From ada9b2b3b470ec372e521ee2c1f82f8bc87b1e0a Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering@redhat.com>
Date: Thu, 2 Oct 2008 10:00:46 +0200
Subject: [PATCH] fts.c: sync with similar code from coreutils' remove.c

* lib/fts.c (dirent_inode_sort_may_be_useful): Merge from coreutils.
Guard also with "#if defined __linux__", since for now at least,
this code is Linux-kernel-specific.
---
 ChangeLog |  8 ++++++++
 lib/fts.c | 57 +++++++++++++++++++++++++++++++--------------------------
 2 files changed, 39 insertions(+), 26 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index c69b59483..057938c6f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,8 +1,16 @@
 2008-10-02  Jim Meyering  <meyering@redhat.com>
 
+	fts.c: sync with similar code from coreutils' remove.c
+	* lib/fts.c (dirent_inode_sort_may_be_useful): Merge from coreutils.
+	Guard also with "#if defined __linux__", since for now at least,
+	this code is Linux-kernel-specific.
+
+2008-10-02  Jim Meyering  <meyering@redhat.com>
+
 	fts: bug fixes
 	* lib/fts.c: Remove unnecessary "defined" in cpp directive.
 	Include <sys/vfs.h>, not <sys/statfs.h>.
+
 	* m4/fts.m4 (gl_FUNC_FTS_CORE): Fix typo s/vfs/vfs.h/.
 	Include <sys/vfs.h>, not <sys/statfs.h>.
 
diff --git a/lib/fts.c b/lib/fts.c
index a55a98dd0..d4f7db21c 100644
--- a/lib/fts.c
+++ b/lib/fts.c
@@ -934,29 +934,19 @@ fts_children (register FTS *sp, int instr)
 	return (sp->fts_child);
 }
 
-#if HAVE_SYS_VFS_H && HAVE_FSTATFS && HAVE_STRUCT_STATFS_F_TYPE
-# include <sys/vfs.h>
-/* FIXME: what about when f_type is not an integral type?
-   deal with that if/when it's encountered.  */
-static bool
-fs_handles_readdir_ordered_dirents_efficiently (uintmax_t fs_type)
-{
-/* From coreutils' src/fs.h */
-#define S_MAGIC_TMPFS 0x1021994
-#define S_MAGIC_NFS 0x6969
-  switch (fs_type)
-    {
-    case S_MAGIC_TMPFS:
-    case S_MAGIC_NFS:
-      return true;
-    default:
-      return false;
-    }
-}
+#if defined __linux__ \
+  && HAVE_SYS_VFS_H && HAVE_FSTATFS && HAVE_STRUCT_STATFS_F_TYPE
+
+#include <sys/vfs.h>
 
-/* Return true if it is easy to determine the file system type of the
-   directory on which DIR_FD is open, and sorting dirents on inode numbers
-   is known to improve traversal performance with that type of file system.  */
+/* Linux-specific constants from coreutils' src/fs.h */
+# define S_MAGIC_TMPFS 0x1021994
+# define S_MAGIC_NFS 0x6969
+
+/* Return false if it is easy to determine the file system type of
+   the directory on which DIR_FD is open, and sorting dirents on
+   inode numbers is known not to improve traversal performance with
+   that type of file system.  Otherwise, return true.  */
 static bool
 dirent_inode_sort_may_be_useful (int dir_fd)
 {
@@ -966,12 +956,27 @@ dirent_inode_sort_may_be_useful (int dir_fd)
      while the cost of *not* performing it can be O(N^2) with
      a very large constant.  */
   struct statfs fs_buf;
-  bool skip = (fstatfs (dir_fd, &fs_buf) == 0
-	       && fs_handles_readdir_ordered_dirents_efficiently (dir_fd));
-  return !skip;
+
+  /* If fstatfs fails, assume sorting would be useful.  */
+  if (fstatfs (dir_fd, &fs_buf) != 0)
+    return true;
+
+  /* FIXME: what about when f_type is not an integral type?
+     deal with that if/when it's encountered.  */
+  switch (fs_buf.f_type)
+    {
+    case S_MAGIC_TMPFS:
+    case S_MAGIC_NFS:
+      /* On a file system of any of these types, sorting
+	 is unnecessary, and hence wasteful.  */
+      return false;
+
+    default:
+      return true;
+    }
 }
 #else
-static bool dirent_inode_sort_may_be_useful (FTS const *sp) { return true; }
+static bool dirent_inode_sort_may_be_useful (int dir_fd) { return true; }
 #endif
 
 /* A comparison function to sort on increasing inode number.
-- 
2.11.0