From b743612c0aaa49a781f1f0c760e35d7298b5c5b4 Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Tue, 12 Sep 2023 17:53:19 -0400 Subject: lockd: don't call vfs_lock_file() for pending requests This patch returns nlm_lck_blocked in nlmsvc_lock() when an asynchronous lock request is pending. During testing I ran into the case with the side-effects that lockd is waiting for only one lm_grant() callback because it's already part of the nlm_blocked list. If another asynchronous for the same nlm_block is triggered two lm_grant() callbacks will occur but lockd was only waiting for one. To avoid any change of existing users this handling will only being made when export_op_support_safe_async_lock() returns true. Reviewed-by: Jeff Layton Signed-off-by: Alexander Aring Signed-off-by: Chuck Lever --- fs/lockd/svclock.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) (limited to 'fs/lockd') diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c index d500e32ebb18..c313622a9578 100644 --- a/fs/lockd/svclock.c +++ b/fs/lockd/svclock.c @@ -541,6 +541,22 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, goto out; } + spin_lock(&nlm_blocked_lock); + /* + * If this is a lock request for an already pending + * lock request we return nlm_lck_blocked without calling + * vfs_lock_file() again. Otherwise we have two pending + * requests on the underlaying ->lock() implementation but + * only one nlm_block to being granted by lm_grant(). + */ + if (exportfs_lock_op_is_async(inode->i_sb->s_export_op) && + !list_empty(&block->b_list)) { + spin_unlock(&nlm_blocked_lock); + ret = nlm_lck_blocked; + goto out; + } + spin_unlock(&nlm_blocked_lock); + if (!wait) lock->fl.fl_flags &= ~FL_SLEEP; mode = lock_to_openmode(&lock->fl); @@ -553,13 +569,6 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, ret = nlm_granted; goto out; case -EAGAIN: - /* - * If this is a blocking request for an - * already pending lock request then we need - * to put it back on lockd's block list - */ - if (wait) - break; ret = async_block ? nlm_lck_blocked : nlm_lck_denied; goto out; case FILE_LOCK_DEFERRED: -- cgit v1.2.3