2021-12-24 21:31 GMT+09:00, Vasily Averin <vvs@xxxxxxxxxxxxx>: > On 22.12.2021 18:17, Vasily Averin wrote: >> On 22.12.2021 11:58, Namjae Jeon wrote: >>> 2021-12-22 15:51 GMT+09:00, Vasily Averin <vvs@xxxxxxxxxxxxx>: >>>> On 22.12.2021 08:25, Namjae Jeon wrote: >>>>> 2021-12-22 13:32 GMT+09:00, Vasily Averin <vvs@xxxxxxxxxxxxx>: >>>>>> On 22.12.2021 05:50, Namjae Jeon wrote: >>>>>>> 2021-12-21 22:08 GMT+09:00, Vasily Averin <vvs@xxxxxxxxxxxxx>: >>>>>>>> On 21.12.2021 15:02, Namjae Jeon wrote: >>>>>>>>> 2021-12-19 18:34 GMT+09:00, Vasily Averin <vvs@xxxxxxxxxxxxx>: >>>>>>>>>> To avoid possible deadlock ksmbd should process locks >>>>>>>>>> asynchronously. >>>>>>>>>> Callers expecting vfs_file_locks() to return asynchronously >>>>>>>>>> should >>>>>>>>>> only >>>>>>>>>> use F_SETLK, not F_SETLKW. >>>>>>>>> Should I check this patch instead of >>>>>>>>> [PATCH] ksmbd: force "fail immediately" flag on fs with its own >>>>>>>>> ->lock >>>>>>>>> ? >>>>>>>> >>>>>>>> no, these patches are independent and both ones are required. >>>>>>>> current patch fixes incorrect kernel thread behaviour: >>>>>>>> kernel threads should not use F_SETLKW for locking requests. >>>>>>> How does this patch work? posix_lock_file in vfs_lock_file() does >>>>>>> not >>>>>>> use >>>>>>> cmd. >>>>>>> And your patch still leaves FL_SLEEP. >>>>>> >>>>>> "use F_SETLK, not F_SETLKW" was copy-pasted from requirement >>>>>> described >>>>>> in >>>>>> comment above vfs_lock_file(). >>>>>> >>>>>> posix_lock_file() is not used in all ->lock() functions, and use >>>>>> F_SETLKW >>>>>> forces some of affected filesystem use blocking locks: >>>>> What I'm saying is that when we apply "ksmbd: force "fail immediately" >>>>> flag on fs with its own ->lock ", this patch is meaningless. How is >>>>> ->lock() with F_SETLKW called? >>>> >>>> I got your point finally, >>>> yes, you are right, now this cannot happen. >>>> However I'm going to fix all affected filesystems and then revert >>>> "ksmbd: force "fail immediately" flag on fs with its own ->lock" >>>> When this happen and ksmbd will still use IS_SETLKW it will trigger the >>>> problems described below. >>> If so, You can include one patch(this patch + revert patch) in patch >>> series for fixing ->lock of all filesystem. > > I've checked how smb2_lock() handles FILE_LOCK_DEFERRED returned by > vfs_lock_file() call. > It seems for me, working thread will be blocked in > ksmbd_vfs_posix_lock_wait(), > so whole ksmbd server still can deadlock. Am I wrong probably? No, Each commands are handled by ksmbd-io kworkers. Thanks! > > Thank you, > Vasily Averin >
