ceph: pre-allocate ceph_cap struct for ceph_add_cap()

So that ceph_add_cap() can be used while i_ceph_lock is locked.
This simplifies the code that handle cap import/export.
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>

fs/ceph/caps.c

@@ -221,8 +221,8 @@ int ceph_unreserve_caps(struct ceph_mds_client *mdsc,
 	return 0;
 }
 
-static struct ceph_cap *get_cap(struct ceph_mds_client *mdsc,
-				struct ceph_cap_reservation *ctx)
+struct ceph_cap *ceph_get_cap(struct ceph_mds_client *mdsc,
+			      struct ceph_cap_reservation *ctx)
 {
 	struct ceph_cap *cap = NULL;
 
@@ -508,15 +508,14 @@ static void __check_cap_issue(struct ceph_inode_info *ci, struct ceph_cap *cap,
  * it is < 0.  (This is so we can atomically add the cap and add an
  * open file reference to it.)
  */
-int ceph_add_cap(struct inode *inode,
-		 struct ceph_mds_session *session, u64 cap_id,
-		 int fmode, unsigned issued, unsigned wanted,
-		 unsigned seq, unsigned mseq, u64 realmino, int flags,
-		 struct ceph_cap_reservation *caps_reservation)
+void ceph_add_cap(struct inode *inode,
+		  struct ceph_mds_session *session, u64 cap_id,
+		  int fmode, unsigned issued, unsigned wanted,
+		  unsigned seq, unsigned mseq, u64 realmino, int flags,
+		  struct ceph_cap **new_cap)
 {
 	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
 	struct ceph_inode_info *ci = ceph_inode(inode);
-	struct ceph_cap *new_cap = NULL;
 	struct ceph_cap *cap;
 	int mds = session->s_mds;
 	int actual_wanted;
@@ -531,20 +530,10 @@ int ceph_add_cap(struct inode *inode,
 	if (fmode >= 0)
 		wanted |= ceph_caps_for_mode(fmode);
 
-retry:
-	spin_lock(&ci->i_ceph_lock);
 	cap = __get_cap_for_mds(ci, mds);
 	if (!cap) {
-		if (new_cap) {
-			cap = new_cap;
-			new_cap = NULL;
-		} else {
-			spin_unlock(&ci->i_ceph_lock);
-			new_cap = get_cap(mdsc, caps_reservation);
-			if (new_cap == NULL)
-				return -ENOMEM;
-			goto retry;
-		}
+		cap = *new_cap;
+		*new_cap = NULL;
 
 		cap->issued = 0;
 		cap->implemented = 0;
@@ -562,9 +551,6 @@ int ceph_add_cap(struct inode *inode,
 		session->s_nr_caps++;
 		spin_unlock(&session->s_cap_lock);
 	} else {
-		if (new_cap)
-			ceph_put_cap(mdsc, new_cap);
-
 		/*
 		 * auth mds of the inode changed. we received the cap export
 		 * message, but still haven't received the cap import message.
@@ -626,7 +612,6 @@ int ceph_add_cap(struct inode *inode,
 			ci->i_auth_cap = cap;
 			cap->mds_wanted = wanted;
 		}
-		ci->i_cap_exporting_issued = 0;
 	} else {
 		WARN_ON(ci->i_auth_cap == cap);
 	}
@@ -648,9 +633,6 @@ int ceph_add_cap(struct inode *inode,
 
 	if (fmode >= 0)
 		__ceph_get_fmode(ci, fmode);
-	spin_unlock(&ci->i_ceph_lock);
-	wake_up_all(&ci->i_cap_wq);
-	return 0;
 }
 
 /*
@@ -685,7 +667,7 @@ static int __cap_is_valid(struct ceph_cap *cap)
  */
 int __ceph_caps_issued(struct ceph_inode_info *ci, int *implemented)
 {
-	int have = ci->i_snap_caps | ci->i_cap_exporting_issued;
+	int have = ci->i_snap_caps;
 	struct ceph_cap *cap;
 	struct rb_node *p;
 
