linux-kernel - [PATCH 1/2] f2fs: fix return value of f2fs_recover_fsync

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Message-ID: <20251105065023.3656975-1-chao@kernel.org>
Date: Wed,  5 Nov 2025 14:50:22 +0800
From: Chao Yu <chao@...nel.org>
To: jaegeuk@...nel.org
Cc: linux-f2fs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org,
	Chao Yu <chao@...nel.org>,
	stable@...nel.org
Subject: [PATCH 1/2] f2fs: fix return value of f2fs_recover_fsync_data()

With below scripts, it will trigger panic in f2fs:

mkfs.f2fs -f /dev/vdd
mount /dev/vdd /mnt/f2fs
touch /mnt/f2fs/foo
sync
echo 111 >> /mnt/f2fs/foo
f2fs_io fsync /mnt/f2fs/foo
f2fs_io shutdown 2 /mnt/f2fs
umount /mnt/f2fs
mount -o ro,norecovery /dev/vdd /mnt/f2fs
or
mount -o ro,disable_roll_forward /dev/vdd /mnt/f2fs

F2FS-fs (vdd): f2fs_recover_fsync_data: recovery fsync data, check_only: 0
F2FS-fs (vdd): Mounted with checkpoint version = 7f5c361f
F2FS-fs (vdd): Stopped filesystem due to reason: 0
F2FS-fs (vdd): f2fs_recover_fsync_data: recovery fsync data, check_only: 1
Filesystem f2fs get_tree() didn't set fc->root, returned 1
------------[ cut here ]------------
kernel BUG at fs/super.c:1761!
Oops: invalid opcode: 0000 [#1] SMP PTI
CPU: 3 UID: 0 PID: 722 Comm: mount Not tainted 6.18.0-rc2+ #721 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:vfs_get_tree.cold+0x18/0x1a
Call Trace:
 <TASK>
 fc_mount+0x13/0xa0
 path_mount+0x34e/0xc50
 __x64_sys_mount+0x121/0x150
 do_syscall_64+0x84/0x800
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fa6cc126cfe

The root cause is we missed to handle error number returned from
f2fs_recover_fsync_data() when mounting image w/ ro,norecovery or
ro,disable_roll_forward mount option, result in returning a positive
error number to vfs_get_tree(), fix it.

Cc: stable@...nel.org
Fixes: 6781eabba1bd ("f2fs: give -EINVAL for norecovery and rw mount")
Signed-off-by: Chao Yu <chao@...nel.org>
---
 fs/f2fs/super.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 0b0ef8ba243b..8cf98c40b160 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -5211,11 +5211,15 @@ static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc)
 		}
 	} else {
 		err = f2fs_recover_fsync_data(sbi, true);
-
-		if (!f2fs_readonly(sb) && err > 0) {
-			err = -EINVAL;
-			f2fs_err(sbi, "Need to recover fsync data");
-			goto free_meta;
+		if (err > 0) {
+			if (!f2fs_readonly(sb)) {
+				f2fs_err(sbi, "Need to recover fsync data");
+				err = -EINVAL;
+				goto free_meta;
+			} else {
+				f2fs_info(sbi, "drop all fsynced data");
+				err = 0;
+			}
 		}
 	}
 
-- 
2.49.0