From 4d1ea8455716ca070e3cd85767e6f6a562a58b1b Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Fri, 28 Oct 2022 10:46:51 -0400 Subject: NFSD: Add an NFSD_FILE_GC flag to enable nfsd_file garbage collection NFSv4 operations manage the lifetime of nfsd_file items they use by means of NFSv4 OPEN and CLOSE. Hence there's no need for them to be garbage collected. Introduce a mechanism to enable garbage collection for nfsd_file items used only by NFSv2/3 callers. Note that the change in nfsd_file_put() ensures that both CLOSE and DELEGRETURN will actually close out and free an nfsd_file on last reference of a non-garbage-collected file. Link: https://bugzilla.linux-nfs.org/show_bug.cgi?id=394 Suggested-by: Trond Myklebust Signed-off-by: Chuck Lever Tested-by: Jeff Layton Reviewed-by: NeilBrown Reviewed-by: Jeff Layton --- fs/nfsd/filecache.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 55 insertions(+), 8 deletions(-) (limited to 'fs/nfsd/filecache.c') diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index babea79d3f6f..cee44405cf7d 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -63,6 +63,7 @@ struct nfsd_file_lookup_key { struct net *net; const struct cred *cred; unsigned char need; + bool gc; enum nfsd_file_lookup_type type; }; @@ -162,6 +163,8 @@ static int nfsd_file_obj_cmpfn(struct rhashtable_compare_arg *arg, return 1; if (!nfsd_match_cred(nf->nf_cred, key->cred)) return 1; + if (!!test_bit(NFSD_FILE_GC, &nf->nf_flags) != key->gc) + return 1; if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags) == 0) return 1; break; @@ -297,6 +300,8 @@ nfsd_file_alloc(struct nfsd_file_lookup_key *key, unsigned int may) nf->nf_flags = 0; __set_bit(NFSD_FILE_HASHED, &nf->nf_flags); __set_bit(NFSD_FILE_PENDING, &nf->nf_flags); + if (key->gc) + __set_bit(NFSD_FILE_GC, &nf->nf_flags); nf->nf_inode = key->inode; /* nf_ref is pre-incremented for hash table */ refcount_set(&nf->nf_ref, 2); @@ -428,16 +433,27 @@ nfsd_file_put_noref(struct nfsd_file *nf) } } +static void +nfsd_file_unhash_and_put(struct nfsd_file *nf) +{ + if (nfsd_file_unhash(nf)) + nfsd_file_put_noref(nf); +} + void nfsd_file_put(struct nfsd_file *nf) { might_sleep(); - nfsd_file_lru_add(nf); - if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags) == 0) { + if (test_bit(NFSD_FILE_GC, &nf->nf_flags)) + nfsd_file_lru_add(nf); + else if (refcount_read(&nf->nf_ref) == 2) + nfsd_file_unhash_and_put(nf); + + if (!test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) { nfsd_file_flush(nf); nfsd_file_put_noref(nf); - } else if (nf->nf_file) { + } else if (nf->nf_file && test_bit(NFSD_FILE_GC, &nf->nf_flags)) { nfsd_file_put_noref(nf); nfsd_file_schedule_laundrette(); } else @@ -1016,12 +1032,14 @@ nfsd_file_is_cached(struct inode *inode) static __be32 nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, - unsigned int may_flags, struct nfsd_file **pnf, bool open) + unsigned int may_flags, struct nfsd_file **pnf, + bool open, bool want_gc) { struct nfsd_file_lookup_key key = { .type = NFSD_FILE_KEY_FULL, .need = may_flags & NFSD_FILE_MAY_MASK, .net = SVC_NET(rqstp), + .gc = want_gc, }; bool open_retry = true; struct nfsd_file *nf; @@ -1117,14 +1135,35 @@ open_file: * then unhash. */ if (status != nfs_ok || key.inode->i_nlink == 0) - if (nfsd_file_unhash(nf)) - nfsd_file_put_noref(nf); + nfsd_file_unhash_and_put(nf); clear_bit_unlock(NFSD_FILE_PENDING, &nf->nf_flags); smp_mb__after_atomic(); wake_up_bit(&nf->nf_flags, NFSD_FILE_PENDING); goto out; } +/** + * nfsd_file_acquire_gc - Get a struct nfsd_file with an open file + * @rqstp: the RPC transaction being executed + * @fhp: the NFS filehandle of the file to be opened + * @may_flags: NFSD_MAY_ settings for the file + * @pnf: OUT: new or found "struct nfsd_file" object + * + * The nfsd_file object returned by this API is reference-counted + * and garbage-collected. The object is retained for a few + * seconds after the final nfsd_file_put() in case the caller + * wants to re-use it. + * + * Returns nfs_ok and sets @pnf on success; otherwise an nfsstat in + * network byte order is returned. + */ +__be32 +nfsd_file_acquire_gc(struct svc_rqst *rqstp, struct svc_fh *fhp, + unsigned int may_flags, struct nfsd_file **pnf) +{ + return nfsd_file_do_acquire(rqstp, fhp, may_flags, pnf, true, true); +} + /** * nfsd_file_acquire - Get a struct nfsd_file with an open file * @rqstp: the RPC transaction being executed @@ -1132,6 +1171,10 @@ open_file: * @may_flags: NFSD_MAY_ settings for the file * @pnf: OUT: new or found "struct nfsd_file" object * + * The nfsd_file_object returned by this API is reference-counted + * but not garbage-collected. The object is unhashed after the + * final nfsd_file_put(). + * * Returns nfs_ok and sets @pnf on success; otherwise an nfsstat in * network byte order is returned. */ @@ -1139,7 +1182,7 @@ __be32 nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, unsigned int may_flags, struct nfsd_file **pnf) { - return nfsd_file_do_acquire(rqstp, fhp, may_flags, pnf, true); + return nfsd_file_do_acquire(rqstp, fhp, may_flags, pnf, true, false); } /** @@ -1149,6 +1192,10 @@ nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, * @may_flags: NFSD_MAY_ settings for the file * @pnf: OUT: new or found "struct nfsd_file" object * + * The nfsd_file_object returned by this API is reference-counted + * but not garbage-collected. The object is released immediately + * one RCU grace period after the final nfsd_file_put(). + * * Returns nfs_ok and sets @pnf on success; otherwise an nfsstat in * network byte order is returned. */ @@ -1156,7 +1203,7 @@ __be32 nfsd_file_create(struct svc_rqst *rqstp, struct svc_fh *fhp, unsigned int may_flags, struct nfsd_file **pnf) { - return nfsd_file_do_acquire(rqstp, fhp, may_flags, pnf, false); + return nfsd_file_do_acquire(rqstp, fhp, may_flags, pnf, false, false); } /* -- cgit v1.2.3