Enhance nfsd to detect internal mounts and to cross them without
requiring a new export.
Also ensure the fsid reported is different for different submounts. We
do this by xoring in the ino of the mounted-on directory. This makes
sense for btrfs at least.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
fs/nfsd/nfs3xdr.c | 28 +++++++++++++++++++++-------
fs/nfsd/nfs4xdr.c | 34 +++++++++++++++++++++++-----------
fs/nfsd/nfsfh.c | 7 ++++++-
fs/nfsd/vfs.c | 11 +++++++++--
4 files changed, 59 insertions(+), 21 deletions(-)
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 67af0c5c1543..80b1cc0334fa 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -370,6 +370,8 @@ svcxdr_encode_fattr3(struct svc_rqst *rqstp, struct xdr_stream *xdr,
case FSIDSOURCE_UUID:
fsid = ((u64 *)fhp->fh_export->ex_uuid)[0];
fsid ^= ((u64 *)fhp->fh_export->ex_uuid)[1];
+ if (fhp->fh_mnt != fhp->fh_export->ex_path.mnt)
+ fsid ^= nfsd_get_mounted_on(fhp->fh_mnt);
break;
default:
fsid = (u64)huge_encode_dev(fhp->fh_dentry->d_sb->s_dev);
@@ -1094,8 +1096,8 @@ compose_entry_fh(struct nfsd3_readdirres *cd, struct svc_fh *fhp,
__be32 rv = nfserr_noent;
dparent = cd->fh.fh_dentry;
- exp = cd->fh.fh_export;
- child.mnt = cd->fh.fh_mnt;
+ exp = exp_get(cd->fh.fh_export);
+ child.mnt = mntget(cd->fh.fh_mnt);
if (isdotent(name, namlen)) {
if (namlen == 2) {
@@ -1112,15 +1114,27 @@ compose_entry_fh(struct nfsd3_readdirres *cd, struct svc_fh *fhp,
child.dentry = dget(dparent);
} else
child.dentry = lookup_positive_unlocked(name, dparent, namlen);
- if (IS_ERR(child.dentry))
+ if (IS_ERR(child.dentry)) {
+ mntput(child.mnt);
+ exp_put(exp);
return rv;
- if (d_mountpoint(child.dentry))
- goto out;
- if (child.dentry->d_inode->i_ino != ino)
+ }
+ /* If child is a mountpoint, then we want to expose the fact
+ * so client can create a mountpoint. If not, then a different
+ * ino number probably means a race with rename, so avoid providing
+ * too much detail.
+ */
+ if (nfsd_mountpoint(child.dentry, exp)) {
+ int err;
+ err = nfsd_cross_mnt(cd->rqstp, &child, &exp);
+ if (err)
+ goto out;
+ } else if (child.dentry->d_inode->i_ino != ino)
goto out;
rv = fh_compose(fhp, exp, &child, &cd->fh);
out:
- dput(child.dentry);
+ path_put(&child);
+ exp_put(exp);
return rv;
}
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index d5683b6a74b2..4dbc99ed2c8b 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2817,6 +2817,8 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
struct kstat stat;
struct svc_fh *tempfh = NULL;
struct kstatfs statfs;
+ u64 mounted_on_ino;
+ u64 sub_fsid;
__be32 *p;
int starting_len = xdr->buf->len;
int attrlen_offset;
@@ -2871,6 +2873,24 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
goto out;
fhp = tempfh;
}
+ if ((bmval0 & FATTR4_WORD0_FSID) ||
+ (bmval1 & FATTR4_WORD1_MOUNTED_ON_FILEID)) {
+ mounted_on_ino = stat.ino;
+ sub_fsid = 0;
+ /*
+ * The inode number that the current mnt is mounted on is
+ * used for MOUNTED_ON_FILED if we are at the root,
+ * and for sub_fsid if mnt is not the export mnt.
+ */
+ if (ignore_crossmnt == 0) {
+ u64 moi = nfsd_get_mounted_on(mnt);
+
+ if (dentry == mnt->mnt_root && moi)
+ mounted_on_ino = moi;
+ if (mnt != exp->ex_path.mnt)
+ sub_fsid = moi;
+ }
+ }
if (bmval0 & FATTR4_WORD0_ACL) {
err = nfsd4_get_nfs4_acl(rqstp, dentry, &acl);
if (err == -EOPNOTSUPP)
@@ -3008,6 +3028,8 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
case FSIDSOURCE_UUID:
p = xdr_encode_opaque_fixed(p, exp->ex_uuid,
EX_UUID_LEN);
+ if (mnt != exp->ex_path.mnt)
+ *(u64*)(p-2) ^= sub_fsid;
break;
}
}
@@ -3253,20 +3275,10 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
*p++ = cpu_to_be32(stat.mtime.tv_nsec);
}
if (bmval1 & FATTR4_WORD1_MOUNTED_ON_FILEID) {
- u64 ino;
-
p = xdr_reserve_space(xdr, 8);
if (!p)
goto out_resource;
- /*
- * Get parent's attributes if not ignoring crossmount
- * and this is the root of a cross-mounted filesystem.
- */
- if (ignore_crossmnt == 0 && dentry == mnt->mnt_root)
- ino = nfsd_get_mounted_on(mnt);
- if (!ino)
- ino = stat.ino;
- p = xdr_encode_hyper(p, ino);
+ p = xdr_encode_hyper(p, mounted_on_ino);
}
#ifdef CONFIG_NFSD_PNFS
if (bmval1 & FATTR4_WORD1_FS_LAYOUT_TYPES) {
diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index 4023046f63e2..4b53838bca89 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -9,7 +9,7 @@
*/
#include <linux/exportfs.h>
-
+#include <linux/namei.h>
#include <linux/sunrpc/svcauth_gss.h>
#include "nfsd.h"
#include "vfs.h"
@@ -285,6 +285,11 @@ static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
default:
dentry = ERR_PTR(-ESTALE);
}
+ } else if (nfsd_mountpoint(dentry, exp)) {
+ struct path path = { .mnt = mnt, .dentry = dentry };
+ follow_down(&path, LOOKUP_AUTOMOUNT);
+ mnt = path.mnt;
+ dentry = path.dentry;
}
}
if (dentry == NULL)
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index baa12ac36ece..22523e1cd478 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -64,7 +64,7 @@ nfsd_cross_mnt(struct svc_rqst *rqstp, struct path *path_parent,
.dentry = dget(path_parent->dentry)};
int err = 0;
- err = follow_down(&path, 0);
+ err = follow_down(&path, LOOKUP_AUTOMOUNT);
if (err < 0)
goto out;
if (path.mnt == path_parent->mnt && path.dentry == path_parent->dentry &&
@@ -73,6 +73,13 @@ nfsd_cross_mnt(struct svc_rqst *rqstp, struct path *path_parent,
path_put(&path);
goto out;
}
+ if (mount_is_internal(path.mnt)) {
+ /* Use the new path, but don't look for a new export */
+ /* FIXME should I check NOHIDE in this case?? */
+ path_put(path_parent);
+ *path_parent = path;
+ goto out;
+ }
exp2 = rqst_exp_get_by_name(rqstp, &path);
if (IS_ERR(exp2)) {
@@ -157,7 +164,7 @@ int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
return 1;
if (nfsd4_is_junction(dentry))
return 1;
- if (d_mountpoint(dentry))
+ if (d_managed(dentry))
/*
* Might only be a mountpoint in a different namespace,
* but we need to check.
