Adding a log_overlay filesystem layer. It passes through all calls to the other

layer(s) and logs a timestamp, the thread id, the super volume or super vnode
and interesting bits about call arguments/results to a file (in /var/log). This
can be used for example to debug filesystems without having to manually add
debug output to all the calls, or to analyze access patterns. To add the logging
layer just mount the layer with whatever actual filesystem you have:

  mount -t "bfs:log_overlay" /dev/disk/usb/0/0/0 /mountpoint

This would then create the logfile /var/log/log_overlay_dev_disk_usb_0_0_0.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35194 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/kernel/file_systems/layers/Jamfile

@@ -1,4 +1,5 @@
 SubDir HAIKU_TOP src add-ons kernel file_systems layers ;
 
 SubInclude HAIKU_TOP src add-ons kernel file_systems layers attribute_overlay ;
+SubInclude HAIKU_TOP src add-ons kernel file_systems layers log_overlay ;
 SubInclude HAIKU_TOP src add-ons kernel file_systems layers write_overlay ;

src/add-ons/kernel/file_systems/layers/log_overlay/Jamfile

@@ -0,0 +1,7 @@
+SubDir HAIKU_TOP src add-ons kernel file_systems layers log_overlay ;
+
+UsePrivateKernelHeaders ;
+
+KernelAddon log_overlay :
+	log_overlay.cpp
+	;