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authorJeff Layton <jlayton@redhat.com>2013-07-26 14:23:25 +0400
committerAl Viro <viro@zeniv.linux.org.uk>2013-09-04 06:50:29 +0400
commit8033426e6bdb2690d302872ac1e1fadaec1a5581 (patch)
treec6f1a95b751575b7d3af19df48bea3bd0a0c4748 /include/linux/namei.h
parent590fb51f1cf99c4a48a3b1bd65885192e877b561 (diff)
downloadlinux-8033426e6bdb2690d302872ac1e1fadaec1a5581.tar.xz
vfs: allow umount to handle mountpoints without revalidating them
Christopher reported a regression where he was unable to unmount a NFS filesystem where the root had gone stale. The problem is that d_revalidate handles the root of the filesystem differently from other dentries, but d_weak_revalidate does not. We could simply fix this by making d_weak_revalidate return success on IS_ROOT dentries, but there are cases where we do want to revalidate the root of the fs. A umount is really a special case. We generally aren't interested in anything but the dentry and vfsmount that's attached at that point. If the inode turns out to be stale we just don't care since the intent is to stop using it anyway. Try to handle this situation better by treating umount as a special case in the lookup code. Have it resolve the parent using normal means, and then do a lookup of the final dentry without revalidating it. In most cases, the final lookup will come out of the dcache, but the case where there's a trailing symlink or !LAST_NORM entry on the end complicates things a bit. Cc: Neil Brown <neilb@suse.de> Reported-by: Christopher T Vogan <cvogan@us.ibm.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'include/linux/namei.h')
-rw-r--r--include/linux/namei.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/namei.h b/include/linux/namei.h
index 5a5ff57ceed4..cd09751c71a0 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -58,6 +58,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
extern int user_path_at(int, const char __user *, unsigned, struct path *);
extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
+extern int user_path_umountat(int, const char __user *, unsigned int, struct path *);
#define user_path(name, path) user_path_at(AT_FDCWD, name, LOOKUP_FOLLOW, path)
#define user_lpath(name, path) user_path_at(AT_FDCWD, name, 0, path)