| Message ID | 150730500019.6182.15975727444128962384.stgit@warthog.procyon.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 2017-10-06 at 16:50 +0100, David Howells wrote: > Add a sample program for driving fsopen/fsmount. > > Signed-off-by: David Howells <dhowells@redhat.com> > --- > > samples/fsmount/test-fsmount.c | 94 ++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 94 insertions(+) > create mode 100644 samples/fsmount/test-fsmount.c > > diff --git a/samples/fsmount/test-fsmount.c b/samples/fsmount/test-fsmount.c > new file mode 100644 > index 000000000000..75f91d272a19 > --- /dev/null > +++ b/samples/fsmount/test-fsmount.c > @@ -0,0 +1,94 @@ > +/* fd-based mount test. > + * > + * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved. > + * Written by David Howells (dhowells@redhat.com) > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public Licence > + * as published by the Free Software Foundation; either version > + * 2 of the Licence, or (at your option) any later version. > + */ > + > +#include <stdio.h> > +#include <stdlib.h> > +#include <unistd.h> > +#include <errno.h> > +#include <fcntl.h> > +#include <sys/prctl.h> > +#include <sys/wait.h> > + > +#define PR_ERRMSG_ENABLE 48 > +#define PR_ERRMSG_READ 49 > + > +#define E(x) do { if ((x) == -1) { perror(#x); exit(1); } } while(0) > + > +static __attribute__((noreturn)) > +void mount_error(int fd, const char *s) > +{ > + char buf[4096]; > + int err, n, perr; > + > + do { > + err = errno; > + errno = 0; > + n = prctl(PR_ERRMSG_READ, buf, sizeof(buf)); > + perr = errno; > + errno = err; > + if (n > 0) { > + fprintf(stderr, "Error: '%s': %*.*s: %m\n", s, n, n, buf); > + } else { > + fprintf(stderr, "%s: %m\n", s); > + } > + } while (perr == 0); > + exit(1); > +} > + > +#define E_write(fd, s) \ > + do { \ > + if (write(fd, s, sizeof(s) - 1) == -1) \ > + mount_error(fd, s); \ > + } while (0) > + > +static inline int fsopen(const char *fs_name, int flags, > + void *reserved3, void *reserved4, void *reserved5); > + > +{ > + return syscall(333, fs_name, flags, reserved3, reserved4, reserved5); > +} > + > +static inline int fsmount(int fsfd, int dfd, const char *path, > + unsigned int at_flags, unsigned int flags) > +{ > + return syscall(334, fsfd, dfd, path, at_flags, flags); > +} > + > +int main() > +{ > + int mfd; > + > + if (prctl(PR_ERRMSG_ENABLE, 1) < 0) { > + perror("prctl/en"); > + exit(1); > + } > + > + /* Mount an NFS filesystem */ > + mfd = fsopen("nfs4", 0, NULL, NULL, NULL); > + if (mfd == -1) { > + perror("fsopen"); > + exit(1); > + } > + > + E_write(mfd, "s warthog:/data"); > + E_write(mfd, "o fsc"); > + E_write(mfd, "o sync"); > + E_write(mfd, "o intr"); > + E_write(mfd, "o vers=4.2"); > + E_write(mfd, "o addr=90.155.74.18"); > + E_write(mfd, "o clientaddr=90.155.74.21"); > + E_write(mfd, "x create"); > + if (fsmount(mfd, AT_FDCWD, "/mnt", 0, 0) < 0) > + mount_error(mfd, "fsmount"); > + E(close(mfd)); > + > + exit(0); > +} > So to make sure I understand.... Suppose I want to do a bind mount with the new API. Would I do something like this? mfd = fsopen("???"); write(mfd, "s /path/to/old/mount"); write(mfd, "o bind"); fsmount(mfd, ...); That seems a bit klunkier than before as I now need to pay attention to the fstype. I guess I'd have to scrape /proc/mounts for that info?
