Date: Sat, 1 Oct 2016 15:51:38 -0400 From: Anton Yuzhaninov <citrin@citrin.ru> To: Konstantin Belousov <kostikbel@gmail.com> Cc: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: UFS: unaligned read from GELI with 8k sectorsize Message-ID: <be912fbc-fcbf-aa53-0e58-039fd7d251aa@citrin.ru> In-Reply-To: <20161001114536.GX38409@kib.kiev.ua> References: <f84b069b-aeee-ff3c-d4f9-e2fe3caaddb1@citrin.ru> <20161001114536.GX38409@kib.kiev.ua>
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On 2016-10-01 07:45, Konstantin Belousov wrote: > On Sat, Oct 01, 2016 at 12:42:09AM -0400, Anton Yuzhaninov wrote: > FreeBSD vnode pager assumes that it can read at page granularity. > Since x86 page size is 4k, sometimes page-in has to occur not on the > fragment boundary. In other words, fragment size > 4k are effectively > not supported. You mean that geom sector size > 4k is not supported? UFS with 8k fragment should work (over geom provider with sector size <= 4k). > Boot needs to execute files from the root mount, which results in the > mmap(2) attempts on your file system. While mount and reads/writes do > not involve the pager, which does not trigger further bugs in the > buffer cache code. It should break if you try to execute badly aligned > ELF binary from your stick, or just mmap() a file from the stick with > non-8k aligned offset. Thank you for detailed answer!
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