From: Gang He ghe@suse.com
[ Upstream commit 9673e0050c39b0534d0e2ca431223f52089f4959 ]
Usually, ocfs2_downconvert_lock() function always downconverts dlm lock to the expected level for satisfy dlm bast requests from the other nodes.
But there is a rare situation. When dlm lock conversion is being canceled, ocfs2_downconvert_lock() function will return -EBUSY. You need to be aware that ocfs2_cancel_convert() function is asynchronous in fsdlm implementation.
If we does not requeue this lockres entry, ocfs2 downconvert thread no longer handles this dlm lock bast request. Then, the other nodes will not get the dlm lock again, the current node's process will be blocked when acquire this dlm lock again.
Link: https://lkml.kernel.org/r/20210830044621.12544-1-ghe@suse.com Signed-off-by: Gang He ghe@suse.com Reviewed-by: Joseph Qi joseph.qi@linux.alibaba.com Cc: Mark Fasheh mark@fasheh.com Cc: Joel Becker jlbec@evilplan.org Cc: Junxiao Bi junxiao.bi@oracle.com Cc: Changwei Ge gechangwei@live.cn Cc: Gang He ghe@suse.com Cc: Jun Piao piaojun@huawei.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ocfs2/dlmglue.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c index 8e3a369086db..01cf5211b5c8 100644 --- a/fs/ocfs2/dlmglue.c +++ b/fs/ocfs2/dlmglue.c @@ -18,6 +18,7 @@ #include <linux/debugfs.h> #include <linux/seq_file.h> #include <linux/time.h> +#include <linux/delay.h> #include <linux/quotaops.h> #include <linux/sched/signal.h>
@@ -3906,6 +3907,17 @@ static int ocfs2_unblock_lock(struct ocfs2_super *osb, spin_unlock_irqrestore(&lockres->l_lock, flags); ret = ocfs2_downconvert_lock(osb, lockres, new_level, set_lvb, gen); + /* The dlm lock convert is being cancelled in background, + * ocfs2_cancel_convert() is asynchronous in fs/dlm, + * requeue it, try again later. + */ + if (ret == -EBUSY) { + ctl->requeue = 1; + mlog(ML_BASTS, "lockres %s, ReQ: Downconvert busy\n", + lockres->l_name); + ret = 0; + msleep(20); + }
leave: if (ret)