1 files changed, 85 insertions, 52 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index db122bb357b..d9400534b27 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -3,6 +3,7 @@
 #include <linux/fs.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
+#include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/wait.h>
 #include <linux/writeback.h>
@@ -857,6 +858,8 @@ static int __ceph_is_any_caps(struct ceph_inode_info *ci)
 }
 
 /*
+ * Remove a cap.  Take steps to deal with a racing iterate_session_caps.
+ *
  * caller should hold i_lock.
  * caller will not hold session s_mutex if called from destroy_inode.
  */
@@ -865,15 +868,10 @@ void __ceph_remove_cap(struct ceph_cap *cap)
 	struct ceph_mds_session *session = cap->session;
 	struct ceph_inode_info *ci = cap->ci;
 	struct ceph_mds_client *mdsc = &ceph_client(ci->vfs_inode.i_sb)->mdsc;
+	int removed = 0;
 
 	dout("__ceph_remove_cap %p from %p\n", cap, &ci->vfs_inode);
 
-	/* remove from inode list */
-	rb_erase(&cap->ci_node, &ci->i_caps);
-	cap->ci = NULL;
-	if (ci->i_auth_cap == cap)
-		ci->i_auth_cap = NULL;
-
 	/* remove from session list */
 	spin_lock(&session->s_cap_lock);
 	if (session->s_cap_iterator == cap) {
@@ -884,10 +882,18 @@ void __ceph_remove_cap(struct ceph_cap *cap)
 		list_del_init(&cap->session_caps);
 		session->s_nr_caps--;
 		cap->session = NULL;
+		removed = 1;
 	}
+	/* protect backpointer with s_cap_lock: see iterate_session_caps */
+	cap->ci = NULL;
 	spin_unlock(&session->s_cap_lock);
 
-	if (cap->session == NULL)
+	/* remove from inode list */
+	rb_erase(&cap->ci_node, &ci->i_caps);
+	if (ci->i_auth_cap == cap)
+		ci->i_auth_cap = NULL;
+
+	if (removed)
 		ceph_put_cap(cap);
 
 	if (!__ceph_is_any_caps(ci) && ci->i_snap_realm) {
@@ -1204,6 +1210,12 @@ retry:
 		if (capsnap->dirty_pages || capsnap->writing)
 			continue;
 
+		/*
+		 * if cap writeback already occurred, we should have dropped
+		 * the capsnap in ceph_put_wrbuffer_cap_refs.
+		 */
+		BUG_ON(capsnap->dirty == 0);
+
 		/* pick mds, take s_mutex */
 		mds = __ceph_get_cap_mds(ci, &mseq);
 		if (session && session->s_mds != mds) {
@@ -1407,6 +1419,7 @@ static int try_nonblocking_invalidate(struct inode *inode)
  */
 void ceph_check_caps(struct ceph_inode_info *ci, int flags,
 		     struct ceph_mds_session *session)
+	__releases(session->s_mutex)
 {
 	struct ceph_client *client = ceph_inode_to_client(&ci->vfs_inode);
 	struct ceph_mds_client *mdsc = &client->mdsc;
@@ -1414,7 +1427,6 @@ void ceph_check_caps(struct ceph_inode_info *ci, int flags,
 	struct ceph_cap *cap;
 	int file_wanted, used;
 	int took_snap_rwsem = 0;             /* true if mdsc->snap_rwsem held */
-	int drop_session_lock = session ? 0 : 1;
 	int issued, implemented, want, retain, revoking, flushing = 0;
 	int mds = -1;   /* keep track of how far we've gone through i_caps list
 			   to avoid an infinite loop on retry */
@@ -1639,7 +1651,7 @@ ack:
 	if (queue_invalidate)
 		ceph_queue_invalidate(inode);
 
-	if (session && drop_session_lock)
+	if (session)
 		mutex_unlock(&session->s_mutex);
 	if (took_snap_rwsem)
 		up_read(&mdsc->snap_rwsem);
@@ -1854,8 +1866,8 @@ static void kick_flushing_capsnaps(struct ceph_mds_client *mdsc,
 		} else {
 			pr_err("%p auth cap %p not mds%d ???\n", inode,
 			       cap, session->s_mds);
-			spin_unlock(&inode->i_lock);
 		}
+		spin_unlock(&inode->i_lock);
 	}
 }
 
@@ -2117,8 +2129,8 @@ void ceph_put_cap_refs(struct ceph_inode_info *ci, int had)
 		}
 	spin_unlock(&inode->i_lock);
 
