Return-Path: Received: from mail-io0-f174.google.com ([209.85.223.174]:35259 "EHLO mail-io0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751432AbbHUBCS (ORCPT ); Thu, 20 Aug 2015 21:02:18 -0400 Received: by iodt126 with SMTP id t126so66062322iod.2 for ; Thu, 20 Aug 2015 18:02:17 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1440069440-27454-16-git-send-email-jeff.layton@primarydata.com> References: <1440069440-27454-1-git-send-email-jeff.layton@primarydata.com> <1440069440-27454-16-git-send-email-jeff.layton@primarydata.com> From: Peng Tao Date: Thu, 20 Aug 2015 18:01:58 -0700 Message-ID: Subject: Re: [PATCH v3 15/20] nfsd: call flush_delayed_fput from nfsd_file_close_fh To: Jeff Layton Cc: bfields@fieldses.org, Linux NFS Mailing List , Christoph Hellwig , kinglongmee@gmail.com Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu, Aug 20, 2015 at 4:17 AM, Jeff Layton wrote: > ...when there are open files to be closed. > > When knfsd does an fput(), it gets queued to a list and a workqueue job > is then scheduled to do the actual __fput work. In the case of knfsd > closing down the file prior to a REMOVE or RENAME, we really want to > ensure that those files are closed prior to returning. When there are > files to be closed, call flush_delayed_fput to ensure this. > > There are deadlock possibilities if you call flush_delayed_fput while > holding locks, however. In the case of nfsd_rename, we don't even do the > lookups of the dentries to be renamed until we've locked for rename. > > Once we've figured out what the target dentry is for a rename, check to > see whether there are cached open files associated with it. If there > are, then unwind all of the locking, close them all, and then reattempt > the rename. > > Signed-off-by: Jeff Layton > --- > fs/file_table.c | 1 + > fs/nfsd/filecache.c | 33 ++++++++++++++++++++++++++++++++- > fs/nfsd/filecache.h | 1 + > fs/nfsd/trace.h | 10 +++++++++- > fs/nfsd/vfs.c | 47 +++++++++++++++++++++++++++++++++++++++-------- > 5 files changed, 82 insertions(+), 10 deletions(-) > > diff --git a/fs/file_table.c b/fs/file_table.c > index 7f9d407c7595..33898e72618c 100644 > --- a/fs/file_table.c > +++ b/fs/file_table.c > @@ -257,6 +257,7 @@ void flush_delayed_fput(void) > { > delayed_fput(NULL); > } > +EXPORT_SYMBOL_GPL(flush_delayed_fput); > > static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput); > > diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c > index 4bd683f03b6e..b62942ba6e7b 100644 > --- a/fs/nfsd/filecache.c > +++ b/fs/nfsd/filecache.c > @@ -284,6 +284,34 @@ nfsd_file_find_locked(struct inode *inode, unsigned int may_flags, > } > > /** > + * nfsd_file_is_cached - are there any cached open files for this fh? > + * @inode: inode of the file to check > + * > + * Scan the hashtable for open files that match this fh. Returns true if there > + * are any, and false if not. > + */ > +bool > +nfsd_file_is_cached(struct inode *inode) > +{ > + bool ret = false; > + struct nfsd_file *nf; > + unsigned int hashval = (unsigned int)hash_ptr(inode, NFSD_FILE_HASH_BITS); > + > + rcu_read_lock(); > + hlist_for_each_entry_rcu(nf, &nfsd_file_hashtbl[hashval].nfb_head, > + nf_node) { > + if (inode == nf->nf_inode) { > + ret = true; > + break; > + } > + } > + rcu_read_unlock(); > + trace_nfsd_file_is_cached(hashval, inode, (int)ret); > + return ret; > +} > + > + > +/** > * nfsd_file_close_inode - attempt to forcibly close a nfsd_file > * @inode: inode of the file to attempt to remove > * > @@ -305,7 +333,10 @@ nfsd_file_close_inode(struct inode *inode) > } > spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock); > trace_nfsd_file_close_inode(hashval, inode, !list_empty(&dispose)); > - nfsd_file_dispose_list(&dispose); > + if (!list_empty(&dispose)) { > + nfsd_file_dispose_list(&dispose); > + flush_delayed_fput(); It looks like flush_delayed_fput() is not exported symbol? And if flush_delayed_fput() is acceptable, it looks like __fput_sync() is a better fit, because knfsd would not try to do all the delayed fput() work, just the dispose list... Cheers, Tao > + } > } > > __be32 > diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h > index 191cdb25aa66..4a873efb7953 100644 > --- a/fs/nfsd/filecache.h > +++ b/fs/nfsd/filecache.h > @@ -27,6 +27,7 @@ void nfsd_file_cache_shutdown(void); > void nfsd_file_put(struct nfsd_file *nf); > struct nfsd_file *nfsd_file_get(struct nfsd_file *nf); > void nfsd_file_close_inode(struct inode *inode); > +bool nfsd_file_is_cached(struct inode *inode); > __be32 nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, > unsigned int may_flags, struct nfsd_file **nfp); > #endif /* _FS_NFSD_FILECACHE_H */ > diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h > index 95af3b9c7b66..fc6d8ee51a00 100644 > --- a/fs/nfsd/trace.h > +++ b/fs/nfsd/trace.h > @@ -140,7 +140,7 @@ TRACE_EVENT(nfsd_file_acquire, > be32_to_cpu(__entry->status)) > ); > > -TRACE_EVENT(nfsd_file_close_inode, > +DECLARE_EVENT_CLASS(nfsd_file_search_class, > TP_PROTO(unsigned int hash, struct inode *inode, int found), > TP_ARGS(hash, inode, found), > TP_STRUCT__entry( > @@ -156,6 +156,14 @@ TRACE_EVENT(nfsd_file_close_inode, > TP_printk("hash=0x%x inode=0x%p found=%d", __entry->hash, > __entry->inode, __entry->found) > ); > + > +#define DEFINE_NFSD_FILE_SEARCH_EVENT(name) \ > +DEFINE_EVENT(nfsd_file_search_class, name, \ > + TP_PROTO(unsigned int hash, struct inode *inode, int found), \ > + TP_ARGS(hash, inode, found)) > + > +DEFINE_NFSD_FILE_SEARCH_EVENT(nfsd_file_close_inode); > +DEFINE_NFSD_FILE_SEARCH_EVENT(nfsd_file_is_cached); > #endif /* _NFSD_TRACE_H */ > > #undef TRACE_INCLUDE_PATH > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c > index 98d3b9d96480..4cc78a4ec694 100644 > --- a/fs/nfsd/vfs.c > +++ b/fs/nfsd/vfs.c > @@ -1592,6 +1592,17 @@ nfsd_close_cached_files(struct dentry *dentry) > nfsd_file_close_inode(inode); > } > > +static bool > +nfsd_has_cached_files(struct dentry *dentry) > +{ > + bool ret = false; > + struct inode *inode = d_inode(dentry); > + > + if (inode && S_ISREG(inode->i_mode)) > + ret = nfsd_file_is_cached(inode); > + return ret; > +} > + > /* > * Rename a file > * N.B. After this call _both_ ffhp and tfhp need an fh_put > @@ -1604,6 +1615,7 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, > struct inode *fdir, *tdir; > __be32 err; > int host_err; > + bool has_cached = false; > > err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE); > if (err) > @@ -1622,6 +1634,7 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, > if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen)) > goto out; > > +retry: > host_err = fh_want_write(ffhp); > if (host_err) { > err = nfserrno(host_err); > @@ -1661,12 +1674,16 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, > if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry) > goto out_dput_new; > > - nfsd_close_cached_files(ndentry); > - host_err = vfs_rename(fdir, odentry, tdir, ndentry, NULL, 0); > - if (!host_err) { > - host_err = commit_metadata(tfhp); > - if (!host_err) > - host_err = commit_metadata(ffhp); > + if (nfsd_has_cached_files(ndentry)) { > + has_cached = true; > + goto out_dput_old; > + } else { > + host_err = vfs_rename(fdir, odentry, tdir, ndentry, NULL, 0); > + if (!host_err) { > + host_err = commit_metadata(tfhp); > + if (!host_err) > + host_err = commit_metadata(ffhp); > + } > } > out_dput_new: > dput(ndentry); > @@ -1679,12 +1696,26 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, > * as that would do the wrong thing if the two directories > * were the same, so again we do it by hand. > */ > - fill_post_wcc(ffhp); > - fill_post_wcc(tfhp); > + if (!has_cached) { > + fill_post_wcc(ffhp); > + fill_post_wcc(tfhp); > + } > unlock_rename(tdentry, fdentry); > ffhp->fh_locked = tfhp->fh_locked = 0; > fh_drop_write(ffhp); > > + /* > + * If the target dentry has cached open files, then we need to try to > + * close them prior to doing the rename. Flushing delayed fput > + * shouldn't be done with locks held however, so we delay it until this > + * point and then reattempt the whole shebang. > + */ > + if (has_cached) { > + has_cached = false; > + nfsd_close_cached_files(ndentry); > + dput(ndentry); > + goto retry; > + } > out: > return err; > } > -- > 2.4.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html