[PATCH 1/1] libfuse: enable iomap cache management

["Darrick J. Wong" <djwong@kernel.org>]

From: Darrick J. Wong <djwong@kernel.org>

Add the library methods so that fuse servers can manage an in-kernel
iomap cache.  This enables better performance on small IOs and is
required if the filesystem needs synchronization between pagecache
writes and writeback.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 include/fuse_common.h   |    9 +++++
 include/fuse_kernel.h   |   34 +++++++++++++++++++
 include/fuse_lowlevel.h |   39 ++++++++++++++++++++++
 lib/fuse_lowlevel.c     |   82 +++++++++++++++++++++++++++++++++++++++++++++++
 lib/fuse_versionscript  |    2 +
 5 files changed, 166 insertions(+)


diff --git a/include/fuse_common.h b/include/fuse_common.h
index 98cb8f656efd13..1237cc2656b9c4 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -1164,6 +1164,7 @@ int fuse_convert_to_conn_want_ext(struct fuse_conn_info *conn);
  */
 #if FUSE_USE_VERSION >= FUSE_MAKE_VERSION(3, 18)
 #define FUSE_IOMAP_TYPE_PURE_OVERWRITE	(0xFFFF) /* use read mapping data */
+#define FUSE_IOMAP_TYPE_NULL		(0xFFFE) /* no mapping here */
 #define FUSE_IOMAP_TYPE_HOLE		0	/* no blocks allocated, need allocation */
 #define FUSE_IOMAP_TYPE_DELALLOC	1	/* delayed allocation blocks */
 #define FUSE_IOMAP_TYPE_MAPPED		2	/* blocks allocated at @addr */
@@ -1208,6 +1209,11 @@ struct fuse_iomap {
 	uint32_t dev;		/* device cookie */
 };
 
+struct fuse_iomap_inval {
+	uint64_t offset;	/* file offset to invalidate, bytes */
+	uint64_t length;	/* length to invalidate, bytes */
+};
+
 /* out of place write extent */
 #define FUSE_IOMAP_IOEND_SHARED		(1U << 0)
 /* unwritten extent */
@@ -1258,6 +1264,9 @@ struct fuse_iomap_config{
 	int64_t s_maxbytes;	/* max file size */
 };
 
+/* invalidate to end of file */
+#define FUSE_IOMAP_INVAL_TO_EOF		(~0ULL)
+
 #endif /* FUSE_USE_VERSION >= 318 */
 
 /* ----------------------------------------------------------- *
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 3c704f03434693..f1a93dbd1ff443 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -243,6 +243,8 @@
  *  - add FUSE_IOMAP_DIRECTIO/FUSE_ATTR_IOMAP_DIRECTIO for direct I/O support
  *  - add FUSE_IOMAP_FILEIO/FUSE_ATTR_IOMAP_FILEIO for buffered I/O support
  *  - add FUSE_IOMAP_CONFIG so the fuse server can configure more fs geometry
+ *  - add FUSE_NOTIFY_IOMAP_UPSERT and FUSE_NOTIFY_IOMAP_INVAL so fuse servers
+ *    can cache iomappings in the kernel
  */
 
 #ifndef _LINUX_FUSE_H
@@ -699,6 +701,8 @@ enum fuse_notify_code {
 	FUSE_NOTIFY_DELETE = 6,
 	FUSE_NOTIFY_RESEND = 7,
 	FUSE_NOTIFY_INC_EPOCH = 8,
+	FUSE_NOTIFY_IOMAP_UPSERT = 9,
+	FUSE_NOTIFY_IOMAP_INVAL = 10,
 	FUSE_NOTIFY_CODE_MAX,
 };
 
@@ -1406,4 +1410,34 @@ struct fuse_iomap_config_out {
 	int64_t s_maxbytes;	/* max file size */
 };
 
