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由 Prasad Joshi 提交于
The block device driver puts a limit on maximum number of pages that can be sent with the bio. Not all block devices can handle BIO_MAX_PAGES number of pages in bio. Specifically the virtio-blk diriver limits it to 126. When the LogFS file system was excersized in KVM, the following bug from do_virtblk_request() was observed static void do_virtblk_request(struct request_queue *q) { .... .... while ((req = blk_peek_request(q)) != NULL) { BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems); .... .... } .... } The patch fixes the problem by querring the maximum number of pages in bio allowed from block device driver and then using those many pages during submit_bio. Signed-off-by: NPrasad Joshi <prasadjoshi.linux@gmail.com>
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