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

"The biggest change is to rename the filesystem from "overlayfs" to "overlay".
This will allow legacy overlayfs to be easily carried by distros alongside the
new mainline one.  Also fix a couple of copy-up races and allow escaping comma
character in filenames."

The last bit is about commas in pathname mount options...

6 files changed, 105 insertions, 59 deletions

diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig
index e6012597687..34355818a2e 100644
--- a/fs/overlayfs/Kconfig
+++ b/fs/overlayfs/Kconfig
@@ -1,4 +1,4 @@
-config OVERLAYFS_FS
+config OVERLAY_FS
 	tristate "Overlay filesystem support"
 	help
 	  An overlay filesystem combines two filesystems - an 'upper' filesystem
diff --git a/fs/overlayfs/Makefile b/fs/overlayfs/Makefile
index 8f91889480d..900daed3e91 100644
--- a/fs/overlayfs/Makefile
+++ b/fs/overlayfs/Makefile
@@ -2,6 +2,6 @@
 # Makefile for the overlay filesystem.
 #
 
-obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o
+obj-$(CONFIG_OVERLAY_FS) += overlay.o
 
-overlayfs-objs := super.o inode.o dir.o readdir.o copy_up.o
+overlay-objs := super.o inode.o dir.o readdir.o copy_up.o
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 15cd91ad994..8ffc4b980f1 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -284,8 +284,7 @@ out:
 	return ERR_PTR(err);
 }
 
-static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry,
-						enum ovl_path_type type)
+static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
 {
 	int err;
 	struct dentry *ret = NULL;
@@ -294,8 +293,17 @@ static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry,
 	err = ovl_check_empty_dir(dentry, &list);
 	if (err)
 		ret = ERR_PTR(err);
-	else if (type == OVL_PATH_MERGE)
-		ret = ovl_clear_empty(dentry, &list);
+	else {
+		/*
+		 * If no upperdentry then skip clearing whiteouts.
+		 *
+		 * Can race with copy-up, since we don't hold the upperdir
+		 * mutex.  Doesn't matter, since copy-up can't create a
+		 * non-empty directory from an empty one.
+		 */
+		if (ovl_dentry_upper(dentry))
+			ret = ovl_clear_empty(dentry, &list);
+	}
 
 	ovl_cache_free(&list);
 
@@ -487,8 +495,7 @@ out:
 	return err;
 }
 
-static int ovl_remove_and_whiteout(struct dentry *dentry,
-				   enum ovl_path_type type, bool is_dir)
+static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
 {
 	struct dentry *workdir = ovl_workdir(dentry);
 	struct inode *wdir = workdir->d_inode;
@@ -500,7 +507,7 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
 	int err;
 
 	if (is_dir) {
-		opaquedir = ovl_check_empty_and_clear(dentry, type);
+		opaquedir = ovl_check_empty_and_clear(dentry);
 		err = PTR_ERR(opaquedir);
 		if (IS_ERR(opaquedir))
 			goto out;
@@ -515,9 +522,10 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
 	if (IS_ERR(whiteout))
 		goto out_unlock;
 
-	if (type == OVL_PATH_LOWER) {
+	upper = ovl_dentry_upper(dentry);
+	if (!upper) {
 		upper = lookup_one_len(dentry->d_name.name, upperdir,
-					   dentry->d_name.len);
+				       dentry->d_name.len);
 		err = PTR_ERR(upper);
 		if (IS_ERR(upper))
 			goto kill_whiteout;
@@ -529,7 +537,6 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
 	} else {
 		int flags = 0;
 
-		upper = ovl_dentry_upper(dentry);
 		if (opaquedir)
 			upper = opaquedir;
 		err = -ESTALE;
@@ -648,7 +655,7 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 		cap_raise(override_cred->cap_effective, CAP_CHOWN);
 		old_cred = override_creds(override_cred);
 
-		err = ovl_remove_and_whiteout(dentry, type, is_dir);
+		err = ovl_remove_and_whiteout(dentry, is_dir);
 
 		revert_creds(old_cred);
 		put_cred(override_cred);
@@ -781,7 +788,7 @@ static int ovl_rename2(struct inode *olddir, struct dentry *old,
 	}
 
 	if (overwrite && (new_type == OVL_PATH_LOWER || new_type == OVL_PATH_MERGE) && new_is_dir) {
-		opaquedir = ovl_check_empty_and_clear(new, new_type);
+		opaquedir = ovl_check_empty_and_clear(new);
 		err = PTR_ERR(opaquedir);
 		if (IS_ERR(opaquedir)) {
 			opaquedir = NULL;
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index af2d18c9fce..07d74b24913 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -235,26 +235,36 @@ out:
 	return err;
 }
 
