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rbd: read image size for discard check safely

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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>
This commit is contained in:
Josh Durgin 2014-04-04 12:06:32 -07:00 committed by Ilya Dryomov
parent 90e98c5229
commit 3c5df89367
1 changed files with 12 additions and 6 deletions
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18
drivers/block/rbd.c
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@ -2332,7 +2332,6 @@ static int rbd_img_request_fill(struct rbd_img_request *img_request,
(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 @@ static int rbd_img_request_fill(struct rbd_img_request *img_request,
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;