backref.h
@@ -72,4 +72,6 @@ int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
 			  struct btrfs_inode_extref **ret_extref,
 			  u64 *found_off);
 
+int __init btrfs_prelim_ref_init(void);
+void btrfs_prelim_ref_exit(void);
 #endif
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index b64d762..de7eb3d 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -56,6 +56,7 @@
 #include "rcu-string.h"
 #include "dev-replace.h"
 #include "free-space-cache.h"
+#include "backref.h"
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/btrfs.h>
@@ -1774,6 +1775,10 @@ static int __init init_btrfs_fs(void)
 	if (err)
 		goto free_auto_defrag;
 
+	err = btrfs_prelim_ref_init();
+	if (err)
+		goto free_prelim_ref;
+
 	err = btrfs_interface_init();
 	if (err)
 		goto free_delayed_ref;
@@ -1791,6 +1796,8 @@ static int __init init_btrfs_fs(void)
 
 unregister_ioctl:
 	btrfs_interface_exit();
+free_prelim_ref:
+	btrfs_prelim_ref_exit();
 free_delayed_ref:
 	btrfs_delayed_ref_exit();
 free_auto_defrag:
@@ -1817,6 +1824,7 @@ static void __exit exit_btrfs_fs(void)
 	btrfs_delayed_ref_exit();
 	btrfs_auto_defrag_exit();
 	btrfs_delayed_inode_exit();
+	btrfs_prelim_ref_exit();
 	ordered_data_exit();
 	extent_map_exit();
 	extent_io_exit();
-- 
1.8.0.1

Re: [PATCH 1/3] Btrfs: fix possible memory leak in find_parent_nodes()

[Liu Bo]

On Thu, Aug 08, 2013 at 01:04:17PM +0800, Wang Shilong wrote:
> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>

Sorry, I don't think I understand why it's a memory leak, some explanation
is needed here.

-liubo

> ---
>  fs/btrfs/backref.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
> index cb73a12..54e7610 100644
> --- a/fs/btrfs/backref.c
> +++ b/fs/btrfs/backref.c
> @@ -911,7 +911,6 @@ again:
>  
>  	while (!list_empty(&prefs)) {
>  		ref = list_first_entry(&prefs, struct __prelim_ref, list);
> -		list_del(&ref->list);
>  		WARN_ON(ref->count < 0);
>  		if (ref->count && ref->root_id && ref->parent == 0) {
>  			/* no parent == root of tree */
> @@ -954,6 +953,7 @@ again:
>  				eie->next = ref->inode_list;
>  			}
>  		}
> +		list_del(&ref->list);
>  		kfree(ref);
>  	}
>  
> -- 
> 1.8.0.1
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 1/3] Btrfs: fix possible memory leak in find_parent_nodes()

[Liu Bo]

On Thu, Aug 08, 2013 at 01:04:17PM +0800, Wang Shilong wrote:
> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>

I think I know the whys :p, but still a log is preferred.

-liubo

> ---
>  fs/btrfs/backref.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
> index cb73a12..54e7610 100644
> --- a/fs/btrfs/backref.c
> +++ b/fs/btrfs/backref.c
> @@ -911,7 +911,6 @@ again:
>  
>  	while (!list_empty(&prefs)) {
>  		ref = list_first_entry(&prefs, struct __prelim_ref, list);
> -		list_del(&ref->list);
>  		WARN_ON(ref->count < 0);
>  		if (ref->count && ref->root_id && ref->parent == 0) {
>  			/* no parent == root of tree */
> @@ -954,6 +953,7 @@ again:
>  				eie->next = ref->inode_list;
>  			}
>  		}
> +		list_del(&ref->list);
>  		kfree(ref);
>  	}
>  
> -- 
> 1.8.0.1
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 1/3] Btrfs: fix possible memory leak in find_parent_nodes()

[Miao Xie]

On thu, 8 Aug 2013 13:22:12 +0800, Liu Bo wrote:
> On Thu, Aug 08, 2013 at 01:04:17PM +0800, Wang Shilong wrote:
>> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
>> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
> 
> I think I know the whys :p, but still a log is preferred.

