From 02c74fbad9d4a5149756eb35be7300736e4904e9 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Mon, 6 May 2013 17:40:33 -0500 Subject: [PATCH] rbd: re-submit read request for flattened clone If a clone image gets flattened while a parent read request is underway, the original rbd object request needs to be resubmitted. The reason is that by the time we get the response to the parent read request, the data read from the parent may be out of date. In other words, we could see this sequence of events: rbd client parent image/osd ---------- ---------------- original object ENOENT; issue parent read respond to parent read child image flattened original image header refresh <--- original object written independently here parent read response received Add code to rbd_img_parent_read_callback() to detect when a clone's parent image has disappeared (as evidenced by its parent overlap becoming 0), and re-submit the original read request in that case. Signed-off-by: Alex Elder Reviewed-by: Josh Durgin --- drivers/block/rbd.c | 30 +++++++++++++++++++++++++----- 1 file changed, 25 insertions(+), 5 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 9717e20f3477..4edcb6d85f01 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -2682,14 +2682,36 @@ static void rbd_img_parent_read_callback(struct rbd_img_request *img_request) struct rbd_obj_request *obj_request; struct rbd_device *rbd_dev; u64 obj_end; + u64 img_xferred; + int img_result; rbd_assert(img_request_child_test(img_request)); + /* First get what we need from the image request and release it */ + obj_request = img_request->obj_request; + img_xferred = img_request->xferred; + img_result = img_request->result; + rbd_img_request_put(img_request); + + /* + * If the overlap has become 0 (most likely because the + * image has been flattened) we need to re-submit the + * original request. + */ rbd_assert(obj_request); rbd_assert(obj_request->img_request); + rbd_dev = obj_request->img_request->rbd_dev; + if (!rbd_dev->parent_overlap) { + struct ceph_osd_client *osdc; + + osdc = &rbd_dev->rbd_client->client->osdc; + img_result = rbd_obj_request_submit(osdc, obj_request); + if (!img_result) + return; + } - obj_request->result = img_request->result; + obj_request->result = img_result; if (obj_request->result) goto out; @@ -2702,7 +2724,6 @@ static void rbd_img_parent_read_callback(struct rbd_img_request *img_request) */ rbd_assert(obj_request->img_offset < U64_MAX - obj_request->length); obj_end = obj_request->img_offset + obj_request->length; - rbd_dev = obj_request->img_request->rbd_dev; if (obj_end > rbd_dev->parent_overlap) { u64 xferred = 0; @@ -2710,12 +2731,11 @@ static void rbd_img_parent_read_callback(struct rbd_img_request *img_request) xferred = rbd_dev->parent_overlap - obj_request->img_offset; - obj_request->xferred = min(img_request->xferred, xferred); + obj_request->xferred = min(img_xferred, xferred); } else { - obj_request->xferred = img_request->xferred; + obj_request->xferred = img_xferred; } out: - rbd_img_request_put(img_request); rbd_img_obj_request_read_callback(obj_request); rbd_obj_request_complete(obj_request); } -- GitLab