1 files changed, 132 insertions, 47 deletions

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 923d66d131c1..7ef9e13c404a 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -83,33 +83,84 @@ bool ovl_verify_lower(struct super_block *sb)
 	return ofs->config.nfs_export && ofs->config.index;
 }
 
+struct ovl_path *ovl_stack_alloc(unsigned int n)
+{
+	return kcalloc(n, sizeof(struct ovl_path), GFP_KERNEL);
+}
+
+void ovl_stack_cpy(struct ovl_path *dst, struct ovl_path *src, unsigned int n)
+{
+	unsigned int i;
+
+	memcpy(dst, src, sizeof(struct ovl_path) * n);
+	for (i = 0; i < n; i++)
+		dget(src[i].dentry);
+}
+
+void ovl_stack_put(struct ovl_path *stack, unsigned int n)
+{
+	unsigned int i;
+
+	for (i = 0; stack && i < n; i++)
+		dput(stack[i].dentry);
+}
+
+void ovl_stack_free(struct ovl_path *stack, unsigned int n)
+{
+	ovl_stack_put(stack, n);
+	kfree(stack);
+}
+
 struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
 {
-	size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
+	size_t size = offsetof(struct ovl_entry, __lowerstack[numlower]);
 	struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
 
 	if (oe)
-		oe->numlower = numlower;
+		oe->__numlower = numlower;
 
 	return oe;
 }
 
+void ovl_free_entry(struct ovl_entry *oe)
+{
+	ovl_stack_put(ovl_lowerstack(oe), ovl_numlower(oe));
+	kfree(oe);
+}
+
+#define OVL_D_REVALIDATE (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE)
+
 bool ovl_dentry_remote(struct dentry *dentry)
 {
-	return dentry->d_flags &
-		(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+	return dentry->d_flags & OVL_D_REVALIDATE;
 }
 
-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)
 {
-	struct ovl_entry *oe = OVL_E(dentry);
+	if (!ovl_dentry_remote(realdentry))
+		return;
+
+	spin_lock(&dentry->d_lock);
+	dentry->d_flags |= realdentry->d_flags & OVL_D_REVALIDATE;
+	spin_unlock(&dentry->d_lock);
+}
+
+void ovl_dentry_init_reval(struct dentry *dentry, struct dentry *upperdentry,
+			   struct ovl_entry *oe)
+{
+	return ovl_dentry_init_flags(dentry, upperdentry, oe, OVL_D_REVALIDATE);
+}
+
+void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry,
+			   struct ovl_entry *oe, unsigned int mask)
+{
+	struct ovl_path *lowerstack = ovl_lowerstack(oe);
 	unsigned int i, flags = 0;
 
 	if (upperdentry)
 		flags |= upperdentry->d_flags;
-	for (i = 0; i < oe->numlower; i++)
-		flags |= oe->lowerstack[i].dentry->d_flags;
+	for (i = 0; i < ovl_numlower(oe) && lowerstack[i].dentry; i++)
+		flags |= lowerstack[i].dentry->d_flags;
 
 	spin_lock(&dentry->d_lock);
 	dentry->d_flags &= ~mask;
@@ -127,7 +178,7 @@ bool ovl_dentry_weird(struct dentry *dentry)
 
 enum ovl_path_type ovl_path_type(struct dentry *dentry)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct ovl_entry *oe = OVL_E(dentry);
 	enum ovl_path_type type = 0;
 
 	if (ovl_dentry_upper(dentry)) {
@@ -136,7 +187,7 @@ enum ovl_path_type ovl_path_type(struct dentry *dentry)
 		/*
 		 * Non-dir dentry can hold lower dentry of its copy up origin.
 		 */
-		if (oe->numlower) {
+		if (ovl_numlower(oe)) {
 			if (ovl_test_flag(OVL_CONST_INO, d_inode(dentry)))
 				type |= __OVL_PATH_ORIGIN;
 			if (d_is_dir(dentry) ||
@@ -144,7 +195,7 @@ enum ovl_path_type ovl_path_type(struct dentry *dentry)
 				type |= __OVL_PATH_MERGE;
 		}
 	} else {
-		if (oe->numlower > 1)
+		if (ovl_numlower(oe) > 1)
 			type |= __OVL_PATH_MERGE;
 	}
 	return type;
@@ -160,11 +211,12 @@ void ovl_path_upper(struct dentry *dentry, struct path *path)
 
 void ovl_path_lower(struct dentry *dentry, struct path *path)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct ovl_entry *oe = OVL_E(dentry);
+	struct ovl_path *lowerpath = ovl_lowerstack(oe);
 