Right, we need a explanation, we will update this patch soon.

Thanks
Miao

> 
> -liubo
> 
>> ---
>>  fs/btrfs/backref.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
>> index cb73a12..54e7610 100644
>> --- a/fs/btrfs/backref.c
>> +++ b/fs/btrfs/backref.c
>> @@ -911,7 +911,6 @@ again:
>>  
>>  	while (!list_empty(&prefs)) {
>>  		ref = list_first_entry(&prefs, struct __prelim_ref, list);
>> -		list_del(&ref->list);
>>  		WARN_ON(ref->count < 0);
>>  		if (ref->count && ref->root_id && ref->parent == 0) {
>>  			/* no parent == root of tree */
>> @@ -954,6 +953,7 @@ again:
>>  				eie->next = ref->inode_list;
>>  			}
>>  		}
>> +		list_del(&ref->list);
>>  		kfree(ref);
>>  	}
>>  
>> -- 
>> 1.8.0.1
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Re: [PATCH 2/3] Btrfs: catch error return value from find_extent_in_eb()

[Filipe David Manana]

On Thu, Aug 8, 2013 at 6:04 AM, Wang Shilong <wangsl.fnst@cn.fujitsu.com> wrote:
> find_extent_in_eb() may return ENOMEM, catch this error return value.
>
> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
> ---
>  fs/btrfs/backref.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
> index 54e7610..f7781e6 100644
> --- a/fs/btrfs/backref.c
> +++ b/fs/btrfs/backref.c
> @@ -934,6 +934,10 @@ again:
>                                 }
>                                 ret = find_extent_in_eb(eb, bytenr,
>                                                         *extent_item_pos, &eie);
> +                               if (ret) {
> +                                       free_extent_buffer(eb);
> +                                       goto out;
> +                               }
>                                 ref->inode_list = eie;
>                                 free_extent_buffer(eb);
>                         }

Hello, this is a duplicate of:  https://patchwork.kernel.org/patch/2835989/

thanks

Re: [PATCH 2/3] Btrfs: catch error return value from find_extent_in_eb()

[Wang Shilong]

On 08/08/2013 06:24 PM, Filipe David Manana wrote:
> On Thu, Aug 8, 2013 at 6:04 AM, Wang Shilong <wangsl.fnst@cn.fujitsu.com> wrote:
>> find_extent_in_eb() may return ENOMEM, catch this error return value.
>>
>> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
>> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
>> ---
>>  fs/btrfs/backref.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
>> index 54e7610..f7781e6 100644
>> --- a/fs/btrfs/backref.c
>> +++ b/fs/btrfs/backref.c
>> @@ -934,6 +934,10 @@ again:
>>                                 }
>>                                 ret = find_extent_in_eb(eb, bytenr,
>>                                                         *extent_item_pos, &eie);
>> +                               if (ret) {
>> +                                       free_extent_buffer(eb);
>> +                                       goto out;
>> +                               }
>>                                 ref->inode_list = eie;
>>                                 free_extent_buffer(eb);
>>                         }
> 
> Hello, this is a duplicate of:  https://patchwork.kernel.org/patch/2835989/

Yeah, just ignore my patch.

