Merge tag 'fuse-update-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse

Pull fuse updates from Miklos Szeredi:

 - Allow mounting an active fuse device. Previously the fuse device
   would always be mounted during initialization, and sharing a fuse
   superblock was only possible through mount or namespace cloning

 - Fix data flushing in syncfs (virtiofs only)

 - Fix data flushing in copy_file_range()

 - Fix a possible deadlock in atomic O_TRUNC

 - Misc fixes and cleanups

* tag 'fuse-update-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  fuse: remove unused arg in fuse_write_file_get()
  fuse: wait for writepages in syncfs
  fuse: flush extending writes
  fuse: truncate pagecache on atomic_o_trunc
  fuse: allow sharing existing sb
  fuse: move fget() to fuse_get_tree()
  fuse: move option checking into fuse_fill_super()
  fuse: name fs_context consistently
  fuse: fix use after free in fuse_read_interrupt()

1 files changed, 20 insertions, 0 deletions

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 3d18556a01ad..319596df5dc6 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -482,6 +482,7 @@ struct fuse_dev {
 
 struct fuse_fs_context {
 	int fd;
+	struct file *file;
 	unsigned int rootmode;
 	kuid_t user_id;
 	kgid_t group_id;
@@ -508,6 +509,13 @@ struct fuse_fs_context {
 	void **fudptr;
 };
 
+struct fuse_sync_bucket {
+	/* count is a possible scalability bottleneck */
+	atomic_t count;
+	wait_queue_head_t waitq;
+	struct rcu_head rcu;
+};
+
 /**
  * A Fuse connection.
  *
@@ -800,6 +808,9 @@ struct fuse_conn {
 
 	/** List of filesystems using this connection */
 	struct list_head mounts;
+
+	/* New writepages go into this bucket */
+	struct fuse_sync_bucket __rcu *curr_bucket;
 };
 
 /*
@@ -903,6 +914,15 @@ static inline void fuse_page_descs_length_init(struct fuse_page_desc *descs,
 		descs[i].length = PAGE_SIZE - descs[i].offset;
 }
 
+static inline void fuse_sync_bucket_dec(struct fuse_sync_bucket *bucket)
+{
+	/* Need RCU protection to prevent use after free after the decrement */
+	rcu_read_lock();
+	if (atomic_dec_and_test(&bucket->count))
+		wake_up(&bucket->waitq);
+	rcu_read_unlock();
+}
+
 /** Device operations */
 extern const struct file_operations fuse_dev_operations;