linux-kernel - [PATCH] fs: allow d_instantiate to be called with negative parent dentry

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Message-Id: <1246257118.265649.273423097532.1.gpush@pingu>
Date:	Mon, 29 Jun 2009 14:31:58 +0800
From:	Jeremy Kerr <jk@...abs.org>
To:	<linux-kernel@...r.kernel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Eric Paris <eparis@...hat.com>, Christoph Hellwig <hch@....de>,
	<cbe-oss-dev@...abs.org>
Subject: [PATCH] fs: allow d_instantiate to be called with negative parent
	dentry

The new fsnotify infrastructure (starting at 90586523) causes an oops in
spufs, where we populate a directory with files before instantiating the
directory itself. The new changes seem to have introduced an assumption
that a dentry's parent will be positive when instantiating.

This change makes it once again possible to d_instantiate a dentry
with a negative parent, and brings __fsnotify_d_instantiate() into
line with inotify_d_instantiate(), which already has this NULL check.

Signed-off-by: Jeremy Kerr <jk@...abs.org>

---
Apologies for the resend, fixed lkml address

---
 include/linux/fsnotify_backend.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 44848aa..6c3de99 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -280,7 +280,7 @@ static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
 	assert_spin_locked(&dentry->d_lock);
 
 	parent = dentry->d_parent;
-	if (fsnotify_inode_watches_children(parent->d_inode))
+	if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode))
 		dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
 	else
 		dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
--
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