Re: [libvirt] [PATCH v4 06/15] security_manager: Rework metadata locking

On 11/14/18 7:44 AM, Michal Privoznik wrote: > Trying to use virlockd to lock metadata turns out to be too big > gun. Since we will always spawn a separate process for relabeling > we are safe to use thread unsafe POSIX locks and take out > virtlockd completely out of the picture. > NB: This patch has a 1 second delay loop in the event the lock is already taken by another thread. Since it's not expected that threads holding the lock will need more than a second or two to process the various file security operations, it was felt this was a good starting point. The time taken to execute has two factors - the number of files to be locked and the time the operation required by the security driver to perform it's operation. Usage of virTimeBackOffStart may or may not help. Similarly a configurable delay time or delay maximum time is also possible, but was deemed unnecessary at this time.

[fair enough statement?? - pick and choose if you want to add all, any part, or none of it... I think it's a fair representation for someone coming along and looking at this commit to consider if they wanted to make a change to help perceived performance if the delay loop becomes that type of problem. It's not that it wasn't considered, it just wasn't easily quantifiable]. > Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; > --- > src/security/security_dac.c | 12 +- > src/security/security_manager.c | 225 +++++++++++++++++--------------- > src/security/security_manager.h | 17 ++- > src/security/security_selinux.c | 11 +- > 4 files changed, 141 insertions(+), 124 deletions(-) > Reviewed-by: John Ferlan <jferlan(a)redhat.com&gt;