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nfsd: fix handling of cached open files in nfsd4_open codepath
Commitfb70bf124b
("NFSD: Instantiate a struct file when creating a regular NFSv4 file") added the ability to cache an open fd over a compound. There are a couple of problems with the way this currently works: It's racy, as a newly-created nfsd_file can end up with its PENDING bit cleared while the nf is hashed, and the nf_file pointer is still zeroed out. Other tasks can find it in this state and they expect to see a valid nf_file, and can oops if nf_file is NULL. Also, there is no guarantee that we'll end up creating a new nfsd_file if one is already in the hash. If an extant entry is in the hash with a valid nf_file, nfs4_get_vfs_file will clobber its nf_file pointer with the value of op_file and the old nf_file will leak. Fix both issues by making a new nfsd_file_acquirei_opened variant that takes an optional file pointer. If one is present when this is called, we'll take a new reference to it instead of trying to open the file. If the nfsd_file already has a valid nf_file, we'll just ignore the optional file and pass the nfsd_file back as-is. Also rework the tracepoints a bit to allow for an "opened" variant and don't try to avoid counting acquisitions in the case where we already have a cached open file. Fixes:fb70bf124b
("NFSD: Instantiate a struct file when creating a regular NFSv4 file") Cc: Trond Myklebust <trondmy@hammerspace.com> Reported-by: Stanislav Saner <ssaner@redhat.com> Reported-and-Tested-by: Ruben Vestergaard <rubenv@drcmr.dk> Reported-and-Tested-by: Torkil Svensgaard <torkil@drcmr.dk> Signed-off-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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cad853374d
commit
0b3a551fa5
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@ -1071,8 +1071,8 @@ nfsd_file_is_cached(struct inode *inode)
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static __be32
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nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct nfsd_file **pnf,
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bool open, bool want_gc)
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unsigned int may_flags, struct file *file,
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struct nfsd_file **pnf, bool want_gc)
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{
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struct nfsd_file_lookup_key key = {
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.type = NFSD_FILE_KEY_FULL,
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@ -1147,8 +1147,7 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
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status = nfserrno(nfsd_open_break_lease(file_inode(nf->nf_file), may_flags));
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out:
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if (status == nfs_ok) {
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if (open)
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this_cpu_inc(nfsd_file_acquisitions);
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this_cpu_inc(nfsd_file_acquisitions);
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*pnf = nf;
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} else {
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if (refcount_dec_and_test(&nf->nf_ref))
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@ -1158,20 +1157,23 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
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out_status:
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put_cred(key.cred);
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if (open)
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trace_nfsd_file_acquire(rqstp, key.inode, may_flags, nf, status);
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trace_nfsd_file_acquire(rqstp, key.inode, may_flags, nf, status);
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return status;
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open_file:
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trace_nfsd_file_alloc(nf);
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nf->nf_mark = nfsd_file_mark_find_or_create(nf, key.inode);
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if (nf->nf_mark) {
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if (open) {
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if (file) {
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get_file(file);
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nf->nf_file = file;
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status = nfs_ok;
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trace_nfsd_file_opened(nf, status);
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} else {
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status = nfsd_open_verified(rqstp, fhp, may_flags,
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&nf->nf_file);
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trace_nfsd_file_open(nf, status);
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} else
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status = nfs_ok;
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}
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} else
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status = nfserr_jukebox;
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/*
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@ -1207,7 +1209,7 @@ __be32
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nfsd_file_acquire_gc(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct nfsd_file **pnf)
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{
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return nfsd_file_do_acquire(rqstp, fhp, may_flags, pnf, true, true);
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return nfsd_file_do_acquire(rqstp, fhp, may_flags, NULL, pnf, true);
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}
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/**
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@ -1228,28 +1230,30 @@ __be32
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nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct nfsd_file **pnf)
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{
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return nfsd_file_do_acquire(rqstp, fhp, may_flags, pnf, true, false);
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return nfsd_file_do_acquire(rqstp, fhp, may_flags, NULL, pnf, false);
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}
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/**
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* nfsd_file_create - Get a struct nfsd_file, do not open
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* nfsd_file_acquire_opened - Get a struct nfsd_file using existing open file
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* @rqstp: the RPC transaction being executed
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* @fhp: the NFS filehandle of the file just created
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* @may_flags: NFSD_MAY_ settings for the file
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* @file: cached, already-open file (may be NULL)
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* @pnf: OUT: new or found "struct nfsd_file" object
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*
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* The nfsd_file_object returned by this API is reference-counted
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* but not garbage-collected. The object is released immediately
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* one RCU grace period after the final nfsd_file_put().
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* Acquire a nfsd_file object that is not GC'ed. If one doesn't already exist,
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* and @file is non-NULL, use it to instantiate a new nfsd_file instead of
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* opening a new one.