-	if (oe->numlower) {
-		path->mnt = oe->lowerstack[0].layer->mnt;
-		path->dentry = oe->lowerstack[0].dentry;
+	if (ovl_numlower(oe)) {
+		path->mnt = lowerpath->layer->mnt;
+		path->dentry = lowerpath->dentry;
 	} else {
 		*path = (struct path) { };
 	}
@@ -172,11 +224,19 @@ void ovl_path_lower(struct dentry *dentry, struct path *path)
 
 void ovl_path_lowerdata(struct dentry *dentry, struct path *path)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct ovl_entry *oe = OVL_E(dentry);
+	struct ovl_path *lowerdata = ovl_lowerdata(oe);
+	struct dentry *lowerdata_dentry = ovl_lowerdata_dentry(oe);
 
-	if (oe->numlower) {
-		path->mnt = oe->lowerstack[oe->numlower - 1].layer->mnt;
-		path->dentry = oe->lowerstack[oe->numlower - 1].dentry;
+	if (lowerdata_dentry) {
+		path->dentry = lowerdata_dentry;
+		/*
+		 * Pairs with smp_wmb() in ovl_dentry_set_lowerdata().
+		 * Make sure that if lowerdata->dentry is visible, then
+		 * datapath->layer is visible as well.
+		 */
+		smp_rmb();
+		path->mnt = READ_ONCE(lowerdata->layer)->mnt;
 	} else {
 		*path = (struct path) { };
 	}
@@ -215,16 +275,16 @@ struct dentry *ovl_dentry_upper(struct dentry *dentry)
 
 struct dentry *ovl_dentry_lower(struct dentry *dentry)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct ovl_entry *oe = OVL_E(dentry);
 
-	return oe->numlower ? oe->lowerstack[0].dentry : NULL;
+	return ovl_numlower(oe) ? ovl_lowerstack(oe)->dentry : NULL;
 }
 
 const struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct ovl_entry *oe = OVL_E(dentry);
 
-	return oe->numlower ? oe->lowerstack[0].layer : NULL;
+	return ovl_numlower(oe) ? ovl_lowerstack(oe)->layer : NULL;
 }
 
 /*
@@ -235,9 +295,30 @@ const struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
  */
 struct dentry *ovl_dentry_lowerdata(struct dentry *dentry)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	return ovl_lowerdata_dentry(OVL_E(dentry));
+}
+
+int ovl_dentry_set_lowerdata(struct dentry *dentry, struct ovl_path *datapath)
+{
+	struct ovl_entry *oe = OVL_E(dentry);
+	struct ovl_path *lowerdata = ovl_lowerdata(oe);
+	struct dentry *datadentry = datapath->dentry;
+
+	if (WARN_ON_ONCE(ovl_numlower(oe) <= 1))
+		return -EIO;
+
+	WRITE_ONCE(lowerdata->layer, datapath->layer);
+	/*
+	 * Pairs with smp_rmb() in ovl_path_lowerdata().
+	 * Make sure that if lowerdata->dentry is visible, then
+	 * lowerdata->layer is visible as well.
+	 */
+	smp_wmb();
+	WRITE_ONCE(lowerdata->dentry, dget(datadentry));
 
-	return oe->numlower ? oe->lowerstack[oe->numlower - 1].dentry : NULL;
+	ovl_dentry_update_reval(dentry, datadentry);
+
+	return 0;
 }
 
 struct dentry *ovl_dentry_real(struct dentry *dentry)
@@ -250,15 +331,19 @@ struct dentry *ovl_i_dentry_upper(struct inode *inode)
 	return ovl_upperdentry_dereference(OVL_I(inode));
 }
 
