Merge tag 'ovl-update-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs

Pull overlayfs update from Amir Goldstein:

 - fix two NULL pointer deref bugs (Zhihao Cheng)

 - add support for "data-only" lower layers destined to be used by
   composefs

 - port overlayfs to the new mount api (Christian Brauner)

* tag 'ovl-update-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs: (26 commits)
  ovl: add Amir as co-maintainer
  ovl: reserve ability to reconfigure mount options with new mount api
  ovl: modify layer parameter parsing
  ovl: port to new mount api
  ovl: factor out ovl_parse_options() helper
  ovl: store enum redirect_mode in config instead of a string
  ovl: pass ovl_fs to xino helpers
  ovl: clarify ovl_get_root() semantics
  ovl: negate the ofs->share_whiteout boolean
  ovl: check type and offset of struct vfsmount in ovl_entry
  ovl: implement lazy lookup of lowerdata in data-only layers
  ovl: prepare for lazy lookup of lowerdata inode
  ovl: prepare to store lowerdata redirect for lazy lowerdata lookup
  ovl: implement lookup in data-only layers
  ovl: introduce data-only lower layers
  ovl: remove unneeded goto instructions
  ovl: deduplicate lowerdata and lowerstack[]
  ovl: deduplicate lowerpath and lowerstack[]
  ovl: move ovl_entry into ovl_inode
  ovl: factor out ovl_free_entry() and ovl_stack_*() helpers
  ...

13 files changed, 1350 insertions, 699 deletions

diff --git a/fs/overlayfs/Makefile b/fs/overlayfs/Makefile
index 9164c585eb2f..4e173d56b11f 100644
--- a/fs/overlayfs/Makefile
+++ b/fs/overlayfs/Makefile
@@ -6,4 +6,4 @@
 obj-$(CONFIG_OVERLAY_FS) += overlay.o
 
 overlay-objs := super.o namei.o util.o inode.o file.o dir.o readdir.o \
-		copy_up.o export.o
+		copy_up.o export.o params.o
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index f658cc8ea492..568f743a5584 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -575,6 +575,7 @@ static int ovl_link_up(struct ovl_copy_up_ctx *c)
 			/* Restore timestamps on parent (best effort) */
 			ovl_set_timestamps(ofs, upperdir, &c->pstat);
 			ovl_dentry_set_upper_alias(c->dentry);
+			ovl_dentry_update_reval(c->dentry, upper);
 		}
 	}
 	inode_unlock(udir);
@@ -894,6 +895,7 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
 		inode_unlock(udir);
 
 		ovl_dentry_set_upper_alias(c->dentry);
+		ovl_dentry_update_reval(c->dentry, ovl_dentry_upper(c->dentry));
 	}
 
 out:
@@ -1071,6 +1073,15 @@ static int ovl_copy_up_flags(struct dentry *dentry, int flags)
 	if (WARN_ON(disconnected && d_is_dir(dentry)))
 		return -EIO;
 
+	/*
+	 * We may not need lowerdata if we are only doing metacopy up, but it is
+	 * not very important to optimize this case, so do lazy lowerdata lookup
+	 * before any copy up, so we can do it before taking ovl_inode_lock().
+	 */
+	err = ovl_maybe_lookup_lowerdata(dentry);
+	if (err)
+		return err;
+
 	old_cred = ovl_override_creds(dentry->d_sb);
 	while (!err) {
 		struct dentry *next;
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index fc25fb95d5fc..033fc0458a3d 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -83,7 +83,7 @@ static struct dentry *ovl_whiteout(struct ovl_fs *ofs)
 		ofs->whiteout = whiteout;
 	}
 
-	if (ofs->share_whiteout) {
+	if (!ofs->no_shared_whiteout) {
 		whiteout = ovl_lookup_temp(ofs, workdir);
 		if (IS_ERR(whiteout))
 			goto out;
@@ -95,7 +95,7 @@ static struct dentry *ovl_whiteout(struct ovl_fs *ofs)
 		if (err != -EMLINK) {
 			pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%i)\n",
 				ofs->whiteout->d_inode->i_nlink, err);
-			ofs->share_whiteout = false;
+			ofs->no_shared_whiteout = true;
 		}
 		dput(whiteout);
 	}
@@ -269,8 +269,7 @@ static int ovl_instantiate(struct dentry *dentry, struct inode *inode,
 
 	ovl_dir_modified(dentry->d_parent, false);
 	ovl_dentry_set_upper_alias(dentry);
-	ovl_dentry_update_reval(dentry, newdentry,
-			DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+	ovl_dentry_init_reval(dentry, newdentry, NULL);
 
 	if (!hardlink) {
 		/*
@@ -953,7 +952,7 @@ static bool ovl_type_merge_or_lower(struct dentry *dentry)
 
 static bool ovl_can_move(struct dentry *dentry)
 {
-	return ovl_redirect_dir(dentry->d_sb) ||
+	return ovl_redirect_dir(OVL_FS(dentry->d_sb)) ||
 		!d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry);
 }
 