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*
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* Returns nfs_ok and sets @pnf on success; otherwise an nfsstat in
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* network byte order is returned.
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*/
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__be32
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nfsd_file_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct nfsd_file **pnf)
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nfsd_file_acquire_opened(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct file *file,
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struct nfsd_file **pnf)
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{
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return nfsd_file_do_acquire(rqstp, fhp, may_flags, pnf, false, false);
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return nfsd_file_do_acquire(rqstp, fhp, may_flags, file, pnf, false);
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}
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/*
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@ -60,7 +60,8 @@ __be32 nfsd_file_acquire_gc(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct nfsd_file **nfp);
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__be32 nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct nfsd_file **nfp);
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__be32 nfsd_file_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct nfsd_file **nfp);
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__be32 nfsd_file_acquire_opened(struct svc_rqst *rqstp, struct svc_fh *fhp,
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unsigned int may_flags, struct file *file,
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struct nfsd_file **nfp);
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int nfsd_file_cache_stats_show(struct seq_file *m, void *v);
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#endif /* _FS_NFSD_FILECACHE_H */
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@ -5262,18 +5262,10 @@ static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
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if (!fp->fi_fds[oflag]) {
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spin_unlock(&fp->fi_lock);
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if (!open->op_filp) {
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status = nfsd_file_acquire(rqstp, cur_fh, access, &nf);
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if (status != nfs_ok)
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goto out_put_access;
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} else {
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status = nfsd_file_create(rqstp, cur_fh, access, &nf);
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if (status != nfs_ok)
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goto out_put_access;
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nf->nf_file = open->op_filp;
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open->op_filp = NULL;
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trace_nfsd_file_create(rqstp, access, nf);
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}
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status = nfsd_file_acquire_opened(rqstp, cur_fh, access,
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open->op_filp, &nf);
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if (status != nfs_ok)
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goto out_put_access;
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spin_lock(&fp->fi_lock);
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if (!fp->fi_fds[oflag]) {
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@ -981,43 +981,6 @@ TRACE_EVENT(nfsd_file_acquire,
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)
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);
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TRACE_EVENT(nfsd_file_create,
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TP_PROTO(
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const struct svc_rqst *rqstp,
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unsigned int may_flags,
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const struct nfsd_file *nf
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),
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TP_ARGS(rqstp, may_flags, nf),
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TP_STRUCT__entry(
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__field(const void *, nf_inode)
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__field(const void *, nf_file)
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__field(unsigned long, may_flags)
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__field(unsigned long, nf_flags)
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__field(unsigned long, nf_may)
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__field(unsigned int, nf_ref)
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__field(u32, xid)
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),
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TP_fast_assign(
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__entry->nf_inode = nf->nf_inode;
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__entry->nf_file = nf->nf_file;
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__entry->may_flags = may_flags;
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__entry->nf_flags = nf->nf_flags;
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__entry->nf_may = nf->nf_may;
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__entry->nf_ref = refcount_read(&nf->nf_ref);
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__entry->xid = be32_to_cpu(rqstp->rq_xid);
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),
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TP_printk("xid=0x%x inode=%p may_flags=%s ref=%u nf_flags=%s nf_may=%s nf_file=%p",
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__entry->xid, __entry->nf_inode,
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show_nfsd_may_flags(__entry->may_flags),
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__entry->nf_ref, show_nf_flags(__entry->nf_flags),
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show_nfsd_may_flags(__entry->nf_may), __entry->nf_file
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)
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);
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TRACE_EVENT(nfsd_file_insert_err,
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TP_PROTO(
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const struct svc_rqst *rqstp,
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)
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);
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TRACE_EVENT(nfsd_file_open,
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TP_PROTO(struct nfsd_file *nf, __be32 status),
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DECLARE_EVENT_CLASS(nfsd_file_open_class,
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TP_PROTO(const struct nfsd_file *nf, __be32 status),
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TP_ARGS(nf, status),
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TP_STRUCT__entry(
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__field(void *, nf_inode) /* cannot be dereferenced */
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__entry->nf_file)
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)
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#define DEFINE_NFSD_FILE_OPEN_EVENT(name) \
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DEFINE_EVENT(nfsd_file_open_class, name, \
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TP_PROTO( \
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const struct nfsd_file *nf, \
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__be32 status \
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), \
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TP_ARGS(nf, status))
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DEFINE_NFSD_FILE_OPEN_EVENT(nfsd_file_open);
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DEFINE_NFSD_FILE_OPEN_EVENT(nfsd_file_opened);
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TRACE_EVENT(nfsd_file_is_cached,
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TP_PROTO(
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const struct inode *inode,
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