+static bool ovl_need_xattr_filter(struct dentry *dentry,
+				  enum ovl_path_type type)
+{
+	return type == OVL_PATH_UPPER && S_ISDIR(dentry->d_inode->i_mode);
+}
+
 ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
 		     void *value, size_t size)
 {
-	if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE &&
-	    ovl_is_private_xattr(name))
+	struct path realpath;
+	enum ovl_path_type type = ovl_path_real(dentry, &realpath);
+
+	if (ovl_need_xattr_filter(dentry, type) && ovl_is_private_xattr(name))
 		return -ENODATA;
 
-	return vfs_getxattr(ovl_dentry_real(dentry), name, value, size);
+	return vfs_getxattr(realpath.dentry, name, value, size);
 }
 
 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
 {
+	struct path realpath;
+	enum ovl_path_type type = ovl_path_real(dentry, &realpath);
 	ssize_t res;
 	int off;
 
-	res = vfs_listxattr(ovl_dentry_real(dentry), list, size);
+	res = vfs_listxattr(realpath.dentry, list, size);
 	if (res <= 0 || size == 0)
 		return res;
 
-	if (ovl_path_type(dentry->d_parent) != OVL_PATH_MERGE)
+	if (!ovl_need_xattr_filter(dentry, type))
 		return res;
 
 	/* filter out private xattrs */
@@ -279,17 +289,16 @@ int ovl_removexattr(struct dentry *dentry, const char *name)
 {
 	int err;
 	struct path realpath;
-	enum ovl_path_type type;
+	enum ovl_path_type type = ovl_path_real(dentry, &realpath);
 
 	err = ovl_want_write(dentry);
 	if (err)
 		goto out;
 
-	if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE &&
-	    ovl_is_private_xattr(name))
+	err = -ENODATA;
+	if (ovl_need_xattr_filter(dentry, type) && ovl_is_private_xattr(name))
 		goto out_drop_write;
 
-	type = ovl_path_real(dentry, &realpath);
 	if (type == OVL_PATH_LOWER) {
 		err = vfs_getxattr(realpath.dentry, name, NULL, 0);
 		if (err < 0)
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 2a7ef4f8e2a..ab1e3dcbed9 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -274,11 +274,11 @@ static int ovl_dir_mark_whiteouts(struct dentry *dir,
 	return 0;
 }
 
-static inline int ovl_dir_read_merged(struct path *upperpath,
-				      struct path *lowerpath,
-				      struct list_head *list)
+static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list)
 {
 	int err;
+	struct path lowerpath;
+	struct path upperpath;
 	struct ovl_readdir_data rdd = {
 		.ctx.actor = ovl_fill_merge,
 		.list = list,
@@ -286,25 +286,28 @@ static inline int ovl_dir_read_merged(struct path *upperpath,
 		.is_merge = false,
 	};
 
-	if (upperpath->dentry) {
-		err = ovl_dir_read(upperpath, &rdd);
+	ovl_path_lower(dentry, &lowerpath);
+	ovl_path_upper(dentry, &upperpath);
+
+	if (upperpath.dentry) {
+		err = ovl_dir_read(&upperpath, &rdd);
 		if (err)
 			goto out;
 
-		if (lowerpath->dentry) {
-			err = ovl_dir_mark_whiteouts(upperpath->dentry, &rdd);
+		if (lowerpath.dentry) {
+			err = ovl_dir_mark_whiteouts(upperpath.dentry, &rdd);
 			if (err)
 				goto out;
 		}
 	}
-	if (lowerpath->dentry) {
+	if (lowerpath.dentry) {
 		/*
 		 * Insert lowerpath entries before upperpath ones, this allows
 		 * offsets to be reasonably constant
 		 */
 		list_add(&rdd.middle, rdd.list);
 		rdd.is_merge = true;
-		err = ovl_dir_read(lowerpath, &rdd);
+		err = ovl_dir_read(&lowerpath, &rdd);
 		list_del(&rdd.middle);
 	}
 out:
@@ -329,8 +332,6 @@ static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
 static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
 {
 	int res;
-	struct path lowerpath;
-	struct path upperpath;
 	struct ovl_dir_cache *cache;
 
 	cache = ovl_dir_cache(dentry);
@@ -347,10 +348,7 @@ static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
 	cache->refcount = 1;
 	INIT_LIST_HEAD(&cache->entries);
 
