Commit 243a5263 authored by Jeff Layton's avatar Jeff Layton Committed by Chuck Lever
Browse files

nfsd: rework hashtable handling in nfsd_do_file_acquire 



nfsd_file is RCU-freed, so we need to hold the rcu_read_lock long enough
to get a reference after finding it in the hash. Take the
rcu_read_lock() and call rhashtable_lookup directly.

Switch to using rhashtable_lookup_insert_key as well, and use the usual
retry mechanism if we hit an -EEXIST. Rename the "retry" bool to
open_retry, and eliminiate the insert_err goto target.

Signed-off-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 8d0d254b

fs/nfsd/filecache.c

+22 −30
Original line number Diff line number Diff line
@@ -1042,9 +1042,10 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, 
		.need	= may_flags & NFSD_FILE_MAY_MASK,

		.net	= SVC_NET(rqstp),

	};

	struct nfsd_file *nf, *new;

	bool retry = true;

	bool open_retry = true;

	struct nfsd_file *nf;

	__be32 status;

	int ret;



	status = fh_verify(rqstp, fhp, S_IFREG,

				may_flags|NFSD_MAY_OWNER_OVERRIDE);
@@ -1054,35 +1055,33 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, 
	key.cred = get_current_cred();



retry:

	/* Avoid allocation if the item is already in cache */

	nf = rhashtable_lookup_fast(&nfsd_file_rhash_tbl, &key,

	rcu_read_lock();

	nf = rhashtable_lookup(&nfsd_file_rhash_tbl, &key,

			       nfsd_file_rhash_params);

	if (nf)

		nf = nfsd_file_get(nf);

	rcu_read_unlock();

	if (nf)

		goto wait_for_construction;



	new = nfsd_file_alloc(&key, may_flags);

	if (!new) {

	nf = nfsd_file_alloc(&key, may_flags);

	if (!nf) {

		status = nfserr_jukebox;

		goto out_status;

	}



	nf = rhashtable_lookup_get_insert_key(&nfsd_file_rhash_tbl,

					      &key, &new->nf_rhash,

	ret = rhashtable_lookup_insert_key(&nfsd_file_rhash_tbl,

					   &key, &nf->nf_rhash,

					   nfsd_file_rhash_params);

	if (!nf) {

		nf = new;

		goto open_file;

	}

	if (IS_ERR(nf))

		goto insert_err;

	nf = nfsd_file_get(nf);

	if (nf == NULL) {

		nf = new;

	if (likely(ret == 0))

		goto open_file;

	}

	nfsd_file_slab_free(&new->nf_rcu);



	nfsd_file_slab_free(&nf->nf_rcu);

	if (ret == -EEXIST)

		goto retry;

	trace_nfsd_file_insert_err(rqstp, key.inode, may_flags, ret);

	status = nfserr_jukebox;

	goto out_status;



wait_for_construction:

	wait_on_bit(&nf->nf_flags, NFSD_FILE_PENDING, TASK_UNINTERRUPTIBLE);
@@ -1090,11 +1089,11 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, 
	/* Did construction of this file fail? */

	if (!test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {

		trace_nfsd_file_cons_err(rqstp, key.inode, may_flags, nf);

		if (!retry) {

		if (!open_retry) {

			status = nfserr_jukebox;

			goto out;

		}

		retry = false;

		open_retry = false;

		nfsd_file_put_noref(nf);

		goto retry;

	}
@@ -1142,13 +1141,6 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, 
	smp_mb__after_atomic();

	wake_up_bit(&nf->nf_flags, NFSD_FILE_PENDING);

	goto out;



insert_err:

	nfsd_file_slab_free(&new->nf_rcu);

	trace_nfsd_file_insert_err(rqstp, key.inode, may_flags, PTR_ERR(nf));

	nf = NULL;

	status = nfserr_jukebox;

	goto out_status;

}



/**