Thanks,
Wang
> 
> thanks
> 

Re: [PATCH 1/3] Btrfs: fix possible memory leak in find_parent_nodes()

[Jan Schmidt]

 
On Thu, August 08, 2013 at 07:04 (+0200), Wang Shilong wrote:
> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
> ---
>  fs/btrfs/backref.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
> index cb73a12..54e7610 100644
> --- a/fs/btrfs/backref.c
> +++ b/fs/btrfs/backref.c
> @@ -911,7 +911,6 @@ again:
>  
>  	while (!list_empty(&prefs)) {
>  		ref = list_first_entry(&prefs, struct __prelim_ref, list);
> -		list_del(&ref->list);
>  		WARN_ON(ref->count < 0);
>  		if (ref->count && ref->root_id && ref->parent == 0) {
>  			/* no parent == root of tree */
> @@ -954,6 +953,7 @@ again:
>  				eie->next = ref->inode_list;
>  			}
>  		}
> +		list_del(&ref->list);
>  		kfree(ref);
>  	}
>  
> 

I'm not convinced, you're not calling kfree() more often. Can you please add
some patch description?

-Jan

Re: [PATCH 1/3] Btrfs: fix possible memory leak in find_parent_nodes()

[Wang Shilong]

On 08/08/2013 07:02 PM, Jan Schmidt wrote:
>  
> On Thu, August 08, 2013 at 07:04 (+0200), Wang Shilong wrote:
>> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
>> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
>> ---
>>  fs/btrfs/backref.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
>> index cb73a12..54e7610 100644
>> --- a/fs/btrfs/backref.c
>> +++ b/fs/btrfs/backref.c
>> @@ -911,7 +911,6 @@ again:
>>  
>>  	while (!list_empty(&prefs)) {
>>  		ref = list_first_entry(&prefs, struct __prelim_ref, list);
>> -		list_del(&ref->list);
>>  		WARN_ON(ref->count < 0);
>>  		if (ref->count && ref->root_id && ref->parent == 0) {
>>  			/* no parent == root of tree */
>> @@ -954,6 +953,7 @@ again:
>>  				eie->next = ref->inode_list;
>>  			}
>>  		}
>> +		list_del(&ref->list);
>>  		kfree(ref);
>>  	}
>>  
>>
> 
> I'm not convinced, you're not calling kfree() more often. Can you please add
> some patch description?

Yeah. i will add more description in V2.

Thanks
Wang
> 
> -Jan
> 

Re: [PATCH 2/3] Btrfs: catch error return value from find_extent_in_eb()

[Jan Schmidt]

 
On Thu, August 08, 2013 at 12:24 (+0200), Filipe David Manana wrote:
> On Thu, Aug 8, 2013 at 6:04 AM, Wang Shilong <wangsl.fnst@cn.fujitsu.com> wrote:
>> find_extent_in_eb() may return ENOMEM, catch this error return value.
>>
>> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
>> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
>> ---
>>  fs/btrfs/backref.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
>> index 54e7610..f7781e6 100644
>> --- a/fs/btrfs/backref.c
>> +++ b/fs/btrfs/backref.c
>> @@ -934,6 +934,10 @@ again:
>>                                 }
>>                                 ret = find_extent_in_eb(eb, bytenr,
>>                                                         *extent_item_pos, &eie);
>> +                               if (ret) {
>> +                                       free_extent_buffer(eb);
>> +                                       goto out;
>> +                               }
>>                                 ref->inode_list = eie;
>>                                 free_extent_buffer(eb);
>>                         }
> 
> Hello, this is a duplicate of:  https://patchwork.kernel.org/patch/2835989/

Your linked patch checks for ret < 0, which is a safer option since there are
functions down the stack returning > 0 or 0 for success and < 0 for errors.
Currently, find_extent_in_eb doesn't return their return values, but I'd rather
be a bit more on the safe side and use your patch.

