[PATCH 0/14 v4] audit: Fix various races when tagging and untagging mounts

[Jan Kara]

Hello,

this is the fourth revision of the series that addresses problems I have
identified when trying to understand how exactly is kernel/audit_tree.c using
generic fsnotify framework. I hope I have understood all the interactions right
but careful review is certainly welcome.

The patches have been tested by a stress test I have written which mounts &
unmounts filesystems in the directory tree while adding and removing audit
rules for this tree in parallel and accessing the tree to generate events.

Note that after running the stress test for ~10 hours, the kernel crashed in
shmem_evict_inode() but I have tracked that down to an independent bug in
fsnotify infrastructure which I'll fix separately and push the fix through
my tree.

Changes since v3:
* Renamed mark to amark in alloc_mark()
* Fixed intermediate compilation breakage in one patch
* Fixed possible lockup due to prune_one() racing with
  audit_tree_freeing_mark() and never making progress
* Simplified locking around untag_chunk()
* Fixed list corruption of chunk->trees list when tag_chunk() added a tree to
  chunk->trees and then replace_chunk() called
  list_replace(&old->trees, &chunk->trees);
* I've dropped the patch for audit testsuite from this posting since it
  didn't change since v2 and Paul picked it up AFAIU.
* Added reviewed-by tags for unchanged patches

Changes since v2:
* Fixed up mark freeing to use proper pointer as pointed out by Amir
* Changed some naming based on Paul's review

Changes since v1:
* Split the last patch to ease review
* Rewrite test script so that it can be included in audit testsuite
* Some cleanups and improvements suggested by Amir

								Honza