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

Pull overlayfs updates from Miklos Szeredi:
 "This contains several bug fixes and a new mount option
  'default_permissions' that allows read-only exported NFS
  filesystems to be used as lower layer"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: check dentry positiveness in ovl_cleanup_whiteouts()
  ovl: setattr: check permissions before copy-up
  ovl: root: copy attr
  ovl: move super block magic number to magic.h
  ovl: use a minimal buffer in ovl_copy_xattr
  ovl: allow zero size xattr
  ovl: default permissions

1 files changed, 33 insertions, 2 deletions

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index e38ee0fed24a..a4cbdf9824c7 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -9,6 +9,7 @@
 
 #include <linux/fs.h>
 #include <linux/namei.h>
+#include <linux/pagemap.h>
 #include <linux/xattr.h>
 #include <linux/security.h>
 #include <linux/mount.h>
@@ -24,12 +25,11 @@ MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
 MODULE_DESCRIPTION("Overlay filesystem");
 MODULE_LICENSE("GPL");
 
-#define OVERLAYFS_SUPER_MAGIC 0x794c7630
-
 struct ovl_config {
 	char *lowerdir;
 	char *upperdir;
 	char *workdir;
+	bool default_permissions;
 };
 
 /* private information held for overlayfs's superblock */
@@ -154,6 +154,18 @@ struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper)
 	return realdentry;
 }
 
+struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,
+				    bool is_upper)
+{
+	if (is_upper) {
+		struct ovl_fs *ofs = inode->i_sb->s_fs_info;
+
+		return ofs->upper_mnt;
+	} else {
+		return oe->numlower ? oe->lowerstack[0].mnt : NULL;
+	}
+}
+
 struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
 {
 	struct ovl_entry *oe = dentry->d_fsdata;
@@ -161,6 +173,13 @@ struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
 	return oe->cache;
 }
 
+bool ovl_is_default_permissions(struct inode *inode)
+{
+	struct ovl_fs *ofs = inode->i_sb->s_fs_info;
+
+	return ofs->config.default_permissions;
+}
+
 void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
 {
 	struct ovl_entry *oe = dentry->d_fsdata;
@@ -594,6 +613,8 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
 		seq_show_option(m, "upperdir", ufs->config.upperdir);
 		seq_show_option(m, "workdir", ufs->config.workdir);
 	}
+	if (ufs->config.default_permissions)
+		seq_puts(m, ",default_permissions");
 	return 0;
 }
 
@@ -618,6 +639,7 @@ enum {
 	OPT_LOWERDIR,
 	OPT_UPPERDIR,
 	OPT_WORKDIR,
+	OPT_DEFAULT_PERMISSIONS,
 	OPT_ERR,
 };
 
@@ -625,6 +647,7 @@ static const match_table_t ovl_tokens = {
 	{OPT_LOWERDIR,			"lowerdir=%s"},
 	{OPT_UPPERDIR,			"upperdir=%s"},
 	{OPT_WORKDIR,			"workdir=%s"},
+	{OPT_DEFAULT_PERMISSIONS,	"default_permissions"},
 	{OPT_ERR,			NULL}
 };
 
@@ -685,6 +708,10 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
 				return -ENOMEM;
 			break;
 
+		case OPT_DEFAULT_PERMISSIONS:
+			config->default_permissions = true;
+			break;
+
 		default:
 			pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
 			return -EINVAL;
@@ -910,6 +937,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 	}
 
 	sb->s_stack_depth = 0;
+	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	if (ufs->config.upperdir) {
 		if (!ufs->config.workdir) {
 			pr_err("overlayfs: missing 'workdir'\n");
@@ -1053,6 +1081,9 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 
 	root_dentry->d_fsdata = oe;
 
+	ovl_copyattr(ovl_dentry_real(root_dentry)->d_inode,
+		     root_dentry->d_inode);
+
 	sb->s_magic = OVERLAYFS_SUPER_MAGIC;
 	sb->s_op = &ovl_super_operations;
 	sb->s_root = root_dentry;