e1f493235e
- Implement real draining for vfs consumers by not relying on the mnt_lock and using instead a refcount in order to keep track of lock requesters. - Due to the change above, remove the mnt_lock lockmgr because it is now useless. - Due to the change above, vfs_busy() is no more linked to a lockmgr. Change so its KPI by removing the interlock argument and defining 2 new flags for it: MBF_NOWAIT which basically replaces the LK_NOWAIT of the old version (which was unlinked from the lockmgr alredy) and MBF_MNTLSTLOCK which provides the ability to drop the mountlist_mtx once the mnt interlock is held (ability still desired by most consumers). - The stub used into vfs_mount_destroy(), that allows to override the mnt_ref if running for more than 3 seconds, make it totally useless. Remove it as it was thought to work into older versions. If a problem of "refcount held never going away" should appear, we will need to fix properly instead than trust on such hackish solution. - Fix a bug where returning (with an error) from dounmount() was still leaving the MNTK_MWAIT flag on even if it the waiters were actually woken up. Just a place in vfs_mount_destroy() is left because it is going to recycle the structure in any case, so it doesn't matter. - Remove the markercnt refcount as it is useless. This patch modifies VFS ABI and breaks KPI for vfs_busy() so manpages and __FreeBSD_version will be modified accordingly. Discussed with: kib Tested by: pho |
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