On 20/10/2022 17:32, Mateusz Guzik wrote:
This is a false-positive -- the seqc stuff is not modified on replay
and zfs internal asserts check for it. I think the easiest way forward
for this one is to appease the assert by entering it seqc.
That said, could it be it is an invariant there are no nc entries at
this stage anyway and the call to cache_vop_rmdir can be avoided? I
can add cache_assert_no_entries or similar routine to be called
instead.
I've checked the code and, indeed, the name cache is doubly disabled while ZIL
is replayed. ZFS sets z_use_namecache to false and z_replay to true before the
replay. And either is sufficient to disable ZFS name cache calls (which is
redundant, but that's a different topic).
So, I came up with this small proof-of-concept patch (and it helped with the
problem at hand).
It does not assert that the name cache for the filesystem being mounted is
actually empty. That would be a good addition, if you wish to add it.
diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
index f6bc9c0c6afb..87fa271dfd5c 100644
--- a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
+++ b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
@@ -1622,7 +1622,8 @@ zfs_rmdir_(vnode_t *dvp, vnode_t *vp, const char *name,
cred_t *cr)
dmu_tx_commit(tx);
- cache_vop_rmdir(dvp, vp);
+ if (zfsvfs->z_use_namecache)
+ cache_vop_rmdir(dvp, vp);
out:
if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
zil_commit(zilog, 0);
On 10/20/22, Andriy Gapon <[email protected]> wrote:
This happens on stable/13, custom kernel compiled with DEBUG_VFS_LOCKS, from
mid-September after an ungraceful reboot (unrelated crash). As far as I can
see
in kgdb, both dvp and vp have v_seqc == 0.
VNASSERT failed: ({ seqc_t __seqc = (_vp->v_seqc); __builtin_expect((__seqc
&
1), 0); }) not true at
/usr/home/avg/devel/freebsd-src-new/machines/trant/sys/kern/vfs_cache.c:2976
(cache_vop_rmdir)
0xfffff8004bc0bd58: type VDIR
usecount 1, writecount 0, refcount 1 seqc users 0 mountedhere 0
hold count flags ()
flags ()
lock type zfs: UNLOCKED
panic: condition seqc_in_modify(_vp->v_seqc) not met at
/usr/home/avg/devel/freebsd-src-new/machines/trant/sys/kern/vfs_cache.c:2976
(cache_vop_rmdir)
cpuid = 5
time = 1666250711
KDB: stack backtrace:
db_trace_self_wrapper() at 0xffffffff8061549b =
db_trace_self_wrapper+0x2b/frame
0xfffffe01ce6c7090
kdb_backtrace() at 0xffffffff80942927 = kdb_backtrace+0x37/frame
0xfffffe01ce6c7140
vpanic() at 0xffffffff808f4fb4 = vpanic+0x184/frame 0xfffffe01ce6c71a0
panic() at 0xffffffff808f4d63 = panic+0x43/frame 0xfffffe01ce6c7200
cache_vop_rmdir() at 0xffffffff809b9b9f = cache_vop_rmdir+0xdf/frame
0xfffffe01ce6c7220
zfs_rmdir_() at 0xffffffff80391cff = zfs_rmdir_+0x1df/frame
0xfffffe01ce6c7290
zfs_rmdir() at 0xffffffff80391af8 = zfs_rmdir+0x48/frame 0xfffffe01ce6c7310
zfs_replay_remove() at 0xffffffff804fc53b = zfs_replay_remove+0x7b/frame
0xfffffe01ce6c7340
zil_replay_log_record() at 0xffffffff80508462 =
zil_replay_log_record+0x212/frame 0xfffffe01ce6c7490
zil_parse() at 0xffffffff80502f4b = zil_parse+0x5cb/frame
0xfffffe01ce6c76a0
zil_replay() at 0xffffffff805081d8 = zil_replay+0xd8/frame
0xfffffe01ce6c7700
zfsvfs_setup() at 0xffffffff8038f09d = zfsvfs_setup+0x24d/frame
0xfffffe01ce6c7930
zfs_mount() at 0xffffffff8038c9b2 = zfs_mount+0x652/frame
0xfffffe01ce6c7ad0
vfs_domount_first() at 0xffffffff809d0d66 = vfs_domount_first+0x216/frame
0xfffffe01ce6c7c00
vfs_domount() at 0xffffffff809cdd43 = vfs_domount+0x2d3/frame
0xfffffe01ce6c7d30
vfs_donmount() at 0xffffffff809ccb6f = vfs_donmount+0x81f/frame
0xfffffe01ce6c7dc0
sys_nmount() at 0xffffffff809cc318 = sys_nmount+0x108/frame
0xfffffe01ce6c7df0
amd64_syscall() at 0xffffffff80c31d16 = amd64_syscall+0x186/frame
0xfffffe01ce6c7f30
fast_syscall_common() at 0xffffffff80c0889b = fast_syscall_common+0xf8/frame
0xfffffe01ce6c7f30
--- syscall (378, FreeBSD ELF64, sys_nmount), rip = 0xb6aac9dd1a, rsp =
0xb6b538f468, rbp = 0xb6b538f4d0 ---
Uptime: 37s
Dumping 1426 out of 32644 MB: (CTRL-C to abort)
..2%..11%..21%..31%..41%..51%..61%..71%..81%..91%
--
Andriy Gapon
--
Andriy Gapon
