On Wed, Nov 29, 2023 at 10:07 PM Amir Goldstein <amir73il@xxxxxxxxx> wrote: > > Christian, > > Josef has helped me see the light and figure out how to avoid the > possible deadlock, which involves: > - splice() from source file in a loop mounted fs to dest file in > a host fs, where the loop image file is > - fsfreeze on host fs > - write to host fs in context of fanotify permission event handler > (FAN_ACCESS_PERM) on the splice source file > > The first patch should not be changing any logic. > I only build tested the ceph patch, so hoping to get an > Acked-by/Tested-by from Jeff. > > The second patch rids us of the deadlock by not holding > file_start_write() while reading from splice source file. > OOPS, I missed another corner case: The COPY_FILE_SPLICE fallback of server-side-copy in nfsd/ksmbd needs to use the start-write-safe variant of do_splice_direct(), because in this case src and dst can be on any two fs. Expect an extra patch in v2. Thanks, Amir.