Thanks,
-Jan

Re: [PATCH 3/3] Btrfs: allocate prelim_ref with a slab allocater

[Jan Schmidt]

 
On Thu, August 08, 2013 at 07:04 (+0200), Wang Shilong wrote:
> struct __prelim_ref is allocated and freed frequently when
> walking backref tree, using slab allocater can not only
> speed up allocating but also detect memory leaks.
> 
> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
> ---
>  fs/btrfs/backref.c | 30 +++++++++++++++++++++++++-----
>  fs/btrfs/backref.h |  2 ++
>  fs/btrfs/super.c   |  8 ++++++++
>  3 files changed, 35 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
> index f7781e6..916e4f1 100644
> --- a/fs/btrfs/backref.c
> +++ b/fs/btrfs/backref.c
> @@ -119,6 +119,26 @@ struct __prelim_ref {
>  	u64 wanted_disk_byte;
>  };
>  
> +static struct kmem_cache *prelim_ref_cache;
> +
> +int __init btrfs_prelim_ref_init(void)
> +{
> +	prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
> +					sizeof(struct __prelim_ref),
> +					0,
> +					SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
> +					NULL);
> +	if (!prelim_ref_cache)
> +		return -ENOMEM;
> +	return 0;
> +}
> +
> +void btrfs_prelim_ref_exit(void)
> +{
> +	if (prelim_ref_cache)
> +		kmem_cache_destroy(prelim_ref_cache);
> +}
> +
>  /*
>   * the rules for all callers of this function are:
>   * - obtaining the parent is the goal
> @@ -165,7 +185,7 @@ static int __add_prelim_ref(struct list_head *head, u64 root_id,
>  {
>  	struct __prelim_ref *ref;
>  
> -	ref = kmalloc(sizeof(*ref), gfp_mask);
> +	ref = kmem_cache_alloc(prelim_ref_cache, gfp_mask);
>  	if (!ref)
>  		return -ENOMEM;
>  
> @@ -493,7 +513,7 @@ static void __merge_refs(struct list_head *head, int mode)
>  			ref1->count += ref2->count;
>  
>  			list_del(&ref2->list);
> -			kfree(ref2);
> +			kmem_cache_free(prelim_ref_cache, ref2);
>  		}
>  
>  	}
> @@ -958,7 +978,7 @@ again:
>  			}
>  		}
>  		list_del(&ref->list);
> -		kfree(ref);
> +		kmem_cache_free(prelim_ref_cache, ref);
>  	}
>  
>  out:
> @@ -966,13 +986,13 @@ out:
>  	while (!list_empty(&prefs)) {
>  		ref = list_first_entry(&prefs, struct __prelim_ref, list);
>  		list_del(&ref->list);
> -		kfree(ref);
> +		kmem_cache_free(prelim_ref_cache, ref);
>  	}
>  	while (!list_empty(&prefs_delayed)) {
>  		ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
>  				       list);
>  		list_del(&ref->list);
> -		kfree(ref);
> +		kmem_cache_free(prelim_ref_cache, ref);
>  	}
>  
>  	return ret;
> diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
> index 8f2e767..a910b27 100644
> --- a/fs/btrfs/backref.h
> +++ b/fs/btrfs/backref.h
> @@ -72,4 +72,6 @@ int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
>  			  struct btrfs_inode_extref **ret_extref,
>  			  u64 *found_off);
>  
> +int __init btrfs_prelim_ref_init(void);
> +void btrfs_prelim_ref_exit(void);
>  #endif
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index b64d762..de7eb3d 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -56,6 +56,7 @@
>  #include "rcu-string.h"
>  #include "dev-replace.h"
>  #include "free-space-cache.h"
> +#include "backref.h"
>  
>  #define CREATE_TRACE_POINTS
>  #include <trace/events/btrfs.h>
> @@ -1774,6 +1775,10 @@ static int __init init_btrfs_fs(void)
>  	if (err)
>  		goto free_auto_defrag;
>  
> +	err = btrfs_prelim_ref_init();
> +	if (err)
> +		goto free_prelim_ref;
> +
>  	err = btrfs_interface_init();
>  	if (err)
>  		goto free_delayed_ref;
> @@ -1791,6 +1796,8 @@ static int __init init_btrfs_fs(void)
>  
>  unregister_ioctl:
>  	btrfs_interface_exit();
> +free_prelim_ref:
> +	btrfs_prelim_ref_exit();
>  free_delayed_ref:
>  	btrfs_delayed_ref_exit();
>  free_auto_defrag:
> @@ -1817,6 +1824,7 @@ static void __exit exit_btrfs_fs(void)
>  	btrfs_delayed_ref_exit();
>  	btrfs_auto_defrag_exit();
>  	btrfs_delayed_inode_exit();
> +	btrfs_prelim_ref_exit();
>  	ordered_data_exit();
>  	extent_map_exit();
>  	extent_io_exit();
> 

I generally like the idea of using a custom cache here. What about this one?

