svn commit: r303763 - in head/sys/cddl: compat/opensolaris/sys contrib/opensolaris/uts/common/fs/zfs contrib/opensolaris/uts/common/fs/zfs/sys

Andriy Gapon avg at FreeBSD.org
Tue Aug 9 05:11:53 UTC 2016 

On 09/08/2016 02:48, Navdeep Parhar wrote:
> Hello Andriy,
> 
> I'm at r303837 and have had two panics today in zfs_rename.  I have a
> core for a kernel built with -O0.  Let me know if you think it's related
> to this commit and need more information.  This is the stack:
> 
> (also available at https://people.freebsd.org/~np/rename_panic.txt in
> case the wide lines are hard to read in email).

Thank you very much for the report.
More details are required for analysis. In frame 11 I would like to see objects
pointed to by all arguments and additionally local variables tdzp, sdzp, zfsvfs
and zilog.

> (kgdb) bt
> #0  doadump (textdump=0) at /root/ws/head/sys/kern/kern_shutdown.c:298
> #1  0xffffffff803f8692 in db_dump (dummy=-2100833195, dummy2=false,
> dummy3=-1, dummy4=0xfffffe08604c6810 "") at
> /root/ws/head/sys/ddb/db_command.c:533
> #2  0xffffffff803f847e in db_command (last_cmdp=0xffffffff821d40d8
> <db_last_command>, cmd_table=0x0, dopager=1) at
> /root/ws/head/sys/ddb/db_command.c:440
> #3  0xffffffff803f801e in db_command_loop () at
> /root/ws/head/sys/ddb/db_command.c:493
> #4  0xffffffff803fcf13 in db_trap (type=12, code=0) at
> /root/ws/head/sys/ddb/db_main.c:251
> #5  0xffffffff8100116f in kdb_trap (type=12, code=0,
> tf=0xfffffe08604c6fe0) at /root/ws/head/sys/kern/subr_kdb.c:654
> #6  0xffffffff8163df24 in trap_fatal (frame=0xfffffe08604c6fe0,
> eva=18446744069414584336) at /root/ws/head/sys/amd64/amd64/trap.c:836
> #7  0xffffffff8163e53b in trap_pfault (frame=0xfffffe08604c6fe0,
> usermode=0) at /root/ws/head/sys/amd64/amd64/trap.c:763
> #8  0xffffffff8163d1e2 in trap (frame=0xfffffe08604c6fe0) at
> /root/ws/head/sys/amd64/amd64/trap.c:442
> #9  0xffffffff8163e63a in trap_check (frame=0xfffffe08604c6fe0) at
> /root/ws/head/sys/amd64/amd64/trap.c:635
> #10 <signal handler called>
> #11 0xffffffff82c7d455 in zfs_rename (sdvp=0xfffff80016e331d8,
> svpp=0xfffffe08604c7318, scnp=0xfffffe08604c7750,
> tdvp=0xfffff80156440000, tvpp=0xfffffe08604c7308,
> tcnp=0xfffffe08604c7688, cr=0xfffff8001612e600)
>     at
> /root/ws/head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c:3959
> #12 0xffffffff82c6f6a9 in zfs_freebsd_rename (ap=0xfffffe08604c73c8) at
> /root/ws/head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c:5275
> #13 0xffffffff8187d484 in VOP_RENAME_APV (vop=0xffffffff82d19bb0
> <zfs_vnodeops>, a=0xfffffe08604c73c8) at vnode_if.c:1547
> #14 0xffffffff810e5d41 in VOP_RENAME (fdvp=0xfffff80016e331d8,
> fvp=0xfffff80174c02588, fcnp=0xfffffe08604c7750,
> tdvp=0xfffff80156440000, tvp=0xfffff8017d7d1ce8,
> tcnp=0xfffffe08604c7688) at ./vnode_if.h:636
> #15 0xffffffff810e5b17 in kern_renameat (td=0xfffff8010b855a40,
> oldfd=-100, old=0x800a121a0 <error: Cannot access memory at address
> 0x800a121a0>, newfd=-100, new=0x7fffffffcfee <error: Cannot access
> memory at address 0x7fffffffcfee>,
>     pathseg=UIO_USERSPACE) at /root/ws/head/sys/kern/vfs_syscalls.c:3553
> #16 0xffffffff810e53d7 in sys_rename (td=0xfffff8010b855a40,
> uap=0xfffffe08604c7a58) at /root/ws/head/sys/kern/vfs_syscalls.c:3427
