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>
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@ -2332,7 +2332,6 @@ static int rbd_img_request_fill(struct rbd_img_request *img_request,
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(int)type, data_desc);
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img_offset = img_request->offset;
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img_end = rbd_dev->header.image_size;
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resid = img_request->length;
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rbd_assert(resid > 0);
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@ -2397,13 +2396,20 @@ static int rbd_img_request_fill(struct rbd_img_request *img_request,
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if (!offset && (length == object_size)
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&& (!img_request_layered_test(img_request) ||
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(rbd_dev->parent_overlap <=
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obj_request->img_offset)))
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obj_request->img_offset))) {
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opcode = CEPH_OSD_OP_DELETE;
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else if ((offset + length == object_size) ||
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(obj_request->img_offset + length == img_end))
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} else if ((offset + length == object_size)) {
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opcode = CEPH_OSD_OP_TRUNCATE;
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else
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opcode = CEPH_OSD_OP_ZERO;
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} else {
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down_read(&rbd_dev->header_rwsem);
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img_end = rbd_dev->header.image_size;
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up_read(&rbd_dev->header_rwsem);
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if (obj_request->img_offset + length == img_end)
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opcode = CEPH_OSD_OP_TRUNCATE;
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else
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opcode = CEPH_OSD_OP_ZERO;
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}
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} else if (img_request_write_test(img_request)) {
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op_type = OBJ_OP_WRITE;
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opcode = CEPH_OSD_OP_WRITE;
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