-	dout("put_cap_refs %p had %s %s\n", inode, ceph_cap_string(had),
-	     last ? "last" : "");
+	dout("put_cap_refs %p had %s%s%s\n", inode, ceph_cap_string(had),
+	     last ? " last" : "", put ? " put" : "");
 
 	if (last && !flushsnaps)
 		ceph_check_caps(ci, 0, NULL);
@@ -2142,7 +2154,8 @@ void ceph_put_wrbuffer_cap_refs(struct ceph_inode_info *ci, int nr,
 {
 	struct inode *inode = &ci->vfs_inode;
 	int last = 0;
-	int last_snap = 0;
+	int complete_capsnap = 0;
+	int drop_capsnap = 0;
 	int found = 0;
 	struct ceph_cap_snap *capsnap = NULL;
 
@@ -2165,19 +2178,32 @@ void ceph_put_wrbuffer_cap_refs(struct ceph_inode_info *ci, int nr,
 		list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
 			if (capsnap->context == snapc) {
 				found = 1;
-				capsnap->dirty_pages -= nr;
-				last_snap = !capsnap->dirty_pages;
 				break;
 			}
 		}
 		BUG_ON(!found);
+		capsnap->dirty_pages -= nr;
+		if (capsnap->dirty_pages == 0) {
+			complete_capsnap = 1;
+			if (capsnap->dirty == 0)
+				/* cap writeback completed before we created
+				 * the cap_snap; no FLUSHSNAP is needed */
+				drop_capsnap = 1;
+		}
 		dout("put_wrbuffer_cap_refs on %p cap_snap %p "
-		     " snap %lld %d/%d -> %d/%d %s%s\n",
+		     " snap %lld %d/%d -> %d/%d %s%s%s\n",
 		     inode, capsnap, capsnap->context->seq,
 		     ci->i_wrbuffer_ref+nr, capsnap->dirty_pages + nr,
 		     ci->i_wrbuffer_ref, capsnap->dirty_pages,
 		     last ? " (wrbuffer last)" : "",
-		     last_snap ? " (capsnap last)" : "");
+		     complete_capsnap ? " (complete capsnap)" : "",
+		     drop_capsnap ? " (drop capsnap)" : "");
+		if (drop_capsnap) {
+			ceph_put_snap_context(capsnap->context);
+			list_del(&capsnap->ci_item);
+			list_del(&capsnap->flushing_item);
+			ceph_put_cap_snap(capsnap);
+		}
 	}
 
 	spin_unlock(&inode->i_lock);
@@ -2185,28 +2211,31 @@ void ceph_put_wrbuffer_cap_refs(struct ceph_inode_info *ci, int nr,
 	if (last) {
 		ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);
 		iput(inode);
-	} else if (last_snap) {
+	} else if (complete_capsnap) {
 		ceph_flush_snaps(ci);
 		wake_up(&ci->i_cap_wq);
 	}
+	if (drop_capsnap)
+		iput(inode);
 }
 
 /*
  * Handle a cap GRANT message from the MDS.  (Note that a GRANT may
  * actually be a revocation if it specifies a smaller cap set.)
  *
- * caller holds s_mutex.
+ * caller holds s_mutex and i_lock, we drop both.
+ *
  * return value:
  *  0 - ok
  *  1 - check_caps on auth cap only (writeback)
  *  2 - check_caps (ack revoke)
  */
-static int handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
-			    struct ceph_mds_session *session,
-			    struct ceph_cap *cap,
-			    struct ceph_buffer *xattr_buf)
+static void handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
+			     struct ceph_mds_session *session,
+			     struct ceph_cap *cap,
+			     struct ceph_buffer *xattr_buf)
 	__releases(inode->i_lock)
-
+	__releases(session->s_mutex)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	int mds = session->s_mds;
@@ -2216,7 +2245,7 @@ static int handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
 	u64 size = le64_to_cpu(grant->size);
 	u64 max_size = le64_to_cpu(grant->max_size);
 	struct timespec mtime, atime, ctime;
-	int reply = 0;
+	int check_caps = 0;
 	int wake = 0;
 	int writeback = 0;
 	int revoked_rdcache = 0;
@@ -2329,11 +2358,12 @@ static int handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
 		if ((used & ~newcaps) & CEPH_CAP_FILE_BUFFER)
 			writeback = 1; /* will delay ack */
 		else if (dirty & ~newcaps)
-			reply = 1;     /* initiate writeback in check_caps */
+			check_caps = 1;  /* initiate writeback in check_caps */
 		else if (((used & ~newcaps) & CEPH_CAP_FILE_CACHE) == 0 ||
 			   revoked_rdcache)
-			reply = 2;     /* send revoke ack in check_caps */
+			check_caps = 2;     /* send revoke ack in check_caps */
 		cap->issued = newcaps;
+		cap->implemented |= newcaps;
 	} else if (cap->issued == newcaps) {
 		dout("caps unchanged: %s -> %s\n",
 		     ceph_cap_string(cap->issued), ceph_cap_string(newcaps));
@@ -2346,6 +2376,7 @@ static int handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
 					      * pending revocation */
 		wake = 1;
 	}
+	BUG_ON(cap->issued & ~cap->implemented);
 
