From e1c207b3e7cdfd98ce1120a38c979d748e95f958 Mon Sep 17 00:00:00 2001
From: Peng Hao <flyingpeng@tencent.com>
Date: Tue, 12 Oct 2021 09:22:27 +0800
Subject: [PATCH] fuse: add a dev ioctl for recovery

 For a simple read-only file system, as long as the connection
 is not broken, the recovery of the user-mode read-only file
 system process can be realized by putting the request of the
 processing list back into the pending list.

Signed-off-by: Peng Hao <flyingpeng@tencent.com>
---
 fs/fuse/dev.c             | 24 ++++++++++++++++++++++++
 include/uapi/linux/fuse.h |  1 +
 2 files changed, 25 insertions(+)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 40c262b3f..adc8e6b5e 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -2255,6 +2255,30 @@ static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
 			}
 		}
 	}
+	if (cmd == FUSE_DEV_IOC_RECOVERY) {
+		struct fuse_dev *fud = fuse_get_dev(file);
+		struct fuse_iqueue *fiq = &fud->fc->iq;
+		struct fuse_pqueue *fpq = &fud->pq;
+		struct fuse_req *req, *next;
+		LIST_HEAD(recovery);
+		unsigned int i;
+
+		spin_lock(&fpq->lock);
+		for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
+			list_splice_tail_init(&fpq->processing[i],
+					      &recovery);
+		spin_unlock(&fpq->lock);
+
+		list_for_each_entry_safe(req, next, &recovery, list) {
+			clear_bit(FR_SENT, &req->flags);
+			set_bit(FR_PENDING, &req->flags);
+		}
+
+		spin_lock(&fiq->lock);
+		list_splice(&recovery, &fiq->pending);
+		spin_unlock(&fiq->lock);
+		err = 0;
+        }
 	return err;
 }
 
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 373cada89..3ebc07e2e 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -870,6 +870,7 @@ struct fuse_notify_retrieve_in {
 
 /* Device ioctls: */
 #define FUSE_DEV_IOC_CLONE	_IOR(229, 0, uint32_t)
+#define FUSE_DEV_IOC_RECOVERY   _IOR(230, 0, uint32_t)
 
 struct fuse_lseek_in {
 	uint64_t	fh;