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Date: Sat, 28 Feb 2004 11:42:25 +0000
From: viro@parcelfarce.linux.theplanet.co.uk
To: Maurice van der Stee <stee@planet.nl>
Cc: linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@osdl.org>
Subject: Re: 2.6.4-rc1 oops on HPFS filesystem file rename
Message-ID: <20040228114225.GC16357@parcelfarce.linux.theplanet.co.uk>
References: <20040228110403.GC557@maurice.stee.nl>
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On Sat, Feb 28, 2004 at 12:04:03PM +0100, Maurice van der Stee wrote:
> When saving an edited file residing on a HPFS filesystem I get the  
> following
> oops.
> Kernel is 2.6.4-rc1, compiled with gcc 3.3.2. After this any access to  
> the
> filesystem hangs the session. Kernel 2.6.3 has the same behavior. Don't  
> know
> about earlier ones.

<stares at the code>
<blinks>
<wonders whereTF do we assign hpfs1_i and hpfs2_i if both inodes are non-NULL>
<finds the patch in question>
<stares at jgarzik>

Fix follows.  That, BTW, means that *nobody* had ever tried to use hpfs
r/w since 2.5.3-pre3.

diff -urN RC4-rc1/fs/hpfs/buffer.c RC4-rc1-current/fs/hpfs/buffer.c
--- RC4-rc1/fs/hpfs/buffer.c	Mon Oct  7 15:58:24 2002
+++ RC4-rc1-current/fs/hpfs/buffer.c	Sat Feb 28 06:33:29 2004
@@ -62,56 +62,28 @@
 
 void hpfs_lock_2inodes(struct inode *i1, struct inode *i2)
 {
-	struct hpfs_inode_info *hpfs_i1 = NULL, *hpfs_i2 = NULL;
-
-	if (!i1) {
-		if (i2) {
-			hpfs_i2 = hpfs_i(i2);
+	if (!i2 || i1 == i2) {
+		hpfs_lock_inode(i1);
+	} else if (!i1) {
+		hpfs_lock_inode(i2);
+	} else {
+		struct hpfs_inode_info *hpfs_i1 = hpfs_i(i1);
+		struct hpfs_inode_info *hpfs_i2 = hpfs_i(i2);
+		if (i1->i_ino < i2->i_ino) {
+			down(&hpfs_i1->i_sem);
+			down(&hpfs_i2->i_sem);
+		} else {
 			down(&hpfs_i2->i_sem);
-		}
-		return;
-	}
-	if (!i2) {
-		if (i1) {
-			hpfs_i1 = hpfs_i(i1);
 			down(&hpfs_i1->i_sem);
 		}
-		return;
 	}
-	if (i1->i_ino < i2->i_ino) {
-		down(&hpfs_i1->i_sem);
-		down(&hpfs_i2->i_sem);
-	} else if (i1->i_ino > i2->i_ino) {
-		down(&hpfs_i2->i_sem);
-		down(&hpfs_i1->i_sem);
-	} else down(&hpfs_i1->i_sem);
 }
 
 void hpfs_unlock_2inodes(struct inode *i1, struct inode *i2)
 {
-	struct hpfs_inode_info *hpfs_i1 = NULL, *hpfs_i2 = NULL;
-
-	if (!i1) {
-		if (i2) {
-			hpfs_i2 = hpfs_i(i2);
-			up(&hpfs_i2->i_sem);
-		}
-		return;
-	}
-	if (!i2) {
-		if (i1) {
-			hpfs_i1 = hpfs_i(i1);
-			up(&hpfs_i1->i_sem);
-		}
-		return;
-	}
-	if (i1->i_ino < i2->i_ino) {
-		up(&hpfs_i2->i_sem);
-		up(&hpfs_i1->i_sem);
-	} else if (i1->i_ino > i2->i_ino) {
-		up(&hpfs_i1->i_sem);
-		up(&hpfs_i2->i_sem);
-	} else up(&hpfs_i1->i_sem);
+	/* order of up() doesn't matter here */
+	hpfs_unlock_inode(i1);
+	hpfs_unlock_inode(i2);
 }
 
 void hpfs_lock_3inodes(struct inode *i1, struct inode *i2, struct inode *i3)