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nfs: Skip pathconf probe when neither field is consumed

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The PATHCONF RPC issued from nfs_probe_fsinfo() supplies two pieces of
information: max_namelen, used only when server->namelen has not been
pinned by mount options, and the case_insensitive / case_preserving
fields, used only by the NFSv2/NFSv3 path. NFSv4 receives its case
sensitivity caps from the FATTR4_CASE_* attributes during the
set_capabilities probe, and a non-zero server->namelen short-circuits
the only other field of interest.

When both conditions hold (NFSv4 with namelen pinned), the pathconf
reply is discarded in full but the round-trip is still on the mount
critical path. Gate the call on version < 4 || namelen == 0 so that
mounts which cannot benefit from the reply do not pay for it.

Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260507-case-sensitivity-v14-0-e62cc8200435@oracle.com?part=10
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://patch.msgid.link/20260515153515.362266-4-cel@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Chuck Lever 2026-05-15 11:35:11 -04:00 committed by Christian Brauner
parent c6eb07d3da
commit 425294293c
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
1 changed files with 17 additions and 15 deletions
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32
fs/nfs/client.c
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@ -937,23 +937,25 @@ static int nfs_probe_fsinfo(struct nfs_server *server, struct nfs_fh *mntfh, str
pathinfo.fattr = fattr;
nfs_fattr_init(fattr);
if (clp->rpc_ops->pathconf(server, mntfh, &pathinfo) >= 0) {
if (server->namelen == 0)
server->namelen = pathinfo.max_namelen;
if (clp->rpc_ops->version < 4) {
unsigned int caps = server->caps;
if (clp->rpc_ops->version < 4 || server->namelen == 0) {
if (clp->rpc_ops->pathconf(server, mntfh, &pathinfo) >= 0) {
if (server->namelen == 0)
server->namelen = pathinfo.max_namelen;
if (clp->rpc_ops->version < 4) {
unsigned int caps = server->caps;
caps &= ~(NFS_CAP_CASE_INSENSITIVE |
NFS_CAP_CASE_NONPRESERVING);
if (pathinfo.case_insensitive)
caps |= NFS_CAP_CASE_INSENSITIVE;
if (!pathinfo.case_preserving)
caps |= NFS_CAP_CASE_NONPRESERVING;
server->caps = caps;
caps &= ~(NFS_CAP_CASE_INSENSITIVE |
NFS_CAP_CASE_NONPRESERVING);
if (pathinfo.case_insensitive)
caps |= NFS_CAP_CASE_INSENSITIVE;
if (!pathinfo.case_preserving)
caps |= NFS_CAP_CASE_NONPRESERVING;
server->caps = caps;
}
} else if (clp->rpc_ops->version < 4) {
server->caps &= ~(NFS_CAP_CASE_INSENSITIVE |
NFS_CAP_CASE_NONPRESERVING);
}
} else if (clp->rpc_ops->version < 4) {
server->caps &= ~(NFS_CAP_CASE_INSENSITIVE |
NFS_CAP_CASE_NONPRESERVING);
}
if (clp->rpc_ops->discover_trunking != NULL &&