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A long, complicated sequence of events, beginning with the RESEND flag not being cleared on an lkb, can result in an unlock never completing. - lkb on waiters list for remote lookup - the remote node is both the dir node and the master node, so it optimizes the lookup into a request and sends a request reply back - the request reply is saved on the requestqueue to be processed after recovery - recovery runs dlm_recover_waiters_pre() which sets RESEND flag so the lookup will be resent after recovery - end of recovery: process_requestqueue takes saved request reply which removes the lkb off the waitesr list, _without_ clearing the RESEND flag - end of recovery: dlm_recover_waiters_post() doesn't do anything with the now completed lookup lkb (would usually clear RESEND) - later, the node unmounts, unlocks this lkb that still has RESEND flag set - the lkb is on the waiters list again, now for unlock, when recovery occurs, dlm_recover_waiters_pre() shows the lkb for unlock with RESEND set, doesn't do anything since the master still exists - end of recovery: dlm_recover_waiters_post() takes this lkb off the waiters list because it has the RESEND flag set, then reports an error because unlocks are never supposed to be handled in recover_waiters_post(). - later, the unlock reply is received, doesn't find the lkb on the waiters list because recover_waiters_post() has wrongly removed it. - the unlock operation has been lost, and we're left with a stray granted lock - unmount spins waiting for the unlock to complete The visible evidence of this problem will be a node where gfs umount is spinning, the dlm waiters list will be empty, and the dlm locks list will show a granted lock. The fix is simply to clear the RESEND flag when taking an lkb off the waiters list. Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> |
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| .. | ||
| ast.c | ||
| ast.h | ||
| config.c | ||
| config.h | ||
| debug_fs.c | ||
| dir.c | ||
| dir.h | ||
| dlm_internal.h | ||
| Kconfig | ||
| lock.c | ||
| lock.h | ||
| lockspace.c | ||
| lockspace.h | ||
| lowcomms-sctp.c | ||
| lowcomms-tcp.c | ||
| lowcomms.h | ||
| lvb_table.h | ||
| main.c | ||
| Makefile | ||
| member.c | ||
| member.h | ||
| memory.c | ||
| memory.h | ||
| midcomms.c | ||
| midcomms.h | ||
| rcom.c | ||
| rcom.h | ||
| recover.c | ||
| recover.h | ||
| recoverd.c | ||
| recoverd.h | ||
| requestqueue.c | ||
| requestqueue.h | ||
| user.c | ||
| user.h | ||
| util.c | ||
| util.h | ||