save a patch for the next 5.4 release so I don't forget...

diff --git a/next-5.4/ovl-simplify-file-splice.patch b/next-5.4/ovl-simplify-file-splice.patch
new file mode 100644 (file)
index 0000000..64dd774
--- /dev/null
+++ b/next-5.4/ovl-simplify-file-splice.patch
@@ -0,0 +1,89 @@
+From 82a763e61e2b601309d696d4fa514c77d64ee1be Mon Sep 17 00:00:00 2001
+From: Miklos Szeredi <mszeredi@redhat.com>
+Date: Mon, 14 Dec 2020 15:26:14 +0100
+Subject: ovl: simplify file splice
+
+From: Miklos Szeredi <mszeredi@redhat.com>
+
+commit 82a763e61e2b601309d696d4fa514c77d64ee1be upstream.
+
+generic_file_splice_read() and iter_file_splice_write() will call back into
+f_op->iter_read() and f_op->iter_write() respectively.  These already do
+the real file lookup and cred override.  So the code in ovl_splice_read()
+and ovl_splice_write() is redundant.
+
+In addition the ovl_file_accessed() call in ovl_splice_write() is
+incorrect, though probably harmless.
+
+Fix by calling generic_file_splice_read() and iter_file_splice_write()
+directly.
+
+Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
+[reported to resolve issues with 1a980b8cbf00 ("ovl: add splice file read write helper")]
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/overlayfs/file.c |   46 ++--------------------------------------------
+ 1 file changed, 2 insertions(+), 44 deletions(-)
+
+--- a/fs/overlayfs/file.c
++++ b/fs/overlayfs/file.c
+@@ -296,48 +296,6 @@ out_unlock:
+       return ret;
+ }
+ 
+-static ssize_t ovl_splice_read(struct file *in, loff_t *ppos,
+-                       struct pipe_inode_info *pipe, size_t len,
+-                       unsigned int flags)
+-{
+-      ssize_t ret;
+-      struct fd real;
+-      const struct cred *old_cred;
+-
+-      ret = ovl_real_fdget(in, &real);
+-      if (ret)
+-              return ret;
+-
+-      old_cred = ovl_override_creds(file_inode(in)->i_sb);
+-      ret = generic_file_splice_read(real.file, ppos, pipe, len, flags);
+-      revert_creds(old_cred);
+-
+-      ovl_file_accessed(in);
+-      fdput(real);
+-      return ret;
+-}
+-
+-static ssize_t
+-ovl_splice_write(struct pipe_inode_info *pipe, struct file *out,
+-                        loff_t *ppos, size_t len, unsigned int flags)
+-{
+-      struct fd real;
+-      const struct cred *old_cred;
+-      ssize_t ret;
+-
+-      ret = ovl_real_fdget(out, &real);
+-      if (ret)
+-              return ret;
+-
+-      old_cred = ovl_override_creds(file_inode(out)->i_sb);
+-      ret = iter_file_splice_write(pipe, real.file, ppos, len, flags);
+-      revert_creds(old_cred);
+-
+-      ovl_file_accessed(out);
+-      fdput(real);
+-      return ret;
+-}
+-
+ static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+ {
+       struct fd real;
+@@ -694,8 +652,8 @@ const struct file_operations ovl_file_op
+       .fadvise        = ovl_fadvise,
+       .unlocked_ioctl = ovl_ioctl,
+       .compat_ioctl   = ovl_compat_ioctl,
+-      .splice_read    = ovl_splice_read,
+-      .splice_write   = ovl_splice_write,
++      .splice_read    = generic_file_splice_read,
++      .splice_write   = iter_file_splice_write,
+ 
+       .copy_file_range        = ovl_copy_file_range,
+       .remap_file_range       = ovl_remap_file_range,