From 99d1419d96d7df9cfa56bc977810be831bd5ef64 Mon Sep 17 00:00:00 2001
From: JANAK DESAI <janak@us.ibm.com>
Date: Tue, 7 Feb 2006 12:58:59 -0800
Subject: [PATCH] unshare system call -v5: unshare filesystem info

If filesystem structure is being shared, allocate a new one and copy
information from the current, shared, structure.

Signed-off-by: Janak Desai <janak@us.ibm.com>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/fork.c b/kernel/fork.c
index 6eb9362..598e5c2 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1371,15 +1371,18 @@ static int unshare_thread(unsigned long unshare_flags)
 }
 
 /*
- * Unsharing of fs info for tasks created with CLONE_FS is not supported yet
+ * Unshare the filesystem structure if it is being shared
  */
 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
 {
 	struct fs_struct *fs = current->fs;
 
 	if ((unshare_flags & CLONE_FS) &&
-	    (fs && atomic_read(&fs->count) > 1))
-		return -EINVAL;
+	    (fs && atomic_read(&fs->count) > 1)) {
+		*new_fsp = __copy_fs_struct(current->fs);
+		if (!*new_fsp)
+			return -ENOMEM;
+	}
 
 	return 0;
 }
-- 
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