vfs_crossrename not working in samba-4.15.*

Stefan Metzmacher metze at samba.org
Mon Oct 10 10:34:24 UTC 2022

Hi Pavel,

> Program received signal SIGABRT, Aborted.
> __pthread_kill_implementation (threadid=<optimized out>, signo=signo at entry=6, no_tid=no_tid at entry=0) at pthread_kill.c:44
> 44»·      return INTERNAL_SYSCALL_ERROR_P (ret) ? INTERNAL_SYSCALL_ERRNO (ret) : 0;
> #0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo at entry=6, no_tid=no_tid at entry=0) at pthread_kill.c:44
> #1  0x00007fc04abb7cb3 in __pthread_kill_internal (signo=6, threadid=<optimized out>) at pthread_kill.c:78
> #2  0x00007fc04ab679c6 in __GI_raise (sig=sig at entry=6) at ../sysdeps/posix/raise.c:26
> #3  0x00007fc04ab517f4 in __GI_abort () at abort.c:79
> #4  0x00007fc04b076bfa in dump_core () at ../../source3/lib/dumpcore.c:338
> #5  0x00007fc04b088661 in smb_panic_s3 (why=0x7fc04b311928 "assert failed: share_mode_lock_key_refcount == 0") at ../../source3/lib/util.c:713
> #6  0x00007fc04ad7c9a1 in smb_panic (why=0x7fc04b311928 "assert failed: share_mode_lock_key_refcount == 0") at ../../lib/util/fault.c:198
> #7  0x00007fc04b1bfd7a in _share_mode_entry_prepare_lock (prepare_state=0x7fffa9900f60, id=..., servicepath=0x565379144e10 
> "/home/pfilipen/workspace/projects/samba/2571/st/ad_member/share",
>      smb_fname=0x565379162da0, old_write_time=0x7fffa9900eb0, fn=0x7fc04b2145d9 <open_ntcreate_lock_add_entry>, private_data=0x7fffa9900f60, location=0x7fc04b32c0f0 
> "../../source3/smbd/open.c:4342")
>      at ../../source3/locking/share_mode_lock.c:3010


> How this should be fixed? Can we remove the assert and allow to grab the share_mode_lock_key_refcount
>   again give the owner is the process itself?

It seems the problem got introduced by this commit:
"share_mode_lock: DEBUG/ASSERT recursion deadlock detection"

Before open_file_ntcreate() just failed with NT_STATUS_SHARING_VIOLATION if
get_share_mode_lock() returned NULL... But in 4.14 copy_reg() also used raw open() syscalls...

So the specific problem comes from
     s3: VFS: crossrename. Use real dirfsp for SMB_VFS_RENAMEAT()

     Finally fix the promise from the docs that this module is stackable. Re-use copy_internals().

     This is a horrible module that must be removed !

     Signed-off-by: Jeremy Allison <jra at samba.org>
     Reviewed-by: Noel Power <npower at samba.org>

That commit came after db743ab005bc7671d4fb0f5bea895c1097b707c5
and seems it was not tested at all (at least together with the recycle module)

I guess we can't use copy_internals() here.

Now that we use g_lock we may allow share_mode_do_locked_vfs_allowed() or
share_mode_entry_prepare_lock_del() with close_share_mode_lock_prepare() setting
*keep_locked = true to lock multiple file_ids at the same time...
But it will be a tricky change.


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