Cherrypick 2 snapshot fixes for 2.1.13 #15187
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On Linux, sometimes, when ZFS goes to unmount an automounted snap, it fails a VERIFY check on debug builds, because taskq_cancel_id returned ENOENT after not finding the taskq it was trying to cancel. This presumably happens when it already died for some reason; in this case, we don't really mind it already being dead, since we're just going to dispatch a new task to unmount it right after. So we just ignore it if we get back ENOENT trying to cancel here, retry a couple times if we get back the only other possible condition (EBUSY), and log to dbgmsg if we got anything but ENOENT or success. (We also add some locking around taskqid, to avoid one or two cases of two instances of trying to cancel something at once.) Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Tony Nguyen <[email protected]> Signed-off-by: Rich Ercolani <[email protected]> Closes openzfs#11632 Closes openzfs#12670
Unfortunately, even after e79b680, I still, much more rarely, tripped asserts when playing with many ctldir mounts at once. Since this appears to happen if we dispatched twice too fast, just ignore it. We don't actually need to do anything if someone already started doing it for us. Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Rich Ercolani <[email protected]> Closes openzfs#14462
behlendorf
approved these changes
Aug 25, 2023
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Motivation and Context
Someone pinged #13327 and I noticed I never got either of these into 2.1. Oops.
Description
See #12670 and #14462, but briefly, sometimes you can wind up with snapshots never getting cleaned up because the unmount fails, and on debug builds, you can trip asserts racing yourself to unmount.
How Has This Been Tested?
I've been running this as a local patchset for a long time now, but never pushed it to upstream 2.1. Oopsie.
Types of changes
Checklist:
Signed-off-by.