btrfs: reserve correct number of items for inode creation

The various inode creation code paths do not account for the compression
property, POSIX ACLs, or the parent inode item when starting a
transaction. Fix it by refactoring all of these code paths to use a new
function, btrfs_new_inode_prepare(), which computes the correct number
of items. To do so, it needs to know whether POSIX ACLs will be created,
so move the ACL creation into that function. To reduce the number of
arguments that need to be passed around for inode creation, define
struct btrfs_new_inode_args containing all of the relevant information.

btrfs_new_inode_prepare() will also be a good place to set up the
fscrypt context and encrypted filename in the future.

Reviewed-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 182 insertions, 67 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ad446bbebf23..beafdb4ff873 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -222,15 +222,25 @@ static inline void btrfs_cleanup_ordered_extents(struct btrfs_inode *inode,
 static int btrfs_dirty_inode(struct inode *inode);
 
 static int btrfs_init_inode_security(struct btrfs_trans_handle *trans,
-				     struct inode *inode,  struct inode *dir,
-				     const struct qstr *qstr)
+				     struct btrfs_new_inode_args *args)
 {
 	int err;
 
-	err = btrfs_init_acl(trans, inode, dir);
-	if (!err)
-		err = btrfs_xattr_security_init(trans, inode, dir, qstr);
-	return err;
+	if (args->default_acl) {
+		err = __btrfs_set_acl(trans, args->inode, args->default_acl,
+				      ACL_TYPE_DEFAULT);
+		if (err)
+			return err;
+	}
+	if (args->acl) {
+		err = __btrfs_set_acl(trans, args->inode, args->acl, ACL_TYPE_ACCESS);
+		if (err)
+			return err;
+	}
+	if (!args->default_acl && !args->acl)
+		cache_no_acl(args->inode);
+	return btrfs_xattr_security_init(trans, args->inode, args->dir,
+					 &args->dentry->d_name);
 }
 
 /*
@@ -6038,6 +6048,54 @@ static int btrfs_insert_inode_locked(struct inode *inode)
 		   btrfs_find_actor, &args);
 }
 
+int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args,
+			    unsigned int *trans_num_items)
+{
+	struct inode *dir = args->dir;
+	struct inode *inode = args->inode;
+	int ret;
+
+	ret = posix_acl_create(dir, &inode->i_mode, &args->default_acl, &args->acl);
+	if (ret)
+		return ret;
+
+	/* 1 to add inode item */
+	*trans_num_items = 1;
+	/* 1 to add compression property */
+	if (BTRFS_I(dir)->prop_compress)
+		(*trans_num_items)++;
+	/* 1 to add default ACL xattr */
+	if (args->default_acl)
+		(*trans_num_items)++;
+	/* 1 to add access ACL xattr */
+	if (args->acl)
+		(*trans_num_items)++;
+#ifdef CONFIG_SECURITY
+	/* 1 to add LSM xattr */
+	if (dir->i_security)
+		(*trans_num_items)++;
+#endif
+	if (args->orphan) {
+		/* 1 to add orphan item */
+		(*trans_num_items)++;
+	} else {
+		/*
+		 * 1 to add inode ref
+		 * 1 to add dir item
+		 * 1 to add dir index
+		 * 1 to update parent inode item
+		 */
+		*trans_num_items += 4;
+	}
+	return 0;
+}
+
+void btrfs_new_inode_args_destroy(struct btrfs_new_inode_args *args)
+{
+	posix_acl_release(args->acl);
+	posix_acl_release(args->default_acl);
+}
+
 /*
  * Inherit flags from the parent inode.
  *
@@ -6069,12 +6127,16 @@ static void btrfs_inherit_iflags(struct inode *inode, struct inode *dir)
 	btrfs_sync_inode_flags_to_i_flags(inode);
 }
 
-static int btrfs_new_inode(struct btrfs_trans_handle *trans,
-			   struct btrfs_root *root, struct inode *inode,
-			   struct inode *dir, const char *name, int name_len,
+int btrfs_create_new_inode(struct btrfs_trans_handle *trans,
+			   struct btrfs_new_inode_args *args,
 			   u64 *index)
 {
-	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct inode *dir = args->subvol ? NULL : args->dir;
+	struct inode *inode = args->inode;
+	const char *name;
+	int name_len;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_root *root;
 	struct btrfs_inode_item *inode_item;
 	struct btrfs_key *location;
 	struct btrfs_path *path;
@@ -6086,6 +6148,17 @@ static int btrfs_new_inode(struct btrfs_trans_handle *trans,
 	unsigned long ptr;
 	int ret;
 
+	if (args->subvol) {
+		name = "..";
+		name_len = 2;
+	} else if (args->orphan) {
+		name = NULL;
+		name_len = 0;
+	} else {
+		name = args->dentry->d_name.name;
+		name_len = args->dentry->d_name.len;
+	}
+
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
@@ -6097,6 +6170,10 @@ static int btrfs_new_inode(struct btrfs_trans_handle *trans,
 	if (!name)
 		set_nlink(inode, 0);
 
+	if (!args->subvol)
+		BTRFS_I(inode)->root = btrfs_grab_root(BTRFS_I(dir)->root);
+	root = BTRFS_I(inode)->root;
+
 	ret = btrfs_get_free_objectid(root, &objectid);
 	if (ret) {
 		btrfs_free_path(path);
@@ -6122,8 +6199,6 @@ static int btrfs_new_inode(struct btrfs_trans_handle *trans,
 	 */
 	BTRFS_I(inode)->index_cnt = 2;
 	BTRFS_I(inode)->dir_index = *index;
-	if (!BTRFS_I(inode)->root)
-		BTRFS_I(inode)->root = btrfs_grab_root(root);
 	BTRFS_I(inode)->generation = trans->transid;
 	inode->i_generation = BTRFS_I(inode)->generation;
 
@@ -6331,30 +6406,37 @@ static int btrfs_create_common(struct inode *dir, struct dentry *dentry,
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
 	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_new_inode_args new_inode_args = {
+		.dir = dir,
+		.dentry = dentry,
+		.inode = inode,
+	};
+	unsigned int trans_num_items;
 	struct btrfs_trans_handle *trans;
 	int err;
 	u64 index = 0;
 
-	/*
-	 * 2 for inode item and ref
-	 * 2 for dir items
-	 * 1 for xattr if selinux is on
-	 */
-	trans = btrfs_start_transaction(root, 5);
+	err = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
+	if (err) {
+		iput(inode);
+		return err;
+	}
+
+	trans = btrfs_start_transaction(root, trans_num_items);
 	if (IS_ERR(trans)) {
 		iput(inode);
-		return PTR_ERR(trans);
+		err = PTR_ERR(trans);
+		goto out_new_inode_args;
 	}
 
-	err = btrfs_new_inode(trans, root, inode, dir, dentry->d_name.name,
-			      dentry->d_name.len, &index);
+	err = btrfs_create_new_inode(trans, &new_inode_args, &index);
 	if (err) {
 		iput(inode);
 		inode = NULL;
 		goto out_unlock;
 	}
 
-	err = btrfs_init_inode_security(trans, inode, dir, &dentry->d_name);
+	err = btrfs_init_inode_security(trans, &new_inode_args);
 	if (err)
 		goto out_unlock;
 
@@ -6376,6 +6458,8 @@ out_unlock:
 		discard_new_inode(inode);
 	}
 	btrfs_btree_balance_dirty(fs_info);
+out_new_inode_args:
+	btrfs_new_inode_args_destroy(&new_inode_args);
 	return err;
 }
 
@@ -8653,13 +8737,14 @@ struct inode *btrfs_new_subvol_inode(struct user_namespace *mnt_userns,
  */
 int btrfs_create_subvol_root(struct btrfs_trans_handle *trans,
 			     struct btrfs_root *parent_root,
-			     struct inode *inode)
+			     struct btrfs_new_inode_args *args)
 {
+	struct inode *inode = args->inode;
 	struct btrfs_root *new_root = BTRFS_I(inode)->root;
 	int err;
 	u64 index = 0;
 
-	err = btrfs_new_inode(trans, new_root, inode, NULL, "..", 2, &index);
+	err = btrfs_create_new_inode(trans, args, &index);
 	if (err)
 		return err;
 
@@ -9164,22 +9249,22 @@ static struct inode *new_whiteout_inode(struct user_namespace *mnt_userns,
 }
 
 static int btrfs_whiteout_for_rename(struct btrfs_trans_handle *trans,
-				     struct btrfs_root *root,
-				     struct inode *inode, struct inode *dir,
-				     struct dentry *dentry)
+				     struct btrfs_new_inode_args *args)
 {
+	struct inode *inode = args->inode;
+	struct inode *dir = args->dir;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct dentry *dentry = args->dentry;
 	int ret;
 	u64 index;
 
