This is a note to let you know that I've just added the patch titled
f2fs: fix to drop all discards after creating snapshot on lvm device
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
f2fs-fix-to-drop-all-discards-after-creating-snapsho.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 4b9b904a869202f57de21ba665362b51809569d2
Author: Chao Yu <chao@xxxxxxxxxx>
Date: Thu Nov 21 22:17:16 2024 +0800
f2fs: fix to drop all discards after creating snapshot on lvm device
[ Upstream commit bc8aeb04fd80cb8cfae3058445c84410fd0beb5e ]
Piergiorgio reported a bug in bugzilla as below:
------------[ cut here ]------------
WARNING: CPU: 2 PID: 969 at fs/f2fs/segment.c:1330
RIP: 0010:__submit_discard_cmd+0x27d/0x400 [f2fs]
Call Trace:
__issue_discard_cmd+0x1ca/0x350 [f2fs]
issue_discard_thread+0x191/0x480 [f2fs]
kthread+0xcf/0x100
ret_from_fork+0x31/0x50
ret_from_fork_asm+0x1a/0x30
w/ below testcase, it can reproduce this bug quickly:
- pvcreate /dev/vdb
- vgcreate myvg1 /dev/vdb
- lvcreate -L 1024m -n mylv1 myvg1
- mount /dev/myvg1/mylv1 /mnt/f2fs
- dd if=/dev/zero of=/mnt/f2fs/file bs=1M count=20
- sync
- rm /mnt/f2fs/file
- sync
- lvcreate -L 1024m -s -n mylv1-snapshot /dev/myvg1/mylv1
- umount /mnt/f2fs
The root cause is: it will update discard_max_bytes of mounted lvm
device to zero after creating snapshot on this lvm device, then,
__submit_discard_cmd() will pass parameter @nr_sects w/ zero value
to __blkdev_issue_discard(), it returns a NULL bio pointer, result
in panic.
This patch changes as below for fixing:
1. Let's drop all remained discards in f2fs_unfreeze() if snapshot
of lvm device is created.
2. Checking discard_max_bytes before submitting discard during
__submit_discard_cmd().
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 35ec7d574884 ("f2fs: split discard command in prior to block layer")
Reported-by: Piergiorgio Sartor <piergiorgio.sartor@xxxxxxxx>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219484
Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 670104628ddbe..156d92b945258 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1282,6 +1282,15 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
}
#endif
+ /*
+ * stop issuing discard for any of below cases:
+ * 1. device is conventional zone, but it doesn't support discard.
+ * 2. device is regulare device, after snapshot it doesn't support
+ * discard.
+ */
+ if (!bdev_max_discard_sectors(bdev))
+ return -EOPNOTSUPP;
+
trace_f2fs_issue_discard(bdev, dc->di.start, dc->di.len);
lstart = dc->di.lstart;
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index f05d0e43db9e2..b72fa103b9632 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1735,6 +1735,18 @@ static int f2fs_freeze(struct super_block *sb)
static int f2fs_unfreeze(struct super_block *sb)
{
+ struct f2fs_sb_info *sbi = F2FS_SB(sb);
+
+ /*
+ * It will update discard_max_bytes of mounted lvm device to zero
+ * after creating snapshot on this lvm device, let's drop all
+ * remained discards.
+ * We don't need to disable real-time discard because discard_max_bytes
+ * will recover after removal of snapshot.
+ */
+ if (test_opt(sbi, DISCARD) && !f2fs_hw_support_discard(sbi))
+ f2fs_issue_discard_timeout(sbi);
+
clear_sbi_flag(F2FS_SB(sb), SBI_IS_FREEZING);
return 0;
}
