logfs: get rid of magical inodes

ordering problems at ->kill_sb() time are solved by doing iput()
of these suckers in ->put_super()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/logfs/inode.c

@@ -235,33 +235,21 @@ static struct inode *logfs_alloc_inode(struct super_block *sb)
  * purpose is to create a new inode that will not trigger the warning if such
  * an inode is still in use.  An ugly hack, no doubt.  Suggections for
  * improvement are welcome.
+ *
+ * AV: that's what ->put_super() is for...
  */
 struct inode *logfs_new_meta_inode(struct super_block *sb, u64 ino)
 {
 	struct inode *inode;
 
-	inode = logfs_alloc_inode(sb);
+	inode = new_inode(sb);
 	if (!inode)
 		return ERR_PTR(-ENOMEM);
 
 	inode->i_mode = S_IFREG;
 	inode->i_ino = ino;
-	inode->i_sb = sb;
-
-	/* This is a blatant copy of alloc_inode code.  We'd need alloc_inode
-	 * to be nonstatic, alas. */
-	{
-		struct address_space * const mapping = &inode->i_data;
-
-		mapping->a_ops = &logfs_reg_aops;
-		mapping->host = inode;
-		mapping->flags = 0;
-		mapping_set_gfp_mask(mapping, GFP_NOFS);
-		mapping->assoc_mapping = NULL;
-		mapping->backing_dev_info = &default_backing_dev_info;
-		inode->i_mapping = mapping;
-		inode->i_nlink = 1;
-	}
+	inode->i_data.a_ops = &logfs_reg_aops;
+	mapping_set_gfp_mask(&inode->i_data, GFP_NOFS);
 
 	return inode;
 }
@@ -277,7 +265,7 @@ struct inode *logfs_read_meta_inode(struct super_block *sb, u64 ino)
 
 	err = logfs_read_inode(inode);
 	if (err) {
-		destroy_meta_inode(inode);
+		iput(inode);
 		return ERR_PTR(err);
 	}
 	logfs_inode_setops(inode);
@@ -298,16 +286,6 @@ static int logfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 	return ret;
 }
 
-void destroy_meta_inode(struct inode *inode)
-{
-	if (inode) {
-		if (inode->i_data.nrpages)
-			truncate_inode_pages(&inode->i_data, 0);
-		logfs_clear_inode(inode);
-		kmem_cache_free(logfs_inode_cache, logfs_inode(inode));
-	}
-}
-
 /* called with inode_lock held */
 static void logfs_drop_inode(struct inode *inode)
 {
@@ -384,12 +362,22 @@ static int logfs_sync_fs(struct super_block *sb, int wait)
 	return 0;
 }
 
+static void logfs_put_super(struct super_block *sb)
+{
+	struct logfs_super *super = logfs_super(sb);
+	/* kill the meta-inodes */
+	iput(super->s_master_inode);
+	iput(super->s_segfile_inode);
+	iput(super->s_mapping_inode);
+}
+
 const struct super_operations logfs_super_operations = {
 	.alloc_inode	= logfs_alloc_inode,
 	.clear_inode	= logfs_clear_inode,
 	.delete_inode	= logfs_delete_inode,
 	.destroy_inode	= logfs_destroy_inode,
 	.drop_inode	= logfs_drop_inode,
+	.put_super	= logfs_put_super,
 	.write_inode	= logfs_write_inode,
 	.statfs		= logfs_statfs,
 	.sync_fs	= logfs_sync_fs,

fs/logfs/journal.c

@@ -889,8 +889,6 @@ void logfs_cleanup_journal(struct super_block *sb)
 	struct logfs_super *super = logfs_super(sb);
 
 	btree_grim_visitor32(&super->s_reserved_segments, 0, NULL);
-	destroy_meta_inode(super->s_master_inode);
-	super->s_master_inode = NULL;
 
 	kfree(super->s_compressed_je);
 	kfree(super->s_je);

fs/logfs/logfs.h

@@ -525,7 +525,6 @@ struct inode *logfs_new_meta_inode(struct super_block *sb, u64 ino);
 struct inode *logfs_read_meta_inode(struct super_block *sb, u64 ino);
 int logfs_init_inode_cache(void);
 void logfs_destroy_inode_cache(void);
-void destroy_meta_inode(struct inode *inode);
 void logfs_set_blocks(struct inode *inode, u64 no);
 /* these logically belong into inode.c but actually reside in readwrite.c */
 int logfs_read_inode(struct inode *inode);

fs/logfs/readwrite.c

@@ -2272,7 +2272,6 @@ void logfs_cleanup_rw(struct super_block *sb)
 {
 	struct logfs_super *super = logfs_super(sb);
 
-	destroy_meta_inode(super->s_segfile_inode);
 	logfs_mempool_destroy(super->s_block_pool);
 	logfs_mempool_destroy(super->s_shadow_pool);
 }

fs/logfs/segment.c

@@ -929,5 +929,4 @@ void logfs_cleanup_areas(struct super_block *sb)
 	for_each_area(i)
 		free_area(super->s_area[i]);
 	free_area(super->s_journal_area);
-	destroy_meta_inode(super->s_mapping_inode);
 }

fs/logfs/super.c

@@ -342,24 +342,27 @@ static int logfs_get_sb_final(struct super_block *sb, struct vfsmount *mnt)
 		goto fail;
 	}
 
+	/* at that point we know that ->put_super() will be called */
 	super->s_erase_page = alloc_pages(GFP_KERNEL, 0);
 	if (!super->s_erase_page)
-		goto fail;
+		return -ENOMEM;
 	memset(page_address(super->s_erase_page), 0xFF, PAGE_SIZE);
 
 	/* FIXME: check for read-only mounts */
 	err = logfs_make_writeable(sb);
-	if (err)
-		goto fail1;
+	if (err) {
+		__free_page(super->s_erase_page);
+		return err;
+	}
 
 	log_super("LogFS: Finished mounting\n");
 	simple_set_mnt(mnt, sb);
 	return 0;
 
-fail1:
-	__free_page(super->s_erase_page);
 fail:
-	iput(logfs_super(sb)->s_master_inode);
+	iput(super->s_master_inode);
+	iput(super->s_segfile_inode);
+	iput(super->s_mapping_inode);
 	return -EIO;
 }
 
@@ -580,10 +583,14 @@ int logfs_get_sb_device(struct file_system_type *type, int flags,
 	sb->s_flags |= MS_ACTIVE;
 	err = logfs_get_sb_final(sb, mnt);
 	if (err)
-		goto err1;
-	return 0;
+		deactivate_locked_super(sb);
+	return err;
 
 err1:
+	/* no ->s_root, no ->put_super() */
+	iput(super->s_master_inode);
+	iput(super->s_segfile_inode);
+	iput(super->s_mapping_inode);
 	deactivate_locked_super(sb);
 	return err;
 err0: