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NFSD: Add a mechanism to wait for a DELEGRETURN

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Subsequent patches will use this mechanism to wake up an operation
that is waiting for a client to return a delegation.

The new tracepoint records whether the wait timed out or was
properly awoken by the expected DELEGRETURN:

            nfsd-1155  [002] 83799.493199: nfsd_delegret_wakeup: xid=0x14b7d6ef fh_hash=0xf6826792 (timed out)

Suggested-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
This commit is contained in:
Chuck Lever 2022-09-08 18:14:00 -04:00
parent 1035d65446
commit c035362eb9
3 changed files with 60 additions and 0 deletions
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30
fs/nfsd/nfs4state.c
View File

@ -4717,6 +4717,35 @@ nfs4_share_conflict(struct svc_fh *current_fh, unsigned int deny_type)
return ret;
}
static bool nfsd4_deleg_present(const struct inode *inode)
{
struct file_lock_context *ctx = smp_load_acquire(&inode->i_flctx);
return ctx && !list_empty_careful(&ctx->flc_lease);
}
/**
* nfsd_wait_for_delegreturn - wait for delegations to be returned
* @rqstp: the RPC transaction being executed
* @inode: in-core inode of the file being waited for
*
* The timeout prevents deadlock if all nfsd threads happen to be
* tied up waiting for returning delegations.
*
* Return values:
* %true: delegation was returned
* %false: timed out waiting for delegreturn
*/
bool nfsd_wait_for_delegreturn(struct svc_rqst *rqstp, struct inode *inode)
{
long __maybe_unused timeo;
timeo = wait_var_event_timeout(inode, !nfsd4_deleg_present(inode),
NFSD_DELEGRETURN_TIMEOUT);
trace_nfsd_delegret_wakeup(rqstp, inode, timeo);
return timeo > 0;
}
static void nfsd4_cb_recall_prepare(struct nfsd4_callback *cb)
{
struct nfs4_delegation *dp = cb_to_delegation(cb);
@ -6779,6 +6808,7 @@ nfsd4_delegreturn(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
if (status)
goto put_stateid;
wake_up_var(d_inode(cstate->current_fh.fh_dentry));
destroy_delegation(dp);
put_stateid:
nfs4_put_stid(&dp->dl_stid);

7
fs/nfsd/nfsd.h
View File

@ -164,6 +164,7 @@ char * nfs4_recoverydir(void);
bool nfsd4_spo_must_allow(struct svc_rqst *rqstp);
int nfsd4_create_laundry_wq(void);
void nfsd4_destroy_laundry_wq(void);
bool nfsd_wait_for_delegreturn(struct svc_rqst *rqstp, struct inode *inode);
#else
static inline int nfsd4_init_slabs(void) { return 0; }
static inline void nfsd4_free_slabs(void) { }
@ -179,6 +180,11 @@ static inline bool nfsd4_spo_must_allow(struct svc_rqst *rqstp)
}
static inline int nfsd4_create_laundry_wq(void) { return 0; };
static inline void nfsd4_destroy_laundry_wq(void) {};
static inline bool nfsd_wait_for_delegreturn(struct svc_rqst *rqstp,
struct inode *inode)
{
return false;
}
#endif
/*
@ -343,6 +349,7 @@ void nfsd_lockd_shutdown(void);
#define NFSD_COURTESY_CLIENT_TIMEOUT (24 * 60 * 60) /* seconds */
#define NFSD_CLIENT_MAX_TRIM_PER_RUN 128
#define NFS4_CLIENTS_PER_GB 1024
#define NFSD_DELEGRETURN_TIMEOUT (HZ / 34) /* 30ms */
/*
* The following attributes are currently not supported by the NFSv4 server:

23
fs/nfsd/trace.h
View File

@ -538,6 +538,29 @@ DEFINE_NFSD_COPY_ERR_EVENT(clone_file_range_err);
#include "filecache.h"
#include "vfs.h"
TRACE_EVENT(nfsd_delegret_wakeup,
TP_PROTO(
const struct svc_rqst *rqstp,
const struct inode *inode,
long timeo
),
TP_ARGS(rqstp, inode, timeo),
TP_STRUCT__entry(
__field(u32, xid)
__field(const void *, inode)
__field(long, timeo)
),
TP_fast_assign(
__entry->xid = be32_to_cpu(rqstp->rq_xid);
__entry->inode = inode;
__entry->timeo = timeo;
),
TP_printk("xid=0x%08x inode=%p%s",
__entry->xid, __entry->inode,
__entry->timeo == 0 ? " (timed out)" : ""
)
);
DECLARE_EVENT_CLASS(nfsd_stateid_class,
TP_PROTO(stateid_t *stp),
TP_ARGS(stp),