[PATCH 11/13] fuse: query filesystem geometry when using iomap

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

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

Add a new upcall to the fuse server so that the kernel can request
filesystem geometry bits when iomap mode is in use.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/fuse/fuse_trace.h      |   48 +++++++++++++++++++++++
 include/uapi/linux/fuse.h |   38 +++++++++++++++++++
 fs/fuse/file_iomap.c      |   92 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 178 insertions(+)


diff --git a/fs/fuse/fuse_trace.h b/fs/fuse/fuse_trace.h
index 5d9b5a4e93fca5..0078a9ad2a2871 100644
--- a/fs/fuse/fuse_trace.h
+++ b/fs/fuse/fuse_trace.h
@@ -58,6 +58,7 @@
 	EM( FUSE_SYNCFS,		"FUSE_SYNCFS")		\
 	EM( FUSE_TMPFILE,		"FUSE_TMPFILE")		\
 	EM( FUSE_STATX,			"FUSE_STATX")		\
+	EM( FUSE_IOMAP_CONFIG,		"FUSE_IOMAP_CONFIG")	\
 	EM( FUSE_IOMAP_BEGIN,		"FUSE_IOMAP_BEGIN")	\
 	EM( FUSE_IOMAP_END,		"FUSE_IOMAP_END")	\
 	EM( FUSE_IOMAP_IOEND,		"FUSE_IOMAP_IOEND")	\
@@ -198,6 +199,14 @@ TRACE_DEFINE_ENUM(FUSE_I_IOMAP_FILEIO);
 	{ IOMAP_IOEND_BOUNDARY,			"boundary" }, \
 	{ IOMAP_IOEND_DIRECT,			"direct" }
 
+#define FUSE_IOMAP_CONFIG_STRINGS \
+	{ FUSE_IOMAP_CONFIG_SID,		"sid" }, \
+	{ FUSE_IOMAP_CONFIG_UUID,		"uuid" }, \
+	{ FUSE_IOMAP_CONFIG_BLOCKSIZE,		"blocksize" }, \
+	{ FUSE_IOMAP_CONFIG_MAX_LINKS,		"max_links" }, \
+	{ FUSE_IOMAP_CONFIG_TIME,		"time" }, \
+	{ FUSE_IOMAP_CONFIG_MAXBYTES,		"maxbytes" }
+
 TRACE_EVENT(fuse_iomap_begin,
 	TP_PROTO(const struct inode *inode, loff_t pos, loff_t count,
 		 unsigned opflags),
@@ -1184,6 +1193,45 @@ TRACE_EVENT(fuse_iomap_fallocate,
 		  __entry->isize, __entry->mode, __entry->offset,
 		  __entry->length, __entry->newsize)
 );
+
+TRACE_EVENT(fuse_iomap_config,
+	TP_PROTO(const struct fuse_mount *fm,
+		 const struct fuse_iomap_config_out *outarg),
+	TP_ARGS(fm, outarg),
+
+	TP_STRUCT__entry(
+		__field(dev_t,			connection)
+
+		__field(uint32_t,		flags)
+		__field(uint32_t,		blocksize)
+		__field(uint32_t,		max_links)
+		__field(uint32_t,		time_gran)
+
+		__field(int64_t,		time_min)
+		__field(int64_t,		time_max)
+		__field(int64_t,		maxbytes)
+		__field(uint8_t,		uuid_len)
+	),
+
+	TP_fast_assign(
+		__entry->connection	=	fm->fc->dev;
+		__entry->flags		=	outarg->flags;
+		__entry->blocksize	=	outarg->s_blocksize;
+		__entry->max_links	=	outarg->s_max_links;
+		__entry->time_gran	=	outarg->s_time_gran;
+		__entry->time_min	=	outarg->s_time_min;
+		__entry->time_max	=	outarg->s_time_max;
+		__entry->maxbytes	=	outarg->s_maxbytes;
+		__entry->uuid_len	=	outarg->s_uuid_len;
+	),
+
+	TP_printk("connection %u flags (%s) blocksize 0x%x max_links %u time_gran %u time_min %lld time_max %lld maxbytes 0x%llx uuid_len %u",
+		  __entry->connection,
+		  __print_flags(__entry->flags, "|", FUSE_IOMAP_CONFIG_STRINGS),
+		  __entry->blocksize, __entry->max_links, __entry->time_gran,
+		  __entry->time_min, __entry->time_max, __entry->maxbytes,
+		  __entry->uuid_len)
+);
 #endif /* CONFIG_FUSE_IOMAP */
 
 #endif /* _TRACE_FUSE_H */
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index cd484de60a7c09..2aac5a0c4cef0a 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -242,6 +242,7 @@
  *  - add FUSE_DEV_IOC_IOMAP_DEV_ADD to configure block devices for iomap
  *  - 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
  */
 
 #ifndef _LINUX_FUSE_H
@@ -676,6 +677,7 @@ enum fuse_opcode {
 	FUSE_TMPFILE		= 51,
 	FUSE_STATX		= 52,
 
+	FUSE_IOMAP_CONFIG	= 4092,
 	FUSE_IOMAP_IOEND	= 4093,
 	FUSE_IOMAP_BEGIN	= 4094,
 	FUSE_IOMAP_END		= 4095,
@@ -1424,4 +1426,40 @@ struct fuse_iomap_ioend_in {
 	uint32_t reserved1;	/* zero */
 };
 
