kclient: optimistically adjust dirty accounting before taking tree lock (to avoid...

diff --git a/src/kernel/addr.c b/src/kernel/addr.c
index 0f42179155e4d1aef927315b5dbfb57382a31e66..ca57d34379f0d1826cf2c513a3488d7d229ccc30 100644 (file)
--- a/src/kernel/addr.c
+++ b/src/kernel/addr.c
@@ -25,6 +25,7 @@ static int ceph_set_page_dirty(struct page *page,
        struct address_space *mapping = page->mapping;
        struct inode *inode;
        struct ceph_inode_info *ci;
+       int undo = 0;
 
        if (unlikely(!mapping))
                return !TestSetPageDirty(page);
@@ -35,6 +36,47 @@ static int ceph_set_page_dirty(struct page *page,
                return 0;
        }
 
+       /*
+        * optimistically adjust accounting, on the assumption that
+        * we won't race with invalidate.
+        */
+       inode = mapping->host;
+       ci = ceph_inode(inode);
+
+       spin_lock(&inode->i_lock);
+       ++ci->i_wrbuffer_ref;
+       if (!snapc || snapc == ci->i_snap_realm->cached_context) {
+               /* dirty the head */
+               ++ci->i_wrbuffer_ref_head;
+               snapc = ceph_get_snap_context(ci->i_snap_realm->cached_context);
+               dout(20, "%p set_page_dirty %p head %d/%d -> %d/%d "
+                    "snapc %p seq %lld (%d snaps)\n",
+                    mapping->host, page,
+                    ci->i_wrbuffer_ref-1, ci->i_wrbuffer_ref_head-1,
+                    ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
+                    snapc, snapc->seq, snapc->num_snaps);
+       } else {
+               struct list_head *p;
+               struct ceph_cap_snap *capsnap = 0;
+               list_for_each(p, &ci->i_cap_snaps) {
+                       capsnap = list_entry(p, struct ceph_cap_snap,
+                                            ci_item);
+                       if (capsnap->context == snapc) {
+                               capsnap->dirty++;
+                               break;
+                       }
+               }
+               BUG_ON(!capsnap);
+               dout(20, "%p set_page_dirty %p snap %lld %d/%d -> %d/%d"
+                    " snapc %p seq %lld (%d snaps)\n",
+                    mapping->host, page, capsnap->follows,
+                    ci->i_wrbuffer_ref-1, capsnap->dirty-1,
+                    ci->i_wrbuffer_ref, capsnap->dirty,
+                    snapc, snapc->seq, snapc->num_snaps);
+       }
+       spin_unlock(&inode->i_lock);
+
+       /* now adjust page */
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,26)
        spin_lock_irq(&mapping->tree_lock);
 #else
@@ -52,42 +94,6 @@ static int ceph_set_page_dirty(struct page *page,
                radix_tree_tag_set(&mapping->page_tree,
                                page_index(page), PAGECACHE_TAG_DIRTY);
 
-               inode = mapping->host;
-               ci = ceph_inode(inode);
-
-               spin_lock(&inode->i_lock);
-               ++ci->i_wrbuffer_ref;
-               if (!snapc || snapc == ci->i_snap_realm->cached_context) {
-                       /* dirty the head */
-                       ++ci->i_wrbuffer_ref_head;
-                       snapc = ceph_get_snap_context(ci->i_snap_realm->cached_context);
-                       dout(20, "%p set_page_dirty %p head %d/%d -> %d/%d "
-                            "snapc %p seq %lld (%d snaps)\n",
-                            mapping->host, page,
-                            ci->i_wrbuffer_ref-1, ci->i_wrbuffer_ref_head-1,
-                            ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
-                            snapc, snapc->seq, snapc->num_snaps);
-               } else {
-                       struct list_head *p;
-                       struct ceph_cap_snap *capsnap = 0;
-                       list_for_each(p, &ci->i_cap_snaps) {
-                               capsnap = list_entry(p, struct ceph_cap_snap,
-                                                    ci_item);
-                               if (capsnap->context == snapc) {
-                                       capsnap->dirty++;
-                                       break;
-                               }
-                       }
-                       BUG_ON(!capsnap);
-                       dout(20, "%p set_page_dirty %p snap %lld %d/%d -> %d/%d"
-                            " snapc %p seq %lld (%d snaps)\n",
-                            mapping->host, page, capsnap->follows,
-                            ci->i_wrbuffer_ref-1, capsnap->dirty-1,
-                            ci->i_wrbuffer_ref, capsnap->dirty,
-                            snapc, snapc->seq, snapc->num_snaps);
-               }
-               spin_unlock(&inode->i_lock);
-
                /*
                 * reference snap context in page->private.  also set
                 * PagePrivate so that we get invalidatepage callback
@@ -96,14 +102,20 @@ static int ceph_set_page_dirty(struct page *page,
                ceph_put_snap_context((void *)page->private);
                page->private = (unsigned long)snapc;
                SetPagePrivate(page);
-
-       } else
+       } else {
                dout(20, "ANON set_page_dirty %p (raced truncate?)\n", page);
+               undo = 1;
+       }
+
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,26)
        spin_unlock_irq(&mapping->tree_lock);
 #else
        write_unlock_irq(&mapping->tree_lock);
 #endif
+
+       if (undo)
+               ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
+
        __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
 
        return 1;