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@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

2 files changed, 24 insertions, 5 deletions

diff --git a/fs/dquot.c b/fs/dquot.c
index c237ccc8581c..1b5fc4b7fbeb 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -415,6 +415,16 @@ out_dqlock:
         return ret;
 }
 
+static void dquot_destroy(struct dquot *dquot)
+{
+        kmem_cache_free(dquot_cachep, dquot);
+}
+
+static inline void do_destroy_dquot(struct dquot *dquot)
+{
+        dquot->dq_sb->dq_op->destroy_dquot(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
@@ -463,7 +473,7 @@ restart:
                 remove_dquot_hash(dquot);
                 remove_free_dquot(dquot);
                 remove_inuse(dquot);
-                kmem_cache_free(dquot_cachep, dquot);
+                do_destroy_dquot(dquot);
         }
         spin_unlock(&dq_list_lock);
 }
@@ -527,7 +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);
+                do_destroy_dquot(dquot);
                 count--;
                 head = free_dquots.prev;
         }
@@ -625,11 +635,16 @@ we_slept:
         spin_unlock(&dq_list_lock);
 }
 
+static struct dquot *dquot_alloc(struct super_block *sb, int type)
+{
+        return kmem_cache_zalloc(dquot_cachep, GFP_NOFS);
+}
+
 static struct dquot *get_empty_dquot(struct super_block *sb, int type)
 {
         struct dquot *dquot;
 
-        dquot = kmem_cache_zalloc(dquot_cachep, GFP_NOFS);
+        dquot = sb->dq_op->alloc_dquot(sb, type);
         if(!dquot)
                 return NODQUOT;
 
@@ -682,7 +697,7 @@ we_slept:
                 dqstats.lookups++;
                 spin_unlock(&dq_list_lock);
                 if (empty)
-                        kmem_cache_free(dquot_cachep, empty);
+                        do_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 */
@@ -1533,7 +1548,9 @@ struct dquot_operations dquot_operations = {
         .acquire_dquot  = dquot_acquire,
         .release_dquot  = dquot_release,
         .mark_dirty     = dquot_mark_dquot_dirty,
-        .write_info     = dquot_commit_info
+        .write_info     = dquot_commit_info,
+        .alloc_dquot    = dquot_alloc,
+        .destroy_dquot  = dquot_destroy,
 };
 
 static inline void set_enable_flags(struct quota_info *dqopt, int type)
diff --git a/include/linux/quota.h b/include/linux/quota.h
index 40401b554484..3ce708c2cb3c 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -292,6 +292,8 @@ 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 */
+        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 */