Jeff Layton <jlayton@redhat.com> wrote: > So to make sure I understand.... > > Suppose I want to do a bind mount with the new API. Would I do something > like this? > > mfd = fsopen("???"); > write(mfd, "s /path/to/old/mount"); You would have to use something other than "s" as that indicates the medium source, but there are plenty of other options. Alternatively, something like: mfd = mntopen("/path/to/old/mount", ...); You would need some way to retrieve the fs type, though. Maybe the first read() you do will return it: char fstype[256]; read(mfd, fstype, 256); ends up with: "fs <type>" in the buffer, though I think I'd prefer it to be manually elicited. > write(mfd, "o bind"); This is unnecessary as you can just do: > fsmount(mfd, ...); at this point to achieve the effect. > That seems a bit klunkier than before as I now need to pay attention to > the fstype. I guess I'd have to scrape /proc/mounts for that info? I haven't worked out this interface yet. I'm not sure it's actually necessary at this point, though it'd be nice to have. David -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/samples/fsmount/test-fsmount.c b/samples/fsmount/test-fsmount.c new file mode 100644 index 000000000000..75f91d272a19 --- /dev/null +++ b/samples/fsmount/test-fsmount.c @@ -0,0 +1,94 @@ +/* fd-based mount test. + * + * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <errno.h> +#include <fcntl.h> +#include <sys/prctl.h> +#include <sys/wait.h> + +#define PR_ERRMSG_ENABLE 48 +#define PR_ERRMSG_READ 49 + +#define E(x) do { if ((x) == -1) { perror(#x); exit(1); } } while(0) + +static __attribute__((noreturn)) +void mount_error(int fd, const char *s) +{ + char buf[4096]; + int err, n, perr; + + do { + err = errno; + errno = 0; + n = prctl(PR_ERRMSG_READ, buf, sizeof(buf)); + perr = errno; + errno = err; + if (n > 0) { + fprintf(stderr, "Error: '%s': %*.*s: %m\n", s, n, n, buf); + } else { + fprintf(stderr, "%s: %m\n", s); + } + } while (perr == 0); + exit(1); +} + +#define E_write(fd, s) \ + do { \ + if (write(fd, s, sizeof(s) - 1) == -1) \ + mount_error(fd, s); \ + } while (0) + +static inline int fsopen(const char *fs_name, int flags, + void *reserved3, void *reserved4, void *reserved5); + +{ + return syscall(333, fs_name, flags, reserved3, reserved4, reserved5); +} + +static inline int fsmount(int fsfd, int dfd, const char *path, + unsigned int at_flags, unsigned int flags) +{ + return syscall(334, fsfd, dfd, path, at_flags, flags); +} + +int main() +{ + int mfd; + + if (prctl(PR_ERRMSG_ENABLE, 1) < 0) { + perror("prctl/en"); + exit(1); + } + + /* Mount an NFS filesystem */ + mfd = fsopen("nfs4", 0, NULL, NULL, NULL); + if (mfd == -1) { + perror("fsopen"); + exit(1); + } + + E_write(mfd, "s warthog:/data"); + E_write(mfd, "o fsc"); + E_write(mfd, "o sync"); + E_write(mfd, "o intr"); + E_write(mfd, "o vers=4.2"); + E_write(mfd, "o addr=90.155.74.18"); + E_write(mfd, "o clientaddr=90.155.74.21"); + E_write(mfd, "x create"); + if (fsmount(mfd, AT_FDCWD, "/mnt", 0, 0) < 0) + mount_error(mfd, "fsmount"); + E(close(mfd)); + + exit(0); +}
Add a sample program for driving fsopen/fsmount. Signed-off-by: David Howells <dhowells@redhat.com> --- samples/fsmount/test-fsmount.c | 94 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 94 insertions(+) create mode 100644 samples/fsmount/test-fsmount.c -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html