@@ -900,7 +882,7 @@ int __ceph_caps_mds_wanted(struct ceph_inode_info *ci)
  */
 static int __ceph_is_any_caps(struct ceph_inode_info *ci)
 {
-	return !RB_EMPTY_ROOT(&ci->i_caps) || ci->i_cap_exporting_issued;
+	return !RB_EMPTY_ROOT(&ci->i_caps);
 }
 
 int ceph_is_any_caps(struct inode *inode)
@@ -2796,7 +2778,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 {
 	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
 	struct ceph_mds_session *tsession = NULL;
-	struct ceph_cap *cap, *tcap;
+	struct ceph_cap *cap, *tcap, *new_cap = NULL;
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	u64 t_cap_id;
 	unsigned mseq = le32_to_cpu(ex->migrate_seq);
@@ -2858,15 +2840,14 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 		}
 		__ceph_remove_cap(cap, false);
 		goto out_unlock;
-	}
-
-	if (tsession) {
-		int flag = (cap == ci->i_auth_cap) ? CEPH_CAP_FLAG_AUTH : 0;
-		spin_unlock(&ci->i_ceph_lock);
+	} else if (tsession) {
 		/* add placeholder for the export tagert */
+		int flag = (cap == ci->i_auth_cap) ? CEPH_CAP_FLAG_AUTH : 0;
 		ceph_add_cap(inode, tsession, t_cap_id, -1, issued, 0,
-			     t_seq - 1, t_mseq, (u64)-1, flag, NULL);
-		goto retry;
+			     t_seq - 1, t_mseq, (u64)-1, flag, &new_cap);
+
+		__ceph_remove_cap(cap, false);
+		goto out_unlock;
 	}
 
 	spin_unlock(&ci->i_ceph_lock);
@@ -2885,6 +2866,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 					  SINGLE_DEPTH_NESTING);
 		}
 		ceph_add_cap_releases(mdsc, tsession);
+		new_cap = ceph_get_cap(mdsc, NULL);
 	} else {
 		WARN_ON(1);
 		tsession = NULL;
@@ -2899,6 +2881,8 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 		mutex_unlock(&tsession->s_mutex);
 		ceph_put_mds_session(tsession);
 	}
+	if (new_cap)
+		ceph_put_cap(mdsc, new_cap);
 }
 
 /*
@@ -2914,7 +2898,7 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
 			      void *snaptrace, int snaptrace_len)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);
-	struct ceph_cap *cap;
+	struct ceph_cap *cap, *new_cap = NULL;
 	int mds = session->s_mds;
 	unsigned issued = le32_to_cpu(im->caps);
 	unsigned wanted = le32_to_cpu(im->wanted);
@@ -2936,7 +2920,20 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
 	dout("handle_cap_import inode %p ci %p mds%d mseq %d peer %d\n",
 	     inode, ci, mds, mseq, peer);
 
+retry:
 	spin_lock(&ci->i_ceph_lock);
+	cap = __get_cap_for_mds(ci, mds);
+	if (!cap) {
+		if (!new_cap) {
+			spin_unlock(&ci->i_ceph_lock);
+			new_cap = ceph_get_cap(mdsc, NULL);
+			goto retry;
+		}
+	}
+
+	ceph_add_cap(inode, session, cap_id, -1, issued, wanted, seq, mseq,
+		     realmino, CEPH_CAP_FLAG_AUTH, &new_cap);
+
 	cap = peer >= 0 ? __get_cap_for_mds(ci, peer) : NULL;
 	if (cap && cap->cap_id == p_cap_id) {
 		dout(" remove export cap %p mds%d flags %d\n",
@@ -2951,7 +2948,6 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
 			       cap->mseq, mds, le32_to_cpu(ph->seq),
 			       le32_to_cpu(ph->mseq));
 		}
-		ci->i_cap_exporting_issued = cap->issued;
 		__ceph_remove_cap(cap, (ph->flags & CEPH_CAP_FLAG_RELEASE));
 	}
 
