fs: port vfs_*() helpers to struct mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

3 files changed, 16 insertions, 15 deletions

diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index d01b29aba662..f41992ecd0d7 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -320,7 +320,7 @@ nfsd3_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		iap->ia_mode &= ~current_umask();
 
 	fh_fill_pre_attrs(fhp);
-	host_err = vfs_create(&init_user_ns, inode, child, iap->ia_mode, true);
+	host_err = vfs_create(&nop_mnt_idmap, inode, child, iap->ia_mode, true);
 	if (host_err < 0) {
 		status = nfserrno(host_err);
 		goto out;
diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 78b8cd9651d5..3509e73abe1f 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -233,7 +233,7 @@ nfsd4_create_clid_dir(struct nfs4_client *clp)
 		 * as well be forgiving and just succeed silently.
 		 */
 		goto out_put;
-	status = vfs_mkdir(&init_user_ns, d_inode(dir), dentry, S_IRWXU);
+	status = vfs_mkdir(&nop_mnt_idmap, d_inode(dir), dentry, S_IRWXU);
 out_put:
 	dput(dentry);
 out_unlock:
@@ -353,7 +353,7 @@ nfsd4_unlink_clid_dir(char *name, int namlen, struct nfsd_net *nn)
 	status = -ENOENT;
 	if (d_really_is_negative(dentry))
 		goto out;
-	status = vfs_rmdir(&init_user_ns, d_inode(dir), dentry);
+	status = vfs_rmdir(&nop_mnt_idmap, d_inode(dir), dentry);
 out:
 	dput(dentry);
 out_unlock:
@@ -443,7 +443,7 @@ purge_old(struct dentry *parent, struct dentry *child, struct nfsd_net *nn)
 	if (nfs4_has_reclaimed_state(name, nn))
 		goto out_free;
 
-	status = vfs_rmdir(&init_user_ns, d_inode(parent), child);
+	status = vfs_rmdir(&nop_mnt_idmap, d_inode(parent), child);
 	if (status)
 		printk("failed to remove client recovery directory %pd\n",
 				child);
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 4c3a0d84043c..371d7f03fe2d 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -426,7 +426,7 @@ static int __nfsd_setattr(struct dentry *dentry, struct iattr *iap)
 		if (iap->ia_size < 0)
 			return -EFBIG;
 
-		host_err = notify_change(&init_user_ns, dentry, &size_attr, NULL);
+		host_err = notify_change(&nop_mnt_idmap, dentry, &size_attr, NULL);
 		if (host_err)
 			return host_err;
 		iap->ia_valid &= ~ATTR_SIZE;
@@ -444,7 +444,7 @@ static int __nfsd_setattr(struct dentry *dentry, struct iattr *iap)
 		return 0;
 
 	iap->ia_valid |= ATTR_CTIME;
-	return notify_change(&init_user_ns, dentry, iap, NULL);
+	return notify_change(&nop_mnt_idmap, dentry, iap, NULL);
 }
 
 /**
@@ -1363,12 +1363,13 @@ nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	err = 0;
 	switch (type) {
 	case S_IFREG:
-		host_err = vfs_create(&init_user_ns, dirp, dchild, iap->ia_mode, true);
+		host_err = vfs_create(&nop_mnt_idmap, dirp, dchild,
+				      iap->ia_mode, true);
 		if (!host_err)
 			nfsd_check_ignore_resizing(iap);
 		break;
 	case S_IFDIR:
-		host_err = vfs_mkdir(&init_user_ns, dirp, dchild, iap->ia_mode);
+		host_err = vfs_mkdir(&nop_mnt_idmap, dirp, dchild, iap->ia_mode);
 		if (!host_err && unlikely(d_unhashed(dchild))) {
 			struct dentry *d;
 			d = lookup_one_len(dchild->d_name.name,
@@ -1396,7 +1397,7 @@ nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	case S_IFBLK:
 	case S_IFIFO:
 	case S_IFSOCK:
-		host_err = vfs_mknod(&init_user_ns, dirp, dchild,
+		host_err = vfs_mknod(&nop_mnt_idmap, dirp, dchild,
 				     iap->ia_mode, rdev);
 		break;
 	default:
@@ -1557,7 +1558,7 @@ nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		goto out_drop_write;
 	}
 	fh_fill_pre_attrs(fhp);
-	host_err = vfs_symlink(&init_user_ns, d_inode(dentry), dnew, path);
+	host_err = vfs_symlink(&nop_mnt_idmap, d_inode(dentry), dnew, path);
 	err = nfserrno(host_err);
 	cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
 	if (!err)
@@ -1625,7 +1626,7 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
 	if (d_really_is_negative(dold))
 		goto out_dput;
 	fh_fill_pre_attrs(ffhp);
-	host_err = vfs_link(dold, &init_user_ns, dirp, dnew, NULL);
+	host_err = vfs_link(dold, &nop_mnt_idmap, dirp, dnew, NULL);
 	fh_fill_post_attrs(ffhp);
 	inode_unlock(dirp);
 	if (!host_err) {
@@ -1745,10 +1746,10 @@ retry:
 		goto out_dput_old;
 	} else {
 		struct renamedata rd = {
-			.old_mnt_userns	= &init_user_ns,
+			.old_mnt_idmap	= &nop_mnt_idmap,
 			.old_dir	= fdir,
 			.old_dentry	= odentry,
-			.new_mnt_userns	= &init_user_ns,
+			.new_mnt_idmap	= &nop_mnt_idmap,
 			.new_dir	= tdir,
 			.new_dentry	= ndentry,
 		};
@@ -1850,14 +1851,14 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
 			nfsd_close_cached_files(rdentry);
 
 		for (retries = 1;;) {
-			host_err = vfs_unlink(&init_user_ns, dirp, rdentry, NULL);
+			host_err = vfs_unlink(&nop_mnt_idmap, dirp, rdentry, NULL);
 			if (host_err != -EAGAIN || !retries--)
 				break;
 			if (!nfsd_wait_for_delegreturn(rqstp, rinode))
 				break;
 		}
 	} else {
-		host_err = vfs_rmdir(&init_user_ns, dirp, rdentry);
+		host_err = vfs_rmdir(&nop_mnt_idmap, dirp, rdentry);
 	}
 	fh_fill_post_attrs(fhp);