From c64cd6e34ea340adbb2a0a2f99cc884b96dcdca5 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 10 Jan 2020 17:17:19 -0500 Subject: reimplement path_mountpoint() with less magic ... and get rid of a bunch of bugs in it. Background: the reason for path_mountpoint() is that umount() really doesn't want attempts to revalidate the root of what it's trying to umount. The thing we want to avoid actually happen from complete_walk(); solution was to do something parallel to normal path_lookupat() and it both went overboard and got the boilerplate subtly (and not so subtly) wrong. A better solution is to do pretty much what the normal path_lookupat() does, but instead of complete_walk() do unlazy_walk(). All it takes to avoid that ->d_weak_revalidate() call... mountpoint_last() goes away, along with everything it got wrong, and so does the magic around LOOKUP_NO_REVAL. Another source of bugs is that when we traverse mounts at the final location (and we need to do that - umount . expects to get whatever's overmounting ., if any, out of the lookup) we really ought to take care of ->d_manage() - as it is, manual umount of autofs automount in progress can lead to unpleasant surprises for the daemon. Easily solved by using handle_lookup_down() instead of follow_mount(). Tested-by: Ian Kent Signed-off-by: Al Viro --- include/linux/namei.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include') diff --git a/include/linux/namei.h b/include/linux/namei.h index 7fe7b87a3ded..07bfb0874033 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -34,7 +34,6 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND}; /* internal use only */ #define LOOKUP_PARENT 0x0010 -#define LOOKUP_NO_REVAL 0x0080 #define LOOKUP_JUMPED 0x1000 #define LOOKUP_ROOT 0x2000 #define LOOKUP_ROOT_GRABBED 0x0008 -- cgit v1.2.3