From: "Aurélien Aptel" <aaptel@suse.com>
To: Muhammad Usama Anjum <musamaanjum@gmail.com>,
Steve French <sfrench@samba.org>,
Ronnie Sahlberg <lsahlber@redhat.com>,
"open list:COMMON INTERNET FILE SYSTEM CLIENT (CIFS)"
<linux-cifs@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>
Cc: musamaanjum@gmail.com, kernel-janitors@vger.kernel.org,
dan.carpenter@oracle.com, colin.king@canonical.com
Subject: Re: [PATCH v2] cifs: remove unnecessary copies of tcon->crfid.fid
Date: Sat, 17 Apr 2021 12:53:37 +0200 [thread overview]
Message-ID: <8735vp18su.fsf@suse.com> (raw)
In-Reply-To: <20210415152409.GA2286719@LEGION>
Hi,
This is better I think.
Muhammad Usama Anjum <musamaanjum@gmail.com> writes:
> @@ -894,6 +891,10 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
>
> /* BB TBD check to see if oplock level check can be removed below */
> if (o_rsp->OplockLevel == SMB2_OPLOCK_LEVEL_LEASE) {
> + /*
> + * caller expects this func to set the fid in crfid to valid
> + * cached root, so increment the refcount.
> + */
This comment is misleading. crfid variable doesn't exist anymore, and
the kref_get() here is because of this commit:
commit 2f94a3125b87
Author: Ronnie Sahlberg <lsahlber@redhat.com>
Date: Thu Mar 28 11:20:02 2019 +1000
cifs: fix kref underflow in close_shroot()
[...]
--> This extra get() is only used to hold the structure until we get a lease
--> break from the server at which point we will kref_put() it during lease
--> processing.
[...]
When we queue a lease break, we usually get() the cifsFileInfo, but if
that cifsFileInfo is backed by a cached_fid, the cached_fid isn't
bumped. That commit was probably a work around for that.
@Ronnie :
struct cached_fid is starting to look very much like struct
cifsFileInfo. I wonder why we couldn't use it, along with
find_writable_file()/find_readable_file() to handle the caching.
Alternatively, make cifsFileInfo use cached_fid (perhaps renaming it in
the process, I don't know)
Because I suspect a lot more issues will come up regarding cached_fid
refcount and cifsFileInfo refcount going out of sync otherwise.
Cheers,
--
Aurélien Aptel / SUSE Labs Samba Team
GPG: 1839 CB5F 9F5B FB9B AA97 8C99 03C8 A49B 521B D5D3
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg, DE
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 247165 (AG München)
next prev parent reply other threads:[~2021-04-17 10:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-15 15:24 [PATCH v2] cifs: remove unnecessary copies of tcon->crfid.fid Muhammad Usama Anjum
2021-04-17 10:53 ` Aurélien Aptel [this message]
2021-04-19 23:39 ` Steve French
2021-04-28 16:12 ` Muhammad Usama Anjum
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