On Mon, Sep 11, 2023 at 02:30:27PM -0400, trondmy@xxxxxxxxx wrote:
> From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
>
> The nfsd_open code handles EOPENSTALE correctly, by retrying the call to
> fh_verify() and __nfsd_open(). However the filecache just drops the
> error on the floor, and immediately returns nfserr_stale to the caller.
>
> This patch ensures that we propagate the EOPENSTALE code back to
> nfsd_file_do_acquire, and that we handle it correctly.
>
> Fixes: 65294c1f2c5e ("nfsd: add a new struct file caching facility to nfsd")
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> fs/nfsd/filecache.c | 27 +++++++++++++++++++--------
> fs/nfsd/vfs.c | 28 +++++++++++++---------------
> fs/nfsd/vfs.h | 2 +-
> 3 files changed, 33 insertions(+), 24 deletions(-)
>
> diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
> index ee9c923192e0..07bf219f9ae4 100644
> --- a/fs/nfsd/filecache.c
> +++ b/fs/nfsd/filecache.c
> @@ -989,22 +989,21 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
> unsigned char need = may_flags & NFSD_FILE_MAY_MASK;
> struct net *net = SVC_NET(rqstp);
> struct nfsd_file *new, *nf;
> - const struct cred *cred;
> + bool stale_retry = true;
> bool open_retry = true;
> struct inode *inode;
> __be32 status;
> int ret;
>
> +retry:
> status = fh_verify(rqstp, fhp, S_IFREG,
> may_flags|NFSD_MAY_OWNER_OVERRIDE);
> if (status != nfs_ok)
> return status;
> inode = d_inode(fhp->fh_dentry);
> - cred = get_current_cred();
If memory serves, we have to hold a reference to the current cred
through the acquire process. Otherwise, the cred can be released
while nfsd_file_do_acquire() is still running, which results in an
oops.
What's the reason to replace get_current_cred() with current_cred()?
> -retry:
> rcu_read_lock();
> - nf = nfsd_file_lookup_locked(net, cred, inode, need, want_gc);
> + nf = nfsd_file_lookup_locked(net, current_cred(), inode, need, want_gc);
> rcu_read_unlock();
>
> if (nf) {
> @@ -1026,7 +1025,7 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
>
> rcu_read_lock();
> spin_lock(&inode->i_lock);
> - nf = nfsd_file_lookup_locked(net, cred, inode, need, want_gc);
> + nf = nfsd_file_lookup_locked(net, current_cred(), inode, need, want_gc);
> if (unlikely(nf)) {
> spin_unlock(&inode->i_lock);
> rcu_read_unlock();
> @@ -1058,6 +1057,7 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
> goto construction_err;
> }
> open_retry = false;
> + fh_put(fhp);
> goto retry;
> }
> this_cpu_inc(nfsd_file_cache_hits);
> @@ -1074,7 +1074,6 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
> nfsd_file_check_write_error(nf);
> *pnf = nf;
> }
> - put_cred(cred);
> trace_nfsd_file_acquire(rqstp, inode, may_flags, nf, status);
> return status;
>
> @@ -1088,8 +1087,20 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
> status = nfs_ok;
> trace_nfsd_file_opened(nf, status);
> } else {
> - status = nfsd_open_verified(rqstp, fhp, may_flags,
> - &nf->nf_file);
> + ret = nfsd_open_verified(rqstp, fhp, may_flags,
> + &nf->nf_file);
> + if (ret == -EOPENSTALE && stale_retry) {
> + stale_retry = false;
> + nfsd_file_unhash(nf);
> + clear_and_wake_up_bit(NFSD_FILE_PENDING,
> + &nf->nf_flags);
> + if (refcount_dec_and_test(&nf->nf_ref))
> + nfsd_file_free(nf);
> + nf = NULL;
> + fh_put(fhp);
> + goto retry;
> + }
> + status = nfserrno(ret);
> trace_nfsd_file_open(nf, status);
> }
> } else
> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index 2c9074ab2315..98fa4fd0556d 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -823,7 +823,7 @@ int nfsd_open_break_lease(struct inode *inode, int access)
> * and additional flags.
> * N.B. After this call fhp needs an fh_put
> */
> -static __be32
> +static int
> __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
> int may_flags, struct file **filp)
> {
> @@ -831,14 +831,12 @@ __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
> struct inode *inode;
> struct file *file;
> int flags = O_RDONLY|O_LARGEFILE;
> - __be32 err;
> - int host_err = 0;
> + int host_err = -EPERM;
>
> path.mnt = fhp->fh_export->ex_path.mnt;
> path.dentry = fhp->fh_dentry;
> inode = d_inode(path.dentry);
>
> - err = nfserr_perm;
> if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
> goto out;
>
> @@ -847,7 +845,7 @@ __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
>
> host_err = nfsd_open_break_lease(inode, may_flags);
> if (host_err) /* NOMEM or WOULDBLOCK */
> - goto out_nfserr;
> + goto out;
>
> if (may_flags & NFSD_MAY_WRITE) {
> if (may_flags & NFSD_MAY_READ)
> @@ -859,13 +857,13 @@ __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
> file = dentry_open(&path, flags, current_cred());
> if (IS_ERR(file)) {
> host_err = PTR_ERR(file);
> - goto out_nfserr;
> + goto out;
> }
>
> host_err = ima_file_check(file, may_flags);
> if (host_err) {
> fput(file);
> - goto out_nfserr;
> + goto out;
> }
>
> if (may_flags & NFSD_MAY_64BIT_COOKIE)
> @@ -874,10 +872,8 @@ __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
> file->f_mode |= FMODE_32BITHASH;
>
> *filp = file;
> -out_nfserr:
> - err = nfserrno(host_err);
> out:
> - return err;
> + return host_err;
> }
>
> __be32
> @@ -885,6 +881,7 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
> int may_flags, struct file **filp)
> {
> __be32 err;
> + int host_err;
> bool retried = false;
>
> validate_process_creds();
> @@ -904,12 +901,13 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
> retry:
> err = fh_verify(rqstp, fhp, type, may_flags);
> if (!err) {
> - err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
> - if (err == nfserr_stale && !retried) {
> + host_err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
> + if (host_err == -EOPENSTALE && !retried) {
> retried = true;
> fh_put(fhp);
> goto retry;
> }
> + err = nfserrno(host_err);
> }
> validate_process_creds();
> return err;
> @@ -922,13 +920,13 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
> * @may_flags: internal permission flags
> * @filp: OUT: open "struct file *"
> *
> - * Returns an nfsstat value in network byte order.
> + * Returns a posix error.
> */
> -__be32
> +int
> nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp, int may_flags,
> struct file **filp)
> {
> - __be32 err;
> + int err;
>
> validate_process_creds();
> err = __nfsd_open(rqstp, fhp, S_IFREG, may_flags, filp);
> diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
> index a6890ea7b765..e4b7207ef2e0 100644
> --- a/fs/nfsd/vfs.h
> +++ b/fs/nfsd/vfs.h
> @@ -104,7 +104,7 @@ __be32 nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
> int nfsd_open_break_lease(struct inode *, int);
> __be32 nfsd_open(struct svc_rqst *, struct svc_fh *, umode_t,
> int, struct file **);
> -__be32 nfsd_open_verified(struct svc_rqst *, struct svc_fh *,
> +int nfsd_open_verified(struct svc_rqst *, struct svc_fh *,
> int, struct file **);
> __be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
> struct file *file, loff_t offset,
> --
> 2.41.0
>
--
Chuck Lever