-	ret = btrfs_new_inode(trans, root, inode, dir, dentry->d_name.name,
-			      dentry->d_name.len, &index);
+	ret = btrfs_create_new_inode(trans, args, &index);
 	if (ret) {
 		iput(inode);
 		return ret;
 	}
 
-	ret = btrfs_init_inode_security(trans, inode, dir,
-				&dentry->d_name);
+	ret = btrfs_init_inode_security(trans, args);
 	if (ret)
 		goto out;
 
@@ -9204,7 +9289,10 @@ static int btrfs_rename(struct user_namespace *mnt_userns,
 			unsigned int flags)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(old_dir->i_sb);
-	struct inode *whiteout_inode;
+	struct btrfs_new_inode_args whiteout_args = {
+		.dir = old_dir,
+		.dentry = old_dentry,
+	};
 	struct btrfs_trans_handle *trans;
 	unsigned int trans_num_items;
 	struct btrfs_root *root = BTRFS_I(old_dir)->root;
@@ -9260,9 +9348,15 @@ static int btrfs_rename(struct user_namespace *mnt_userns,
 		filemap_flush(old_inode->i_mapping);
 
 	if (flags & RENAME_WHITEOUT) {
-		whiteout_inode = new_whiteout_inode(mnt_userns, old_dir);
-		if (!whiteout_inode)
+		whiteout_args.inode = new_whiteout_inode(mnt_userns, old_dir);
+		if (!whiteout_args.inode)
 			return -ENOMEM;
+		ret = btrfs_new_inode_prepare(&whiteout_args, &trans_num_items);
+		if (ret)
+			goto out_whiteout_inode;
+	} else {
+		/* 1 to update the old parent inode. */
+		trans_num_items = 1;
 	}
 
 	if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
@@ -9274,24 +9368,23 @@ static int btrfs_rename(struct user_namespace *mnt_userns,
 		 * 1 to add new root ref
 		 * 1 to add new root backref
 		 */
-		trans_num_items = 4;
+		trans_num_items += 4;
 	} else {
 		/*
 		 * 1 to update inode
 		 * 1 to remove old inode ref
 		 * 1 to add new inode ref
 		 */
-		trans_num_items = 3;
+		trans_num_items += 3;
 	}
 	/*
 	 * 1 to remove old dir item
 	 * 1 to remove old dir index
-	 * 1 to update old parent inode
 	 * 1 to add new dir item
 	 * 1 to add new dir index
-	 * 1 to update new parent inode (if it's not the same as the old parent)
 	 */
-	trans_num_items += 6;
+	trans_num_items += 4;
+	/* 1 to update new parent inode if it's not the same as the old parent */
 	if (new_dir != old_dir)
 		trans_num_items++;
 	if (new_inode) {
@@ -9304,8 +9397,6 @@ static int btrfs_rename(struct user_namespace *mnt_userns,
 		 */
 		trans_num_items += 5;
 	}
-	if (flags & RENAME_WHITEOUT)
-		trans_num_items += 5;
 	trans = btrfs_start_transaction(root, trans_num_items);
 	if (IS_ERR(trans)) {
 		ret = PTR_ERR(trans);
@@ -9401,9 +9492,8 @@ static int btrfs_rename(struct user_namespace *mnt_userns,
 				   rename_ctx.index, new_dentry->d_parent);
 
 	if (flags & RENAME_WHITEOUT) {
-		ret = btrfs_whiteout_for_rename(trans, root, whiteout_inode,
-						old_dir, old_dentry);
-		whiteout_inode = NULL;
+		ret = btrfs_whiteout_for_rename(trans, &whiteout_args);
+		whiteout_args.inode = NULL;
 		if (ret) {
 			btrfs_abort_transaction(trans, ret);
 			goto out_fail;
@@ -9416,7 +9506,10 @@ out_notrans:
 	if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
 		up_read(&fs_info->subvol_sem);
 	if (flags & RENAME_WHITEOUT)
-		iput(whiteout_inode);
+		btrfs_new_inode_args_destroy(&whiteout_args);
+out_whiteout_inode:
+	if (flags & RENAME_WHITEOUT)
+		iput(whiteout_args.inode);
 	return ret;
 }
 
