From: Qu Wenruo wqu@suse.com
stable inclusion from stable-v6.6.5 commit 9f7894e299140bb0e52c099ebb0813f4b3f3cfb0 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8N21P
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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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@vger.kernel.org # 5.4+ Link: https://github.com/kdave/btrfs-progs/issues/689 Reviewed-by: Anand Jain anand.jain@oracle.com Signed-off-by: Qu Wenruo wqu@suse.com Reviewed-by: David Sterba dsterba@suse.com [ update changelog ] Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- fs/btrfs/disk-io.c | 1 + fs/btrfs/super.c | 5 ++++- 2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 6b78517b1fd5..71efb6883f30 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3197,6 +3197,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device 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 diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 1a093ec0f7e3..de0bfebce126 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -79,7 +79,10 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data);
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 {