linux-kernel - [PATCH 5.9 091/255] gfs2: check for live vs. read-only file system in gfs2

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Message-Id: <20201117122143.388063276@linuxfoundation.org>
Date:   Tue, 17 Nov 2020 14:03:51 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Bob Peterson <rpeterso@...hat.com>,
        Andreas Gruenbacher <agruenba@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.9 091/255] gfs2: check for live vs. read-only file system in gfs2_fitrim

From: Bob Peterson <rpeterso@...hat.com>

[ Upstream commit c5c68724696e7d2f8db58a5fce3673208d35c485 ]

Before this patch, gfs2_fitrim was not properly checking for a "live" file
system. If the file system had something to trim and the file system
was read-only (or spectator) it would start the trim, but when it starts
the transaction, gfs2_trans_begin returns -EROFS (read-only file system)
and it errors out. However, if the file system was already trimmed so
there's no work to do, it never called gfs2_trans_begin. That code is
bypassed so it never returns the error. Instead, it returns a good
return code with 0 work. All this makes for inconsistent behavior:
The same fstrim command can return -EROFS in one case and 0 in another.
This tripped up xfstests generic/537 which reports the error as:

    +fstrim with unrecovered metadata just ate your filesystem

This patch adds a check for a "live" (iow, active journal, iow, RW)
file system, and if not, returns the error properly.

Signed-off-by: Bob Peterson <rpeterso@...hat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/gfs2/rgrp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 1d65db1b3914a..ac306895bbbcc 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -1374,6 +1374,9 @@ int gfs2_fitrim(struct file *filp, void __user *argp)
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;

+	if (!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
+		return -EROFS;
+
 	if (!blk_queue_discard(q))
 		return -EOPNOTSUPP;

-- 
2.27.0