[PATCH] btrfs: add mount umount logs

[PATCH] btrfs: add mount umount logs

[Anand Jain]

By looking at the logs we should be able to know when the FS was
mounted and unmounted and the options used, so to help forensic
investigations.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/super.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 827a8305da50..a123bc46b521 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1408,6 +1408,17 @@ static char *setup_root_args(char *args)
 	return buf;
 }
 
+static void print_mount_info(struct btrfs_fs_info *info, int flag, char *opt,
+		char *prefix)
+{
+	char f[10] = {0};
+
+	if (flag & MS_RDONLY)
+		strcpy(f, "rdonly");
+
+	btrfs_notice(info, "%s: flags:%s opt:%s\n", prefix, f, opt);
+}
+
 static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
 				   int flags, const char *device_name,
 				   char *data)
@@ -1502,6 +1513,8 @@ static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
 			dput(root);
 			root = ERR_PTR(ret);
 			deactivate_locked_super(s);
+		} else {
+			print_mount_info(fs_info, flags, data, "mount");
 		}
 	}
 
@@ -1882,6 +1895,9 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 out:
 	wake_up_process(fs_info->transaction_kthread);
 	btrfs_remount_cleanup(fs_info, old_opts);
+
+	print_mount_info(fs_info, *flags, data, "remount");
+
 	return 0;
 
 restore:
@@ -2212,6 +2228,7 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 static void btrfs_kill_super(struct super_block *sb)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
+	btrfs_notice(fs_info, "%s\n", "unmount");
 	kill_anon_super(sb);
 	free_fs_info(fs_info);
 }
-- 
2.10.0

Re: [PATCH] btrfs: add mount umount logs

[Qu Wenruo]

Yes, this is indeed a nice feature.

But what about only outputting this info when BTRFS_DEBUG is selected?
I'm sure there will be some guys not liking such kernel message flooding 
everywhere when doing testing.

Thanks,
Qu

At 05/16/2017 04:41 PM, Anand Jain wrote:
> By looking at the logs we should be able to know when the FS was
> mounted and unmounted and the options used, so to help forensic
> investigations.
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>   fs/btrfs/super.c | 17 +++++++++++++++++
>   1 file changed, 17 insertions(+)
> 
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 827a8305da50..a123bc46b521 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -1408,6 +1408,17 @@ static char *setup_root_args(char *args)
>   	return buf;
>   }
>   
> +static void print_mount_info(struct btrfs_fs_info *info, int flag, char *opt,
> +		char *prefix)
> +{
> +	char f[10] = {0};
> +
> +	if (flag & MS_RDONLY)
> +		strcpy(f, "rdonly");

Isn't "ro" more common?

Thanks,
Qu

> +
> +	btrfs_notice(info, "%s: flags:%s opt:%s\n", prefix, f, opt);
> +}
> +
>   static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
>   				   int flags, const char *device_name,
>   				   char *data)
> @@ -1502,6 +1513,8 @@ static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
>   			dput(root);
>   			root = ERR_PTR(ret);
>   			deactivate_locked_super(s);
> +		} else {
> +			print_mount_info(fs_info, flags, data, "mount");
>   		}
>   	}
>   
> @@ -1882,6 +1895,9 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
>   out:
>   	wake_up_process(fs_info->transaction_kthread);
>   	btrfs_remount_cleanup(fs_info, old_opts);
> +
> +	print_mount_info(fs_info, *flags, data, "remount");
> +
>   	return 0;
>   
>   restore:
> @@ -2212,6 +2228,7 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
>   static void btrfs_kill_super(struct super_block *sb)
>   {
>   	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
> +	btrfs_notice(fs_info, "%s\n", "unmount");
>   	kill_anon_super(sb);
>   	free_fs_info(fs_info);
>   }
> 

Re: [PATCH] btrfs: add mount umount logs

[David Sterba]

On Tue, May 16, 2017 at 04:41:49PM +0800, Anand Jain wrote:
> By looking at the logs we should be able to know when the FS was
> mounted and unmounted and the options used, so to help forensic
> investigations.

Could be a useful feature, but you're adding it to the wrong layer.

Re: [PATCH] btrfs: add mount umount logs

[Anand Jain]

On 05/16/2017 05:25 PM, Qu Wenruo wrote:
> Yes, this is indeed a nice feature.
>
> But what about only outputting this info when BTRFS_DEBUG is selected?
> I'm sure there will be some guys not liking such kernel message flooding
> everywhere when doing testing.

  Thanks. Will keep in mind to make that changes if received confirmed 
objection.

Thanks. Anand


> Thanks,
> Qu
>
> At 05/16/2017 04:41 PM, Anand Jain wrote:
>> By looking at the logs we should be able to know when the FS was
>> mounted and unmounted and the options used, so to help forensic
>> investigations.
>>
>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>> ---
>>   fs/btrfs/super.c | 17 +++++++++++++++++
>>   1 file changed, 17 insertions(+)
>>
>> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
>> index 827a8305da50..a123bc46b521 100644
>> --- a/fs/btrfs/super.c
>> +++ b/fs/btrfs/super.c
>> @@ -1408,6 +1408,17 @@ static char *setup_root_args(char *args)
>>       return buf;
>>   }
>>   +static void print_mount_info(struct btrfs_fs_info *info, int flag,
>> char *opt,
>> +        char *prefix)
>> +{
>> +    char f[10] = {0};
>> +
>> +    if (flag & MS_RDONLY)
>> +        strcpy(f, "rdonly");
>
> Isn't "ro" more common?
>
> Thanks,
> Qu
>
>> +
>> +    btrfs_notice(info, "%s: flags:%s opt:%s\n", prefix, f, opt);
>> +}
>> +
>>   static struct dentry *mount_subvol(const char *subvol_name, u64
>> subvol_objectid,
>>                      int flags, const char *device_name,
>>                      char *data)
>> @@ -1502,6 +1513,8 @@ static struct dentry *mount_subvol(const char
>> *subvol_name, u64 subvol_objectid,
>>               dput(root);
>>               root = ERR_PTR(ret);
>>               deactivate_locked_super(s);
>> +        } else {
>> +            print_mount_info(fs_info, flags, data, "mount");
>>           }
>>       }
>>   @@ -1882,6 +1895,9 @@ static int btrfs_remount(struct super_block
>> *sb, int *flags, char *data)
>>   out:
>>       wake_up_process(fs_info->transaction_kthread);
>>       btrfs_remount_cleanup(fs_info, old_opts);
>> +
>> +    print_mount_info(fs_info, *flags, data, "remount");
>> +
>>       return 0;
>>     restore:
>> @@ -2212,6 +2228,7 @@ static int btrfs_statfs(struct dentry *dentry,
>> struct kstatfs *buf)
>>   static void btrfs_kill_super(struct super_block *sb)
>>   {
>>       struct btrfs_fs_info *fs_info = btrfs_sb(sb);
>> +    btrfs_notice(fs_info, "%s\n", "unmount");
>>       kill_anon_super(sb);
>>       free_fs_info(fs_info);
>>   }
>>
>
>
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Re: [PATCH] btrfs: add mount umount logs

[Anand Jain]

On 05/16/2017 07:23 PM, David Sterba wrote:
> On Tue, May 16, 2017 at 04:41:49PM +0800, Anand Jain wrote:
>> By looking at the logs we should be able to know when the FS was
>> mounted and unmounted and the options used, so to help forensic
>> investigations.
>
> Could be a useful feature, but you're adding it to the wrong layer.

  Ok proposing to be added to the vfs layer.

Thanks, Anand


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