+struct fuse_iomap_config_in {
+	uint64_t flags;		/* zero for now */
+	int64_t maxbytes;	/* maximum supported file size */
+};
+
+/* Which fields are set in fuse_iomap_config_out? */
+#define FUSE_IOMAP_CONFIG_SID		(1 << 0ULL)
+#define FUSE_IOMAP_CONFIG_UUID		(1 << 1ULL)
+#define FUSE_IOMAP_CONFIG_BLOCKSIZE	(1 << 2ULL)
+#define FUSE_IOMAP_CONFIG_MAX_LINKS	(1 << 3ULL)
+#define FUSE_IOMAP_CONFIG_TIME		(1 << 4ULL)
+#define FUSE_IOMAP_CONFIG_MAXBYTES	(1 << 5ULL)
+
+struct fuse_iomap_config_out {
+	uint64_t flags;		/* FUSE_IOMAP_CONFIG_* */
+
+	char s_id[32];		/* Informational name */
+	char s_uuid[16];	/* UUID */
+
+	uint8_t s_uuid_len;	/* length of s_uuid */
+
+	uint8_t s_pad[3];	/* must be zeroes */
+
+	uint32_t s_blocksize;	/* fs block size */
+	uint32_t s_max_links;	/* max hard links */
+
+	/* Granularity of c/m/atime in ns (cannot be worse than a second) */
+	uint32_t s_time_gran;
+
+	/* Time limits for c/m/atime in seconds */
+	int64_t s_time_min;
+	int64_t s_time_max;
+
+	int64_t s_maxbytes;	/* max file size */
+};
+
 #endif /* _LINUX_FUSE_H */
diff --git a/fs/fuse/file_iomap.c b/fs/fuse/file_iomap.c
index 673647ddda0ccd..5253f7ef88c110 100644
--- a/fs/fuse/file_iomap.c
+++ b/fs/fuse/file_iomap.c
@@ -575,12 +575,104 @@ static struct fuse_iomap_dev *fuse_iomap_dev_alloc(struct file *file)
 	return fb;
 }
 
+#define FUSE_IOMAP_CONFIG_ALL (FUSE_IOMAP_CONFIG_SID | \
+			       FUSE_IOMAP_CONFIG_UUID | \
+			       FUSE_IOMAP_CONFIG_BLOCKSIZE | \
+			       FUSE_IOMAP_CONFIG_MAX_LINKS | \
+			       FUSE_IOMAP_CONFIG_TIME | \
+			       FUSE_IOMAP_CONFIG_MAXBYTES)
+
+static int fuse_iomap_config(struct fuse_mount *fm)
+{
+	struct fuse_iomap_config_in inarg = {
+		.maxbytes = MAX_LFS_FILESIZE,
+	};
+	struct fuse_iomap_config_out outarg = { };
+	FUSE_ARGS(args);
+	struct super_block *sb = fm->sb;
+	int err;
+
+	args.opcode = FUSE_IOMAP_CONFIG;
+	args.nodeid = 0;
+	args.in_numargs = 1;
+	args.in_args[0].size = sizeof(inarg);
+	args.in_args[0].value = &inarg;
+	args.out_numargs = 1;
+	args.out_args[0].size = sizeof(outarg);
+	args.out_args[0].value = &outarg;
+	args.force = true;
+	args.nocreds = true;
+	err = fuse_simple_request(fm, &args);
+	if (err == -ENOSYS)
+		return 0;
+	if (err)
+		return err;
+
+	trace_fuse_iomap_config(fm, &outarg);
+
+	if (outarg.flags & ~FUSE_IOMAP_CONFIG_ALL)
+		return -EINVAL;
+
+	if (outarg.s_uuid_len > sizeof(outarg.s_uuid))
+		return -EINVAL;
+
+	if (memchr_inv(outarg.s_pad, 0, sizeof(outarg.s_pad)))
+		return -EINVAL;
+
+	if (outarg.flags & FUSE_IOMAP_CONFIG_BLOCKSIZE) {
+		if (sb->s_bdev) {
+#ifdef CONFIG_BLOCK
+			if (!sb_set_blocksize(sb, outarg.s_blocksize))
+				return -EINVAL;
+#else
+			/*
+			 * XXX: how do we have a bdev filesystem without
+			 * CONFIG_BLOCK???
+			 */
+			return -EINVAL;
+#endif
+		} else {
+			sb->s_blocksize = outarg.s_blocksize;
+			sb->s_blocksize_bits = blksize_bits(outarg.s_blocksize);
+		}
+	}
+
+	if (outarg.flags & FUSE_IOMAP_CONFIG_SID)
+		memcpy(sb->s_id, outarg.s_id, sizeof(sb->s_id));
+
+	if (outarg.flags & FUSE_IOMAP_CONFIG_UUID) {
+		memcpy(&sb->s_uuid, outarg.s_uuid, outarg.s_uuid_len);
+		sb->s_uuid_len = outarg.s_uuid_len;
+	}
+
+	if (outarg.flags & FUSE_IOMAP_CONFIG_MAX_LINKS)
+		sb->s_max_links = outarg.s_max_links;
+
+	if (outarg.flags & FUSE_IOMAP_CONFIG_TIME) {
+		sb->s_time_gran = outarg.s_time_gran;
+		sb->s_time_min = outarg.s_time_min;
+		sb->s_time_max = outarg.s_time_max;
+	}
+
+	if (outarg.flags & FUSE_IOMAP_CONFIG_MAXBYTES)
+		sb->s_maxbytes = outarg.s_maxbytes;
+
+	return 0;
+}
+
 bool fuse_iomap_fill_super(struct fuse_mount *fm)
 {
 	struct fuse_conn *fc = fm->fc;
 	struct super_block *sb = fm->sb;
 	int res;
 
+	res = fuse_iomap_config(fm);
+	if (res) {
+		printk(KERN_ERR "%s: could not configure iomap, err=%d",
+		       sb->s_id, res);
+		return false;
+	}
+
 	if (sb->s_bdev) {
 		/*
 		 * Try to install s_bdev as the first iomap device, if this