Merge tag 'ovl-fixes-4.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs fixes from Miklos Szeredi:
 "This fixes a regression in the recent file stacking update, reported
  and fixed by Amir Goldstein. The fix is fairly trivial, but involves
  adding a fadvise() f_op and the associated churn in the vfs. As
  discussed on -fsdevel, there are other possible uses for this method,
  than allowing proper stacking for overlays.

  And there's one other fix for a syzkaller detected oops"

* tag 'ovl-fixes-4.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: fix oopses in ovl_fill_super() failure paths
  ovl: add ovl_fadvise()
  vfs: implement readahead(2) using POSIX_FADV_WILLNEED
  vfs: add the fadvise() file operation
  Documentation/filesystems: update documentation of file_operations
  ovl: fix GPF in swapfile_activate of file from overlayfs over xfs
  ovl: respect FIEMAP_FLAG_SYNC flag

Documentation/filesystems/vfs.txt

@@ -848,7 +848,7 @@ struct file_operations
 ----------------------
 
 This describes how the VFS can manipulate an open file. As of kernel
-4.1, the following members are defined:
+4.18, the following members are defined:
 
 struct file_operations {
 	struct module *owner;
@@ -858,11 +858,11 @@ struct file_operations {
 	ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);
 	ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
 	int (*iterate) (struct file *, struct dir_context *);
+	int (*iterate_shared) (struct file *, struct dir_context *);
 	__poll_t (*poll) (struct file *, struct poll_table_struct *);
 	long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
 	long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
 	int (*mmap) (struct file *, struct vm_area_struct *);
-	int (*mremap)(struct file *, struct vm_area_struct *);
 	int (*open) (struct inode *, struct file *);
 	int (*flush) (struct file *, fl_owner_t id);
 	int (*release) (struct inode *, struct file *);
@@ -882,6 +882,10 @@ struct file_operations {
 #ifndef CONFIG_MMU
 	unsigned (*mmap_capabilities)(struct file *);
 #endif
+	ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t, size_t, unsigned int);
+	int (*clone_file_range)(struct file *, loff_t, struct file *, loff_t, u64);
+	int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t, u64);
+	int (*fadvise)(struct file *, loff_t, loff_t, int);
 };
 
 Again, all methods are called without any locks being held, unless
@@ -899,6 +903,9 @@ otherwise noted.
 
   iterate: called when the VFS needs to read the directory contents
 
+  iterate_shared: called when the VFS needs to read the directory contents
+	when filesystem supports concurrent dir iterators
+
   poll: called by the VFS when a process wants to check if there is
 	activity on this file and (optionally) go to sleep until there
 	is activity. Called by the select(2) and poll(2) system calls
@@ -951,6 +958,16 @@ otherwise noted.
 
   fallocate: called by the VFS to preallocate blocks or punch a hole.
 
+  copy_file_range: called by the copy_file_range(2) system call.
+
+  clone_file_range: called by the ioctl(2) system call for FICLONERANGE and
+	FICLONE commands.
+
+  dedupe_file_range: called by the ioctl(2) system call for FIDEDUPERANGE
+	command.
+
+  fadvise: possibly called by the fadvise64() system call.
+
 Note that the file operations are implemented by the specific
 filesystem in which the inode resides. When opening a device node
 (character or block special) most filesystems will call special