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index defd4e231ad2..35680b6e175b 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -80,7 +80,7 @@ static int ovl_connectable_layer(struct dentry *dentry)
 
 	/* We can get overlay root from root of any layer */
 	if (dentry == dentry->d_sb->s_root)
-		return oe->numlower;
+		return ovl_numlower(oe);
 
 	/*
 	 * If it's an unindexed merge dir, then it's not connectable with any
@@ -91,7 +91,7 @@ static int ovl_connectable_layer(struct dentry *dentry)
 		return 0;
 
 	/* We can get upper/overlay path from indexed/lower dentry */
-	return oe->lowerstack[0].layer->idx;
+	return ovl_lowerstack(oe)->layer->idx;
 }
 
 /*
@@ -105,6 +105,7 @@ static int ovl_connectable_layer(struct dentry *dentry)
 static int ovl_connect_layer(struct dentry *dentry)
 {
 	struct dentry *next, *parent = NULL;
+	struct ovl_entry *oe = OVL_E(dentry);
 	int origin_layer;
 	int err = 0;
 
@@ -112,7 +113,7 @@ static int ovl_connect_layer(struct dentry *dentry)
 	    WARN_ON(!ovl_dentry_lower(dentry)))
 		return -EIO;
 
-	origin_layer = OVL_E(dentry)->lowerstack[0].layer->idx;
+	origin_layer = ovl_lowerstack(oe)->layer->idx;
 	if (ovl_dentry_test_flag(OVL_E_CONNECTED, dentry))
 		return origin_layer;
 
@@ -285,21 +286,29 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb,
 	struct dentry *lower = lowerpath ? lowerpath->dentry : NULL;
 	struct dentry *upper = upper_alias ?: index;
 	struct dentry *dentry;
-	struct inode *inode;
+	struct inode *inode = NULL;
 	struct ovl_entry *oe;
 	struct ovl_inode_params oip = {
-		.lowerpath = lowerpath,
 		.index = index,
-		.numlower = !!lower
 	};
 
 	/* We get overlay directory dentries with ovl_lookup_real() */
 	if (d_is_dir(upper ?: lower))
 		return ERR_PTR(-EIO);
 
+	oe = ovl_alloc_entry(!!lower);
+	if (!oe)
+		return ERR_PTR(-ENOMEM);
+
 	oip.upperdentry = dget(upper);
+	if (lower) {
+		ovl_lowerstack(oe)->dentry = dget(lower);
+		ovl_lowerstack(oe)->layer = lowerpath->layer;
+	}
+	oip.oe = oe;
 	inode = ovl_get_inode(sb, &oip);
 	if (IS_ERR(inode)) {
+		ovl_free_entry(oe);
 		dput(upper);
 		return ERR_CAST(inode);
 	}
@@ -314,20 +323,11 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb,
 	dentry = d_alloc_anon(inode->i_sb);
 	if (unlikely(!dentry))
 		goto nomem;
-	oe = ovl_alloc_entry(lower ? 1 : 0);
-	if (!oe)
-		goto nomem;
 
-	if (lower) {
-		oe->lowerstack->dentry = dget(lower);
-		oe->lowerstack->layer = lowerpath->layer;
-	}
-	dentry->d_fsdata = oe;
 	if (upper_alias)
 		ovl_dentry_set_upper_alias(dentry);
 
-	ovl_dentry_update_reval(dentry, upper,
-			DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+	ovl_dentry_init_reval(dentry, upper, OVL_I_E(inode));
 
 	return d_instantiate_anon(dentry, inode);
 
@@ -342,15 +342,16 @@ out_iput:
 /* Get the upper or lower dentry in stack whose on layer @idx */
 static struct dentry *ovl_dentry_real_at(struct dentry *dentry, int idx)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct ovl_entry *oe = OVL_E(dentry);
+	struct ovl_path *lowerstack = ovl_lowerstack(oe);
 	int i;
 
 	if (!idx)
 		return ovl_dentry_upper(dentry);
 
