Commit cad218ab authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi
Browse files

ovl: check if upper fs supports RENAME_WHITEOUT 



As with other required upper fs features, we only warn if support is
missing to avoid breaking existing sub-optimal setups.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent bccece1e

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 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs, 
	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

	 */