[PATCH] fuse: add a dev ioctl for recovery

[Hao Peng <flyingpenghao@xxxxxxxxx>]

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 can be realized by putting the request of the processing
list back into the pending list.

Signed-off-by: Peng Hao <flyingpeng@xxxxxxxxxxx>
---
 fs/fuse/dev.c             | 38 +++++++++++++++++++++++++++++++++++++-
 include/uapi/linux/fuse.h |  1 +
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 491c092d427b..8e1b69a5b503 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -2239,7 +2239,7 @@ static int fuse_device_clone(struct fuse_conn
*fc, struct file *new)
 static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
                           unsigned long arg)
 {
-       int res;
+       int res = 0;
        int oldfd;
        struct fuse_dev *fud = NULL;

@@ -2268,6 +2268,42 @@ static long fuse_dev_ioctl(struct file *file,
unsigned int cmd,
                        }
                }
                break;
+
+       case FUSE_DEV_IOC_RECOVERY:
+       {
+               struct fuse_iqueue *fiq;
+               struct fuse_pqueue *fpq;
+               struct fuse_req *req, *next;
+               LIST_HEAD(recovery);
+               unsigned int i;
+
+               fud = fuse_get_dev(file);
+               fiq = &fud->fc->iq;
+               fpq = &fud->pq;
+
+               spin_lock(&fpq->lock);
+               list_for_each_entry_safe(req, next, &fpq->io, list) {
+                       spin_lock(&req->waitq.lock);
+                       clear_bit(FR_LOCKED, &req->flags);
+                       list_move(&req->list, &recovery);
+                       spin_unlock(&req->waitq.lock);
+               }
+               for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
+                       list_splice_tail_init(&fpq->processing[i],
+                                             &recovery);
+               list_for_each_entry_safe(req, next, &recovery, list) {
+                       clear_bit(FR_SENT, &req->flags);
+               }
+               spin_unlock(&fpq->lock);
+
+               spin_lock(&fiq->lock);
+               list_for_each_entry_safe(req, next, &recovery, list) {
+                       set_bit(FR_PENDING, &req->flags);
+               }
+               list_splice(&recovery, &fiq->pending);
+               spin_unlock(&fiq->lock);
+               break;
+       }
        default:
                res = -ENOTTY;
                break;
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 36ed092227fa..fc07324efa9d 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -923,6 +923,7 @@ struct fuse_notify_retrieve_in {
 /* Device ioctls: */
 #define FUSE_DEV_IOC_MAGIC             229
 #define FUSE_DEV_IOC_CLONE             _IOR(FUSE_DEV_IOC_MAGIC, 0, uint32_t)
+#define FUSE_DEV_IOC_RECOVERY          _IOR(FUSE_DEV_IOC_MAGIC+1, 0, uint32_t)

 struct fuse_lseek_in {
        uint64_t        fh;
--
2.27.0