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Commit d9e80b7d authored by Al Viro's avatar Al Viro Committed by Linus Torvalds
Browse files

nfs d_revalidate() is too trigger-happy with d_drop() 



If dentry found stale happens to be a root of disconnected tree, we
can't d_drop() it; its d_hash is actually part of s_anon and d_drop()
would simply hide it from shrink_dcache_for_umount(), leading to
all sorts of fun, including busy inodes on umount and oopsen after
that.

Bug had been there since at least 2006 (commit c636eb already has it),
so it's definitely -stable fodder.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Cc: stable@kernel.org
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1d16b0f2

fs/nfs/dir.c

+2 −0
Original line number Original line Diff line number Diff line
@@ -837,6 +837,8 @@ static int nfs_lookup_revalidate(struct dentry * dentry, struct nameidata *nd) 
		/* If we have submounts, don't unhash ! */

		/* If we have submounts, don't unhash ! */

		if (have_submounts(dentry))

		if (have_submounts(dentry))

			goto out_valid;

			goto out_valid;

		if (dentry->d_flags & DCACHE_DISCONNECTED)

			goto out_valid;

		shrink_dcache_parent(dentry);

		shrink_dcache_parent(dentry);

	}

	}

	d_drop(dentry);

	d_drop(dentry);