[PATCH 07/21] libfuse: add iomap ioend low level handler

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

Teach the low level library about the iomap ioend handler, which gets
called by the kernel when we finish a file write that isn't a pure
overwrite operation.

Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
---
 include/fuse_common.h   |   11 +++++++++++
 include/fuse_kernel.h   |   11 +++++++++++
 include/fuse_lowlevel.h |   20 ++++++++++++++++++++
 lib/fuse_lowlevel.c     |   23 +++++++++++++++++++++++
 4 files changed, 65 insertions(+)


diff --git a/include/fuse_common.h b/include/fuse_common.h
index d10364a077f31d..77e971c3fed17d 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -1215,6 +1215,17 @@ static inline bool fuse_iomap_need_write_allocate(unsigned int opflags,
 		!(opflags & FUSE_IOMAP_OP_ZERO);
 }
 
+/* out of place write extent */
+#define FUSE_IOMAP_IOEND_SHARED		(1U << 0)
+/* unwritten extent */
+#define FUSE_IOMAP_IOEND_UNWRITTEN	(1U << 1)
+/* don't merge into previous ioend */
+#define FUSE_IOMAP_IOEND_BOUNDARY	(1U << 2)
+/* is direct I/O */
+#define FUSE_IOMAP_IOEND_DIRECT		(1U << 3)
+/* is append ioend */
+#define FUSE_IOMAP_IOEND_APPEND		(1U << 4)
+
 /* ----------------------------------------------------------- *
  * Compatibility stuff					       *
  * ----------------------------------------------------------- */
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 2bcb3b394c0169..849238c17baf5e 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -665,6 +665,7 @@ enum fuse_opcode {
 	FUSE_TMPFILE		= 51,
 	FUSE_STATX		= 52,
 
+	FUSE_IOMAP_IOEND	= 4093,
 	FUSE_IOMAP_BEGIN	= 4094,
 	FUSE_IOMAP_END		= 4095,
 
@@ -1337,4 +1338,14 @@ struct fuse_iomap_end_in {
 	struct fuse_iomap_io	map;
 };
 
+struct fuse_iomap_ioend_in {
+	uint32_t ioendflags;	/* FUSE_IOMAP_IOEND_* */
+	int32_t error;		/* negative errno or 0 */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+	uint64_t pos;		/* file position, in bytes */
+	uint64_t new_addr;	/* disk offset of new mapping, in bytes */
+	uint32_t written;	/* bytes processed */
+	uint32_t reserved1;	/* zero */
+};
+
 #endif /* _LINUX_FUSE_H */
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 45655781e510a0..7f7f418b281601 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1379,6 +1379,26 @@ struct fuse_lowlevel_ops {
 	void (*iomap_end) (fuse_req_t req, fuse_ino_t nodeid, uint64_t attr_ino,
 			   off_t pos, uint64_t count, uint32_t opflags,
 			   ssize_t written, const struct fuse_file_iomap *iomap);
+
+	/**
+	 * Complete an iomap IO operation
+	 *
+	 * Valid replies:
+	 *   fuse_reply_err
+	 *
+	 * @param req request handle
+	 * @param nodeid the inode number
+	 * @param attr_ino inode number as told by fuse_attr::ino
+	 * @param pos position in file, in bytes
+	 * @param written number of bytes processed, or a negative errno
+	 * @param ioendflags mask of FUSE_IOMAP_IOEND_ flags specifying operation
+	 * @param error errno code of what went wrong
+	 * @param new_addr disk address of new mapping, in bytes
+	 */
+	void (*iomap_ioend) (fuse_req_t req, fuse_ino_t nodeid,
+			     uint64_t attr_ino, off_t pos, size_t written,
+			     uint32_t ioendflags, int error,
+			     uint64_t new_addr);
 };
 
 /**
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index fec4e3265e53c1..ce7971a23be94b 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -2637,6 +2637,27 @@ static void do_iomap_end(fuse_req_t req, const fuse_ino_t nodeid,
 	_do_iomap_end(req, nodeid, inarg, NULL);
 }
 
+static void _do_iomap_ioend(fuse_req_t req, const fuse_ino_t nodeid,
+			    const void *op_in, const void *in_payload)
+{
+	const struct fuse_iomap_ioend_in *arg = op_in;
+	(void)in_payload;
+	(void)nodeid;
+
+	if (req->se->op.iomap_ioend)
+		req->se->op.iomap_ioend(req, nodeid, arg->attr_ino, arg->pos,
+					arg->written, arg->ioendflags,
+					arg->error, arg->new_addr);
+	else
+		fuse_reply_err(req, ENOSYS);
+}
+
+static void do_iomap_ioend(fuse_req_t req, const fuse_ino_t nodeid,
+			   const void *inarg)
+{
+	_do_iomap_ioend(req, nodeid, inarg, NULL);
+}
+
 static bool want_flags_valid(uint64_t capable, uint64_t want)
 {
 	uint64_t unknown_flags = want & (~capable);
@@ -3524,6 +3545,7 @@ static struct {
 	[FUSE_STATX]	   = { do_statx,       "STATX"	     },
 	[FUSE_IOMAP_BEGIN] = { do_iomap_begin,	"IOMAP_BEGIN" },
 	[FUSE_IOMAP_END]   = { do_iomap_end,	"IOMAP_END" },
+	[FUSE_IOMAP_IOEND] = { do_iomap_ioend,	"IOMAP_IOEND" },
 	[CUSE_INIT]	   = { cuse_lowlevel_init, "CUSE_INIT"   },
 };
 
@@ -3581,6 +3603,7 @@ static struct {
 	[FUSE_STATX]		= { _do_statx,		"STATX" },
 	[FUSE_IOMAP_BEGIN]	= { _do_iomap_begin,	"IOMAP_BEGIN" },
 	[FUSE_IOMAP_END]	= { _do_iomap_end,	"IOMAP_END" },
+	[FUSE_IOMAP_IOEND]	= { _do_iomap_ioend,	"IOMAP_IOEND" },
 	[CUSE_INIT]		= { _cuse_lowlevel_init, "CUSE_INIT" },
 };