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From: | Alex Bligh |
Subject: | Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes. |
Date: | Wed, 20 Mar 2013 08:33:02 +0000 |
Stefano,--On 19 March 2013 15:13:29 +0000 Stefano Stabellini <address@hidden> wrote:
Therefore I think that the current change is not safe, but it is pretty easy to make it safe. You just need to move the call to blk_open from blk_init to blk_connect. Actually you can move most of blk_init to blk_connect, you just need to keep the 4 xenstore_write_be_int at the end of the function.
The final of these 4 writes in blk_init is: xenstore_write_be_int(&blkdev->xendev, "sectors", blkdev->file_size / blkdev->file_blk); and blkdev->filesize comes from bdrv_getlength(blkdev->bs), and that requires (I think) bdrv_open to have been called. Can these 4 writes move safely to blk_connect? Or can we write the sectors count as (say) 0 here and fix it later in blk_connect? The remainder look ok. -- Alex Bligh
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