Date: Sun, 14 Mar 2010 18:12:54 +0700 (KRAT) From: Eugene Grosbein <eugen@grosbein.pp.ru> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/144732: [patch] geom_cache erroneously decodes its on-disk label Message-ID: <201003141112.o2EBCsKs002348@grosbein.pp.ru> Resent-Message-ID: <201003141130.o2EBU6jT070393@freefall.freebsd.org>
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>Number: 144732 >Category: kern >Synopsis: [patch] geom_cache erroneously decodes its on-disk label >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Sun Mar 14 11:30:05 UTC 2010 >Closed-Date: >Last-Modified: >Originator: Eugene Grosbein >Release: FreeBSD 8.0-STABLE i386 >Organization: RDTC JSC >Environment: System: FreeBSD grosbein.pp.ru 8.0-STABLE FreeBSD 8.0-STABLE #11: Sat Feb 6 21:23:34 KRAT 2010 root@grosbein.pp.ru:/usr/local/obj/usr/local/src/sys/DADV i386 >Description: Let's take a look at struct g_cache_metadata definition in /usr/src/sys/geom/cache/g_cache.h: struct g_cache_metadata { char md_magic[16]; /* Magic value. */ uint32_t md_version; /* Version number. */ char md_name[16]; /* Cache value. */ uint32_t md_bsize; /* Cache block size. */ uint32_t md_size; /* Cache size. */ uint64_t md_provsize; /* Provider's size. */ }; Note that md_size is 32-bit unsigned value. Next lines present cache_metadata_encode() funtion that uses le32enc() to encode this value, that's right. Now look at cache_metadata_decode() below: it uses le16dec() function to decode stored label. This error effectively limits cache size to 16-bit quantity (and limits stripe/block size too). >How-To-Repeat: kldload geom_cache gcache label -v -b 32768 -s 65536 Label is written successfully but gem_cache compains to kernel log: GEOM_CACHE: Invalid size for device ca0. That's because le16dec() decodes 65536 as zero cache size. >Fix: --- sys/geom/cache/g_cache.h.orig 2010-03-14 17:36:16.000000000 +0700 +++ sys/geom/cache/g_cache.h 2010-03-14 17:35:25.000000000 +0700 @@ -139,7 +139,7 @@ md->md_version = le32dec(data + 16); bcopy(data + 20, md->md_name, sizeof(md->md_name)); md->md_bsize = le32dec(data + 36); - md->md_size = le16dec(data + 40); + md->md_size = le32dec(data + 40); md->md_provsize = le64dec(data + 44); } >Release-Note: >Audit-Trail: >Unformatted:
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