libceph: hold off building osd request

Defer building the osd request until just before submitting it in
all callers except ceph_writepages_start().  (That caller will be
handed in the next patch.)
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

fs/ceph/addr.c

@@ -319,8 +319,6 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max)
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
-	ceph_osdc_build_request(req, off, 1, &op, NULL, vino.snap, NULL);
-
 	/* build page vector */
 	nr_pages = calc_pages_for(0, len);
 	pages = kmalloc(sizeof(*pages) * nr_pages, GFP_NOFS);
@@ -351,6 +349,8 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max)
 	req->r_callback = finish_read;
 	req->r_inode = inode;
 
+	ceph_osdc_build_request(req, off, 1, &op, NULL, vino.snap, NULL);
+
 	dout("start_read %p starting %p %lld~%lld\n", inode, req, off, len);
 	ret = ceph_osdc_start_request(osdc, req, false);
 	if (ret < 0)

fs/ceph/file.c

@@ -540,9 +540,6 @@ static ssize_t ceph_sync_write(struct file *file, const char __user *data,
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
-	ceph_osdc_build_request(req, pos, num_ops, ops,
-				snapc, vino.snap, &mtime);
-
 	/* write from beginning of first page, regardless of io alignment */
 	page_align = file->f_flags & O_DIRECT ? buf_align : io_align;
 	num_pages = calc_pages_for(page_align, len);
@@ -583,6 +580,10 @@ static ssize_t ceph_sync_write(struct file *file, const char __user *data,
 	req->r_data_out.alignment = page_align;
 	req->r_inode = inode;
 
+	/* BUG_ON(vino.snap != CEPH_NOSNAP); */
+	ceph_osdc_build_request(req, pos, num_ops, ops,
+				snapc, vino.snap, &mtime);
+
 	ret = ceph_osdc_start_request(&fsc->client->osdc, req, false);
 	if (!ret) {
 		if (req->r_safe_callback) {

net/ceph/osd_client.c

@@ -2056,8 +2056,6 @@ int ceph_osdc_readpages(struct ceph_osd_client *osdc,
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
-	ceph_osdc_build_request(req, off, 1, &op, NULL, vino.snap, NULL);
-
 	/* it may be a short read due to an object boundary */
 
 	osd_data = &req->r_data_in;
@@ -2069,6 +2067,8 @@ int ceph_osdc_readpages(struct ceph_osd_client *osdc,
 	dout("readpages  final extent is %llu~%llu (%llu bytes align %d)\n",
 	     off, *plen, osd_data->length, page_align);
 
+	ceph_osdc_build_request(req, off, 1, &op, NULL, vino.snap, NULL);
+
 	rc = ceph_osdc_start_request(osdc, req, false);
 	if (!rc)
 		rc = ceph_osdc_wait_request(osdc, req);
@@ -2105,8 +2105,6 @@ int ceph_osdc_writepages(struct ceph_osd_client *osdc, struct ceph_vino vino,
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
-	ceph_osdc_build_request(req, off, 1, &op, snapc, CEPH_NOSNAP, mtime);
-
 	/* it may be a short write due to an object boundary */
 	osd_data = &req->r_data_out;
 	osd_data->type = CEPH_OSD_DATA_TYPE_PAGES;
@@ -2115,6 +2113,8 @@ int ceph_osdc_writepages(struct ceph_osd_client *osdc, struct ceph_vino vino,
 	osd_data->alignment = page_align;
 	dout("writepages %llu~%llu (%llu bytes)\n", off, len, osd_data->length);
 
+	ceph_osdc_build_request(req, off, 1, &op, snapc, CEPH_NOSNAP, mtime);
+
 	rc = ceph_osdc_start_request(osdc, req, true);
 	if (!rc)
 		rc = ceph_osdc_wait_request(osdc, req);