I am monitoring file operations events (VFS).
I have a problem with BTRFS filesystem, BTRFS is using subvolumes, All highest hierarchy directories in btrfs has the same inode (256/512).
When I receive file operation event, I receive the path and then resolve it to inode.
By resolving I mean: given a path, I get its dentry (user_path() call), from dentry i pull: dEntry->d_inode->i_ino
The problem is I receive same inode for different directories on the same Device.
I guess, BTRFS has some sort of abstraction layer, that create a "virtual" inode number (the identical ones are virtual) - there is no way for two identical inodes on same device id.
Proof for device id issue:
From kernel I receive device id 29:
Code: device id resolving: for a given path (/home) -> Get the dentry with user_path, then dEntry->d_inode->i_sb->s_dev OR I run command:
"grep btrfs /proc/self/mountinfo | less"
/proc/self/mountinfo return inode 29 also: 34 18 0:29 /home /home rw,noatime,nodiratime shared:19 - btrfs /dev/md127 rw,nospace_cache,subvolid=257,subvol=/home
From user space I receive device Id 33:
root@nas-B9-43-AA:/# stat /home File: `/home' Size: 90 Blocks: 0 IO Block: 4096 directory Device: 21h/33d Inode: 256 Links: 1 root@nas-B9-43-AA:/# mountpoint -d /home 0:33
So I get 29 and 33 as device id.
Lets call device id 29 "actual id"", and 33 is "virtual id".
Is there a way to obtain the actual id from kernel code ?
I am looking for replacement to dEntry->d_inode->i_sb->s_dev.. to obtain the same id as we receive from user mode.
I am on Debian 7