Inode: Allow external initialisers

To allow XFS to combine the XFS and linux inodes into a single
structure, we need to drive inode lookup from the XFS inode cache,
not the generic inode cache. This means that we need initialise a
struct inode from a context outside alloc_inode() as it is no longer
used by XFS.

Factor and export the struct inode initialisation code from
alloc_inode() to inode_init_always() as a counterpart to
inode_init_once().  i.e. we have to call this init function for each
inode instantiation (always), as opposed inode_init_once() which is
only called on slab object instantiation (once).

Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

diff --git a/fs/inode.c b/fs/inode.c
index 0487ddb..e7ee999 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -108,84 +108,100 @@ static void wake_up_inode(struct inode *inode)
        wake_up_bit(&inode->i_state, __I_LOCK);
 }
 
-static struct inode *alloc_inode(struct super_block *sb)
+/**
+ * inode_init_always - perform inode structure intialisation
+ * @sb         - superblock inode belongs to.
+ * @inode      - inode to initialise
+ *
+ * These are initializations that need to be done on every inode
+ * allocation as the fields are not initialised by slab allocation.
+ */
+struct inode *inode_init_always(struct super_block *sb, struct inode *inode)
 {
        static const struct address_space_operations empty_aops;
        static struct inode_operations empty_iops;
        static const struct file_operations empty_fops;
-       struct inode *inode;
-
-       if (sb->s_op->alloc_inode)
-               inode = sb->s_op->alloc_inode(sb);
-       else
-               inode = (struct inode *) kmem_cache_alloc(inode_cachep, GFP_KERNEL);
 
-       if (inode) {
-               struct address_space * const mapping = &inode->i_data;
-
-               inode->i_sb = sb;
-               inode->i_blkbits = sb->s_blocksize_bits;
-               inode->i_flags = 0;
-               atomic_set(&inode->i_count, 1);
-               inode->i_op = &empty_iops;
-               inode->i_fop = &empty_fops;
-               inode->i_nlink = 1;
-               atomic_set(&inode->i_writecount, 0);
-               inode->i_size = 0;
-               inode->i_blocks = 0;
-               inode->i_bytes = 0;
-               inode->i_generation = 0;
+       struct address_space * const mapping = &inode->i_data;
+
+       inode->i_sb = sb;
+       inode->i_blkbits = sb->s_blocksize_bits;
+       inode->i_flags = 0;
+       atomic_set(&inode->i_count, 1);
+       inode->i_op = &empty_iops;
+       inode->i_fop = &empty_fops;
+       inode->i_nlink = 1;
+       atomic_set(&inode->i_writecount, 0);
+       inode->i_size = 0;
+       inode->i_blocks = 0;
+       inode->i_bytes = 0;
+       inode->i_generation = 0;
 #ifdef CONFIG_QUOTA
-               memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
+       memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
 #endif
-               inode->i_pipe = NULL;
-               inode->i_bdev = NULL;
-               inode->i_cdev = NULL;
-               inode->i_rdev = 0;
-               inode->dirtied_when = 0;
-               if (security_inode_alloc(inode)) {
-                       if (inode->i_sb->s_op->destroy_inode)
-                               inode->i_sb->s_op->destroy_inode(inode);
-                       else
-                               kmem_cache_free(inode_cachep, (inode));
-                       return NULL;
-               }
+       inode->i_pipe = NULL;
+       inode->i_bdev = NULL;
+       inode->i_cdev = NULL;
+       inode->i_rdev = 0;
+       inode->dirtied_when = 0;
+       if (security_inode_alloc(inode)) {
+               if (inode->i_sb->s_op->destroy_inode)
+                       inode->i_sb->s_op->destroy_inode(inode);
+               else
+                       kmem_cache_free(inode_cachep, (inode));
+               return NULL;
+       }
 
-               spin_lock_init(&inode->i_lock);
-               lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
+       spin_lock_init(&inode->i_lock);
+       lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
 
-               mutex_init(&inode->i_mutex);
-               lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);
+       mutex_init(&inode->i_mutex);
+       lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);
 
-               init_rwsem(&inode->i_alloc_sem);
-               lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key);
+       init_rwsem(&inode->i_alloc_sem);
+       lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key);
 
-               mapping->a_ops = &empty_aops;
-               mapping->host = inode;
-               mapping->flags = 0;
-               mapping_set_gfp_mask(mapping, GFP_HIGHUSER_PAGECACHE);
-               mapping->assoc_mapping = NULL;
-               mapping->backing_dev_info = &default_backing_dev_info;
-               mapping->writeback_index = 0;
+       mapping->a_ops = &empty_aops;
+       mapping->host = inode;
+       mapping->flags = 0;
+       mapping_set_gfp_mask(mapping, GFP_HIGHUSER_PAGECACHE);
+       mapping->assoc_mapping = NULL;
+       mapping->backing_dev_info = &default_backing_dev_info;
+       mapping->writeback_index = 0;
 
-               /*
-                * If the block_device provides a backing_dev_info for client
-                * inodes then use that.  Otherwise the inode share the bdev's
-                * backing_dev_info.
-                */
-               if (sb->s_bdev) {
-                       struct backing_dev_info *bdi;
+       /*
+        * If the block_device provides a backing_dev_info for client
+        * inodes then use that.  Otherwise the inode share the bdev's
+        * backing_dev_info.
+        */
+       if (sb->s_bdev) {
+               struct backing_dev_info *bdi;
 
-                       bdi = sb->s_bdev->bd_inode_backing_dev_info;
-                       if (!bdi)
-                               bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
-                       mapping->backing_dev_info = bdi;
-               }
-               inode->i_private = NULL;
-               inode->i_mapping = mapping;
+               bdi = sb->s_bdev->bd_inode_backing_dev_info;
+               if (!bdi)
+                       bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
+               mapping->backing_dev_info = bdi;
        }
+       inode->i_private = NULL;
+       inode->i_mapping = mapping;
+
        return inode;
 }
+EXPORT_SYMBOL(inode_init_always);
+
+static struct inode *alloc_inode(struct super_block *sb)
+{
+       struct inode *inode;
+
+       if (sb->s_op->alloc_inode)
+               inode = sb->s_op->alloc_inode(sb);
+       else
+               inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);
+
+       if (inode)
+               return inode_init_always(sb, inode);
+       return NULL;
+}
 
 void destroy_inode(struct inode *inode) 
 {

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5b248d6..04abead 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1881,6 +1881,7 @@ extern loff_t default_llseek(struct file *file, loff_t offset, int origin);
 
 extern loff_t vfs_llseek(struct file *file, loff_t offset, int origin);
 
+extern struct inode * inode_init_always(struct super_block *, struct inode *);
 extern void inode_init_once(struct inode *);
 extern void iput(struct inode *);
 extern struct inode * igrab(struct inode *);