> #17 0xffffffff83ce244d in filemon_wrapper_rename (td=0xfffff8010b855a40,
> uap=0xfffffe08604c7a58) at
> /root/ws/head/sys/modules/filemon/../../dev/filemon/filemon_wrapper.c:240
> #18 0xffffffff8163f1a9 in syscallenter (td=0xfffff8010b855a40,
> sa=0xfffffe08604c7a48) at
> /root/ws/head/sys/amd64/amd64/../../kern/subr_syscall.c:135
> #19 0xffffffff8163e9ea in amd64_syscall (td=0xfffff8010b855a40,
> traced=0) at /root/ws/head/sys/amd64/amd64/trap.c:942
> 
> Regards,
> Navdeep
> 
> 
> On 08/04/2016 23:23, Andriy Gapon wrote:
>> Author: avg
>> Date: Fri Aug  5 06:23:06 2016
>> New Revision: 303763
>> URL: https://svnweb.freebsd.org/changeset/base/303763
>>
>> Log:
>>   zfs: honour and make use of vfs vnode locking protocol
>>   
>>   ZFS POSIX Layer is originally written for Solaris VFS which is very
>>   different from FreeBSD VFS.  Most importantly many things that FreeBSD VFS
>>   manages on behalf of all filesystems are implemented in ZPL in a different
>>   way.
>>   Thus, ZPL contains code that is redundant on FreeBSD or duplicates VFS
>>   functionality or, in the worst cases, badly interacts / interferes
>>   with VFS.
>>   
>>   The most prominent problem is a deadlock caused by the lock order reversal
>>   of vnode locks that may happen with concurrent zfs_rename() and lookup().
>>   The deadlock is a result of zfs_rename() not observing the vnode locking
>>   contract expected by VFS.
>>   
>>   This commit removes all ZPL internal locking that protects parent-child
>>   relationships of filesystem nodes.  These relationships are protected
>>   by vnode locks and the code is changed to take advantage of that fact
>>   and to properly interact with VFS.
>>   
>>   Removal of the internal locking allowed all ZPL dmu_tx_assign calls to
>>   use TXG_WAIT mode.
>>   
>>   Another victim, disputable perhaps, is ZFS support for filesystems with
>>   mixed case sensitivity.  That support is not provided by the OS anyway,
>>   so in ZFS it was a buch of dead code.
>>   
>>   To do:
>>   - replace ZFS_ENTER mechanism with VFS managed / visible mechanism
>>   - replace zfs_zget with zfs_vget[f] as much as possible
>>   - get rid of not really useful now zfs_freebsd_* adapters
>>   - more cleanups of unneeded / unused code
>>   - fix / replace .zfs support
>>   
>>   PR:		209158
>>   Reported by:	many
>>   Tested by:	many (thank you all!)
>>   MFC after:	5 days
>>   Sponsored by:	HybridCluster / ClusterHQ
>>   Differential Revision: https://reviews.freebsd.org/D6533
>>
>> Modified:
>>   head/sys/cddl/compat/opensolaris/sys/vnode.h
>>   head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zfs_dir.h
>>   head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zfs_vfsops.h
>>   head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zfs_znode.h
>>   head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_acl.c
>>   head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_dir.c
>>   head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_sa.c
>>   head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
>>   head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
>>   head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c
>>
> 


-- 
Andriy Gapon

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