| Message ID | 20230324121608.16808-1-richard@nod.at (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | export: Fix rootdir corner case in next_mnt() | expand |
On 3/24/23 8:16 AM, Richard Weinberger wrote: > Currently the following setup causes failure: > > 1. /etc/exports: > / *(rw,crossmnt,no_subtree_check,fsid=root) > > 2. /etc/nfs.conf: > [exports] > rootdir=/nfs_srv > > 3. Mounts: > /root/fs1.ext4 on /nfs_srv type ext4 (rw,relatime) > /root/fs2.ext4 on /nfs_srv/fs2 type ext4 (rw,relatime) > > 4. On the client: > $ ls /nfs_client/fs2 > ls: cannot open directory '/nfs_client/fs2': Stale file handle > > The problem is that next_mnt() misses the corner case that > every mount is a sub-mount of "/". > So it fails to see that /nfs_srv/fs2 is a mountpoint when the > client asks for fs2 it and as consequence the crossmnt mechanism > fails. > > Signed-off-by: Richard Weinberger <richard@nod.at> Committed... (tag: nfs-utils-2-6-3-rc7) steved. > --- > support/export/cache.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/support/export/cache.c b/support/export/cache.c > index 2497d4f48df3..1c526277d3c6 100644 > --- a/support/export/cache.c > +++ b/support/export/cache.c > @@ -410,12 +410,16 @@ static char *next_mnt(void **v, char *p) > *v = f; > } else > f = *v; > - while ((me = getmntent(f)) != NULL && l > 1) { > + while ((me = getmntent(f)) != NULL && l >= 1) { > char *mnt_dir = nfsd_path_strip_root(me->mnt_dir); > > if (!mnt_dir) > continue; > > + /* Everything below "/" is a proper sub-mount */ > + if (strcmp(p, "/") == 0) > + return mnt_dir; > + > if (strncmp(mnt_dir, p, l) == 0 && mnt_dir[l] == '/') > return mnt_dir; > }
diff --git a/support/export/cache.c b/support/export/cache.c index 2497d4f48df3..1c526277d3c6 100644 --- a/support/export/cache.c +++ b/support/export/cache.c @@ -410,12 +410,16 @@ static char *next_mnt(void **v, char *p) *v = f; } else f = *v; - while ((me = getmntent(f)) != NULL && l > 1) { + while ((me = getmntent(f)) != NULL && l >= 1) { char *mnt_dir = nfsd_path_strip_root(me->mnt_dir); if (!mnt_dir) continue; + /* Everything below "/" is a proper sub-mount */ + if (strcmp(p, "/") == 0) + return mnt_dir; + if (strncmp(mnt_dir, p, l) == 0 && mnt_dir[l] == '/') return mnt_dir; }
Currently the following setup causes failure: 1. /etc/exports: / *(rw,crossmnt,no_subtree_check,fsid=root) 2. /etc/nfs.conf: [exports] rootdir=/nfs_srv 3. Mounts: /root/fs1.ext4 on /nfs_srv type ext4 (rw,relatime) /root/fs2.ext4 on /nfs_srv/fs2 type ext4 (rw,relatime) 4. On the client: $ ls /nfs_client/fs2 ls: cannot open directory '/nfs_client/fs2': Stale file handle The problem is that next_mnt() misses the corner case that every mount is a sub-mount of "/". So it fails to see that /nfs_srv/fs2 is a mountpoint when the client asks for fs2 it and as consequence the crossmnt mechanism fails. Signed-off-by: Richard Weinberger <richard@nod.at> --- support/export/cache.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)