rbd: read image size for discard check safely
In rbd_img_request_fill() the image size is only checked to determine
whether we can truncate an object instead of zeroing it for discard
requests. Take rbd_dev->header_rwsem while reading the image size, and
move this read into the discard check, so that non-discard ops don't
need to take the semaphore in this function.
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index e2f7a70..31ace3d 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2332,7 +2332,6 @@
(int)type, data_desc);
img_offset = img_request->offset;
- img_end = rbd_dev->header.image_size;
resid = img_request->length;
rbd_assert(resid > 0);
@@ -2397,13 +2396,20 @@
if (!offset && (length == object_size)
&& (!img_request_layered_test(img_request) ||
(rbd_dev->parent_overlap <=
- obj_request->img_offset)))
+ obj_request->img_offset))) {
opcode = CEPH_OSD_OP_DELETE;
- else if ((offset + length == object_size) ||
- (obj_request->img_offset + length == img_end))
+ } else if ((offset + length == object_size)) {
opcode = CEPH_OSD_OP_TRUNCATE;
- else
- opcode = CEPH_OSD_OP_ZERO;
+ } else {
+ down_read(&rbd_dev->header_rwsem);
+ img_end = rbd_dev->header.image_size;
+ up_read(&rbd_dev->header_rwsem);
+
+ if (obj_request->img_offset + length == img_end)
+ opcode = CEPH_OSD_OP_TRUNCATE;
+ else
+ opcode = CEPH_OSD_OP_ZERO;
+ }
} else if (img_request_write_test(img_request)) {
op_type = OBJ_OP_WRITE;
opcode = CEPH_OSD_OP_WRITE;