@@ -9636,6 +9729,11 @@ static int btrfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
 	struct btrfs_path *path;
 	struct btrfs_key key;
 	struct inode *inode;
+	struct btrfs_new_inode_args new_inode_args = {
+		.dir = dir,
+		.dentry = dentry,
+	};
+	unsigned int trans_num_items;
 	int err;
 	u64 index = 0;
 	int name_len;
@@ -9656,28 +9754,30 @@ static int btrfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
 	inode_nohighmem(inode);
 	inode->i_mapping->a_ops = &btrfs_aops;
 
-	/*
-	 * 2 items for inode item and ref
-	 * 2 items for dir items
-	 * 1 item for updating parent inode item
-	 * 1 item for the inline extent item
-	 * 1 item for xattr if selinux is on
-	 */
-	trans = btrfs_start_transaction(root, 7);
+	new_inode_args.inode = inode;
+	err = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
+	if (err) {
+		iput(inode);
+		return err;
+	}
+	/* 1 additional item for the inline extent */
+	trans_num_items++;
+
+	trans = btrfs_start_transaction(root, trans_num_items);
 	if (IS_ERR(trans)) {
 		iput(inode);
-		return PTR_ERR(trans);
+		err = PTR_ERR(trans);
+		goto out_new_inode_args;
 	}
 
-	err = btrfs_new_inode(trans, root, inode, dir, dentry->d_name.name,
-			      dentry->d_name.len, &index);
+	err = btrfs_create_new_inode(trans, &new_inode_args, &index);
 	if (err) {
 		iput(inode);
 		inode = NULL;
 		goto out_unlock;
 	}
 
-	err = btrfs_init_inode_security(trans, inode, dir, &dentry->d_name);
+	err = btrfs_init_inode_security(trans, &new_inode_args);
 	if (err)
 		goto out_unlock;
 
@@ -9736,6 +9836,8 @@ out_unlock:
 		discard_new_inode(inode);
 	}
 	btrfs_btree_balance_dirty(fs_info);
+out_new_inode_args:
+	btrfs_new_inode_args_destroy(&new_inode_args);
 	return err;
 }
 
@@ -9987,6 +10089,12 @@ static int btrfs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 	struct btrfs_trans_handle *trans;
 	struct btrfs_root *root = BTRFS_I(dir)->root;
 	struct inode *inode;
+	struct btrfs_new_inode_args new_inode_args = {
+		.dir = dir,
+		.dentry = dentry,
+		.orphan = true,
+	};
+	unsigned int trans_num_items;
 	u64 index;
 	int ret;
 
@@ -9998,23 +10106,28 @@ static int btrfs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 	inode->i_op = &btrfs_file_inode_operations;
 	inode->i_mapping->a_ops = &btrfs_aops;
 
-	/*
-	 * 5 units required for adding orphan entry
-	 */
-	trans = btrfs_start_transaction(root, 5);
+	new_inode_args.inode = inode;
+	ret = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
+	if (ret) {
+		iput(inode);
+		return ret;
+	}
+
+	trans = btrfs_start_transaction(root, trans_num_items);
 	if (IS_ERR(trans)) {
 		iput(inode);
-		return PTR_ERR(trans);
+		ret = PTR_ERR(trans);
+		goto out_new_inode_args;
 	}
 
-	ret = btrfs_new_inode(trans, root, inode, dir, NULL, 0, &index);
+	ret = btrfs_create_new_inode(trans, &new_inode_args, &index);
 	if (ret) {
 		iput(inode);
 		inode = NULL;
 		goto out;
 	}
 
-	ret = btrfs_init_inode_security(trans, inode, dir, NULL);
+	ret = btrfs_init_inode_security(trans, &new_inode_args);
 	if (ret)
 		goto out;
 
@@ -10026,9 +10139,9 @@ static int btrfs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 		goto out;
 
 	/*
-	 * We set number of links to 0 in btrfs_new_inode(), and here we set
-	 * it to 1 because d_tmpfile() will issue a warning if the count is 0,
-	 * through:
+	 * We set number of links to 0 in btrfs_create_new_inode(), and here we
+	 * set it to 1 because d_tmpfile() will issue a warning if the count is
+	 * 0, through:
 	 *
 	 *    d_tmpfile() -> inode_dec_link_count() -> drop_nlink()
 	 */
@@ -10041,6 +10154,8 @@ out:
 	if (ret && inode)
 		discard_new_inode(inode);
 	btrfs_btree_balance_dirty(fs_info);
+out_new_inode_args:
+	btrfs_new_inode_args_destroy(&new_inode_args);
 	return ret;
 }