Justin T. Gibbs 443cc4d407 Fix a bug in the calculation of the maximum I/O request size. ... The previous code did not limit the I/O request size based on the maximum number of segments supported by the back-end. In current practice, since the only back-end supporting chained requests is the FreeBSD implementation, this limit was never exceeded. sys/dev/xen/blkfront/block.h: Add two macros, XBF_SEGS_TO_SIZE() and XBF_SIZE_TO_SEGS(), to centralize the logic of reserving a segment to deal with non-page-aligned I/Os. sys/dev/xen/blkfront/blkfront.c: o When negotiating transfer parameters, limit the max_request_size we use and publish, if it is greater than the maximum, unaligned, I/O we can support with the number of segments advertised by the backend. o Don't unilaterally reduce the I/O size published to the disk layer by a single page. max_request_size is already properly limited in the transfer parameter negotiation code. o Fix typos in printf strings: "max_requests_segments" -> "max_request_segments" "specificed" -> "specified" MFC after: 1 day		2012-02-16 21:58:47 +00:00
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blkfront.c	Fix a bug in the calculation of the maximum I/O request size.	2012-02-16 21:58:47 +00:00
block.h	Fix a bug in the calculation of the maximum I/O request size.	2012-02-16 21:58:47 +00:00