 324 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
[...]
 367                 /* additional parents require new refs being added here */
 368                 while ((node = ulist_next(parents, &uiter))) {
 369                         new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);

That new_ref will also be freed with kmem_cache_free after your patch, I think.

Thanks,
-Jan

Re: [PATCH 3/3] Btrfs: allocate prelim_ref with a slab allocater

[Wang Shilong]

> On Thu, August 08, 2013 at 07:04 (+0200), Wang Shilong wrote:
>> struct __prelim_ref is allocated and freed frequently when
>> walking backref tree, using slab allocater can not only
>> speed up allocating but also detect memory leaks.
>> 
>> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
>> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
>> ---
>> fs/btrfs/backref.c | 30 +++++++++++++++++++++++++-----
>> fs/btrfs/backref.h |  2 ++
>> fs/btrfs/super.c   |  8 ++++++++
>> 3 files changed, 35 insertions(+), 5 deletions(-)
>> 
>> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
>> index f7781e6..916e4f1 100644
>> --- a/fs/btrfs/backref.c
>> +++ b/fs/btrfs/backref.c
>> @@ -119,6 +119,26 @@ struct __prelim_ref {
>> 	u64 wanted_disk_byte;
>> };
>> 
>> +static struct kmem_cache *prelim_ref_cache;
>> +
>> +int __init btrfs_prelim_ref_init(void)
>> +{
>> +	prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
>> +					sizeof(struct __prelim_ref),
>> +					0,
>> +					SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
>> +					NULL);
>> +	if (!prelim_ref_cache)
>> +		return -ENOMEM;
>> +	return 0;
>> +}
>> +
>> +void btrfs_prelim_ref_exit(void)
>> +{
>> +	if (prelim_ref_cache)
>> +		kmem_cache_destroy(prelim_ref_cache);
>> +}
>> +
>> /*
>>  * the rules for all callers of this function are:
>>  * - obtaining the parent is the goal
>> @@ -165,7 +185,7 @@ static int __add_prelim_ref(struct list_head *head, u64 root_id,
>> {
>> 	struct __prelim_ref *ref;
>> 
>> -	ref = kmalloc(sizeof(*ref), gfp_mask);
>> +	ref = kmem_cache_alloc(prelim_ref_cache, gfp_mask);
>> 	if (!ref)
>> 		return -ENOMEM;
>> 
>> @@ -493,7 +513,7 @@ static void __merge_refs(struct list_head *head, int mode)
>> 			ref1->count += ref2->count;
>> 
>> 			list_del(&ref2->list);
>> -			kfree(ref2);
>> +			kmem_cache_free(prelim_ref_cache, ref2);
>> 		}
>> 
>> 	}
>> @@ -958,7 +978,7 @@ again:
>> 			}
>> 		}
>> 		list_del(&ref->list);
>> -		kfree(ref);
>> +		kmem_cache_free(prelim_ref_cache, ref);
>> 	}
>> 
>> out:
>> @@ -966,13 +986,13 @@ out:
>> 	while (!list_empty(&prefs)) {
>> 		ref = list_first_entry(&prefs, struct __prelim_ref, list);
>> 		list_del(&ref->list);
>> -		kfree(ref);
>> +		kmem_cache_free(prelim_ref_cache, ref);
>> 	}
>> 	while (!list_empty(&prefs_delayed)) {
>> 		ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
>> 				       list);
>> 		list_del(&ref->list);
>> -		kfree(ref);
>> +		kmem_cache_free(prelim_ref_cache, ref);
>> 	}
>> 
>> 	return ret;
>> diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
>> index 8f2e767..a910b27 100644
>> --- a/fs/btrfs/backref.h
>> +++ b/fs/btrfs/backref.h
>> @@ -72,4 +72,6 @@ int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
>> 			  struct btrfs_inode_extref **ret_extref,
>> 			  u64 *found_off);
>> 
>> +int __init btrfs_prelim_ref_init(void);
>> +void btrfs_prelim_ref_exit(void);
>> #endif
>> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
>> index b64d762..de7eb3d 100644
>> --- a/fs/btrfs/super.c
>> +++ b/fs/btrfs/super.c
>> @@ -56,6 +56,7 @@
>> #include "rcu-string.h"
>> #include "dev-replace.h"
>> #include "free-space-cache.h"
>> +#include "backref.h"
>> 
>> #define CREATE_TRACE_POINTS
>> #include <trace/events/btrfs.h>
>> @@ -1774,6 +1775,10 @@ static int __init init_btrfs_fs(void)
>> 	if (err)
>> 		goto free_auto_defrag;
>> 
>> +	err = btrfs_prelim_ref_init();
>> +	if (err)
>> +		goto free_prelim_ref;
>> +
>> 	err = btrfs_interface_init();
>> 	if (err)
>> 		goto free_delayed_ref;
>> @@ -1791,6 +1796,8 @@ static int __init init_btrfs_fs(void)
>> 
>> unregister_ioctl:
>> 	btrfs_interface_exit();
>> +free_prelim_ref:
>> +	btrfs_prelim_ref_exit();
>> free_delayed_ref:
>> 	btrfs_delayed_ref_exit();
>> free_auto_defrag:
>> @@ -1817,6 +1824,7 @@ static void __exit exit_btrfs_fs(void)
>> 	btrfs_delayed_ref_exit();
>> 	btrfs_auto_defrag_exit();
>> 	btrfs_delayed_inode_exit();
>> +	btrfs_prelim_ref_exit();
>> 	ordered_data_exit();
>> 	extent_map_exit();
>> 	extent_io_exit();
>> 
> 
> I generally like the idea of using a custom cache here. What about this one?
> 
> 324 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
> [...]
> 367                 /* additional parents require new refs being added here */
> 368                 while ((node = ulist_next(parents, &uiter))) {
> 369                         new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);
> 
> That new_ref will also be freed with kmem_cache_free after your patch, I think.

