ovl: check if upper fs supports RENAME_WHITEOUT (cad218ab) · Commits · 戴 / test

fs/overlayfs/dir.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -42,7 +42,7 @@ int ovl_cleanup(struct inode wdir, struct dentry wdentry)
		return err;
		}

		static struct dentry ovl_lookup_temp(struct dentry workdir)
		struct dentry ovl_lookup_temp(struct dentry workdir)
		{
		struct dentry *temp;
		char name[20];

fs/overlayfs/overlayfs.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -453,6 +453,7 @@ struct ovl_cattr {
		struct dentry ovl_create_real(struct inode dir, struct dentry *newdentry,
		struct ovl_cattr *attr);
		int ovl_cleanup(struct inode dir, struct dentry dentry);
		struct dentry ovl_lookup_temp(struct dentry workdir);
		struct dentry ovl_create_temp(struct dentry workdir, struct ovl_cattr *attr);

		/* file.c */

fs/overlayfs/super.c

+69 −0

Original line number	Diff line number	Diff line
		@@ -1071,6 +1071,66 @@ out:
		return err;
		}

		/*
		* Returns 1 if RENAME_WHITEOUT is supported, 0 if not supported and
		* negative values if error is encountered.
		*/
		static int ovl_check_rename_whiteout(struct dentry *workdir)
		{
		struct inode *dir = d_inode(workdir);
		struct dentry *temp;
		struct dentry *dest;
		struct dentry *whiteout;
		struct name_snapshot name;
		int err;

		inode_lock_nested(dir, I_MUTEX_PARENT);

		temp = ovl_create_temp(workdir, OVL_CATTR(S_IFREG \| 0));
		err = PTR_ERR(temp);
		if (IS_ERR(temp))
		goto out_unlock;

		dest = ovl_lookup_temp(workdir);
		err = PTR_ERR(dest);
		if (IS_ERR(dest)) {
		dput(temp);
		goto out_unlock;
		}

		/* Name is inline and stable - using snapshot as a copy helper */
		take_dentry_name_snapshot(&name, temp);
		err = ovl_do_rename(dir, temp, dir, dest, RENAME_WHITEOUT);
		if (err) {
		if (err == -EINVAL)
		err = 0;
		goto cleanup_temp;
		}

		whiteout = lookup_one_len(name.name.name, workdir, name.name.len);
		err = PTR_ERR(whiteout);
		if (IS_ERR(whiteout))
		goto cleanup_temp;

		err = ovl_is_whiteout(whiteout);

		/* Best effort cleanup of whiteout and temp file */
		if (err)
		ovl_cleanup(dir, whiteout);
		dput(whiteout);

		cleanup_temp:
		ovl_cleanup(dir, temp);
		release_dentry_name_snapshot(&name);
		dput(temp);
		dput(dest);

		out_unlock:
		inode_unlock(dir);

		return err;
		}

		static int ovl_make_workdir(struct super_block sb, struct ovl_fs ofs,
		struct path *workpath)
		{
		@@ -1116,6 +1176,15 @@ static int ovl_make_workdir(struct super_block sb, struct ovl_fs ofs,
		else
		pr_warn("upper fs does not support tmpfile.\n");


		/* Check if upper/work fs supports RENAME_WHITEOUT */
		err = ovl_check_rename_whiteout(ofs->workdir);
		if (err < 0)
		goto out;

		if (!err)
		pr_warn("upper fs does not support RENAME_WHITEOUT.\n");

		/*
		* Check if upper/work fs supports trusted.overlay.* xattr
		*/

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