> On Feb 23, 2022, at 1:16 PM, Dai Ngo <dai.ngo@xxxxxxxxxx> wrote:
>
> Update nfs4_get_vfs_file() to handle share reservation conflict
> with courtesy client. If share/access check fails with share
> denied then check if the conflict was caused by courtesy clients.
> If that's the case then set CLIENT_EXPIRED flag to expire the
> courtesy clients and allow nfs4_get_vfs_file to continue.
> Client with CLIENT_EXPIRED is expired by the laundromat.
>
> Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
I'm still getting my head around this, but there are
some items that can be addressed now, below.
> ---
> fs/nfsd/nfs4state.c | 106 ++++++++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 99 insertions(+), 7 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 542a13676c91..1ffe7bafe90b 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -4965,9 +4965,87 @@ nfsd4_truncate(struct svc_rqst *rqstp, struct svc_fh *fh,
> return nfsd_setattr(rqstp, fh, &iattr, 0, (time64_t)0);
> }
>
> +static bool
> +nfs4_check_access_deny_bmap(struct nfs4_ol_stateid *stp, u32 access,
> + bool share_access)
> +{
> + if (share_access) {
> + if (!stp->st_deny_bmap)
> + return false;
> +
> + if ((stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_BOTH)) ||
> + (access & NFS4_SHARE_ACCESS_READ &&
> + stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_READ)) ||
> + (access & NFS4_SHARE_ACCESS_WRITE &&
> + stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_WRITE))) {
> + return true;
> + }
> + return false;
> + }
> + if ((access & NFS4_SHARE_DENY_BOTH) ||
> + (access & NFS4_SHARE_DENY_READ &&
> + stp->st_access_bmap & (1 << NFS4_SHARE_ACCESS_READ)) ||
> + (access & NFS4_SHARE_DENY_WRITE &&
> + stp->st_access_bmap & (1 << NFS4_SHARE_ACCESS_WRITE))) {
> + return true;
> + }
> + return false;
> +}
> +
> +/*
> + * Check whether nfserr_share_denied should be returned.
This function is doing more than adjusting a return code,
now that I'm reading it more carefully. How about "Check
whether courtesy clients have conflicting access."
> + *
> + * access: is op_share_access if share_access is true.
> + * Check if access mode, op_share_access, would conflict with
> + * the current deny mode of the file 'fp'.
> + * access: is op_share_deny if share_access is false.
> + * Check if the deny mode, op_share_deny, would conflict with
> + * current access of the file 'fp'.
> + * stp: skip checking this entry.
> + * new_stp: normal open, not open upgrade.
> + *
> + * Function returns:
> + * true - access/deny mode conflict with normal client.
> + * false - no conflict or conflict with courtesy client(s) is resolved.
> + */
> +static bool
> +nfs4_conflict_clients(struct nfs4_file *fp, bool new_stp,
> + struct nfs4_ol_stateid *stp, u32 access, bool share_access)
Functions that are called with locks held are usually
suffixed with "_locked" -- this one should be too.
A better name might be "nfs4_resolve_deny_conflicts_locked".
> +{
> + struct nfs4_ol_stateid *st;
> + struct nfs4_client *cl;
Use "clp" to be consistent with other areas of the code.
> + bool conflict = false;
> +
> + lockdep_assert_held(&fp->fi_lock);
> + list_for_each_entry(st, &fp->fi_stateids, st_perfile) {
> + if (st->st_openstp || (st == stp && new_stp) ||
> + (!nfs4_check_access_deny_bmap(st,
> + access, share_access)))
> + continue;
> +
> + /* need to sync with courtesy client trying to reconnect */
> + cl = st->st_stid.sc_client;
> + spin_lock(&cl->cl_cs_lock);
> + if (test_bit(NFSD4_CLIENT_EXPIRED, &cl->cl_flags)) {
> + spin_unlock(&cl->cl_cs_lock);
> + continue;
> + }
> + if (test_bit(NFSD4_CLIENT_COURTESY, &cl->cl_flags)) {
> + set_bit(NFSD4_CLIENT_EXPIRED, &cl->cl_flags);
> + spin_unlock(&cl->cl_cs_lock);
> + continue;
> + }
> + /* conflict not caused by courtesy client */
> + spin_unlock(&cl->cl_cs_lock);
I think I'm seeing similar code as this in some of the
other patches. Whereever you can, please deduplicate by
creating a helper function and moving the common code
there.
> + conflict = true;
> + break;
> + }
> + return conflict;
> +}
> +
> static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
> struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp,
> - struct nfsd4_open *open)
> + struct nfsd4_open *open, bool new_stp)
> {
> struct nfsd_file *nf = NULL;
> __be32 status;
> @@ -4983,15 +5061,29 @@ static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
> */
> status = nfs4_file_check_deny(fp, open->op_share_deny);
> if (status != nfs_ok) {
> - spin_unlock(&fp->fi_lock);
> - goto out;
> + if (status != nfserr_share_denied) {
> + spin_unlock(&fp->fi_lock);
> + goto out;
> + }
> + if (nfs4_conflict_clients(fp, new_stp, stp,
> + open->op_share_deny, false)) {
> + spin_unlock(&fp->fi_lock);
> + goto out;
> + }
> }
Doesn't nfs4_upgrade_open() need to perform the same check?
>
> /* set access to the file */
> status = nfs4_file_get_access(fp, open->op_share_access);
> if (status != nfs_ok) {
> - spin_unlock(&fp->fi_lock);
> - goto out;
> + if (status != nfserr_share_denied) {
> + spin_unlock(&fp->fi_lock);
> + goto out;
> + }
> + if (nfs4_conflict_clients(fp, new_stp, stp,
> + open->op_share_access, true)) {
> + spin_unlock(&fp->fi_lock);
> + goto out;
> + }
This is nfs4_file_get_access()'s only caller. Should the call
to nfs4_conflict_clients() be moved into nfs4_file_get_access() ?
> }
>
> /* Set access bits in stateid */
> @@ -5042,7 +5134,7 @@ nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *c
> unsigned char old_deny_bmap = stp->st_deny_bmap;
>
> if (!test_access(open->op_share_access, stp))
> - return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open);
> + return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open, false);
>
> /* test and set deny mode */
> spin_lock(&fp->fi_lock);
> @@ -5391,7 +5483,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
> goto out;
> }
> } else {
> - status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open);
> + status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open, true);
> if (status) {
> stp->st_stid.sc_type = NFS4_CLOSED_STID;
> release_open_stateid(stp);
> --
> 2.9.5
>
--
Chuck Lever
