On Thu, Jun 06, 2019 at 10:41:59AM +0100, David Howells wrote:

Hi Al,

Here's a set of patches to add a general variable-length notification queue
concept and to add sources of events for:

 (1) Mount topology events, such as mounting, unmounting, mount expiry,
     mount reconfiguration.

 (2) Superblock events, such as R/W<->R/O changes, quota overrun and I/O
     errors (not complete yet).

 (3) Key/keyring events, such as creating, linking and removal of keys.

 (4) General device events (single common queue) including:

     - Block layer events, such as device errors

     - USB subsystem events, such as device/bus attach/remove, device
       reset, device errors.

One of the reasons for this is so that we can remove the issue of processes
having to repeatedly and regularly scan /proc/mounts, which has proven to
be a system performance problem.  To further aid this, the fsinfo() syscall
on which this patch series depends, provides a way to access superblock and
mount information in binary form without the need to parse /proc/mounts.


LSM support is included, but controversial:

Apart from the LSM/security controversy here the general direction of
this patchset is pretty well received it seems.
Imho, having a notification mechanism like this is a very good thing for
userspace. So would be great if there'd be a consensus on the LSM bits.

Christian