Ocfs2 devel - Oct 2008 - [PATCH] quota: Add callbacks for allocating and destroying dquot structures

Some filesystems would like to keep private information together with each
dquot. Add callbacks alloc_dquot and destroy_dquot allowing filesystem to
allocate larger dquots from their private slab in a similar fashion we
currently allocate inodes.

Signed-off-by: Jan Kara <jack at suse.cz>
---
 fs/dquot.c            |   19 +++++++++++++++----
 include/linux/quota.h |    2 ++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/fs/dquot.c b/fs/dquot.c
index 8ec4d6c..e1dac3e 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -417,6 +417,14 @@ out_dqlock:
 	return ret;
 }
 
+static void destroy_dquot(struct dquot *dquot)
+{
+	if (dquot->dq_sb->dq_op->destroy_dquot)
+		dquot->dq_sb->dq_op->destroy_dquot(dquot);
+	else
+		kmem_cache_free(dquot_cachep, dquot);
+}
+
 /* Invalidate all dquots on the list. Note that this function is called after
  * quota is disabled and pointers from inodes removed so there cannot be new
  * quota users. There can still be some users of quotas due to inodes being
@@ -465,7 +473,7 @@ restart:
 		remove_dquot_hash(dquot);
 		remove_free_dquot(dquot);
 		remove_inuse(dquot);
-		kmem_cache_free(dquot_cachep, dquot);
+		destroy_dquot(dquot);
 	}
 	spin_unlock(&dq_list_lock);
 }
@@ -529,7 +537,7 @@ static void prune_dqcache(int count)
 		remove_dquot_hash(dquot);
 		remove_free_dquot(dquot);
 		remove_inuse(dquot);
-		kmem_cache_free(dquot_cachep, dquot);
+		destroy_dquot(dquot);
 		count--;
 		head = free_dquots.prev;
 	}
@@ -631,7 +639,10 @@ static struct dquot *get_empty_dquot(struct super_block
*sb, int type)
 {
 	struct dquot *dquot;
 
-	dquot = kmem_cache_zalloc(dquot_cachep, GFP_NOFS);
+	if (sb->dq_op->alloc_dquot)
+		dquot = sb->dq_op->alloc_dquot(sb, type);
+	else
+		dquot = kmem_cache_zalloc(dquot_cachep, GFP_NOFS);
 	if(!dquot)
 		return NODQUOT;
 
@@ -684,7 +695,7 @@ we_slept:
 		dqstats.lookups++;
 		spin_unlock(&dq_list_lock);
 		if (empty)
-			kmem_cache_free(dquot_cachep, empty);
+			destroy_dquot(empty);
 	}
 	/* Wait for dq_lock - after this we know that either dquot_release() is
already
 	 * finished or it will be canceled due to dq_count > 1 test */
diff --git a/include/linux/quota.h b/include/linux/quota.h
index 376a050..1ac868e 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -294,6 +294,8 @@ struct dquot_operations {
 	int (*free_inode) (const struct inode *, unsigned long);
 	int (*transfer) (struct inode *, struct iattr *);
 	int (*write_dquot) (struct dquot *);		/* Ordinary dquot write */
+	struct dquot *(*alloc_dquot)(struct super_block *, int);	/* Allocate memory
for new dquot (can be NULL if no special entries dquot are needed) */
+	void (*destroy_dquot)(struct dquot *);		/* Free memory for dquot */
 	int (*acquire_dquot) (struct dquot *);		/* Quota is going to be created on
disk */
 	int (*release_dquot) (struct dquot *);		/* Quota is going to be deleted from
disk */
 	int (*mark_dirty) (struct dquot *);		/* Dquot is marked dirty */
-- 
1.5.2.4

On Mon, Oct 20, 2008 at 07:23:34PM +0200, Jan Kara
wrote:
> Some filesystems would like to keep private information together with each
> dquot. Add callbacks alloc_dquot and destroy_dquot allowing filesystem to
> allocate larger dquots from their private slab in a similar fashion we
> currently allocate inodes.
...
> --- a/include/linux/quota.h
> +++ b/include/linux/quota.h
> @@ -294,6 +294,8 @@ struct dquot_operations {
>  	int (*free_inode) (const struct inode *, unsigned long);
>  	int (*transfer) (struct inode *, struct iattr *);
>  	int (*write_dquot) (struct dquot *);		/* Ordinary dquot write */
> +	struct dquot *(*alloc_dquot)(struct super_block *, int);	/* Allocate
memory for new dquot (can be NULL if no special entries dquot are needed) */
> +	void (*destroy_dquot)(struct dquot *);		/* Free memory for dquot */
	Probably want to mention that ->destroy_dquot() is optional and
really matches ->alloc_dquot().

Joel

-- 

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 people in America. If I'm not there, I go to work."
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Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127