On Thu, Mar 24, 2022 at 09:34:45PM -0700, Dai Ngo wrote:
> Update nfs4_get_vfs_file and nfs4_upgrade_open to handle share
> reservation conflict with courtesy client.
>
> Update nfs4_get_vfs_file and nfs4_upgrade_open to handle share
> reservation conflict with courtesy client.
>
> When we have deny/access conflict we walk the fi_stateids of the
> file in question, looking for open stateid and check the deny/access
> of that stateid against the one from the open request. If there is
> a conflict then we check if the client that owns that stateid is
> a courtesy client. If it is then we set the client state to
> CLIENT_EXPIRED and allow the open request to continue. We have
> to scan all the stateid's of the file since the conflict can be
> caused by multiple open stateid's.
>
> Client with CLIENT_EXPIRED is expired by the laundromat.
>
> Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
> ---
> fs/nfsd/nfs4state.c | 85 +++++++++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 72 insertions(+), 13 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index f20c75890594..fe8969ba94b3 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -701,9 +701,56 @@ __nfs4_file_get_access(struct nfs4_file *fp, u32 access)
> atomic_inc(&fp->fi_access[O_RDONLY]);
> }
>
> +/*
> + * Check if courtesy clients have conflicting access and resolve it if possible
> + *
> + * 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:
> + * false - access/deny mode conflict with normal client.
> + * true - no conflict or conflict with courtesy client(s) is resolved.
> + */
> +static bool
> +nfs4_resolve_deny_conflicts_locked(struct nfs4_file *fp, bool new_stp,
> + struct nfs4_ol_stateid *stp, u32 access, bool share_access)
> +{
> + struct nfs4_ol_stateid *st;
> + struct nfs4_client *clp;
> + bool conflict = true;
> + unsigned char bmap;
> +
> + lockdep_assert_held(&fp->fi_lock);
> + list_for_each_entry(st, &fp->fi_stateids, st_perfile) {
> + /* ignore lock stateid */
> + if (st->st_openstp)
> + continue;
> + if (st == stp && new_stp)
> + continue;
> + /* check file access against deny mode or vice versa */
> + bmap = share_access ? st->st_deny_bmap : st->st_access_bmap;
> + if (!(access & bmap_to_share_mode(bmap)))
> + continue;
As I said before, I recommend just doing *both* checks here. Then you
can remove the "bool share_access" argument. I think that'll make the
code easier to read.
Otherwise, this version looks OK to me, thanks for the revisions.
--b.
> + clp = st->st_stid.sc_client;
> + if (nfsd4_expire_courtesy_clnt(clp))
> + continue;
> + conflict = false;
> + break;
> + }
> + return conflict;
> +}
> +
> static __be32
> -nfs4_file_get_access(struct nfs4_file *fp, u32 access)
> +nfs4_file_get_access(struct nfs4_file *fp, u32 access,
> + struct nfs4_ol_stateid *stp, bool new_stp)
> {
> +
> lockdep_assert_held(&fp->fi_lock);
>
> /* Does this access mode make sense? */
> @@ -711,15 +758,21 @@ nfs4_file_get_access(struct nfs4_file *fp, u32 access)
> return nfserr_inval;
>
> /* Does it conflict with a deny mode already set? */
> - if ((access & fp->fi_share_deny) != 0)
> - return nfserr_share_denied;
> + if ((access & fp->fi_share_deny) != 0) {
> + if (!nfs4_resolve_deny_conflicts_locked(fp, new_stp,
> + stp, access, true))
> + return nfserr_share_denied;
> + }
>
> __nfs4_file_get_access(fp, access);
> return nfs_ok;
> }
>
> -static __be32 nfs4_file_check_deny(struct nfs4_file *fp, u32 deny)
> +static __be32 nfs4_file_check_deny(struct nfs4_file *fp, u32 deny,
> + struct nfs4_ol_stateid *stp, bool new_stp)
> {
> + __be32 rc = nfs_ok;
> +
> /* Common case is that there is no deny mode. */
> if (deny) {
> /* Does this deny mode make sense? */
> @@ -728,13 +781,19 @@ static __be32 nfs4_file_check_deny(struct nfs4_file *fp, u32 deny)
>
> if ((deny & NFS4_SHARE_DENY_READ) &&
> atomic_read(&fp->fi_access[O_RDONLY]))
> - return nfserr_share_denied;
> + rc = nfserr_share_denied;
>
> if ((deny & NFS4_SHARE_DENY_WRITE) &&
> atomic_read(&fp->fi_access[O_WRONLY]))
> - return nfserr_share_denied;
> + rc = nfserr_share_denied;
> +
> + if (rc == nfserr_share_denied) {
> + if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
> + stp, deny, false))
> + rc = nfs_ok;
> + }
> }
> - return nfs_ok;
> + return rc;
> }
>
> static void __nfs4_file_put_access(struct nfs4_file *fp, int oflag)
> @@ -4952,7 +5011,7 @@ nfsd4_truncate(struct svc_rqst *rqstp, struct svc_fh *fh,
>
> 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;
> @@ -4966,14 +5025,14 @@ static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
> * Are we trying to set a deny mode that would conflict with
> * current access?
> */
> - status = nfs4_file_check_deny(fp, open->op_share_deny);
> + status = nfs4_file_check_deny(fp, open->op_share_deny, stp, new_stp);
> if (status != nfs_ok) {
> spin_unlock(&fp->fi_lock);
> goto out;
> }
>
> /* set access to the file */
> - status = nfs4_file_get_access(fp, open->op_share_access);
> + status = nfs4_file_get_access(fp, open->op_share_access, stp, new_stp);
> if (status != nfs_ok) {
> spin_unlock(&fp->fi_lock);
> goto out;
> @@ -5027,11 +5086,11 @@ 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);
> - status = nfs4_file_check_deny(fp, open->op_share_deny);
> + status = nfs4_file_check_deny(fp, open->op_share_deny, stp, false);
> if (status == nfs_ok) {
> set_deny(open->op_share_deny, stp);
> fp->fi_share_deny |=
> @@ -5376,7 +5435,7 @@ 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
