Date: Mon, 24 Mar 2014 13:12:50 -0700 From: javocado <javocado@gmail.com> To: FreeBSD Filesystems <freebsd-fs@freebsd.org> Subject: Re: rsync w/ fake-super -> crashes zfs Message-ID: <CAP1HOmRiQtMoOavPGd-ZNAM%2BHdhTtbVCMSMVJuiq8dCB8GVVbg@mail.gmail.com> In-Reply-To: <CAP1HOmRfw0_MkHhu%2BWYu4vac25rx2MGzUAGjdbM8PkPRm5LxtQ@mail.gmail.com> References: <CAP1HOmTiiKp7B1FLQ=Kfq_WUe2=nctMTc0nrtiav5kfAraVHgA@mail.gmail.com> <CAP1HOmRfw0_MkHhu%2BWYu4vac25rx2MGzUAGjdbM8PkPRm5LxtQ@mail.gmail.com>
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A bit more info:
We've been able to reproduce the crash with panic output:
Fatal trap 12: page fault while in kernel mode
cpuid =3D 11; apic id =3D 15
fault virtual address =3D 0x160
fault code =3D supervisor read data, page not present
instruction pointer =3D 0x20:0xffffffff80abb546
stack pointer =3D 0x28:0xffffffa59b580910
frame pointer =3D 0x28:0xffffffa59b5809d0
code segment =3D base 0x0, limit 0xfffff, type 0x1b
=3D DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags =3D interrupt enabled, resume, IOPL =3D 0
current process =3D 93937 (rsync)
[thread pid 93937 tid 102776 ]
Stopped at zfs_freebsd_remove+0x426: movq 0x160(%rax),%rsi
db>
by simply adding --delete to this command:
rsync -av --rsync-path=3D"rsync --fake-super" /src /dst
the file it was deleting at the time of the crash had valid (readable)
extattrs (rsync.%stat - for the fake-super info) and nothing else special
for acl
owner@:rw-p--aARWcCos:------:allow
group@:r-----a-R-c--s:------:allow
everyone@:r-----a-R-c--s:------:allow
Question: should it be safe to remove that file traditionally, as in:
rm /file/that/zfs+rsync+fake_super/croaked/on
How's would that rm differ from what rsync was trying to do?
On Thu, Mar 20, 2014 at 5:33 PM, javocado <javocado@gmail.com> wrote:
> Gathering more info here...
>
> When re-running the rsync command, stripped down:
>
> rsync -av --rsync-path=3D"rsync --fake-super" /src /dst
>
> we're not seeing any system crashes, yet, but rsync is choking/quitting
> quite a bit saying a file here or there has a corrupt extattr. Does this
> point to a problem with ZFS or more with rsync.
>
> Any thoughts on the fake-super impact and how it leads to crashing?
>
>
> On Fri, Mar 14, 2014 at 4:57 PM, javocado <javocado@gmail.com> wrote:
>
>> System specifics:
>> ZFS version 28
>> FreeBSD 8.3-RELEASE
>>
>> We're seeing a repeatable outcome where a remote rsync command like:
>>
>> rsync -axzHAXS --rsync-path=3D"rsync --fake-super" --exclude '*/rsync.%s=
tat'
>>
>> backing up to our zfs filesystem (with 15M inodes) will lead to a panic
>> with output like:
>>
>> Fatal trap 12: page fault while in kernel modecpuid =3D 4; apic id =3D 0=
4fault virtual address =3D 0x160fault code =3D supervisor re=
ad data, page not presentinstruction pointer =3D 0x20:0xffffffff80abb54=
6stack pointer =3D 0x28:0xffffff976c62b910frame pointer =
=3D 0x28:0xffffff976c62b9d0code segment =3D base 0x0, limit 0xf=
ffff, type 0x1b =3D DPL 0, pres 1, long 1, def32 0, =
gran 1processor eflags =3D interrupt enabled, resume, IOPL =3D 0curr=
ent process =3D 7295 (rsync)[thread pid 7295 tid 101008 ]Stopped at=
zfs_freebsd_remove+0x426: movq 0x160(%rax),%rsi
>>
>>
>> On the sending side (RHEL, ext3), rsync reports errors like:
>>
>> rsync: failed to read xattr rsync.%statrsync: failed to write xattr rsyn=
c.%statrsync: get_xattr_names: llistxattr
>>
>> which we've seen occasionally with other systems when running rsync with=
fake-super, but it usually doesn't lead to a crash.*
>>
>> On the receiving side, other than the crashes, we are seeing a few new f=
iles (that don't exist on the source) named:
>>
>> rsync.%stat
>>
>> which correspond to and contain the owner and permission attributes that=
should have been stored in the extattr's for the file or directory. Not su=
re if they are a red herring, but they're usually not something we see (per=
haps that's related to the --exclude '*/rsync.%stat' and rsync not being ab=
le to cleanup properly).
>>
>> We are still testing to see if any options in the rsync command (above) =
may be contributing to the crash, since fake-super in and of itself runs fi=
ne under basic (rsync -av --rsync-path=3D"rsync --fake-super" /src /dst) ci=
rcumstances. But we suspect that the problem is related to fake-super and i=
ts reliance upon extattr's.
>>
>> What we really need is a solution to the crashing - some way to make ZFS=
stop choking on whatever --fake-super produces and/or how it's interacting=
with extattr's on ZFS.
>>
>>
>> Thanks!
>>
>> * we sometimes also see on the sending side w/ fake-super:
>> rsync: failed to write xattr rsync.%stat for "xxxxxx/file" : No such fil=
e
>> or directory (2)
>>
>> when (1) the file exists, (2) it's a symlink
>> but that isn't happening in this instance. We only mention it here as
>> another oddity of fake-super + ZFS + extattr
>>
>>
>
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