On Wed, 2022-10-05 at 10:56 -0400, Chuck Lever wrote: > 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 <trond.myklebust@xxxxxxxxxxxxxxx> > Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> > --- > fs/nfsd/filecache.c | 61 +++++++++++++++++++++++++++++++++++++++++++++------ > fs/nfsd/filecache.h | 3 +++ > fs/nfsd/nfs3proc.c | 4 ++- > fs/nfsd/trace.h | 3 ++- > fs/nfsd/vfs.c | 4 ++- > 5 files changed, 63 insertions(+), 12 deletions(-) > > diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c > index b7aa523c2010..01c27deabf83 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; > + unsigned char gc:1; > 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_GC, &nf->nf_flags) == 1) > + 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) == 0) { > 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) == 1) { > nfsd_file_put_noref(nf); > nfsd_file_schedule_laundrette(); > } else > @@ -1017,12 +1033,14 @@ 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, int want_gc) want_gc should be a bool > { > 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 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, > * 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, 1); > +} > + > /** > * nfsd_file_acquire - Get a struct nfsd_file with an open file > * @rqstp: the RPC transaction being executed > @@ -1132,6 +1171,10 @@ nfsd_file_do_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 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. > */ > @@ -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, 0); > } > > /** > @@ -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, 0); > } > > /* > diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h > index f81c198f4ed6..0f6546bcd3e0 100644 > --- a/fs/nfsd/filecache.h > +++ b/fs/nfsd/filecache.h > @@ -38,6 +38,7 @@ struct nfsd_file { > #define NFSD_FILE_HASHED (0) > #define NFSD_FILE_PENDING (1) > #define NFSD_FILE_REFERENCED (2) > +#define NFSD_FILE_GC (3) > unsigned long nf_flags; > struct inode *nf_inode; /* don't deref */ > refcount_t nf_ref; > @@ -55,6 +56,8 @@ void nfsd_file_put(struct nfsd_file *nf); > struct nfsd_file *nfsd_file_get(struct nfsd_file *nf); > void nfsd_file_close_inode_sync(struct inode *inode); > bool nfsd_file_is_cached(struct inode *inode); > +__be32 nfsd_file_acquire_gc(struct svc_rqst *rqstp, struct svc_fh *fhp, > + unsigned int may_flags, struct nfsd_file **nfp); > __be32 nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, > unsigned int may_flags, struct nfsd_file **nfp); > __be32 nfsd_file_create(struct svc_rqst *rqstp, struct svc_fh *fhp, > diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c > index d12823371857..6a5ad6c91d8e 100644 > --- a/fs/nfsd/nfs3proc.c > +++ b/fs/nfsd/nfs3proc.c > @@ -779,8 +779,8 @@ nfsd3_proc_commit(struct svc_rqst *rqstp) > (unsigned long long) argp->offset); > > fh_copy(&resp->fh, &argp->fh); > - resp->status = nfsd_file_acquire(rqstp, &resp->fh, NFSD_MAY_WRITE | > - NFSD_MAY_NOT_BREAK_LEASE, &nf); > + resp->status = nfsd_file_acquire_gc(rqstp, &resp->fh, NFSD_MAY_WRITE | > + NFSD_MAY_NOT_BREAK_LEASE, &nf); > if (resp->status) > goto out; > resp->status = nfsd_commit(rqstp, &resp->fh, nf, argp->offset, > diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h > index 9ebd67d461f9..4921144880d3 100644 > --- a/fs/nfsd/trace.h > +++ b/fs/nfsd/trace.h > @@ -742,7 +742,8 @@ DEFINE_CLID_EVENT(confirmed_r); > __print_flags(val, "|", \ > { 1 << NFSD_FILE_HASHED, "HASHED" }, \ > { 1 << NFSD_FILE_PENDING, "PENDING" }, \ > - { 1 << NFSD_FILE_REFERENCED, "REFERENCED"}) > + { 1 << NFSD_FILE_REFERENCED, "REFERENCED"}, \ > + { 1 << NFSD_FILE_GC, "GC"}) > > DECLARE_EVENT_CLASS(nfsd_file_class, > TP_PROTO(struct nfsd_file *nf), > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c > index 44f210ba17cc..89d682a56fc4 100644 > --- a/fs/nfsd/vfs.c > +++ b/fs/nfsd/vfs.c > @@ -1060,7 +1060,7 @@ __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp, > __be32 err; > > trace_nfsd_read_start(rqstp, fhp, offset, *count); > - err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_READ, &nf); > + err = nfsd_file_acquire_gc(rqstp, fhp, NFSD_MAY_READ, &nf); > if (err) > return err; > > @@ -1092,7 +1092,7 @@ nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset, > > trace_nfsd_write_start(rqstp, fhp, offset, *cnt); > > - err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_WRITE, &nf); > + err = nfsd_file_acquire_gc(rqstp, fhp, NFSD_MAY_WRITE, &nf); > if (err) > goto out; > > > Looks reasonable otherwise though. I like this approach. -- Jeff Layton <jlayton@xxxxxxxxxx>
