...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 <jeff.layton@xxxxxxxxxxxxxxx>
---
fs/file_table.c | 1 +
fs/nfsd/filecache.c | 33 ++++++++++++++++++++++++++++++++-
fs/nfsd/filecache.h | 1 +
fs/nfsd/trace.h | 10 +++++++++-
fs/nfsd/vfs.c | 52 ++++++++++++++++++++++++++++++++++++++++++++--------
5 files changed, 87 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 a114f3a69117..ce8b8e4f7cf3 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -273,6 +273,34 @@ nfsd_file_find_locked(struct knfsd_fh *fh, unsigned int may_flags,
}
/**
+ * nfsd_file_is_cached - are there any cached open files for this fh?
+ * @fh: filehandle 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 knfsd_fh *fh)
+{
+ bool ret = false;
+ struct nfsd_file *nf;
+ unsigned int hashval = file_hashval(fh);
+
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(nf, &nfsd_file_hashtbl[hashval].nfb_head,
+ nf_node) {
+ if (fh_match(&nf->nf_handle, fh)) {
+ ret = true;
+ break;
+ }
+ }
+ rcu_read_unlock();
+ trace_nfsd_file_is_cached(hashval, fh, (int)ret);
+ return ret;
+}
+
+
+/**
* nfsd_file_force_close - attempt to forcibly close a nfsd_file
* @fh: filehandle of the file to attempt to remove
*
@@ -296,7 +324,10 @@ nfsd_file_close_fh(struct knfsd_fh *fh)
}
spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
trace_nfsd_file_close_fh(hashval, fh, !list_empty(&dispose));
- nfsd_file_dispose_list(&dispose);
+ if (!list_empty(&dispose)) {
+ nfsd_file_dispose_list(&dispose);
+ flush_delayed_fput();
+ }
}
__be32
diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h
index 40c47cac2c33..2a347e16f095 100644
--- a/fs/nfsd/filecache.h
+++ b/fs/nfsd/filecache.h
@@ -44,6 +44,7 @@ int nfsd_file_cache_init(void);
void nfsd_file_cache_purge(void);
void nfsd_file_cache_shutdown(void);
void nfsd_file_put(struct nfsd_file *nf);
+bool nfsd_file_is_cached(struct knfsd_fh *fh);
void nfsd_file_close_fh(struct knfsd_fh *fh);
__be32 nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
unsigned int may_flags, struct nfsd_file **nfp);
diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index c45d318e3a0b..150ce332fbd7 100644
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -148,7 +148,7 @@ TRACE_EVENT(nfsd_file_acquire,
__entry->nf_file, be32_to_cpu(__entry->status))
);
-TRACE_EVENT(nfsd_file_close_fh,
+DECLARE_EVENT_CLASS(nfsd_file_search_class,
TP_PROTO(unsigned int hash, struct knfsd_fh *handle, int found),
TP_ARGS(hash, handle, found),
TP_STRUCT__entry(
@@ -164,6 +164,14 @@ TRACE_EVENT(nfsd_file_close_fh,
TP_printk("hash=0x%x handle=%s found=%d", __entry->hash,
show_nf_fh(__entry->handle), __entry->found)
);
+
+#define DEFINE_NFSD_FILE_SEARCH_EVENT(name) \
+DEFINE_EVENT(nfsd_file_search_class, name, \
+ TP_PROTO(unsigned int hash, struct knfsd_fh *handle, int found), \
+ TP_ARGS(hash, handle, found))
+
+DEFINE_NFSD_FILE_SEARCH_EVENT(nfsd_file_close_fh);
+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 c70c6fbec4d7..464e524e8f6e 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1596,6 +1596,22 @@ nfsd_close_cached_files(struct dentry *dentry, struct svc_fh *fhp)
return err;
}
+static bool
+nfsd_has_cached_files(struct dentry *dentry, struct svc_fh *fhp)
+{
+ __be32 err;
+ bool ret = false;
+ struct knfsd_fh kfh = { 0 };
+
+ if (d_really_is_positive(dentry) && S_ISREG(d_inode(dentry)->i_mode)) {
+ err = fh_compose_shallow(&kfh, fhp->fh_maxsize,
+ fhp->fh_export, dentry, fhp);
+ if (err == nfs_ok)
+ ret = nfsd_file_is_cached(&kfh);
+ }
+ return ret;
+}
+
/*
* Rename a file
* N.B. After this call _both_ ffhp and tfhp need an fh_put
@@ -1608,6 +1624,7 @@ 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)
@@ -1626,6 +1643,7 @@ 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);
@@ -1665,12 +1683,16 @@ 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, tfhp);
- 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, tfhp)) {
+ 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);
@@ -1683,12 +1705,26 @@ 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, tfhp);
+ dput(ndentry);
+ goto retry;
+ }
out:
return err;
}
--
2.4.3
--
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