From: Al Viro <viro@zeniv.linux.org.uk>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Christoph Hellwig <hch@lst.de>,
syzbot <syzbot+69b40dc5fd40f32c199f@syzkaller.appspotmail.com>,
syzkaller-bugs@googlegroups.com,
Andrew Morton <akpm@linux-foundation.org>,
hch@infradead.org, linux-fsdevel <linux-fsdevel@vger.kernel.org>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Chen Zhongjin <chenzhongjin@huawei.com>,
Dave Chinner <dchinner@redhat.com>,
Christian Brauner <brauner@kernel.org>
Subject: Re: [PATCH] sysv: convert pointers_lock from rw_lock to rw_sem
Date: Mon, 27 Mar 2023 14:02:05 +0100 [thread overview]
Message-ID: <20230327130205.GG3390869@ZenIV> (raw)
In-Reply-To: <6bfca9e9-d4d8-37ec-d53c-0c77e7c70e85@I-love.SAKURA.ne.jp>
On Mon, Mar 27, 2023 at 07:19:47PM +0900, Tetsuo Handa wrote:
> I feel worried about
>
> /*
> * Indirect block might be removed by truncate while we were
> * reading it. Handling of that case (forget what we've got and
> * reread) is taken out of the main path.
> */
> if (err == -EAGAIN)
> goto changed;
>
> in get_block()...
Look at the caller of find_shared(); there won't be other truncate messing
up with the indirect blocks. sysv_truncate() is called by sysv_write_failed()
(from ->write_begin()), sysv_setattr() (->setattr(), with ATTR_SIZE) and
sysv_evict_inode() (if there's no links left to on-disk inode; it's an
->evict_inode() instance, so we are dropping the last reference to in-core one).
The first two have i_mutex held by callers, serializing them against each
other, and both have the in-core inode pinned, which gives exclusion with
the third one...
IOW, sysv_truncate() (as well as its minixfs counterpart) relies upon having
serialization wrt other callers of sysv_truncate().
next prev parent reply other threads:[~2023-03-27 13:02 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <0000000000000ccf9a05ee84f5b0@google.com>
2023-03-26 22:24 ` [PATCH] sysv: convert pointers_lock from rw_lock to rw_sem Tetsuo Handa
2023-03-27 0:04 ` Al Viro
2023-03-27 10:19 ` Tetsuo Handa
2023-03-27 13:02 ` Al Viro [this message]
2023-03-27 13:09 ` Tetsuo Handa
2023-04-10 12:04 ` [PATCH] sysv: don't call sb_bread() with pointers_lock held Tetsuo Handa
2023-04-10 14:56 ` [PATCH v2] " Tetsuo Handa
2024-01-30 9:36 ` [PATCH] " Christian Brauner
2024-01-30 1:15 ` [syzbot] [fs?] BUG: sleeping function called from invalid context in __getblk_gfp syzbot
2024-01-30 11:54 ` Jan Kara
2024-01-30 15:57 ` Christoph Hellwig
2024-01-31 10:56 ` Christian Brauner
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