linux-kernel - Re: Commit "new primitive: discard_new

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Message-ID: <20180801163408.GR30522@ZenIV.linux.org.uk>
Date:   Wed, 1 Aug 2018 17:34:08 +0100
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Kirill Tkhai <ktkhai@...tuozzo.com>
Cc:     "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: Commit "new primitive: discard_new_inode()" introduces a problem

On Wed, Aug 01, 2018 at 07:19:35PM +0300, Kirill Tkhai wrote:
> On 01.08.2018 19:16, Al Viro wrote:
> > On Wed, Aug 01, 2018 at 05:11:51PM +0100, Al Viro wrote:
> >> On Wed, Aug 01, 2018 at 06:43:56PM +0300, Kirill Tkhai wrote:
> >>> #git status
> >>> HEAD detached at 22dc9a168272
> >>
> >> Wait a sec - just that commit?  With discard_new_inode() not even
> >> used anywhere?  Then any of those -ENOMEM is disguised ERR_PTR(-ESTALE)
> >> from find_inode()/find_inode_fast(), i.e. an inode found by
> >> iget5_locked() (your /etc is on ext4) with I_CREATING still set.
> > 
> > iget_locked(), that is.

OK, I see what's going on there.  See if this fixes the problem:

diff --git a/fs/dcache.c b/fs/dcache.c
index 0e8e5de3c48a..b11f566bcd66 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1892,7 +1892,7 @@ void d_instantiate_new(struct dentry *entry, struct inode *inode)
 	spin_lock(&inode->i_lock);
 	__d_instantiate(entry, inode);
 	WARN_ON(!(inode->i_state & I_NEW));
-	inode->i_state &= ~I_NEW;
+	inode->i_state &= ~I_NEW & ~I_CREATING;
 	smp_mb();
 	wake_up_bit(&inode->i_state, __I_NEW);
 	spin_unlock(&inode->i_lock);