nfsd: track filehandle aliasing in nfs4_files

It's unusual but possible for multiple filehandles to point to the same
file.  In that case, we may end up with multiple nfs4_files referencing
the same inode.

For delegation purposes it will turn out to be useful to flag those
cases.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 442034633ee8fbbfe5064dc2cf673a74101ed72b..b12f530f6449a43afce4d7f2614890cc7d93c011 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4086,6 +4086,8 @@ static void nfsd4_init_file(struct svc_fh *fh, unsigned int hashval,
        fp->fi_share_deny = 0;
        memset(fp->fi_fds, 0, sizeof(fp->fi_fds));
        memset(fp->fi_access, 0, sizeof(fp->fi_access));
+       fp->fi_aliased = false;
+       fp->fi_inode = d_inode(fh->fh_dentry);
 #ifdef CONFIG_NFSD_PNFS
        INIT_LIST_HEAD(&fp->fi_lo_states);
        atomic_set(&fp->fi_lo_recalls, 0);
@@ -4438,6 +4440,31 @@ find_file_locked(struct svc_fh *fh, unsigned int hashval)
        return NULL;
 }
 
+static struct nfs4_file *insert_file(struct nfs4_file *new, struct svc_fh *fh,
+                                    unsigned int hashval)
+{
+       struct nfs4_file *fp;
+       struct nfs4_file *ret = NULL;
+       bool alias_found = false;
+
+       spin_lock(&state_lock);
+       hlist_for_each_entry_rcu(fp, &file_hashtbl[hashval], fi_hash,
+                                lockdep_is_held(&state_lock)) {
+               if (fh_match(&fp->fi_fhandle, &fh->fh_handle)) {
+                       if (refcount_inc_not_zero(&fp->fi_ref))
+                               ret = fp;
+               } else if (d_inode(fh->fh_dentry) == fp->fi_inode)
+                       fp->fi_aliased = alias_found = true;
+       }
+       if (likely(ret == NULL)) {
+               nfsd4_init_file(fh, hashval, new);
+               new->fi_aliased = alias_found;
+               ret = new;
+       }
+       spin_unlock(&state_lock);
+       return ret;
+}
+
 static struct nfs4_file * find_file(struct svc_fh *fh)
 {
        struct nfs4_file *fp;
@@ -4461,15 +4488,7 @@ find_or_add_file(struct nfs4_file *new, struct svc_fh *fh)
        if (fp)
                return fp;
 
-       spin_lock(&state_lock);
-       fp = find_file_locked(fh, hashval);
-       if (likely(fp == NULL)) {
-               nfsd4_init_file(fh, hashval, new);
-               fp = new;
-       }
-       spin_unlock(&state_lock);
-
-       return fp;
+       return insert_file(new, fh, hashval);
 }
 
 /*

diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 61a2d95d79233dcae914e6d8646b893e99ec98a5..e73bdbb1634ab252008a8cde3f6887d8fa835ca0 100644 (file)
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -516,6 +516,8 @@ struct nfs4_clnt_odstate {
  */
 struct nfs4_file {
        refcount_t              fi_ref;
+       struct inode *          fi_inode;
+       bool                    fi_aliased;
        spinlock_t              fi_lock;
        struct hlist_node       fi_hash;        /* hash on fi_fhandle */
        struct list_head        fi_stateids;