Date: Fri, 23 Apr 2010 14:57:41 -0400 (EDT) From: "Mikhail T." <mi@aldan.algebra.com> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/145999: optional offset for `mdconfig -t vnode' Message-ID: <201004231857.o3NIvf0w052272@aldan.narawntapu> Resent-Message-ID: <201004231900.o3NJ0C7c070008@freefall.freebsd.org>
next in thread | raw e-mail | index | archive | help
>Number: 145999 >Category: kern >Synopsis: optional offset for `mdconfig -t vnode' >Confidential: no >Severity: non-critical >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: change-request >Submitter-Id: current-users >Arrival-Date: Fri Apr 23 19:00:12 UTC 2010 >Closed-Date: >Last-Modified: >Originator: Mikhail T. >Release: FreeBSD 7.3-STABLE amd64 >Organization: Virtual Estates, Inc. http://sybpipe.com/ >Environment: System: FreeBSD aldan.narawntapu 7.3-STABLE FreeBSD 7.3-STABLE #3: Fri Apr 9 17:20:45 EDT 2010 mi@aldan.narawntapu:/var/src/sys/amd64/compile/SILVER-SMP amd64 >Description: It is already possible to use only part of the file by explicitly specifying the size (mdconfig -s) of the md. For completeness, it should also be possible to request, that certain number of bytes be skipped from the beginning... If necessary, requiring that this offset be a multiple of 512 or some such is acceptable. For example: mdconfig -t vnode -f zhoo -b 8192 (-b would stand for "begin"). >How-To-Repeat: This could be useful for people dealing with files, that have file-system images embedded in them -- preceded by some other data... The only existing work-around for such situations is using something like dd skip= to produce a separate file, which can almost double the storage requirements and cause other inconvenience. I propose, that the md_base field of the md_ioctl struct (currently in use only in the MD_PRELOAD cases) be used for this purpose. >Fix: The userland changes (add an option for mdconfig.c) is easy. The kernel changes required are beyond my knowledge... >Release-Note: >Audit-Trail: >Unformatted:
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201004231857.o3NIvf0w052272>