Merge tag 'fuse-update-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse

Pull fuse updates from Miklos Szeredi:

 - Add passthrough mode for regular file I/O.

   This allows performing read and write (also via memory maps) on a
   backing file without incurring the overhead of roundtrips to
   userspace. For now this is only allowed to privileged servers, but
   this limitation will go away in the future (Amir Goldstein)

 - Fix interaction of direct I/O mode with memory maps (Bernd Schubert)

 - Export filesystem tags through sysfs for virtiofs (Stefan Hajnoczi)

 - Allow resending queued requests for server crash recovery (Zhao Chen)

 - Misc fixes and cleanups

* tag 'fuse-update-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (38 commits)
  fuse: get rid of ff->readdir.lock
  fuse: remove unneeded lock which protecting update of congestion_threshold
  fuse: Fix missing FOLL_PIN for direct-io
  fuse: remove an unnecessary if statement
  fuse: Track process write operations in both direct and writethrough modes
  fuse: Use the high bit of request ID for indicating resend requests
  fuse: Introduce a new notification type for resend pending requests
  fuse: add support for explicit export disabling
  fuse: __kuid_val/__kgid_val helpers in fuse_fill_attr_from_inode()
  fuse: fix typo for fuse_permission comment
  fuse: Convert fuse_writepage_locked to take a folio
  fuse: Remove fuse_writepage
  virtio_fs: remove duplicate check if queue is broken
  fuse: use FUSE_ROOT_ID in fuse_get_root_inode()
  fuse: don't unhash root
  fuse: fix root lookup with nonzero generation
  fuse: replace remaining make_bad_inode() with fuse_make_bad()
  virtiofs: drop __exit from virtio_fs_sysfs_exit()
  fuse: implement passthrough for mmap
  fuse: implement splice read/write passthrough
  ...

include/uapi/linux/fuse.h

@@ -211,6 +211,12 @@
  *  7.39
  *  - add FUSE_DIRECT_IO_ALLOW_MMAP
  *  - add FUSE_STATX and related structures
+ *
+ *  7.40
+ *  - add max_stack_depth to fuse_init_out, add FUSE_PASSTHROUGH init flag
+ *  - add backing_id to fuse_open_out, add FOPEN_PASSTHROUGH open flag
+ *  - add FUSE_NO_EXPORT_SUPPORT init flag
+ *  - add FUSE_NOTIFY_RESEND, add FUSE_HAS_RESEND init flag
  */
 
 #ifndef _LINUX_FUSE_H
@@ -246,7 +252,7 @@
 #define FUSE_KERNEL_VERSION 7
 
 /** Minor version number of this interface */
-#define FUSE_KERNEL_MINOR_VERSION 39
+#define FUSE_KERNEL_MINOR_VERSION 40
 
 /** The node ID of the root inode */
 #define FUSE_ROOT_ID 1
@@ -353,6 +359,7 @@ struct fuse_file_lock {
  * FOPEN_STREAM: the file is stream-like (no file position at all)
  * FOPEN_NOFLUSH: don't flush data cache on close (unless FUSE_WRITEBACK_CACHE)
  * FOPEN_PARALLEL_DIRECT_WRITES: Allow concurrent direct writes on the same inode
+ * FOPEN_PASSTHROUGH: passthrough read/write io for this open file
  */
 #define FOPEN_DIRECT_IO		(1 << 0)
 #define FOPEN_KEEP_CACHE	(1 << 1)
@@ -361,6 +368,7 @@ struct fuse_file_lock {
 #define FOPEN_STREAM		(1 << 4)
 #define FOPEN_NOFLUSH		(1 << 5)
 #define FOPEN_PARALLEL_DIRECT_WRITES	(1 << 6)
+#define FOPEN_PASSTHROUGH	(1 << 7)
 
 /**
  * INIT request/reply flags
@@ -410,6 +418,9 @@ struct fuse_file_lock {
  *			symlink and mknod (single group that matches parent)
  * FUSE_HAS_EXPIRE_ONLY: kernel supports expiry-only entry invalidation
  * FUSE_DIRECT_IO_ALLOW_MMAP: allow shared mmap in FOPEN_DIRECT_IO mode.
+ * FUSE_NO_EXPORT_SUPPORT: explicitly disable export support
+ * FUSE_HAS_RESEND: kernel supports resending pending requests, and the high bit
+ *		    of the request ID indicates resend requests
  */
 #define FUSE_ASYNC_READ		(1 << 0)
 #define FUSE_POSIX_LOCKS	(1 << 1)
@@ -449,6 +460,9 @@ struct fuse_file_lock {
 #define FUSE_CREATE_SUPP_GROUP	(1ULL << 34)
 #define FUSE_HAS_EXPIRE_ONLY	(1ULL << 35)
 #define FUSE_DIRECT_IO_ALLOW_MMAP (1ULL << 36)
+#define FUSE_PASSTHROUGH	(1ULL << 37)
+#define FUSE_NO_EXPORT_SUPPORT	(1ULL << 38)
+#define FUSE_HAS_RESEND		(1ULL << 39)
 
 /* Obsolete alias for FUSE_DIRECT_IO_ALLOW_MMAP */
 #define FUSE_DIRECT_IO_RELAX	FUSE_DIRECT_IO_ALLOW_MMAP
@@ -635,6 +649,7 @@ enum fuse_notify_code {
 	FUSE_NOTIFY_STORE = 4,
 	FUSE_NOTIFY_RETRIEVE = 5,
 	FUSE_NOTIFY_DELETE = 6,
+	FUSE_NOTIFY_RESEND = 7,
 	FUSE_NOTIFY_CODE_MAX,
 };
 
@@ -761,7 +776,7 @@ struct fuse_create_in {
 struct fuse_open_out {
 	uint64_t	fh;
 	uint32_t	open_flags;
-	uint32_t	padding;
+	int32_t		backing_id;
 };
 
 struct fuse_release_in {
@@ -877,7 +892,8 @@ struct fuse_init_out {
 	uint16_t	max_pages;
 	uint16_t	map_alignment;
 	uint32_t	flags2;
-	uint32_t	unused[7];
+	uint32_t	max_stack_depth;
+	uint32_t	unused[6];
 };
 
 #define CUSE_INIT_INFO_MAX 4096
@@ -960,6 +976,14 @@ struct fuse_fallocate_in {
 	uint32_t	padding;
 };
 
+/**
+ * FUSE request unique ID flag
+ *
+ * Indicates whether this is a resend request. The receiver should handle this
+ * request accordingly.
+ */
+#define FUSE_UNIQUE_RESEND (1ULL << 63)
+
 struct fuse_in_header {
 	uint32_t	len;
 	uint32_t	opcode;
@@ -1049,9 +1073,18 @@ struct fuse_notify_retrieve_in {
 	uint64_t	dummy4;
 };
 
+struct fuse_backing_map {
+	int32_t		fd;
+	uint32_t	flags;
+	uint64_t	padding;
+};
+
 /* 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_BACKING_OPEN	_IOW(FUSE_DEV_IOC_MAGIC, 1, \
+					     struct fuse_backing_map)
+#define FUSE_DEV_IOC_BACKING_CLOSE	_IOW(FUSE_DEV_IOC_MAGIC, 2, uint32_t)
 
 struct fuse_lseek_in {
 	uint64_t	fh;