ceph: cap tracking for async directory operations

Track and correctly handle directory caps for asynchronous operations.
Add aliases for Frc caps that we now designate at Dcu caps (when dealing
with directories).

Unlike file caps, we don't reclaim these when the session goes away, and
instead preemptively release them. In-flight async dirops are instead
handled during reconnect phase. The client needs to re-do a synchronous
operation in order to re-get directory caps.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/caps.c

@@ -992,7 +992,11 @@ int __ceph_caps_file_wanted(struct ceph_inode_info *ci)
 int __ceph_caps_wanted(struct ceph_inode_info *ci)
 {
 	int w = __ceph_caps_file_wanted(ci) | __ceph_caps_used(ci);
-	if (!S_ISDIR(ci->vfs_inode.i_mode)) {
+	if (S_ISDIR(ci->vfs_inode.i_mode)) {
+		/* we want EXCL if holding caps of dir ops */
+		if (w & CEPH_CAP_ANY_DIR_OPS)
+			w |= CEPH_CAP_FILE_EXCL;
+	} else {
 		/* we want EXCL if dirty data */
 		if (w & CEPH_CAP_FILE_BUFFER)
 			w |= CEPH_CAP_FILE_EXCL;
@@ -1893,10 +1897,13 @@ void ceph_check_caps(struct ceph_inode_info *ci, int flags,
 			 * revoking the shared cap on every create/unlink
 			 * operation.
 			 */
-			if (IS_RDONLY(inode))
+			if (IS_RDONLY(inode)) {
 				want = CEPH_CAP_ANY_SHARED;
-			else
-				want = CEPH_CAP_ANY_SHARED | CEPH_CAP_FILE_EXCL;
+			} else {
+				want = CEPH_CAP_ANY_SHARED |
+				       CEPH_CAP_FILE_EXCL |
+				       CEPH_CAP_ANY_DIR_OPS;
+			}
 			retain |= want;
 		} else {
 
@@ -2749,10 +2756,14 @@ int ceph_try_get_caps(struct inode *inode, int need, int want,
 	int ret;
 
 	BUG_ON(need & ~CEPH_CAP_FILE_RD);
-	BUG_ON(want & ~(CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO|CEPH_CAP_FILE_SHARED));
+	BUG_ON(want & ~(CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO |
+			CEPH_CAP_FILE_SHARED | CEPH_CAP_FILE_EXCL |
+			CEPH_CAP_ANY_DIR_OPS));
+	if (need) {
 		ret = ceph_pool_perm_check(inode, need);
 		if (ret < 0)
 			return ret;
+	}
 
 	ret = try_get_cap_refs(inode, need, want, 0,
 			       (nonblock ? NON_BLOCKING : 0), got);

fs/ceph/mds_client.c

@@ -699,6 +699,7 @@ void ceph_mdsc_release_request(struct kref *kref)
 	struct ceph_mds_request *req = container_of(kref,
 						    struct ceph_mds_request,
 						    r_kref);
+	ceph_mdsc_release_dir_caps(req);
 	destroy_reply_info(&req->r_reply_info);
 	if (req->r_request)
 		ceph_msg_put(req->r_request);
@@ -3280,6 +3281,17 @@ static void handle_session(struct ceph_mds_session *session,
 	return;
 }
 
+void ceph_mdsc_release_dir_caps(struct ceph_mds_request *req)
+{
+	int dcaps;
+
+	dcaps = xchg(&req->r_dir_caps, 0);
+	if (dcaps) {
+		dout("releasing r_dir_caps=%s\n", ceph_cap_string(dcaps));
+		ceph_put_cap_refs(ceph_inode(req->r_parent), dcaps);
+	}
+}
+
 /*
  * called under session->mutex.
  */
@@ -3307,8 +3319,13 @@ static void replay_unsafe_requests(struct ceph_mds_client *mdsc,
 			continue;
 		if (req->r_attempts == 0)
 			continue; /* only old requests */
-		if (req->r_session &&
-		    req->r_session->s_mds == session->s_mds)
+		if (!req->r_session)
+			continue;
+		if (req->r_session->s_mds != session->s_mds)
+			continue;
+
+		ceph_mdsc_release_dir_caps(req);
+
 		__send_request(mdsc, session, req, true);
 	}
 	mutex_unlock(&mdsc->mutex);
@@ -3393,7 +3410,7 @@ static int send_reconnect_partial(struct ceph_reconnect_state *recon_state)
 /*
  * Encode information about a cap for a reconnect with the MDS.
  */
-static int encode_caps_cb(struct inode *inode, struct ceph_cap *cap,
+static int reconnect_caps_cb(struct inode *inode, struct ceph_cap *cap,
 			  void *arg)
 {
 	union {
@@ -3416,6 +3433,10 @@ static int encode_caps_cb(struct inode *inode, struct ceph_cap *cap,
 	cap->mseq = 0;       /* and migrate_seq */
 	cap->cap_gen = cap->session->s_cap_gen;
 
+	/* These are lost when the session goes away */
+	if (S_ISDIR(inode->i_mode))
+		cap->issued &= ~CEPH_CAP_ANY_DIR_OPS;
+
 	if (recon_state->msg_version >= 2) {
 		rec.v2.cap_id = cpu_to_le64(cap->cap_id);
 		rec.v2.wanted = cpu_to_le32(__ceph_caps_wanted(ci));
@@ -3712,7 +3733,7 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
 		recon_state.msg_version = 2;
 	}
 	/* trsaverse this session's caps */
-	err = ceph_iterate_session_caps(session, encode_caps_cb, &recon_state);
+	err = ceph_iterate_session_caps(session, reconnect_caps_cb, &recon_state);
 
 	spin_lock(&session->s_cap_lock);
 	session->s_cap_reconnect = 0;

fs/ceph/mds_client.h

@@ -284,8 +284,11 @@ struct ceph_mds_request {
 	struct ceph_msg  *r_request;  /* original request */
 	struct ceph_msg  *r_reply;
 	struct ceph_mds_reply_info_parsed r_reply_info;
-	struct page *r_locked_page;
 	int r_err;
+
+
+	struct page *r_locked_page;
+	int r_dir_caps;
 	int r_num_caps;
 	u32               r_readdir_offset;
 
@@ -489,6 +492,7 @@ extern int ceph_mdsc_submit_request(struct ceph_mds_client *mdsc,
 extern int ceph_mdsc_do_request(struct ceph_mds_client *mdsc,
 				struct inode *dir,
 				struct ceph_mds_request *req);
+extern void ceph_mdsc_release_dir_caps(struct ceph_mds_request *req);
 static inline void ceph_mdsc_get_request(struct ceph_mds_request *req)
 {
 	kref_get(&req->r_kref);

include/linux/ceph/ceph_fs.h

@@ -663,6 +663,12 @@ int ceph_flags_to_mode(int flags);
 #define CEPH_CAP_LOCKS (CEPH_LOCK_IFILE | CEPH_LOCK_IAUTH | CEPH_LOCK_ILINK | \
 			CEPH_LOCK_IXATTR)
 
+/* cap masks async dir operations */
+#define CEPH_CAP_DIR_CREATE	CEPH_CAP_FILE_CACHE
+#define CEPH_CAP_DIR_UNLINK	CEPH_CAP_FILE_RD
+#define CEPH_CAP_ANY_DIR_OPS	(CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_RD | \
+				 CEPH_CAP_FILE_WREXTEND | CEPH_CAP_FILE_LAZYIO)
+
 int ceph_caps_for_mode(int mode);
 
 enum {