-	for (i = 0; i < oe->numlower; i++) {
-		if (oe->lowerstack[i].layer->idx == idx)
-			return oe->lowerstack[i].dentry;
+	for (i = 0; i < ovl_numlower(oe); i++) {
+		if (lowerstack[i].layer->idx == idx)
+			return lowerstack[i].dentry;
 	}
 
 	return NULL;
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 1f93a3ae113e..21245b00722a 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -107,14 +107,23 @@ static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
 {
 	struct dentry *dentry = file_dentry(file);
 	struct path realpath;
+	int err;
 
 	real->flags = 0;
 	real->file = file->private_data;
 
-	if (allow_meta)
+	if (allow_meta) {
 		ovl_path_real(dentry, &realpath);
-	else
+	} else {
+		/* lazy lookup of lowerdata */
+		err = ovl_maybe_lookup_lowerdata(dentry);
+		if (err)
+			return err;
+
 		ovl_path_realdata(dentry, &realpath);
+	}
+	if (!realpath.dentry)
+		return -EIO;
 
 	/* Has it been copied up since we'd opened it? */
 	if (unlikely(file_inode(real->file) != d_inode(realpath.dentry))) {
@@ -150,6 +159,11 @@ static int ovl_open(struct inode *inode, struct file *file)
 	struct path realpath;
 	int err;
 
+	/* lazy lookup of lowerdata */
+	err = ovl_maybe_lookup_lowerdata(dentry);
+	if (err)
+		return err;
+
 	err = ovl_maybe_copy_up(dentry, file->f_flags);
 	if (err)
 		return err;
@@ -158,6 +172,9 @@ static int ovl_open(struct inode *inode, struct file *file)
 	file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 
 	ovl_path_realdata(dentry, &realpath);
+	if (!realpath.dentry)
+		return -EIO;
+
 	realfile = ovl_open_realfile(file, &realpath);
 	if (IS_ERR(realfile))
 		return PTR_ERR(realfile);
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 541cf3717fc2..a63e57447be9 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -97,8 +97,9 @@ out:
 
 static void ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid)
 {
-	bool samefs = ovl_same_fs(dentry->d_sb);
-	unsigned int xinobits = ovl_xino_bits(dentry->d_sb);
+	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
+	bool samefs = ovl_same_fs(ofs);
+	unsigned int xinobits = ovl_xino_bits(ofs);
 	unsigned int xinoshift = 64 - xinobits;
 
 	if (samefs) {
@@ -123,7 +124,7 @@ static void ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid)
 			stat->ino |= ((u64)fsid) << (xinoshift + 1);
 			stat->dev = dentry->d_sb->s_dev;
 			return;
-		} else if (ovl_xino_warn(dentry->d_sb)) {
+		} else if (ovl_xino_warn(ofs)) {
 			pr_warn_ratelimited("inode number too big (%pd2, ino=%llu, xinobits=%d)\n",
 					    dentry, stat->ino, xinobits);
 		}
@@ -149,7 +150,7 @@ static void ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid)
 		 * is unique per underlying fs, so we use the unique anonymous
 		 * bdev assigned to the underlying fs.
 		 */
-		stat->dev = OVL_FS(dentry->d_sb)->fs[fsid].pseudo_dev;
+		stat->dev = ofs->fs[fsid].pseudo_dev;
 	}
 }
 
@@ -186,7 +187,7 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
 	 * If lower filesystem supports NFS file handles, this also guaranties
 	 * persistent st_ino across mount cycle.
 	 */
-	if (!is_dir || ovl_same_dev(dentry->d_sb)) {
+	if (!is_dir || ovl_same_dev(OVL_FS(dentry->d_sb))) {
 		if (!OVL_TYPE_UPPER(type)) {
 			fsid = ovl_layer_lower(dentry)->fsid;
 		} else if (OVL_TYPE_ORIGIN(type)) {
@@ -240,15 +241,22 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
 			/*
 			 * If lower is not same as lowerdata or if there was
 			 * no origin on upper, we can end up here.
+			 * With lazy lowerdata lookup, guess lowerdata blocks
+			 * from size to avoid lowerdata lookup on stat(2).
 			 */
 			struct kstat lowerdatastat;
 			u32 lowermask = STATX_BLOCKS;
 
 			ovl_path_lowerdata(dentry, &realpath);
-			err = vfs_getattr(&realpath, &lowerdatastat,
-					  lowermask, flags);
-			if (err)
-				goto out;
+			if (realpath.dentry) {
+				err = vfs_getattr(&realpath, &lowerdatastat,
+						  lowermask, flags);
+				if (err)
+					goto out;
+			} else {
+				lowerdatastat.blocks =
+					round_up(stat->size, stat->blksize) >> 9;
+			}
 			stat->blocks = lowerdatastat.blocks;
 		}
 	}
@@ -288,8 +296,8 @@ int ovl_permission(struct mnt_idmap *idmap,
 	int err;
 
