| Message ID | 146976861683.20186.1810009593325251793.stgit@noble (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Jul 29, 2016 at 03:03:36PM +1000, NeilBrown wrote: > If an export point should be mounted ("mountpoint" option set) but > isn't, then an attempt to mount using the MOUNT protocol for NFSv3 > will fail and an attempt to access the filesystem using a pre-existing > filehandle will block because nfsd_fh wont tell the kernel about it. > > However a lookup from the parent, as happens with an NFSv4 mount > request, will pass the name to nfsd_export(), and it doesn't check the > mointpoint option, and so exports the underlying (typically "/") > filesystem. > > So change nfsd_export() to refused to export that exportpoint, but > instead to explictly say that it isn't exported. > This will cause an 'ls' in the parent pseudo-root directory to not show > the name and will cause a "mount" attempt which walks down through the > pseudo root to fail in the same way that it does with NFSv3. > > An access from a pre-existing NFSv4 mount will still hang until the > filesystem is mounted, just like it does with NFSv3. > > In order to be a bit more responsive to the filesystem getting mounted, > just a short timeout (1 minutes) on exports of missing "mountpoint" > exportpoints. OK, I'm still haven't learned to love "mountpoint", but, I agree, it looks like this fixes the complaint about the v4 case with minimal risk of disruption to existing users. ACK.--b. > > Signed-off-by: NeilBrown <neilb@suse.com> > --- > utils/mountd/cache.c | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/utils/mountd/cache.c b/utils/mountd/cache.c > index 9cc270690d90..ca6c84f4d93d 100644 > --- a/utils/mountd/cache.c > +++ b/utils/mountd/cache.c > @@ -1334,7 +1334,23 @@ static void nfsd_export(int f) > found = lookup_export(dom, path, ai); > > if (found) { > - if (dump_to_cache(f, buf, sizeof(buf), dom, path, &found->m_export, 0) < 0) { > + char *mp = found->m_export.e_mountpoint; > + > + if (mp && !*mp) > + mp = found->m_export.e_path; > + if (mp && !is_mountpoint(mp)) > + /* Exportpoint is not mounted, so tell kernel it is > + * not available. > + * This will cause it not to appear in the V4 Pseudo-root > + * and so a "mount" of this path will fail, just like with > + * V3. > + * And filehandle for this mountpoint from an earlier > + * mount will block in nfsd.fh lookup. > + */ > + dump_to_cache(f, buf, sizeof(buf), dom, path, > + NULL, 60); > + else if (dump_to_cache(f, buf, sizeof(buf), dom, path, > + &found->m_export, 0) < 0) { > xlog(L_WARNING, > "Cannot export %s, possibly unsupported filesystem" > " or fsid= required", path); > -- 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/utils/mountd/cache.c b/utils/mountd/cache.c index 9cc270690d90..ca6c84f4d93d 100644 --- a/utils/mountd/cache.c +++ b/utils/mountd/cache.c @@ -1334,7 +1334,23 @@ static void nfsd_export(int f) found = lookup_export(dom, path, ai); if (found) { - if (dump_to_cache(f, buf, sizeof(buf), dom, path, &found->m_export, 0) < 0) { + char *mp = found->m_export.e_mountpoint; + + if (mp && !*mp) + mp = found->m_export.e_path; + if (mp && !is_mountpoint(mp)) + /* Exportpoint is not mounted, so tell kernel it is + * not available. + * This will cause it not to appear in the V4 Pseudo-root + * and so a "mount" of this path will fail, just like with + * V3. + * And filehandle for this mountpoint from an earlier + * mount will block in nfsd.fh lookup. + */ + dump_to_cache(f, buf, sizeof(buf), dom, path, + NULL, 60); + else if (dump_to_cache(f, buf, sizeof(buf), dom, path, + &found->m_export, 0) < 0) { xlog(L_WARNING, "Cannot export %s, possibly unsupported filesystem" " or fsid= required", path);
If an export point should be mounted ("mountpoint" option set) but isn't, then an attempt to mount using the MOUNT protocol for NFSv3 will fail and an attempt to access the filesystem using a pre-existing filehandle will block because nfsd_fh wont tell the kernel about it. However a lookup from the parent, as happens with an NFSv4 mount request, will pass the name to nfsd_export(), and it doesn't check the mointpoint option, and so exports the underlying (typically "/") filesystem. So change nfsd_export() to refused to export that exportpoint, but instead to explictly say that it isn't exported. This will cause an 'ls' in the parent pseudo-root directory to not show the name and will cause a "mount" attempt which walks down through the pseudo root to fail in the same way that it does with NFSv3. An access from a pre-existing NFSv4 mount will still hang until the filesystem is mounted, just like it does with NFSv3. In order to be a bit more responsive to the filesystem getting mounted, just a short timeout (1 minutes) on exports of missing "mountpoint" exportpoints. Signed-off-by: NeilBrown <neilb@suse.com> --- utils/mountd/cache.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) -- 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