This is a note to let you know that I've just added the patch titled
btrfs: add dmesg output for first mount and last unmount of a filesystem
to the 5.15-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:
btrfs-add-dmesg-output-for-first-mount-and-last-unmount-of-a-filesystem.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2db313205f8b96eea467691917138d646bb50aef Mon Sep 17 00:00:00 2001
From: Qu Wenruo <wqu@xxxxxxxx>
Date: Thu, 2 Nov 2023 07:54:50 +1030
Subject: btrfs: add dmesg output for first mount and last unmount of a filesystem
From: Qu Wenruo <wqu@xxxxxxxx>
commit 2db313205f8b96eea467691917138d646bb50aef upstream.
There is a feature request to add dmesg output when unmounting a btrfs.
There are several alternative methods to do the same thing, but with
their own problems:
- Use eBPF to watch btrfs_put_super()/open_ctree()
Not end user friendly, they have to dip their head into the source
code.
- Watch for directory /sys/fs/<uuid>/
This is way more simple, but still requires some simple device -> uuid
lookups. And a script needs to use inotify to watch /sys/fs/.
Compared to all these, directly outputting the information into dmesg
would be the most simple one, with both device and UUID included.
And since we're here, also add the output when mounting a filesystem for
the first time for parity. A more fine grained monitoring of subvolume
mounts should be done by another layer, like audit.
Now mounting a btrfs with all default mkfs options would look like this:
[81.906566] BTRFS info (device dm-8): first mount of filesystem 633b5c16-afe3-4b79-b195-138fe145e4f2
[81.907494] BTRFS info (device dm-8): using crc32c (crc32c-intel) checksum algorithm
[81.908258] BTRFS info (device dm-8): using free space tree
[81.912644] BTRFS info (device dm-8): auto enabling async discard
[81.913277] BTRFS info (device dm-8): checking UUID tree
[91.668256] BTRFS info (device dm-8): last unmount of filesystem 633b5c16-afe3-4b79-b195-138fe145e4f2
CC: stable@xxxxxxxxxxxxxxx # 5.4+
Link: https://github.com/kdave/btrfs-progs/issues/689
Reviewed-by: Anand Jain <anand.jain@xxxxxxxxxx>
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/disk-io.c | 1 +
fs/btrfs/super.c | 5 ++++-
2 files changed, 5 insertions(+), 1 deletion(-)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3204,6 +3204,7 @@ int __cold open_ctree(struct super_block
goto fail_alloc;
}
+ btrfs_info(fs_info, "first mount of filesystem %pU", disk_super->fsid);
/*
* Verify the type first, if that or the checksum value are
* corrupted, we'll find out
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -337,7 +337,10 @@ void __btrfs_panic(struct btrfs_fs_info
static void btrfs_put_super(struct super_block *sb)
{
- close_ctree(btrfs_sb(sb));
+ struct btrfs_fs_info *fs_info = btrfs_sb(sb);
+
+ btrfs_info(fs_info, "last unmount of filesystem %pU", fs_info->fs_devices->fsid);
+ close_ctree(fs_info);
}
enum {
Patches currently in stable-queue which might be from wqu@xxxxxxxx are
queue-5.15/btrfs-add-dmesg-output-for-first-mount-and-last-unmount-of-a-filesystem.patch
