linux-kernel - [RFC PATCH 0/2] vfs:9p: fix open-unlink-fstat bug

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Message-Id: <20200720014622.37364-1-jianyong.wu@arm.com>
Date:   Mon, 20 Jul 2020 09:46:20 +0800
From:   Jianyong Wu <jianyong.wu@....com>
To:     ericvh@...il.com, hch@....de, dhowells@...hat.com,
        lucho@...kov.net, asmadeus@...ewreck.org
Cc:     v9fs-developer@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        Kaly.Xin@....com, justin.he@....com, jianyong.wu@....com,
        wei.chen@....com
Subject: [RFC PATCH 0/2] vfs:9p: fix open-unlink-fstat bug

how to reproduce:
in 9p guest:

struct stat *statbuf;
int fd;

fd = open("tmp", O_RDWR);
unlink("tmp");
fstat(fd, statbuf);

fstat will fail as "tmp" in 9p server side has been removed. 9p server
can't retrieve the file context as the guest has not passed it down.
so we should pass the file info down in 9p guest in getattr op.
it need add a new file member in "struct kstat" as "struct istat" does.

Jianyong Wu (2):
  vfs: pass file down when getattr to avoid losing info.
  9p: retrieve fid from file if it exists when getattr.

 fs/9p/vfs_inode.c      | 9 +++++++--
 fs/9p/vfs_inode_dotl.c | 9 +++++++--
 fs/stat.c              | 1 +
 include/linux/stat.h   | 6 ++++++
 4 files changed, 21 insertions(+), 4 deletions(-)

-- 
2.17.1