 	/* Careful in RCU walk mode */
-	ovl_i_path_real(inode, &realpath);
-	if (!realpath.dentry) {
+	realinode = ovl_i_path_real(inode, &realpath);
+	if (!realinode) {
 		WARN_ON(!(mask & MAY_NOT_BLOCK));
 		return -ECHILD;
 	}
@@ -302,7 +310,6 @@ int ovl_permission(struct mnt_idmap *idmap,
 	if (err)
 		return err;
 
-	realinode = d_inode(realpath.dentry);
 	old_cred = ovl_override_creds(inode->i_sb);
 	if (!upperinode &&
 	    !special_file(realinode->i_mode) && mask & MAY_WRITE) {
@@ -559,20 +566,20 @@ struct posix_acl *do_ovl_get_acl(struct mnt_idmap *idmap,
 				 struct inode *inode, int type,
 				 bool rcu, bool noperm)
 {
-	struct inode *realinode = ovl_inode_real(inode);
+	struct inode *realinode;
 	struct posix_acl *acl;
 	struct path realpath;
 
-	if (!IS_POSIXACL(realinode))
-		return NULL;
-
 	/* Careful in RCU walk mode */
-	ovl_i_path_real(inode, &realpath);
-	if (!realpath.dentry) {
+	realinode = ovl_i_path_real(inode, &realpath);
+	if (!realinode) {
 		WARN_ON(!rcu);
 		return ERR_PTR(-ECHILD);
 	}
 
+	if (!IS_POSIXACL(realinode))
+		return NULL;
+
 	if (rcu) {
 		/*
 		 * If the layer is idmapped drop out of RCU path walk
@@ -710,6 +717,9 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	struct inode *realinode = ovl_inode_realdata(inode);
 	const struct cred *old_cred;
 
+	if (!realinode)
+		return -EIO;
+
 	if (!realinode->i_op->fiemap)
 		return -EOPNOTSUPP;
 
@@ -952,7 +962,7 @@ static inline void ovl_lockdep_annotate_inode_mutex_key(struct inode *inode)
 
 static void ovl_next_ino(struct inode *inode)
 {
-	struct ovl_fs *ofs = inode->i_sb->s_fs_info;
+	struct ovl_fs *ofs = OVL_FS(inode->i_sb);
 
 	inode->i_ino = atomic_long_inc_return(&ofs->last_ino);
 	if (unlikely(!inode->i_ino))
@@ -961,7 +971,8 @@ static void ovl_next_ino(struct inode *inode)
 
 static void ovl_map_ino(struct inode *inode, unsigned long ino, int fsid)
 {
-	int xinobits = ovl_xino_bits(inode->i_sb);
+	struct ovl_fs *ofs = OVL_FS(inode->i_sb);
+	int xinobits = ovl_xino_bits(ofs);
 	unsigned int xinoshift = 64 - xinobits;
 
 	/*
@@ -972,7 +983,7 @@ static void ovl_map_ino(struct inode *inode, unsigned long ino, int fsid)
 	 * with d_ino also causes nfsd readdirplus to fail.
 	 */
 	inode->i_ino = ino;
-	if (ovl_same_fs(inode->i_sb)) {
+	if (ovl_same_fs(ofs)) {
 		return;
 	} else if (xinobits && likely(!(ino >> xinoshift))) {
 		inode->i_ino |= (unsigned long)fsid << (xinoshift + 1);
@@ -1003,14 +1014,10 @@ void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
 	struct inode *realinode;
 	struct ovl_inode *oi = OVL_I(inode);
 
-	if (oip->upperdentry)
-		oi->__upperdentry = oip->upperdentry;
-	if (oip->lowerpath && oip->lowerpath->dentry) {
-		oi->lowerpath.dentry = dget(oip->lowerpath->dentry);
-		oi->lowerpath.layer = oip->lowerpath->layer;
-	}
-	if (oip->lowerdata)
-		oi->lowerdata = igrab(d_inode(oip->lowerdata));
+	oi->__upperdentry = oip->upperdentry;
+	oi->oe = oip->oe;
+	oi->redirect = oip->redirect;
+	oi->lowerdata_redirect = oip->lowerdata_redirect;
 
 	realinode = ovl_inode_real(inode);
 	ovl_copyattr(inode);
@@ -1325,7 +1332,7 @@ struct inode *ovl_get_inode(struct super_block *sb,
 {
 	struct ovl_fs *ofs = OVL_FS(sb);
 	struct dentry *upperdentry = oip->upperdentry;
-	struct ovl_path *lowerpath = oip->lowerpath;
+	struct ovl_path *lowerpath = ovl_lowerpath(oip->oe);
 	struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
 	struct inode *inode;
 	struct dentry *lowerdentry = lowerpath ? lowerpath->dentry : NULL;
@@ -1369,7 +1376,9 @@ struct inode *ovl_get_inode(struct super_block *sb,
 			}
 
 			dput(upperdentry);
+			ovl_free_entry(oip->oe);
 			kfree(oip->redirect);
+			kfree(oip->lowerdata_redirect);
 			goto out;
 		}
 