@@ -2960,16 +2956,17 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
 	ci->i_requested_max_size = 0;
 	spin_unlock(&ci->i_ceph_lock);
 
+	wake_up_all(&ci->i_cap_wq);
+
 	down_write(&mdsc->snap_rwsem);
 	ceph_update_snap_trace(mdsc, snaptrace, snaptrace+snaptrace_len,
 			       false);
 	downgrade_write(&mdsc->snap_rwsem);
-	ceph_add_cap(inode, session, cap_id, -1,
-		     issued, wanted, seq, mseq, realmino, CEPH_CAP_FLAG_AUTH,
-		     NULL /* no caps context */);
 	kick_flushing_inode_caps(mdsc, session, inode);
 	up_read(&mdsc->snap_rwsem);
 
+	if (new_cap)
+		ceph_put_cap(mdsc, new_cap);
 }
 
 /*

fs/ceph/inode.c

@@ -341,7 +341,6 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
 	INIT_LIST_HEAD(&ci->i_cap_snaps);
 	ci->i_head_snapc = NULL;
 	ci->i_snap_caps = 0;
-	ci->i_cap_exporting_issued = 0;
 
 	for (i = 0; i < CEPH_FILE_MODE_NUM; i++)
 		ci->i_nr_by_mode[i] = 0;
@@ -407,7 +406,7 @@ void ceph_destroy_inode(struct inode *inode)
 
 	/*
 	 * we may still have a snap_realm reference if there are stray
-	 * caps in i_cap_exporting_issued or i_snap_caps.
+	 * caps in i_snap_caps.
 	 */
 	if (ci->i_snap_realm) {
 		struct ceph_mds_client *mdsc =
@@ -582,6 +581,7 @@ static int fill_inode(struct inode *inode,
 		      unsigned long ttl_from, int cap_fmode,
 		      struct ceph_cap_reservation *caps_reservation)
 {
+	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
 	struct ceph_mds_reply_inode *info = iinfo->in;
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	int i;
@@ -591,7 +591,9 @@ static int fill_inode(struct inode *inode,
 	struct ceph_inode_frag *frag;
 	struct rb_node *rb_node;
 	struct ceph_buffer *xattr_blob = NULL;
+	struct ceph_cap *new_cap = NULL;
 	int err = 0;
+	bool wake = false;
 	bool queue_trunc = false;
 	bool new_version = false;
 
@@ -599,6 +601,10 @@ static int fill_inode(struct inode *inode,
 	     inode, ceph_vinop(inode), le64_to_cpu(info->version),
 	     ci->i_version);
 
+	/* prealloc new cap struct */
+	if (info->cap.caps && ceph_snap(inode) == CEPH_NOSNAP)
+		new_cap = ceph_get_cap(mdsc, caps_reservation);
+
 	/*
 	 * prealloc xattr data, if it looks like we'll need it.  only
 	 * if len > 4 (meaning there are actually xattrs; the first 4
@@ -762,8 +768,37 @@ static int fill_inode(struct inode *inode,
 		dout(" marking %p complete (empty)\n", inode);
 		__ceph_dir_set_complete(ci, atomic_read(&ci->i_release_count));
 	}
+
+	/* were we issued a capability? */
+	if (info->cap.caps) {
+		if (ceph_snap(inode) == CEPH_NOSNAP) {
+			ceph_add_cap(inode, session,
+				     le64_to_cpu(info->cap.cap_id),
+				     cap_fmode,
+				     le32_to_cpu(info->cap.caps),
+				     le32_to_cpu(info->cap.wanted),
+				     le32_to_cpu(info->cap.seq),
+				     le32_to_cpu(info->cap.mseq),
+				     le64_to_cpu(info->cap.realm),
+				     info->cap.flags, &new_cap);
+			wake = true;
+		} else {
+			dout(" %p got snap_caps %s\n", inode,
+			     ceph_cap_string(le32_to_cpu(info->cap.caps)));
+			ci->i_snap_caps |= le32_to_cpu(info->cap.caps);
+			if (cap_fmode >= 0)
+				__ceph_get_fmode(ci, cap_fmode);
+		}
+	} else if (cap_fmode >= 0) {
+		pr_warning("mds issued no caps on %llx.%llx\n",
+			   ceph_vinop(inode));
+		__ceph_get_fmode(ci, cap_fmode);
+	}
 	spin_unlock(&ci->i_ceph_lock);
 