 	spin_unlock(&inode->i_lock);
 	if (writeback)
@@ -2359,7 +2390,14 @@ static int handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
 		ceph_queue_invalidate(inode);
 	if (wake)
 		wake_up(&ci->i_cap_wq);
-	return reply;
+
+	if (check_caps == 1)
+		ceph_check_caps(ci, CHECK_CAPS_NODELAY|CHECK_CAPS_AUTHONLY,
+				session);
+	else if (check_caps == 2)
+		ceph_check_caps(ci, CHECK_CAPS_NODELAY, session);
+	else
+		mutex_unlock(&session->s_mutex);
 }
 
 /*
@@ -2454,8 +2492,8 @@ static void handle_cap_flushsnap_ack(struct inode *inode, u64 flush_tid,
 				break;
 			}
 			WARN_ON(capsnap->dirty_pages || capsnap->writing);
-			dout(" removing cap_snap %p follows %lld\n",
-			     capsnap, follows);
+			dout(" removing %p cap_snap %p follows %lld\n",
+			     inode, capsnap, follows);
 			ceph_put_snap_context(capsnap->context);
 			list_del(&capsnap->ci_item);
 			list_del(&capsnap->flushing_item);
@@ -2548,9 +2586,8 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 			ci->i_cap_exporting_issued = cap->issued;
 		}
 		__ceph_remove_cap(cap);
-	} else {
-		WARN_ON(!cap);
 	}
+	/* else, we already released it */
 
 	spin_unlock(&inode->i_lock);
 }
@@ -2621,9 +2658,7 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 	u64 cap_id;
 	u64 size, max_size;
 	u64 tid;
-	int check_caps = 0;
 	void *snaptrace;
-	int r;
 
 	dout("handle_caps from mds%d\n", mds);
 
@@ -2668,8 +2703,9 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 	case CEPH_CAP_OP_IMPORT:
 		handle_cap_import(mdsc, inode, h, session,
 				  snaptrace, le32_to_cpu(h->snap_trace_len));
-		check_caps = 1; /* we may have sent a RELEASE to the old auth */
-		goto done;
+		ceph_check_caps(ceph_inode(inode), CHECK_CAPS_NODELAY,
+				session);
+		goto done_unlocked;
 	}
 
 	/* the rest require a cap */
@@ -2686,16 +2722,8 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 	switch (op) {
 	case CEPH_CAP_OP_REVOKE:
 	case CEPH_CAP_OP_GRANT:
-		r = handle_cap_grant(inode, h, session, cap, msg->middle);
-		if (r == 1)
-			ceph_check_caps(ceph_inode(inode),
-					CHECK_CAPS_NODELAY|CHECK_CAPS_AUTHONLY,
-					session);
-		else if (r == 2)
-			ceph_check_caps(ceph_inode(inode),
-					CHECK_CAPS_NODELAY,
-					session);
-		break;
+		handle_cap_grant(inode, h, session, cap, msg->middle);
+		goto done_unlocked;
 
 	case CEPH_CAP_OP_FLUSH_ACK:
 		handle_cap_flush_ack(inode, tid, h, session, cap);
@@ -2713,9 +2741,7 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 
 done:
 	mutex_unlock(&session->s_mutex);
-
-	if (check_caps)
-		ceph_check_caps(ceph_inode(inode), CHECK_CAPS_NODELAY, NULL);
+done_unlocked:
 	if (inode)
 		iput(inode);
 	return;
@@ -2838,11 +2864,18 @@ int ceph_encode_inode_release(void **p, struct inode *inode,
 	struct ceph_cap *cap;
 	struct ceph_mds_request_release *rel = *p;
 	int ret = 0;
-
-	dout("encode_inode_release %p mds%d drop %s unless %s\n", inode,
-	     mds, ceph_cap_string(drop), ceph_cap_string(unless));
+	int used = 0;
 
 	spin_lock(&inode->i_lock);
+	used = __ceph_caps_used(ci);
+
+	dout("encode_inode_release %p mds%d used %s drop %s unless %s\n", inode,
+	     mds, ceph_cap_string(used), ceph_cap_string(drop),
+	     ceph_cap_string(unless));
+
+	/* only drop unused caps */
+	drop &= ~used;
+
 	cap = __get_cap_for_mds(ci, mds);
 	if (cap && __cap_is_valid(cap)) {
 		if (force ||