On Wednesday, 6 May 2020 16:08:03 CEST Stefan Metzmacher via samba-technical wrote: > Am 06.05.20 um 14:41 schrieb Anoop C S: > > On Wed, 2020-05-06 at 12:33 +0200, Stefan Metzmacher wrote: > >> Hi Anoop, > >> > >>> I could reproduce the difference in SHA256 checksum after copying a > >>> directory with 100 copies of test file(provided by reporter) from > >>> io_uring VFS module enabled share using Windows explorer(right- > >>> click- > >>> > >>>> copy/paste). Only 5 out of 100 files had correct checksum after > >>>> copy > >>> > >>> operation :-/ > >> > >> Great! Can you please try to collect level 1 log files with > >> the patch https://bugzilla.samba.org/attachment.cgi?id=15955 > >> applied? > > > > I have attached three log files. > > log.io_uring.smbd -- Copy using Windows explorer > > log.io_uring-mget.smd -- Copy using smbclient > > log.io_uring-powershell.smd -- Copy using `Copy-Item` > > Thanks! All of them show short reads like: > > [2020/05/06 17:27:28.130248, 1] > > ../../source3/modules/vfs_io_uring.c:103(vfs_io_uring_finish_req)> > > vfs_io_uring_finish_req: pread ofs=0 (0x0) len=32768 (0x8000) > > nread=32768 (0x32768) eof=10000000 (0x989680) blks=4096 blocks=19536 > > dir/1.bin fnum 1607026405> > > [2020/05/06 17:27:28.131049, 1] > > ../../source3/modules/vfs_io_uring.c:103(vfs_io_uring_finish_req)> > > vfs_io_uring_finish_req: pread ofs=9969664 (0x982000) len=30336 (0x7680) > > nread=30336 (0x30336) eof=10000000 (0x989680) blks=4096 blocks=19536 > > dir/1.bin fnum 1607026405> > > [2020/05/06 17:27:28.133679, 1] > > ../../source3/modules/vfs_io_uring.c:103(vfs_io_uring_finish_req)> > > vfs_io_uring_finish_req: pread ofs=61440 (0xf000) len=32768 (0x8000) > > nread=32768 (0x32768) eof=10000000 (0x989680) blks=4096 blocks=19536 > > dir/1.bin fnum 1607026405> > > [2020/05/06 17:27:28.140184, 0] > > ../../source3/modules/vfs_io_uring.c:88(vfs_io_uring_finish_req)> > > vfs_io_uring_finish_req: Invalid pread ofs=0 (0x0) len=1048576 > > (0x100000) nread=32768 (0x32768) eof=10000000 (0x989680) blks=4096 > > blocks=19536 dir/1.bin fnum 1607026405 > It seems the first request is at ofs=0 len=32768 (0x8000) and we get > 32768 back. > A follow up request with ofs=0 len=1048576 (0x100000) only gets the > first 32768 bytes which are already in the page cache. > > I can easily reproduce this with the Ubuntu 5.4 kernel once I add > state->ur.sqe.rw_flags |= RWF_NOWAIT; to vfs_io_uring_pread_send() > and use this. > > echo 1 > /proc/sys/vm/drop_caches > head -c 1024 /root/samba-test/ff1.dat | hexdump -C > 00000000 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > > |................| > > * > 00000400 > smbclient //172.31.9.167/uringff -Uroot%test -c "get ff1.dat" > > results in this log entries: > > [2020/05/06 06:51:57.069990, 0] > > ../../source3/modules/vfs_io_uring.c:89(vfs_io_uring_finish_req)> > > vfs_io_uring_finish_req: Invalid pread ofs=0 (0x0) len=8388608 > > (0x800000) nread=16384 (0x4000) eof=8388608 (0x800000) blks=4096 > > blocks=16384 ff1.dat fnum 840153065> > > [2020/05/06 06:51:57.076882, 1] > > ../../source3/modules/vfs_io_uring.c:104(vfs_io_uring_finish_req)> > > vfs_io_uring_finish_req: pread ofs=16384 (0x4000) len=8372224 (0x7fc000) > > nread=8372224 (0x7fc000) eof=8388608 (0x800000) blks=4096 blocks=16384 > > ff1.dat fnum 840153065 > smbclient is just smart enough to recover itself from the short read. > But the windows client isn't. > > The attached test against liburing (git://git.kernel.dk/liburing) should > be able to demonstrate the problem. It can also be found in > https://github.com/metze-samba/liburing/tree/implicit-rwf-nowaithttps://gith > ub.com/metze-samba/liburing/commit/eb06dcfde747e46bd08bedf9def2e6cb536c39e3 > > > I added the sqe->rw_flags = RWF_NOWAIT; line in order to demonstrate it > against the Ubuntu 5.3 and 5.4 kernels. They both seem to have the bug. > > Can someone run the unmodified test/implicit-rwf_nowait against > a newer kernel? $ uname -a Linux magrathea 5.6.8-1-default #1 SMP Thu Apr 30 10:47:01 UTC 2020 (63116ab) x86_64 x86_64 x86_64 GNU/Linux $ ./a.out cqe res=4096 != 8192 Andreas -- Andreas Schneider asn@xxxxxxxxx Samba Team www.samba.org GPG-ID: 8DFF53E18F2ABC8D8F3C92237EE0FC4DCC014E3D
