Date: Fri, 13 Feb 2004 00:05:04 +0900 From: Jun Kuriyama <kuriyama@imgsrc.co.jp> To: Kirk McKusick <mckusick@mckusick.com> Cc: Current <freebsd-current@FreeBSD.org> Subject: -current lock up at dump -L with snapshot Message-ID: <7msmhgz6cf.wl@black.imgsrc.co.jp>
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I'm still tracking down why my box is usually locking up. Reference: http://docs.freebsd.org/cgi/mid.cgi?7mznedas57.wl I try to simplify how to reproduce this. (a) A filesystem without any snapshot, I can take a dump -L. (b) A filesystem with a snapshot, I can take a dump (without -L). (c) A filesystem with a snapshot, I cannot take a dump -L. % dump -1 -f /dev/null -S -L / DUMP: Date of this level 1 dump: Thu Feb 12 23:52:43 2004 DUMP: Date of last level 0 dump: Wed Feb 11 16:30:22 2004 DUMP: Dumping snapshot of /dev/ad4s1a (/) to /dev/null DUMP: mapping (Pass I) [regular files] <--- stopped here This filesystem is /, so softdep is disabled, but situation is the same with softdep. "dump -L" is doing following: 1) take a snapshot: "mksnap_ffs / /.snap/dump_snapshot". 2) open a snapshot: open("/.snap/dump_snapshot", O_RDONLY). 3) unlink a snapshot: unlink("/.snap/dump_snapshot") 4) ... 5) pread(2) opened snapshot. dump(8) is locked at 5) syscall. At that time, ddb's "show lockedvnods" shows (line number may be different by my debug codes): ----- 0xc8194de0: tag ufs, type VREG, usecount 1, writecount 0, refcount 9, flags (VV_SYSTEM|VV_OBJBUF), lock type snplk2: SHARED (count 1) with 3 pending @ kern/vfs_vnops.c:529 by vop_stdlock (thread 0xc809a000 (pid 52934)) ino 187, on dev ad0s1a (4, 12) 0xc777b818: tag ufs, type VREG, usecount 1, writecount 0, refcount 9, flags (VV_SYSTEM), lock type snplk2: SHARED (count 1) with 3 pending @ kern/vfs_vnops.c:529 by vop_stdlock (thread 0xc809a000 (pid 52934)) ino 178, on dev ad0s1a (4, 12) ----- It looks there is a problem around removing a snapshot with opened file descriptor. But I'm not sure why there is no problem when I have no another snapshot in that filesystem. Is there any hints to track this down more? Any comments appreciated. -- Jun Kuriyama <kuriyama@imgsrc.co.jp> // IMG SRC, Inc. <kuriyama@FreeBSD.org> // FreeBSD Project
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