On 6/28/21 1:23 PM, J. Bruce Fields wrote:
On Thu, Jun 03, 2021 at 02:14:38PM -0400, Dai Ngo wrote:@@ -6875,7 +6947,12 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, case -EAGAIN: /* conflock holds conflicting lock */ status = nfserr_denied; dprintk("NFSD: nfsd4_lock: conflicting lock found!\n"); - nfs4_set_lock_denied(conflock, &lock->lk_denied); + + /* try again if conflict with courtesy client */ + if (nfs4_set_lock_denied(conflock, &lock->lk_denied) == -EAGAIN && !retried) { + retried = true; + goto again; + }Ugh, apologies, this was my idea, but I just noticed it only handles conflicts from other NFSv4 clients. The conflicting lock could just as well come from NLM or a local process. So we need cooperation from the common locks.c code. I'm not sure what to suggest.... Maybe something like: @@ -1159,6 +1159,7 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request, }percpu_down_read(&file_rwsem);+retry: spin_lock(&ctx->flc_lock); /* * New lock request. Walk all POSIX locks and look for conflicts. If @@ -1169,6 +1170,11 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request, list_for_each_entry(fl, &ctx->flc_posix, fl_list) { if (!posix_locks_conflict(request, fl)) continue; + if (fl->fl_lops->fl_expire_lock(fl, 1)) { + spin_unlock(&ctx->flc_lock); + fl->fl_lops->fl_expire_locks(fl, 0); + goto retry; + } if (conflock) locks_copy_conflock(conflock, fl); error = -EAGAIN; where ->fl_expire_lock is a new lock callback with second argument "check" where: check = 1 means: just check whether this lock could be freed check = 0 means: go ahead and free this lock if you can
Thanks Bruce, I will look into this approach. -Dai
--b.
