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 <jlayton@xxxxxxxxxx>
Signed-off-by: Alexander Aring <aahringo@xxxxxxxxxx>
---
fs/lockd/svclock.c | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)
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:
--
2.31.1