@@ -1398,14 +1407,12 @@ struct inode *ovl_get_inode(struct super_block *sb,
 	if (oip->index)
 		ovl_set_flag(OVL_INDEX, inode);
 
-	OVL_I(inode)->redirect = oip->redirect;
-
 	if (bylower)
 		ovl_set_flag(OVL_CONST_INO, inode);
 
 	/* Check for non-merge dir that may have whiteouts */
 	if (is_dir) {
-		if (((upperdentry && lowerdentry) || oip->numlower > 1) ||
+		if (((upperdentry && lowerdentry) || ovl_numlower(oip->oe) > 1) ||
 		    ovl_path_check_origin_xattr(ofs, &realpath)) {
 			ovl_set_flag(OVL_WHITEOUTS, inode);
 		}
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index cfb3420b7df0..57adf911735f 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -14,6 +14,8 @@
 #include <linux/exportfs.h>
 #include "overlayfs.h"
 
+#include "../internal.h"	/* for vfs_path_lookup */
+
 struct ovl_lookup_data {
 	struct super_block *sb;
 	struct vfsmount *mnt;
@@ -24,6 +26,8 @@ struct ovl_lookup_data {
 	bool last;
 	char *redirect;
 	bool metacopy;
+	/* Referring to last redirect xattr */
+	bool absolute_redirect;
 };
 
 static int ovl_check_redirect(const struct path *path, struct ovl_lookup_data *d,
@@ -33,11 +37,13 @@ static int ovl_check_redirect(const struct path *path, struct ovl_lookup_data *d
 	char *buf;
 	struct ovl_fs *ofs = OVL_FS(d->sb);
 
+	d->absolute_redirect = false;
 	buf = ovl_get_redirect_xattr(ofs, path, prelen + strlen(post));
 	if (IS_ERR_OR_NULL(buf))
 		return PTR_ERR(buf);
 
 	if (buf[0] == '/') {
+		d->absolute_redirect = true;
 		/*
 		 * One of the ancestor path elements in an absolute path
 		 * lookup in ovl_lookup_layer() could have been opaque and
@@ -349,6 +355,61 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,
 	return 0;
 }
 
+static int ovl_lookup_data_layer(struct dentry *dentry, const char *redirect,
+				 const struct ovl_layer *layer,
+				 struct path *datapath)
+{
+	int err;
+
+	err = vfs_path_lookup(layer->mnt->mnt_root, layer->mnt, redirect,
+			LOOKUP_BENEATH | LOOKUP_NO_SYMLINKS | LOOKUP_NO_XDEV,
+			datapath);
+	pr_debug("lookup lowerdata (%pd2, redirect=\"%s\", layer=%d, err=%i)\n",
+		 dentry, redirect, layer->idx, err);
+
+	if (err)
+		return err;
+
+	err = -EREMOTE;
+	if (ovl_dentry_weird(datapath->dentry))
+		goto out_path_put;
+
+	err = -ENOENT;
+	/* Only regular file is acceptable as lower data */
+	if (!d_is_reg(datapath->dentry))
+		goto out_path_put;
+
+	return 0;
+
+out_path_put:
+	path_put(datapath);
+
+	return err;
+}
+
+/* Lookup in data-only layers by absolute redirect to layer root */
+static int ovl_lookup_data_layers(struct dentry *dentry, const char *redirect,
+				  struct ovl_path *lowerdata)
+{
+	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
+	const struct ovl_layer *layer;
+	struct path datapath;
+	int err = -ENOENT;
+	int i;
+
+	layer = &ofs->layers[ofs->numlayer - ofs->numdatalayer];
+	for (i = 0; i < ofs->numdatalayer; i++, layer++) {
+		err = ovl_lookup_data_layer(dentry, redirect, layer, &datapath);
+		if (!err) {
+			mntput(datapath.mnt);
+			lowerdata->dentry = datapath.dentry;
+			lowerdata->layer = layer;
+			return 0;
+		}
+	}
+
+	return err;
+}
 
 int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
 			struct dentry *upperdentry, struct ovl_path **stackp)
@@ -356,7 +417,7 @@ int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
 	struct dentry *origin = NULL;
 	int i;
 
