2 files changed, 38 insertions, 14 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 7d0a0d0adc18..b6fdf010749b 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -1204,6 +1204,12 @@ 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) {
@@ -2117,8 +2123,8 @@ 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 +2148,8 @@ 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 +2172,32 @@ 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);
@@ -2185,10 +2205,12 @@ 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);
 }
 
 /*
@@ -2464,8 +2486,8 @@ 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);
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index df04e210a055..7e3e5f9edaa4 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -521,15 +521,17 @@ int __ceph_finish_cap_snap(struct ceph_inode_info *ci,
         capsnap->ctime = inode->i_ctime;
         capsnap->time_warp_seq = ci->i_time_warp_seq;
         if (capsnap->dirty_pages) {
-                dout("finish_cap_snap %p cap_snap %p snapc %p %llu s=%llu "
+                dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu "
                      "still has %d dirty pages\n", inode, capsnap,
                      capsnap->context, capsnap->context->seq,
-                     capsnap->size, capsnap->dirty_pages);
+                     ceph_cap_string(capsnap->dirty), capsnap->size,
+                     capsnap->dirty_pages);
                 return 0;
         }
-        dout("finish_cap_snap %p cap_snap %p snapc %p %llu s=%llu clean\n",
+        dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu\n",
              inode, capsnap, capsnap->context,
-             capsnap->context->seq, capsnap->size);
+             capsnap->context->seq, ceph_cap_string(capsnap->dirty),
+             capsnap->size);
 
         spin_lock(&mdsc->snap_flush_lock);
         list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list);