On 2/25/22 9:57 AM, Chuck Lever III wrote:
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."
fix in v15.
+ *
+ * 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".
Fix in v15.
+{
+ struct nfs4_ol_stateid *st;
+ struct nfs4_client *cl;
Use "clp" to be consistent with other areas of the code.
Fix in v15.
+ 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.
Fix in v15.
+ 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?
Yes, we need to do the same check here. Fix in v15.
/* 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() ?
We could, but I think it's better to keep the call sign of
nfs4_file_get_access as is for speed since we don't have to pass
additional parameters for nfs4_resolve_deny_conflicts_locked
which should rarely need to run. Also, I think it's easier to
understand to code when both access and deny check are in the
same place.
-Dai
}
/* 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