-	for (i = 1; i < ofs->numlayer; i++) {
+	for (i = 1; i <= ovl_numlowerlayer(ofs); i++) {
 		/*
 		 * If lower fs uuid is not unique among lower fs we cannot match
 		 * fh->uuid to layer.
@@ -790,20 +851,21 @@ fail:
  */
 int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct ovl_entry *oe = OVL_E(dentry);
+	struct ovl_path *lowerstack = ovl_lowerstack(oe);
 
 	BUG_ON(idx < 0);
 	if (idx == 0) {
 		ovl_path_upper(dentry, path);
 		if (path->dentry)
-			return oe->numlower ? 1 : -1;
+			return ovl_numlower(oe) ? 1 : -1;
 		idx++;
 	}
-	BUG_ON(idx > oe->numlower);
-	path->dentry = oe->lowerstack[idx - 1].dentry;
-	path->mnt = oe->lowerstack[idx - 1].layer->mnt;
+	BUG_ON(idx > ovl_numlower(oe));
+	path->dentry = lowerstack[idx - 1].dentry;
+	path->mnt = lowerstack[idx - 1].layer->mnt;
 
-	return (idx < oe->numlower) ? idx + 1 : -1;
+	return (idx < ovl_numlower(oe)) ? idx + 1 : -1;
 }
 
 /* Fix missing 'origin' xattr */
@@ -827,14 +889,60 @@ static int ovl_fix_origin(struct ovl_fs *ofs, struct dentry *dentry,
 	return err;
 }
 
+/* Lazy lookup of lowerdata */
+int ovl_maybe_lookup_lowerdata(struct dentry *dentry)
+{
+	struct inode *inode = d_inode(dentry);
+	const char *redirect = ovl_lowerdata_redirect(inode);
+	struct ovl_path datapath = {};
+	const struct cred *old_cred;
+	int err;
+
+	if (!redirect || ovl_dentry_lowerdata(dentry))
+		return 0;
+
+	if (redirect[0] != '/')
+		return -EIO;
+
+	err = ovl_inode_lock_interruptible(inode);
+	if (err)
+		return err;
+
+	err = 0;
+	/* Someone got here before us? */
+	if (ovl_dentry_lowerdata(dentry))
+		goto out;
+
+	old_cred = ovl_override_creds(dentry->d_sb);
+	err = ovl_lookup_data_layers(dentry, redirect, &datapath);
+	revert_creds(old_cred);
+	if (err)
+		goto out_err;
+
+	err = ovl_dentry_set_lowerdata(dentry, &datapath);
+	if (err)
+		goto out_err;
+
+out:
+	ovl_inode_unlock(inode);
+	dput(datapath.dentry);
+
+	return err;
+
+out_err:
+	pr_warn_ratelimited("lazy lowerdata lookup failed (%pd2, err=%i)\n",
+			    dentry, err);
+	goto out;
+}
+
 struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 			  unsigned int flags)
 {
-	struct ovl_entry *oe;
+	struct ovl_entry *oe = NULL;
 	const struct cred *old_cred;
 	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
-	struct ovl_entry *poe = dentry->d_parent->d_fsdata;
-	struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata;
+	struct ovl_entry *poe = OVL_E(dentry->d_parent);
+	struct ovl_entry *roe = OVL_E(dentry->d_sb->s_root);
 	struct ovl_path *stack = NULL, *origin_path = NULL;
 	struct dentry *upperdir, *upperdentry = NULL;
 	struct dentry *origin = NULL;
@@ -853,7 +961,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		.is_dir = false,
 		.opaque = false,
 		.stop = false,
-		.last = ofs->config.redirect_follow ? false : !poe->numlower,
+		.last = ovl_redirect_follow(ofs) ? false : !ovl_numlower(poe),
 		.redirect = NULL,
 		.metacopy = false,
 	};
@@ -904,21 +1012,20 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		upperopaque = d.opaque;
 	}
 
-	if (!d.stop && poe->numlower) {
+	if (!d.stop && ovl_numlower(poe)) {
 		err = -ENOMEM;
-		stack = kcalloc(ofs->numlayer - 1, sizeof(struct ovl_path),
-				GFP_KERNEL);
+		stack = ovl_stack_alloc(ofs->numlayer - 1);
 		if (!stack)
 			goto out_put_upper;
 	}
 
