We are taking a look at this - Ronnie had some ideas. Probably simply not implemented - hopefully not too hard to fix. On Mon, Jun 25, 2018 at 6:58 PM Laura Abbott <labbott@xxxxxxxxxx> wrote: > > Hi, > > A while back, someone reported a failure on Fedora when trying to boot > a QEMU image off of a CIFS share. The issue was reduced down to a > test case (https://bugzilla.redhat.com/show_bug.cgi?id=1484130#c8) > > # cat test-ofd-lock.c > #define _GNU_SOURCE > #include <errno.h> > #include <stdio.h> > #include <unistd.h> > #include <fcntl.h> > > int main(int argc, char **argv) > { > int ret; > int fd; > struct flock fl = { > .l_whence = SEEK_SET, > .l_start = 0, > .l_len = 0, > .l_type = F_RDLCK, > }; > if (argc < 2) { > fprintf(stderr, "Usage: %s <file>\n", argv[0]); > return 1; > } > fd = open(argv[1], O_RDWR); > if (fd < 0) { > perror("open"); > return errno; > } > ret = fcntl(fd, F_OFD_SETLK, &fl); > if (ret) { > perror("setlk"); > return errno; > } > fl.l_type = F_WRLCK; > ret = fcntl(fd, F_OFD_GETLK, &fl); > if (ret) { > perror("getlk"); > return errno; > } > if (fl.l_type != F_UNLCK) { > fprintf(stderr, "get lock test failed\n"); > return 1; > } > return 0; > } > [root@localhost ~]# make test-ofd-lock > cc test-ofd-lock.c -o test-ofd-lock > [root@localhost ~]# touch /tmp/test && ./test-ofd-lock /tmp/test > [root@localhost ~]# echo $? > 0 > [root@localhost ~]# touch /mnt/test && ./test-ofd-lock /mnt/test > get lock test failed > [root@localhost ~]# mount | grep /mnt > //192.168.31.1/tddownload on /mnt type cifs (rw,relatime,vers=3.0, > cache=strict,username=admin,domain=,uid=0, > noforceuid,gid=0,noforcegid,addr=192.168.31.1,file_mode=0755, > dir_mode=0755,nounix,serverino,mapposix,rsize=1048576, > wsize=1048576,echo_interval=60,actimeo=1,user=admin) > > > As explained by one of the QEMU developers > (https://bugzilla.redhat.com/show_bug.cgi?id=1484130#c37) > > ''' > It is a kernel bug. The code snippet in comment 8 shows clearly that the kernel > is doing the wrong thing, which cannot be fixed/worked around by QEMU. > > In man 2 fcntl: > > F_OFD_GETLK (struct flock *) > On input to this call, lock describes an open file description lock > we would like to place on the file. If the lock could be placed, fcntl() does not > actually place it, but returns F_UNLCK in the l_type field of lock > and leaves the other fields of the structure unchanged. If one or more incompatible > locks would prevent this lock being placed, then details about one of > these locks are returned via lock, as described above for F_GETLK. > > which is not the case with the new CIFS behaviour. > '' > > You can read the full context at https://bugzilla.redhat.com/show_bug.cgi?id=1484130 > > Any suggestions? > > Thanks, > Laura > -- > To unsubscribe from this list: send the line "unsubscribe linux-cifs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Thanks, Steve -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