+struct fuse_iomap_upsert_out {
+	uint64_t nodeid;	/* Inode ID */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+
+	uint64_t read_offset;	/* file offset of mapping, bytes */
+	uint64_t read_length;	/* length of mapping, bytes */
+	uint64_t read_addr;	/* disk offset of mapping, bytes */
+	uint16_t read_type;	/* FUSE_IOMAP_TYPE_* */
+	uint16_t read_flags;	/* FUSE_IOMAP_F_* */
+	uint32_t read_dev;	/* device cookie */
+
+	uint64_t write_offset;	/* file offset of mapping, bytes */
+	uint64_t write_length;	/* length of mapping, bytes */
+	uint64_t write_addr;	/* disk offset of mapping, bytes */
+	uint16_t write_type;	/* FUSE_IOMAP_TYPE_* */
+	uint16_t write_flags;	/* FUSE_IOMAP_F_* */
+	uint32_t write_dev;	/* device cookie * */
+};
+
+struct fuse_iomap_inval_out {
+	uint64_t nodeid;	/* Inode ID */
+	uint64_t attr_ino;	/* matches fuse_attr:ino */
+
+	uint64_t read_offset;	/* range to invalidate read iomaps, bytes */
+	uint64_t read_length;	/* can be FUSE_IOMAP_INVAL_TO_EOF */
+
+	uint64_t write_offset;	/* range to invalidate write iomaps, bytes */
+	uint64_t write_length;	/* can be FUSE_IOMAP_INVAL_TO_EOF */
+};
+
 #endif /* _LINUX_FUSE_H */
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index fd7df5c2c11e16..f690c62fcdd61c 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -2101,6 +2101,45 @@ int fuse_lowlevel_notify_retrieve(struct fuse_session *se, fuse_ino_t ino,
  * @return positive device id for success, zero for failure
  */
 int fuse_iomap_add_device(struct fuse_session *se, int fd, unsigned int flags);
+
+/**
+ * Upsert some file mapping information into the kernel.  This is necessary
+ * for filesystems that require coordination of mapping state changes between
+ * buffered writes and writeback, and desirable for better performance
+ * elsewhere.
+ *
+ * Added in FUSE protocol version 7.99. If the kernel does not support
+ * this (or a newer) version, the function will return -ENOSYS and do
+ * nothing.
+ *
+ * @param se the session object
+ * @param nodeid the inode number
+ * @param attr_ino inode number as told by fuse_attr::ino
+ * @param read_iomap mapping information for file reads
+ * @param write_iomap mapping information for file reads
+ * @return zero for success, -errno for failure
+ */
+int fuse_lowlevel_notify_iomap_upsert(struct fuse_session *se,
+				      fuse_ino_t nodeid, uint64_t attr_ino,
+				      const struct fuse_iomap *read_iomap,
+				      const struct fuse_iomap *write_iomap);
+
+/**
+ * Invalidate some file mapping information in the kernel.
+ *
+ * Added in FUSE protocol version 7.99. If the kernel does not support
+ * this (or a newer) version, the function will return -ENOSYS and do
+ * nothing.
+ *
+ * @param se the session object
+ * @param read read mapping range to invalidate
+ * @param write write mapping range to invalidate
+ * @return zero for success, -errno for failure
+ */
+int fuse_lowlevel_notify_iomap_inval(struct fuse_session *se,
+				     fuse_ino_t nodeid,
+				     const struct fuse_iomap_inval *read,
+				     const struct fuse_iomap_inval *write);
 #endif
 
 /* ----------------------------------------------------------- *
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index ed9464d592c8a1..e31ce96593a9b3 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -3349,6 +3349,88 @@ int fuse_lowlevel_notify_store(struct fuse_session *se, fuse_ino_t ino,
 	return res;
 }
 
+int fuse_lowlevel_notify_iomap_upsert(struct fuse_session *se,
+				      fuse_ino_t nodeid, uint64_t attr_ino,
+				      const struct fuse_iomap *read_iomap,
+				      const struct fuse_iomap *write_iomap)
+{
+	struct fuse_iomap_upsert_out outarg = {
+		.nodeid		= nodeid,
+		.attr_ino	= attr_ino,
+	};
+	struct iovec iov[2];
+
+	if (!se)
+		return -EINVAL;
+
+	if (se->conn.proto_minor < 44)
+		return -ENOSYS;
+
+	if (!read_iomap && !write_iomap)
+		return 0;
+
+	if (read_iomap) {
+		outarg.read_offset = read_iomap->offset;
+		outarg.read_length = read_iomap->length;
+		outarg.read_addr = read_iomap->addr;
+		outarg.read_type = read_iomap->type;
+		outarg.read_flags = read_iomap->flags;
+		outarg.read_dev = read_iomap->dev;
+	} else {
+		outarg.read_type = FUSE_IOMAP_TYPE_NULL;
+	}
+
+	if (write_iomap) {
+		outarg.write_offset = write_iomap->offset;
+		outarg.write_length = write_iomap->length;
+		outarg.write_addr = write_iomap->addr;
+		outarg.write_type = write_iomap->type;
+		outarg.write_flags = write_iomap->flags;
+		outarg.write_dev = write_iomap->dev;
+	} else {
+		outarg.write_type = FUSE_IOMAP_TYPE_NULL;
+	}
+
+	iov[1].iov_base = &outarg;
+	iov[1].iov_len = sizeof(outarg);
+
+	return send_notify_iov(se, FUSE_NOTIFY_IOMAP_UPSERT, iov, 2);
+}
+
+int fuse_lowlevel_notify_iomap_inval(struct fuse_session *se,
+				     fuse_ino_t nodeid,
+				     const struct fuse_iomap_inval *read,
+				     const struct fuse_iomap_inval *write)
+{
+	struct fuse_iomap_inval_out outarg = {
+		.nodeid		= nodeid,
+	};
+	struct iovec iov[2];
+
+	if (!se)
+		return -EINVAL;
+
+	if (se->conn.proto_minor < 44)
+		return -ENOSYS;
+
+	if (!read && !write)
+		return 0;
+
+	if (read) {
+		outarg.read_offset = read->offset;
+		outarg.read_length = read->length;
+	}
+	if (write) {
+		outarg.write_offset = write->offset;
+		outarg.write_length = write->length;
+	}
+
+	iov[1].iov_base = &outarg;
+	iov[1].iov_len = sizeof(outarg);
+
+	return send_notify_iov(se, FUSE_NOTIFY_IOMAP_INVAL, iov, 2);
+}
+
 struct fuse_retrieve_req {
 	struct fuse_notify_req nreq;
 	void *cookie;
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 9cb46d8a7afdd2..dc9fa2428b5325 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -221,6 +221,8 @@ FUSE_3.18 {
 		fuse_add_direntry_plus_iflags;
 		fuse_discover_iomap;
 		fuse_reply_iomap_config;
+		fuse_lowlevel_notify_iomap_upsert;
+		fuse_lowlevel_notify_iomap_inval;
 } FUSE_3.17;
 
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