-	for (i = 0; !d.stop && i < poe->numlower; i++) {
-		struct ovl_path lower = poe->lowerstack[i];
+	for (i = 0; !d.stop && i < ovl_numlower(poe); i++) {
+		struct ovl_path lower = ovl_lowerstack(poe)[i];
 
-		if (!ofs->config.redirect_follow)
-			d.last = i == poe->numlower - 1;
-		else
-			d.last = lower.layer->idx == roe->numlower;
+		if (!ovl_redirect_follow(ofs))
+			d.last = i == ovl_numlower(poe) - 1;
+		else if (d.is_dir || !ofs->numdatalayer)
+			d.last = lower.layer->idx == ovl_numlower(roe);
 
 		d.mnt = lower.layer->mnt;
 		err = ovl_lookup_layer(lower.dentry, &d, &this, false);
@@ -995,7 +1102,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		 * this attack vector when not necessary.
 		 */
 		err = -EPERM;
-		if (d.redirect && !ofs->config.redirect_follow) {
+		if (d.redirect && !ovl_redirect_follow(ofs)) {
 			pr_warn_ratelimited("refusing to follow redirect for (%pd2)\n",
 					    dentry);
 			goto out_put;
@@ -1011,6 +1118,12 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		}
 	}
 
+	/* Defer lookup of lowerdata in data-only layers to first access */
+	if (d.metacopy && ctr && ofs->numdatalayer && d.absolute_redirect) {
+		d.metacopy = false;
+		ctr++;
+	}
+
 	/*
 	 * For regular non-metacopy upper dentries, there is no lower
 	 * path based lookup, hence ctr will be zero. If a dentry is found
@@ -1067,13 +1180,14 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		}
 	}
 
-	oe = ovl_alloc_entry(ctr);
-	err = -ENOMEM;
-	if (!oe)
-		goto out_put;
+	if (ctr) {
+		oe = ovl_alloc_entry(ctr);
+		err = -ENOMEM;
+		if (!oe)
+			goto out_put;
 
-	memcpy(oe->lowerstack, stack, sizeof(struct ovl_path) * ctr);
-	dentry->d_fsdata = oe;
+		ovl_stack_cpy(ovl_lowerstack(oe), stack, ctr);
+	}
 
 	if (upperopaque)
 		ovl_dentry_set_opaque(dentry);
@@ -1106,14 +1220,16 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 	if (upperdentry || ctr) {
 		struct ovl_inode_params oip = {
 			.upperdentry = upperdentry,
-			.lowerpath = stack,
+			.oe = oe,
 			.index = index,
-			.numlower = ctr,
 			.redirect = upperredirect,
-			.lowerdata = (ctr > 1 && !d.is_dir) ?
-				      stack[ctr - 1].dentry : NULL,
 		};
 
+		/* Store lowerdata redirect for lazy lookup */
+		if (ctr > 1 && !d.is_dir && !stack[ctr - 1].dentry) {
+			oip.lowerdata_redirect = d.redirect;
+			d.redirect = NULL;
+		}
 		inode = ovl_get_inode(dentry->d_sb, &oip);
 		err = PTR_ERR(inode);
 		if (IS_ERR(inode))
@@ -1122,8 +1238,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 			ovl_set_flag(OVL_UPPERDATA, inode);
 	}
 
-	ovl_dentry_update_reval(dentry, upperdentry,
-			DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+	ovl_dentry_init_reval(dentry, upperdentry, OVL_I_E(inode));
 
 	revert_creds(old_cred);
 	if (origin_path) {
@@ -1131,18 +1246,15 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		kfree(origin_path);
 	}
 	dput(index);
-	kfree(stack);
+	ovl_stack_free(stack, ctr);
 	kfree(d.redirect);
 	return d_splice_alias(inode, dentry);
 
 out_free_oe:
-	dentry->d_fsdata = NULL;
-	kfree(oe);
+	ovl_free_entry(oe);
 out_put:
 	dput(index);
-	for (i = 0; i < ctr; i++)
-		dput(stack[i].dentry);
-	kfree(stack);
+	ovl_stack_free(stack, ctr);
 out_put_upper:
 	if (origin_path) {
 		dput(origin_path->dentry);
@@ -1158,7 +1270,7 @@ out:
 
 bool ovl_lower_positive(struct dentry *dentry)
 {
-	struct ovl_entry *poe = dentry->d_parent->d_fsdata;
+	struct ovl_entry *poe = OVL_E(dentry->d_parent);
 	const struct qstr *name = &dentry->d_name;
 	const struct cred *old_cred;
 	unsigned int i;
@@ -1178,12 +1290,13 @@ bool ovl_lower_positive(struct dentry *dentry)
 
 	old_cred = ovl_override_creds(dentry->d_sb);
 	/* Positive upper -> have to look up lower to see whether it exists */
-	for (i = 0; !done && !positive && i < poe->numlower; i++) {
+	for (i = 0; !done && !positive && i < ovl_numlower(poe); i++) {
 		struct dentry *this;
-		struct dentry *lowerdir = poe->lowerstack[i].dentry;
+		struct ovl_path *parentpath = &ovl_lowerstack(poe)[i];
 
