[PATCH 1/2] ocfs2: Use flexible array in 'struct ocfs2_recovery_map'

[PATCH 1/2] ocfs2: Use flexible array in 'struct ocfs2_recovery_map'

[Christophe JAILLET]

Turn 'rm_entries' in 'struct ocfs2_recovery_map' into a flexible array.

The advantages are:
   - save the size of a pointer when the new undo structure is allocated
   - avoid some always ugly pointer arithmetic to get the address of
    'rm_entries'
   - avoid an indirection when the array is accessed

While at it, use struct_size() to compute the size of the new undo
structure.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 fs/ocfs2/journal.c | 5 +----
 fs/ocfs2/journal.h | 2 +-
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 25d8072ccfce..2f7e70109020 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -178,16 +178,13 @@ int ocfs2_recovery_init(struct ocfs2_super *osb)
 	osb->recovery_thread_task = NULL;
 	init_waitqueue_head(&osb->recovery_event);
 
-	rm = kzalloc(sizeof(struct ocfs2_recovery_map) +
-		     osb->max_slots * sizeof(unsigned int),
+	rm = kzalloc(struct_size(rm, rm_entries, osb->max_slots),
 		     GFP_KERNEL);
 	if (!rm) {
 		mlog_errno(-ENOMEM);
 		return -ENOMEM;
 	}
 
-	rm->rm_entries = (unsigned int *)((char *)rm +
-					  sizeof(struct ocfs2_recovery_map));
 	osb->recovery_map = rm;
 
 	return 0;
diff --git a/fs/ocfs2/journal.h b/fs/ocfs2/journal.h
index 41c382f68529..41c9fe7e62f9 100644
--- a/fs/ocfs2/journal.h
+++ b/fs/ocfs2/journal.h
@@ -29,7 +29,7 @@ struct ocfs2_dinode;
 
 struct ocfs2_recovery_map {
 	unsigned int rm_used;
-	unsigned int *rm_entries;
+	unsigned int rm_entries[];
 };
 
 
-- 
2.34.1

[PATCH 2/2] ocfs2: Use struct_size()

[Christophe JAILLET]

Use struct_size() instead of hand-writing it, when allocating a structure
with a flex array.

This is less verbose.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
It will also be helpful if the __counted_by() annotation is added with a
Coccinelle script such as:
   https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?h=devel/counted_by&id=adc5b3cb48a049563dc673f348eab7b6beba8a9b
---
 fs/ocfs2/journal.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 2f7e70109020..4e779efe2a4e 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -114,9 +114,9 @@ int ocfs2_compute_replay_slots(struct ocfs2_super *osb)
 	if (osb->replay_map)
 		return 0;
 
-	replay_map = kzalloc(sizeof(struct ocfs2_replay_map) +
-			     (osb->max_slots * sizeof(char)), GFP_KERNEL);
-
+	replay_map = kzalloc(struct_size(replay_map, rm_replay_slots,
+					 osb->max_slots),
+			     GFP_KERNEL);
 	if (!replay_map) {
 		mlog_errno(-ENOMEM);
 		return -ENOMEM;
-- 
2.34.1

Re: [PATCH 1/2] ocfs2: Use flexible array in 'struct ocfs2_recovery_map'

[Joseph Qi]

On 7/17/23 2:48 AM, Christophe JAILLET wrote:
> Turn 'rm_entries' in 'struct ocfs2_recovery_map' into a flexible array.
> 
> The advantages are:
>    - save the size of a pointer when the new undo structure is allocated
>    - avoid some always ugly pointer arithmetic to get the address of
>     'rm_entries'
>    - avoid an indirection when the array is accessed
> 
> While at it, use struct_size() to compute the size of the new undo
> structure.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

Looks fine.
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>


> ---
>  fs/ocfs2/journal.c | 5 +----
>  fs/ocfs2/journal.h | 2 +-
>  2 files changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
> index 25d8072ccfce..2f7e70109020 100644
> --- a/fs/ocfs2/journal.c
> +++ b/fs/ocfs2/journal.c
> @@ -178,16 +178,13 @@ int ocfs2_recovery_init(struct ocfs2_super *osb)
>  	osb->recovery_thread_task = NULL;
>  	init_waitqueue_head(&osb->recovery_event);
>  
> -	rm = kzalloc(sizeof(struct ocfs2_recovery_map) +
> -		     osb->max_slots * sizeof(unsigned int),
> +	rm = kzalloc(struct_size(rm, rm_entries, osb->max_slots),
>  		     GFP_KERNEL);
>  	if (!rm) {
>  		mlog_errno(-ENOMEM);
>  		return -ENOMEM;
>  	}
>  
> -	rm->rm_entries = (unsigned int *)((char *)rm +
> -					  sizeof(struct ocfs2_recovery_map));
>  	osb->recovery_map = rm;
>  
>  	return 0;
> diff --git a/fs/ocfs2/journal.h b/fs/ocfs2/journal.h
> index 41c382f68529..41c9fe7e62f9 100644
> --- a/fs/ocfs2/journal.h
> +++ b/fs/ocfs2/journal.h
> @@ -29,7 +29,7 @@ struct ocfs2_dinode;
>  
>  struct ocfs2_recovery_map {
>  	unsigned int rm_used;
> -	unsigned int *rm_entries;
> +	unsigned int rm_entries[];
>  };
>  
>  

Re: [PATCH 2/2] ocfs2: Use struct_size()

[Joseph Qi]

On 7/17/23 2:48 AM, Christophe JAILLET wrote:
> Use struct_size() instead of hand-writing it, when allocating a structure
> with a flex array.
> 
> This is less verbose.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

Looks fine.
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>

> ---
> It will also be helpful if the __counted_by() annotation is added with a
> Coccinelle script such as:
>    https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?h=devel/counted_by&id=adc5b3cb48a049563dc673f348eab7b6beba8a9b
> ---
>  fs/ocfs2/journal.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
> index 2f7e70109020..4e779efe2a4e 100644
> --- a/fs/ocfs2/journal.c
> +++ b/fs/ocfs2/journal.c
> @@ -114,9 +114,9 @@ int ocfs2_compute_replay_slots(struct ocfs2_super *osb)
>  	if (osb->replay_map)
>  		return 0;
>  
> -	replay_map = kzalloc(sizeof(struct ocfs2_replay_map) +
> -			     (osb->max_slots * sizeof(char)), GFP_KERNEL);
> -
> +	replay_map = kzalloc(struct_size(replay_map, rm_replay_slots,
> +					 osb->max_slots),
> +			     GFP_KERNEL);
>  	if (!replay_map) {
>  		mlog_errno(-ENOMEM);
>  		return -ENOMEM;