-	ovl_path_lower(dentry, &lowerpath);
-	ovl_path_upper(dentry, &upperpath);
-
-	res = ovl_dir_read_merged(&upperpath, &lowerpath, &cache->entries);
+	res = ovl_dir_read_merged(dentry, &cache->entries);
 	if (res) {
 		ovl_cache_free(&cache->entries);
 		kfree(cache);
@@ -452,10 +450,10 @@ static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
 	/*
 	 * Need to check if we started out being a lower dir, but got copied up
 	 */
-	if (!od->is_upper && ovl_path_type(dentry) == OVL_PATH_MERGE) {
+	if (!od->is_upper && ovl_path_type(dentry) != OVL_PATH_LOWER) {
 		struct inode *inode = file_inode(file);
 
-		realfile =lockless_dereference(od->upperfile);
+		realfile = lockless_dereference(od->upperfile);
 		if (!realfile) {
 			struct path upperpath;
 
@@ -538,14 +536,9 @@ const struct file_operations ovl_dir_operations = {
 int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
 {
 	int err;
-	struct path lowerpath;
-	struct path upperpath;
 	struct ovl_cache_entry *p;
 
-	ovl_path_upper(dentry, &upperpath);
-	ovl_path_lower(dentry, &lowerpath);
-
-	err = ovl_dir_read_merged(&upperpath, &lowerpath, list);
+	err = ovl_dir_read_merged(dentry, list);
 	if (err)
 		return err;
 
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 08b704cebfc..f16d318b71f 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -24,7 +24,7 @@ MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
 MODULE_DESCRIPTION("Overlay filesystem");
 MODULE_LICENSE("GPL");
 
-#define OVERLAYFS_SUPER_MAGIC 0x794c764f
+#define OVERLAYFS_SUPER_MAGIC 0x794c7630
 
 struct ovl_config {
 	char *lowerdir;
@@ -84,12 +84,7 @@ enum ovl_path_type ovl_path_type(struct dentry *dentry)
 
 static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
 {
-	struct dentry *upperdentry = ACCESS_ONCE(oe->__upperdentry);
-	/*
-	 * Make sure to order reads to upperdentry wrt ovl_dentry_update()
-	 */
-	smp_read_barrier_depends();
-	return upperdentry;
+	return lockless_dereference(oe->__upperdentry);
 }
 
 void ovl_path_upper(struct dentry *dentry, struct path *path)
@@ -462,11 +457,34 @@ static const match_table_t ovl_tokens = {
 	{OPT_ERR,			NULL}
 };
 
+static char *ovl_next_opt(char **s)
+{
+	char *sbegin = *s;
+	char *p;
+
+	if (sbegin == NULL)
+		return NULL;
+
+	for (p = sbegin; *p; p++) {
+		if (*p == '\\') {
+			p++;
+			if (!*p)
+				break;
+		} else if (*p == ',') {
+			*p = '\0';
+			*s = p + 1;
+			return sbegin;
+		}
+	}
+	*s = NULL;
+	return sbegin;
+}
+
 static int ovl_parse_opt(char *opt, struct ovl_config *config)
 {
 	char *p;
 
-	while ((p = strsep(&opt, ",")) != NULL) {
+	while ((p = ovl_next_opt(&opt)) != NULL) {
 		int token;
 		substring_t args[MAX_OPT_ARGS];
 
@@ -554,15 +572,34 @@ out_dput:
 	goto out_unlock;
 }
 
+static void ovl_unescape(char *s)
+{
+	char *d = s;
+
+	for (;; s++, d++) {
+		if (*s == '\\')
+			s++;
+		*d = *s;
+		if (!*s)
+			break;
+	}
+}
+
 static int ovl_mount_dir(const char *name, struct path *path)
 {
 	int err;
+	char *tmp = kstrdup(name, GFP_KERNEL);
+
+	if (!tmp)
+		return -ENOMEM;
 
-	err = kern_path(name, LOOKUP_FOLLOW, path);
+	ovl_unescape(tmp);
+	err = kern_path(tmp, LOOKUP_FOLLOW, path);
 	if (err) {
-		pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
+		pr_err("overlayfs: failed to resolve '%s': %i\n", tmp, err);
 		err = -EINVAL;
 	}
+	kfree(tmp);
 	return err;
 }
 
@@ -776,11 +813,11 @@ static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
 
 static struct file_system_type ovl_fs_type = {
 	.owner		= THIS_MODULE,
-	.name		= "overlayfs",
+	.name		= "overlay",
 	.mount		= ovl_mount,
 	.kill_sb	= kill_anon_super,
 };
-MODULE_ALIAS_FS("overlayfs");
+MODULE_ALIAS_FS("overlay");
 
 static int __init ovl_init(void)
 {