-		this = lookup_one_positive_unlocked(mnt_idmap(poe->lowerstack[i].layer->mnt),
-						   name->name, lowerdir, name->len);
+		this = lookup_one_positive_unlocked(
+				mnt_idmap(parentpath->layer->mnt),
+				name->name, parentpath->dentry, name->len);
 		if (IS_ERR(this)) {
 			switch (PTR_ERR(this)) {
 			case -ENOENT:
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 23686e8a06c4..4142d1a457ff 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -58,11 +58,26 @@ enum ovl_entry_flag {
 };
 
 enum {
+	OVL_REDIRECT_OFF,	/* "off" mode is never used. In effect	*/
+	OVL_REDIRECT_FOLLOW,	/* ...it translates to either "follow"	*/
+	OVL_REDIRECT_NOFOLLOW,	/* ...or "nofollow".			*/
+	OVL_REDIRECT_ON,
+};
+
+enum {
 	OVL_XINO_OFF,
 	OVL_XINO_AUTO,
 	OVL_XINO_ON,
 };
 
+/* The set of options that user requested explicitly via mount options */
+struct ovl_opt_set {
+	bool metacopy;
+	bool redirect;
+	bool nfs_export;
+	bool index;
+};
+
 /*
  * The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
  * where:
@@ -353,17 +368,29 @@ static inline bool ovl_open_flags_need_copy_up(int flags)
 	return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
 }
 
-static inline bool ovl_allow_offline_changes(struct ovl_fs *ofs)
-{
-	/*
-	 * To avoid regressions in existing setups with overlay lower offline
-	 * changes, we allow lower changes only if none of the new features
-	 * are used.
-	 */
-	return (!ofs->config.index && !ofs->config.metacopy &&
-		!ofs->config.redirect_dir && ofs->config.xino != OVL_XINO_ON);
-}
 
+/* params.c */
+#define OVL_MAX_STACK 500
+
+struct ovl_fs_context_layer {
+	char *name;
+	struct path path;
+};
+
+struct ovl_fs_context {
+	struct path upper;
+	struct path work;
+	size_t capacity;
+	size_t nr; /* includes nr_data */
+	size_t nr_data;
+	struct ovl_opt_set set;
+	struct ovl_fs_context_layer *lower;
+};
+
+int ovl_parse_param_upperdir(const char *name, struct fs_context *fc,
+			     bool workdir);
+int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc);
+void ovl_parse_param_drop_lowerdir(struct ovl_fs_context *ctx);
 
 /* util.c */
 int ovl_want_write(struct dentry *dentry);
@@ -374,21 +401,30 @@ int ovl_can_decode_fh(struct super_block *sb);
 struct dentry *ovl_indexdir(struct super_block *sb);
 bool ovl_index_all(struct super_block *sb);
 bool ovl_verify_lower(struct super_block *sb);
+struct ovl_path *ovl_stack_alloc(unsigned int n);
+void ovl_stack_cpy(struct ovl_path *dst, struct ovl_path *src, unsigned int n);
+void ovl_stack_put(struct ovl_path *stack, unsigned int n);
+void ovl_stack_free(struct ovl_path *stack, unsigned int n);
 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
+void ovl_free_entry(struct ovl_entry *oe);
 bool ovl_dentry_remote(struct dentry *dentry);
-void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
-			     unsigned int mask);
+void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *realdentry);
+void ovl_dentry_init_reval(struct dentry *dentry, struct dentry *upperdentry,
+			   struct ovl_entry *oe);
+void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry,
+			   struct ovl_entry *oe, unsigned int mask);
 bool ovl_dentry_weird(struct dentry *dentry);
 enum ovl_path_type ovl_path_type(struct dentry *dentry);
 void ovl_path_upper(struct dentry *dentry, struct path *path);
 void ovl_path_lower(struct dentry *dentry, struct path *path);
 void ovl_path_lowerdata(struct dentry *dentry, struct path *path);
-void ovl_i_path_real(struct inode *inode, struct path *path);
+struct inode *ovl_i_path_real(struct inode *inode, struct path *path);
 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);