xfs: fix C++ compilation errors in xfs_fs.h

Several people reported C++ compilation errors due to things that C
compilers allow but C++ compilers do not.  Fix both of these problems,
and hope there aren't more of these brown paper bags in 2 months when we
finally get these fixes through the process into a released xfsprogs.

NOTE: I am submitting this bugfix over the objections of a former
maintainer, who insists that we should remove this function from the
published userspace ABI instead of fixing the C++ compilation errors.
No deprecation period, no discussion, just a hard drop of an already
provided and correct C function, which would be in contravention of
Linus' rules.  IOWs, removing ABI that have already shipped in a
released kernel requires a careful deprecation period, so I will let
that maintainer run that process.

Reported-by: kernel@mattwhitlock.name
Reported-by: sam@gentoo.org
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219203
Fixes: 233f4e12bbb2c ("xfs: add parent pointer ioctls")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index c85c8077fac391ba182fe89334c016d3c6934d38..860284064c5aa9304d045b3e9ebfcf346e9fd968 100644 (file)
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -8,6 +8,7 @@
 
 /*
  * SGI's XFS filesystem's major stuff (constants, structures)
+ * NOTE: This file must be compile-able with C++ compilers.
  */
 
 /*
@@ -930,13 +931,13 @@ static inline struct xfs_getparents_rec *
 xfs_getparents_next_rec(struct xfs_getparents *gp,
                        struct xfs_getparents_rec *gpr)
 {
-       void *next = ((void *)gpr + gpr->gpr_reclen);
+       void *next = ((char *)gpr + gpr->gpr_reclen);
        void *end = (void *)(uintptr_t)(gp->gp_buffer + gp->gp_bufsize);
 
        if (next >= end)
                return NULL;
 
-       return next;
+       return (struct xfs_getparents_rec *)next;
 }
 
 /* Iterate through this file handle's directory parent pointers. */