From: Al Viro <viro@zeniv.linux.org.uk>
To: NeilBrown <neil@brown.name>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: fs/dcache.c: bogus comment re LIST_POISON2 around __d_drop()
Date: Mon, 6 Apr 2026 05:05:30 +0100 [thread overview]
Message-ID: <20260406040530.GX3836593@ZenIV> (raw)
In-Reply-To: <177544136061.1474915.4475662411738222301@noble.neil.brown.name>
On Mon, Apr 06, 2026 at 12:09:20PM +1000, NeilBrown wrote:
> It might be help to add *why* it doesn't. Presumably this is an
> optimisation for when the dentry will soon be added into a different
> list. There is no point setting pprev when it will soon be set to
> something else while the lock is still held.
> Do we know that the compiler won't work out this optimisation itself?
Er... Neil, it was your patch in the first place ;-) I realize that this
was over 8 years ago; for context see 61647823aa92. The short version of
the story: we want to avoid a window during d_move() when d_unhashed()
(actually, d_unlinked()) called without ->d_lock would give false
positives.
next prev parent reply other threads:[~2026-04-06 4:01 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-05 19:04 fs/dcache.c: bogus comment re LIST_POISON2 around __d_drop() Al Viro
2026-04-06 2:09 ` NeilBrown
2026-04-06 4:05 ` Al Viro [this message]
2026-04-06 5:47 ` NeilBrown
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