Date: Tue, 2 Aug 2011 08:47:19 +0400 From: Alexander Zagrebin <alex@zagrebin.ru> To: freebsd-fs@freebsd.org, freebsd-stable@freebsd.org Cc: freebsd-current@freebsd.org Subject: ZFS v28: kernel panics while reading an extended attribute Message-ID: <20110802044718.GA8838@gw.zagrebin.ru>
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Hi!
It seems, I've found a bug in the ZFS v28 on the latest stable:
if we have a snapshot with some files having an extended attributes,
then attempt to read an extended attributes's value leads to a well
reproducible kernel panic.
The part of backtrace follows:
#6 0xffffffff804bbe44 in calltrap ()
at /usr/src/sys/amd64/amd64/exception.S:228
#7 0xffffffff80950ea7 in zil_commit (zilog=0x0, foid=5795917)
at /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c:1497
#8 0xffffffff80979e6b in zfs_freebsd_read (ap=Variable "ap" is not available.)
at /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c:622
#9 0xffffffff80979750 in zfs_getextattr (ap=0xffffff80dd5d8820)
at vnode_if.h:384
#10 0xffffffff8038921b in extattr_get_vp (vp=0xffffff0056a01588,
attrnamespace=1, attrname=0xffffff80dd5d89a0 "DOSATTRIB", data=Variable "data" is not available.)
at vnode_if.h:1332
It seems that ZIL isn't available for snapshots, but zfs_freebsd_read
doesn't check this when calling zil_commit.
The attached patch fixes this issue.
Can anybody confirm this?
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Alexander Zagrebin
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--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c.orig 2011-08-01 23:04:07.358173627 +0400
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c 2011-08-02 00:10:02.674585604 +0400
@@ -618,7 +618,8 @@ zfs_read(vnode_t *vp, uio_t *uio, int io
/*
* If we're in FRSYNC mode, sync out this znode before reading it.
*/
- if (ioflag & FRSYNC || zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
+ if (zfsvfs->z_log &&
+ (ioflag & FRSYNC || zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS))
zil_commit(zfsvfs->z_log, zp->z_id);
/*
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