[Virtio-fs] [PATCH 1/2] virtio-fs: send setupmapping with write flag only if IOMAP_WRITE

[Liu Bo]

This is to let virtiofs daemon to do inline fallocate to preallocate
space for this mapping.

Signed-off-by: Liu Bo <bo.liu at linux.alibaba.com>
---
 fs/fuse/file.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 488e932f..6f403c8 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -251,8 +251,8 @@ static void free_dax_mapping(struct fuse_conn *fc,
 
 /* offset passed in should be aligned to FUSE_DAX_MEM_RANGE_SZ */
 static int fuse_setup_one_mapping(struct inode *inode,
-				struct file *file, loff_t offset,
-				struct fuse_dax_mapping *dmap)
+				  struct file *file, loff_t offset, unsigned flags,
+				  struct fuse_dax_mapping *dmap)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct fuse_inode *fi = get_fuse_inode(inode);
@@ -276,14 +276,21 @@ static int fuse_setup_one_mapping(struct inode *inode,
 		inarg.fh = -1;
 	inarg.moffset = dmap->window_offset;
 	inarg.len = FUSE_DAX_MEM_RANGE_SZ;
+
+       /*
+	* with IOMAP_WRITE, virtiofs daemon will make sure space is
+	* allocated for the range.
+	*/
 	if (file) {
-		inarg.flags |= (file->f_mode & FMODE_WRITE) ?
-				FUSE_SETUPMAPPING_FLAG_WRITE : 0;
+		if (file->f_mode & FMODE_WRITE &&
+		    flags & IOMAP_WRITE)
+			inarg.flags |= FUSE_SETUPMAPPING_FLAG_WRITE;
 		inarg.flags |= (file->f_mode & FMODE_READ) ?
 				FUSE_SETUPMAPPING_FLAG_READ : 0;
 	} else {
 		inarg.flags |= FUSE_SETUPMAPPING_FLAG_READ;
-		inarg.flags |= FUSE_SETUPMAPPING_FLAG_WRITE;
+		if (flags & IOMAP_WRITE)
+			inarg.flags |= FUSE_SETUPMAPPING_FLAG_WRITE;
 	}
 	args.in.h.opcode = FUSE_SETUPMAPPING;
 	args.in.h.nodeid = fi->nodeid;
@@ -1847,8 +1854,8 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
 
 		/* Setup one mapping */
 		ret = fuse_setup_one_mapping(inode, NULL,
-				ALIGN_DOWN(pos, FUSE_DAX_MEM_RANGE_SZ),
-				alloc_dmap);
+					ALIGN_DOWN(pos, FUSE_DAX_MEM_RANGE_SZ),
+					     flags, alloc_dmap);
 		if (ret < 0) {
 			printk("fuse_setup_one_mapping() failed. err=%d"
 				" pos=0x%llx\n", ret, pos);
-- 
1.8.3.1