Yeah, you are right, i just have a question, why i can not cause problems when i free
it with kmem_cahce_free during my test ~_~.


Thanks,
Wang
> 
> Thanks,
> -Jan
> --
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Re: [PATCH 3/3] Btrfs: allocate prelim_ref with a slab allocater

[David Sterba]

On Thu, Aug 08, 2013 at 01:04:19PM +0800, Wang Shilong wrote:
> struct __prelim_ref is allocated and freed frequently when
> walking backref tree, using slab allocater can not only
> speed up allocating but also detect memory leaks.
> 
> Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
> ---
>  fs/btrfs/backref.c | 30 +++++++++++++++++++++++++-----
>  fs/btrfs/backref.h |  2 ++
>  fs/btrfs/super.c   |  8 ++++++++
>  3 files changed, 35 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
> index f7781e6..916e4f1 100644
> --- a/fs/btrfs/backref.c
> +++ b/fs/btrfs/backref.c
> @@ -119,6 +119,26 @@ struct __prelim_ref {
>  	u64 wanted_disk_byte;
>  };
>  
> +static struct kmem_cache *prelim_ref_cache;
> +
> +int __init btrfs_prelim_ref_init(void)
> +{
> +	prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
> +					sizeof(struct __prelim_ref),

Would be nice to give it a name that matches the slab cache,
btrfs_prelim_ref.

david