[PATCH 1/3] ima: Remove inode lock

[Shu Han]

> Finally, expand the critical region in process_measurement() guarded by
> iint->mutex up to where the inode was locked, use only one iint lock in
> __ima_inode_hash(), since the mutex is now in the inode security blob, and
> replace the inode_lock()/inode_unlock() calls in ima_check_last_writer().

I am not familiar with this, so the following statement may be inaccurate:

I suspect that modifying the `i_flags` field through
`inode->i_flags |= S_IMA;` in `ima_inode_get` may cause a
race, as this patch removes the write lock for inodes in
process_measurement().

For example, swapon() adds the S_SWAPFILE tag under inode write lock's
protection.

Perhaps this initialization tag(`S_IMA`) can also be moved into inode's
security blob.