-void ovl_i_path_real(struct inode *inode, struct path *path)
+struct inode *ovl_i_path_real(struct inode *inode, struct path *path)
 {
+	struct ovl_path *lowerpath = ovl_lowerpath(OVL_I_E(inode));
+
 	path->dentry = ovl_i_dentry_upper(inode);
 	if (!path->dentry) {
-		path->dentry = OVL_I(inode)->lowerpath.dentry;
-		path->mnt = OVL_I(inode)->lowerpath.layer->mnt;
+		path->dentry = lowerpath->dentry;
+		path->mnt = lowerpath->layer->mnt;
 	} else {
 		path->mnt = ovl_upper_mnt(OVL_FS(inode->i_sb));
 	}
+
+	return path->dentry ? d_inode_rcu(path->dentry) : NULL;
 }
 
 struct inode *ovl_inode_upper(struct inode *inode)
@@ -270,9 +355,9 @@ struct inode *ovl_inode_upper(struct inode *inode)
 
 struct inode *ovl_inode_lower(struct inode *inode)
 {
-	struct dentry *lowerdentry = OVL_I(inode)->lowerpath.dentry;
+	struct ovl_path *lowerpath = ovl_lowerpath(OVL_I_E(inode));
 
-	return lowerdentry ? d_inode(lowerdentry) : NULL;
+	return lowerpath ? d_inode(lowerpath->dentry) : NULL;
 }
 
 struct inode *ovl_inode_real(struct inode *inode)
@@ -283,10 +368,12 @@ struct inode *ovl_inode_real(struct inode *inode)
 /* Return inode which contains lower data. Do not return metacopy */
 struct inode *ovl_inode_lowerdata(struct inode *inode)
 {
+	struct dentry *lowerdata = ovl_lowerdata_dentry(OVL_I_E(inode));
+
 	if (WARN_ON(!S_ISREG(inode->i_mode)))
 		return NULL;
 
-	return OVL_I(inode)->lowerdata ?: ovl_inode_lower(inode);
+	return lowerdata ? d_inode(lowerdata) : NULL;
 }
 
 /* Return real inode which contains data. Does not return metacopy inode */
@@ -301,9 +388,15 @@ struct inode *ovl_inode_realdata(struct inode *inode)
 	return ovl_inode_lowerdata(inode);
 }
 
+const char *ovl_lowerdata_redirect(struct inode *inode)
+{
+	return inode && S_ISREG(inode->i_mode) ?
+		OVL_I(inode)->lowerdata_redirect : NULL;
+}
+
 struct ovl_dir_cache *ovl_dir_cache(struct inode *inode)
 {
-	return OVL_I(inode)->cache;
+	return inode && S_ISDIR(inode->i_mode) ? OVL_I(inode)->cache : NULL;
 }
 
 void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache)
@@ -313,17 +406,17 @@ void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache)
 
 void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry)
 {
-	set_bit(flag, &OVL_E(dentry)->flags);
+	set_bit(flag, OVL_E_FLAGS(dentry));
 }
 
 void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry)
 {
-	clear_bit(flag, &OVL_E(dentry)->flags);
+	clear_bit(flag, OVL_E_FLAGS(dentry));
 }
 
 bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry)
 {
-	return test_bit(flag, &OVL_E(dentry)->flags);
+	return test_bit(flag, OVL_E_FLAGS(dentry));
 }
 
 bool ovl_dentry_is_opaque(struct dentry *dentry)
@@ -413,13 +506,6 @@ bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags)
 	return !ovl_has_upperdata(d_inode(dentry));
 }
 
-bool ovl_redirect_dir(struct super_block *sb)
-{
-	struct ovl_fs *ofs = sb->s_fs_info;
-
-	return ofs->config.redirect_dir && !ofs->noxattr;
-}
-
 const char *ovl_dentry_get_redirect(struct dentry *dentry)
 {
 	return OVL_I(d_inode(dentry))->redirect;
@@ -999,7 +1085,7 @@ out:
 
 bool ovl_is_metacopy_dentry(struct dentry *dentry)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct ovl_entry *oe = OVL_E(dentry);
 
 	if (!d_is_reg(dentry))
 		return false;
@@ -1010,7 +1096,7 @@ bool ovl_is_metacopy_dentry(struct dentry *dentry)
 		return false;
 	}
 
-	return (oe->numlower > 1);
+	return (ovl_numlower(oe) > 1);
 }
 
 char *ovl_get_redirect_xattr(struct ovl_fs *ofs, const struct path *path, int padding)
@@ -1105,8 +1191,7 @@ void ovl_copyattr(struct inode *inode)
 	vfsuid_t vfsuid;
 	vfsgid_t vfsgid;
 
-	ovl_i_path_real(inode, &realpath);
-	realinode = d_inode(realpath.dentry);
+	realinode = ovl_i_path_real(inode, &realpath);
 	real_idmap = mnt_idmap(realpath.mnt);
 
 	vfsuid = i_uid_into_vfsuid(real_idmap, realinode);