+	if (wake)
+		wake_up_all(&ci->i_cap_wq);
+
 	/* queue truncate if we saw i_size decrease */
 	if (queue_trunc)
 		ceph_queue_vmtruncate(inode);
@@ -806,41 +841,14 @@ static int fill_inode(struct inode *inode,
 	}
 	mutex_unlock(&ci->i_fragtree_mutex);
 
-	/* were we issued a capability? */
-	if (info->cap.caps) {
-		if (ceph_snap(inode) == CEPH_NOSNAP) {
-			ceph_add_cap(inode, session,
-				     le64_to_cpu(info->cap.cap_id),
-				     cap_fmode,
-				     le32_to_cpu(info->cap.caps),
-				     le32_to_cpu(info->cap.wanted),
-				     le32_to_cpu(info->cap.seq),
-				     le32_to_cpu(info->cap.mseq),
-				     le64_to_cpu(info->cap.realm),
-				     info->cap.flags,
-				     caps_reservation);
-		} else {
-			spin_lock(&ci->i_ceph_lock);
-			dout(" %p got snap_caps %s\n", inode,
-			     ceph_cap_string(le32_to_cpu(info->cap.caps)));
-			ci->i_snap_caps |= le32_to_cpu(info->cap.caps);
-			if (cap_fmode >= 0)
-				__ceph_get_fmode(ci, cap_fmode);
-			spin_unlock(&ci->i_ceph_lock);
-		}
-	} else if (cap_fmode >= 0) {
-		pr_warning("mds issued no caps on %llx.%llx\n",
-			   ceph_vinop(inode));
-		__ceph_get_fmode(ci, cap_fmode);
-	}
-
 	/* update delegation info? */
 	if (dirinfo)
 		ceph_fill_dirfrag(inode, dirinfo);
 
 	err = 0;
-
 out:
+	if (new_cap)
+		ceph_put_cap(mdsc, new_cap);
 	if (xattr_blob)
 		ceph_buffer_put(xattr_blob);
 	return err;

fs/ceph/super.h

@@ -292,7 +292,6 @@ struct ceph_inode_info {
 	struct ceph_snap_context *i_head_snapc;  /* set if wr_buffer_head > 0 or
 						    dirty|flushing caps */
 	unsigned i_snap_caps;           /* cap bits for snapped files */
-	unsigned i_cap_exporting_issued;
 
 	int i_nr_by_mode[CEPH_FILE_MODE_NUM];  /* open file counts */
 
@@ -775,11 +774,13 @@ static inline void ceph_forget_all_cached_acls(struct inode *inode)
 extern const char *ceph_cap_string(int c);
 extern void ceph_handle_caps(struct ceph_mds_session *session,
 			     struct ceph_msg *msg);
-extern int ceph_add_cap(struct inode *inode,
-			struct ceph_mds_session *session, u64 cap_id,
-			int fmode, unsigned issued, unsigned wanted,
-			unsigned cap, unsigned seq, u64 realmino, int flags,
-			struct ceph_cap_reservation *caps_reservation);
+extern struct ceph_cap *ceph_get_cap(struct ceph_mds_client *mdsc,
+				     struct ceph_cap_reservation *ctx);
+extern void ceph_add_cap(struct inode *inode,
+			 struct ceph_mds_session *session, u64 cap_id,
+			 int fmode, unsigned issued, unsigned wanted,
+			 unsigned cap, unsigned seq, u64 realmino, int flags,
+			 struct ceph_cap **new_cap);
 extern void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release);
 extern void ceph_put_cap(struct ceph_mds_client *mdsc,
 			 struct ceph_cap *cap);