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

Pull vfs updates from Al Viro:
 "overlayfs merge + leak fix for d_splice_alias() failure exits"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  overlayfs: embed middle into overlay_readdir_data
  overlayfs: embed root into overlay_readdir_data
  overlayfs: make ovl_cache_entry->name an array instead of pointer
  overlayfs: don't hold ->i_mutex over opening the real directory
  fix inode leaks on d_splice_alias() failure exits
  fs: limit filesystem stacking depth
  overlay: overlay filesystem documentation
  overlayfs: implement show_options
  overlayfs: add statfs support
  overlay filesystem
  shmem: support RENAME_WHITEOUT
  ext4: support RENAME_WHITEOUT
  vfs: add RENAME_WHITEOUT
  vfs: add whiteout support
  vfs: export check_sticky()
  vfs: introduce clone_private_mount()
  vfs: export __inode_permission() to modules
  vfs: export do_splice_direct() to modules
  vfs: add i_op->dentry_open()

3 files changed, 43 insertions, 0 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index a957d4366c24..4e41a4a331bb 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -223,6 +223,13 @@ typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 #define ATTR_TIMES_SET  (1 << 16)
 
 /*
+ * Whiteout is represented by a char device.  The following constants define the
+ * mode and device number to use.
+ */
+#define WHITEOUT_MODE 0
+#define WHITEOUT_DEV 0
+
+/*
  * This is the Inode Attributes structure, used for notify_change().  It
  * uses the above definitions as flags, to know which values have changed.
  * Also, in this manner, a Filesystem can look at only the values it cares
@@ -254,6 +261,12 @@ struct iattr {
  */
 #include <linux/quota.h>
 
+/*
+ * Maximum number of layers of fs stack.  Needs to be limited to
+ * prevent kernel stack overflow
+ */
+#define FILESYSTEM_MAX_STACK_DEPTH 2
+
 /** 
  * enum positive_aop_returns - aop return codes with specific semantics
  *
@@ -1266,6 +1279,11 @@ struct super_block {
         struct list_lru         s_dentry_lru ____cacheline_aligned_in_smp;
         struct list_lru         s_inode_lru ____cacheline_aligned_in_smp;
         struct rcu_head         rcu;
+
+        /*
+         * Indicates how deep in a filesystem stack this SB is
+         */
+        int s_stack_depth;
 };
 
 extern struct timespec current_fs_time(struct super_block *sb);
@@ -1398,6 +1416,7 @@ extern int vfs_link(struct dentry *, struct inode *, struct dentry *, struct ino
 extern int vfs_rmdir(struct inode *, struct dentry *);
 extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
 extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **, unsigned int);
+extern int vfs_whiteout(struct inode *, struct dentry *);
 
 /*
  * VFS dentry helper functions.
@@ -1528,6 +1547,9 @@ struct inode_operations {
                            umode_t create_mode, int *opened);
         int (*tmpfile) (struct inode *, struct dentry *, umode_t);
         int (*set_acl)(struct inode *, struct posix_acl *, int);
+
+        /* WARNING: probably going away soon, do not use! */
+        int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
 } ____cacheline_aligned;
 
 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
@@ -1625,6 +1647,9 @@ struct super_operations {
 #define IS_AUTOMOUNT(inode)     ((inode)->i_flags & S_AUTOMOUNT)
 #define IS_NOSEC(inode)         ((inode)->i_flags & S_NOSEC)
 
+#define IS_WHITEOUT(inode)      (S_ISCHR(inode->i_mode) && \
+                                 (inode)->i_rdev == WHITEOUT_DEV)
+
 /*
  * Inode state bits.  Protected by inode->i_lock
  *
@@ -2040,6 +2065,7 @@ extern struct file *file_open_name(struct filename *, int, umode_t);
 extern struct file *filp_open(const char *, int, umode_t);
 extern struct file *file_open_root(struct dentry *, struct vfsmount *,
                                    const char *, int);
+extern int vfs_open(const struct path *, struct file *, const struct cred *);
 extern struct file * dentry_open(const struct path *, int, const struct cred *);
 extern int filp_close(struct file *, fl_owner_t id);
 
@@ -2253,7 +2279,9 @@ extern sector_t bmap(struct inode *, sector_t);
 #endif
 extern int notify_change(struct dentry *, struct iattr *, struct inode **);
 extern int inode_permission(struct inode *, int);
+extern int __inode_permission(struct inode *, int);
 extern int generic_permission(struct inode *, int);
+extern int __check_sticky(struct inode *dir, struct inode *inode);
 
 static inline bool execute_ok(struct inode *inode)
 {
@@ -2452,6 +2480,9 @@ extern ssize_t iter_file_splice_write(struct pipe_inode_info *,
                 struct file *, loff_t *, size_t, unsigned int);
 extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
                 struct file *out, loff_t *, size_t len, unsigned int flags);
+extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
+                loff_t *opos, size_t len, unsigned int flags);
+
 
 extern void
 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
@@ -2737,6 +2768,14 @@ static inline int is_sxid(umode_t mode)
         return (mode & S_ISUID) || ((mode & S_ISGID) && (mode & S_IXGRP));
 }
 
+static inline int check_sticky(struct inode *dir, struct inode *inode)
+{
+        if (!(dir->i_mode & S_ISVTX))
+                return 0;
+
+        return __check_sticky(dir, inode);
+}
+
 static inline void inode_has_no_xattr(struct inode *inode)
 {
         if (!is_sxid(inode->i_mode) && (inode->i_sb->s_flags & MS_NOSEC))
diff --git a/include/linux/mount.h b/include/linux/mount.h
index 9262e4bf0cc3..c2c561dc0114 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -81,6 +81,9 @@ extern struct vfsmount *mntget(struct vfsmount *mnt);
 extern struct vfsmount *mnt_clone_internal(struct path *path);
 extern int __mnt_is_readonly(struct vfsmount *mnt);
 
+struct path;
+extern struct vfsmount *clone_private_mount(struct path *path);
+
 struct file_system_type;
 extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
                                       int flags, const char *name,
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index ca1a11bb4443..3735fa0a6784 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -37,6 +37,7 @@
 
 #define RENAME_NOREPLACE        (1 << 0)        /* Don't overwrite target */
 #define RENAME_EXCHANGE         (1 << 1)        /* Exchange source and dest */
+#define RENAME_WHITEOUT         (1 << 2)        /* Whiteout source */
 
 struct fstrim_range {
         __u64 start;