Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs updates from Miklos Szeredi:
 "In addition to bug fixes and cleanups there are two new features from
  Amir:

   - Consistent inode number support for the case when layers are not
     all on the same filesystem (feature is dubbed "xino").

   - Optimize overlayfs file handle decoding. This one touches the
     exportfs interface to allow detecting the disconnected directory
     case"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: update documentation w.r.t "xino" feature
  ovl: add support for "xino" mount and config options
  ovl: consistent d_ino for non-samefs with xino
  ovl: consistent i_ino for non-samefs with xino
  ovl: constant st_ino for non-samefs with xino
  ovl: allocate anon bdev per unique lower fs
  ovl: factor out ovl_map_dev_ino() helper
  ovl: cleanup ovl_update_time()
  ovl: add WARN_ON() for non-dir redirect cases
  ovl: cleanup setting OVL_INDEX
  ovl: set d->is_dir and d->opaque for last path element
  ovl: Do not check for redirect if this is last layer
  ovl: lookup in inode cache first when decoding lower file handle
  ovl: do not try to reconnect a disconnected origin dentry
  ovl: disambiguate ovl_encode_fh()
  ovl: set lower layer st_dev only if setting lower st_ino
  ovl: fix lookup with middle layer opaque dir and absolute path redirects
  ovl: Set d->last properly during lookup
  ovl: set i_ino to the value of st_ino for NFS export

1 files changed, 48 insertions, 19 deletions

diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 70fcfcc684cc..2dba29eadde6 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -56,6 +56,15 @@ static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
 			if (s == next)
 				goto invalid;
 		}
+		/*
+		 * One of the ancestor path elements in an absolute path
+		 * lookup in ovl_lookup_layer() could have been opaque and
+		 * that will stop further lookup in lower layers (d->stop=true)
+		 * But we have found an absolute redirect in decendant path
+		 * element and that should force continue lookup in lower
+		 * layers (reset d->stop).
+		 */
+		d->stop = false;
 	} else {
 		if (strchr(buf, '/') != NULL)
 			goto invalid;
@@ -171,7 +180,8 @@ invalid:
 	goto out;
 }
 
-struct dentry *ovl_decode_fh(struct ovl_fh *fh, struct vfsmount *mnt)
+struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
+				  bool connected)
 {
 	struct dentry *real;
 	int bytes;
@@ -186,7 +196,7 @@ struct dentry *ovl_decode_fh(struct ovl_fh *fh, struct vfsmount *mnt)
 	bytes = (fh->len - offsetof(struct ovl_fh, fid));
 	real = exportfs_decode_fh(mnt, (struct fid *)fh->fid,
 				  bytes >> 2, (int)fh->type,
-				  ovl_acceptable, mnt);
+				  connected ? ovl_acceptable : NULL, mnt);
 	if (IS_ERR(real)) {
 		/*
 		 * Treat stale file handle to lower file as "origin unknown".
@@ -220,6 +230,7 @@ static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
 {
 	struct dentry *this;
 	int err;
+	bool last_element = !post[0];
 
 	this = lookup_one_len_unlocked(name, base, namelen);
 	if (IS_ERR(this)) {
@@ -245,11 +256,23 @@ static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
 		d->stop = true;
 		if (d->is_dir)
 			goto put_and_out;
+
+		/*
+		 * NB: handle failure to lookup non-last element when non-dir
+		 * redirects become possible
+		 */
+		WARN_ON(!last_element);
 		goto out;
 	}
-	d->is_dir = true;
-	if (!d->last && ovl_is_opaquedir(this)) {
-		d->stop = d->opaque = true;
+	if (last_element)
+		d->is_dir = true;
+	if (d->last)
+		goto out;
+
+	if (ovl_is_opaquedir(this)) {
+		d->stop = true;
+		if (last_element)
+			d->opaque = true;
 		goto out;
 	}
 	err = ovl_check_redirect(this, d, prelen, post);
@@ -310,14 +333,15 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,
 }
 
 
-int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
+int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
 			struct dentry *upperdentry, struct ovl_path **stackp)
 {
 	struct dentry *origin = NULL;
 	int i;
 
 	for (i = 0; i < ofs->numlower; i++) {
-		origin = ovl_decode_fh(fh, ofs->lower_layers[i].mnt);
+		origin = ovl_decode_real_fh(fh, ofs->lower_layers[i].mnt,
+					    connected);
 		if (origin)
 			break;
 	}
@@ -361,7 +385,7 @@ static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry,
 	if (IS_ERR_OR_NULL(fh))
 		return PTR_ERR(fh);
 
-	err = ovl_check_origin_fh(ofs, fh, upperdentry, stackp);
+	err = ovl_check_origin_fh(ofs, fh, false, upperdentry, stackp);
 	kfree(fh);
 
 	if (err) {
@@ -415,7 +439,7 @@ int ovl_verify_set_fh(struct dentry *dentry, const char *name,
 	struct ovl_fh *fh;
 	int err;
 
-	fh = ovl_encode_fh(real, is_upper);
+	fh = ovl_encode_real_fh(real, is_upper);
 	err = PTR_ERR(fh);
 	if (IS_ERR(fh))
 		goto fail;
@@ -451,7 +475,7 @@ struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index)
 	if (IS_ERR_OR_NULL(fh))
 		return ERR_CAST(fh);
 
-	upper = ovl_decode_fh(fh, ofs->upper_mnt);
+	upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true);
 	kfree(fh);
 
 	if (IS_ERR_OR_NULL(upper))
@@ -558,7 +582,7 @@ int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index)
 
 	/* Check if non-dir index is orphan and don't warn before cleaning it */
 	if (!d_is_dir(index) && d_inode(index)->i_nlink == 1) {
-		err = ovl_check_origin_fh(ofs, fh, index, &stack);
+		err = ovl_check_origin_fh(ofs, fh, false, index, &stack);
 		if (err)
 			goto fail;
 
@@ -619,7 +643,7 @@ int ovl_get_index_name(struct dentry *origin, struct qstr *name)
 	struct ovl_fh *fh;
 	int err;
 
-	fh = ovl_encode_fh(origin, false);
+	fh = ovl_encode_real_fh(origin, false);
 	if (IS_ERR(fh))
 		return PTR_ERR(fh);
 
@@ -815,7 +839,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		.is_dir = false,
 		.opaque = false,
 		.stop = false,
-		.last = !poe->numlower,
+		.last = ofs->config.redirect_follow ? false : !poe->numlower,
 		.redirect = NULL,
 	};
 
@@ -873,7 +897,11 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 	for (i = 0; !d.stop && i < poe->numlower; i++) {
 		struct ovl_path lower = poe->lowerstack[i];
 
-		d.last = i == poe->numlower - 1;
+		if (!ofs->config.redirect_follow)
+			d.last = i == poe->numlower - 1;
+		else
+			d.last = lower.layer->idx == roe->numlower;
+
 		err = ovl_lookup_layer(lower.dentry, &d, &this);
 		if (err)
 			goto out_put;
@@ -976,17 +1004,18 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		upperdentry = dget(index);
 
 	if (upperdentry || ctr) {
-		if (ctr)
-			origin = stack[0].dentry;
-		inode = ovl_get_inode(dentry->d_sb, upperdentry, origin, index,
+		inode = ovl_get_inode(dentry->d_sb, upperdentry, stack, index,
 				      ctr);
 		err = PTR_ERR(inode);
 		if (IS_ERR(inode))
 			goto out_free_oe;
 
+		/*
+		 * NB: handle redirected hard links when non-dir redirects
+		 * become possible
+		 */
+		WARN_ON(OVL_I(inode)->redirect);
 		OVL_I(inode)->redirect = upperredirect;
-		if (index)
-			ovl_set_flag(OVL_INDEX, inode);
 	}
 
 	revert_creds(old_cred);