ceph: set dn offset when spliced

We want to assign an offset when the dentry goes from null to linked, which
is always done by splice_dentry().  Notably, we should NOT assign an
offset when a dentry is first created and is still null.

BUG if we try to splice a non-null dentry (we shouldn't).

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 37 insertions, 34 deletions

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index aa22a0bce52f..1bcf98bd0255 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -804,6 +804,37 @@ out_unlock:
 }
 
 /*
+ * Set dentry's directory position based on the current dir's max, and
+ * order it in d_subdirs, so that dcache_readdir behaves.
+ */
+static void ceph_set_dentry_offset(struct dentry *dn)
+{
+        struct dentry *dir = dn->d_parent;
+        struct inode *inode = dn->d_parent->d_inode;
+        struct ceph_dentry_info *di;
+
+        BUG_ON(!inode);
+
+        di = ceph_dentry(dn);
+
+        spin_lock(&inode->i_lock);
+        if ((ceph_inode(inode)->i_ceph_flags & CEPH_I_COMPLETE) == 0) {
+                spin_unlock(&inode->i_lock);
+                return;
+        }
+        di->offset = ceph_inode(inode)->i_max_offset++;
+        spin_unlock(&inode->i_lock);
+
+        spin_lock(&dcache_lock);
+        spin_lock(&dn->d_lock);
+        list_move_tail(&dir->d_subdirs, &dn->d_u.d_child);
+        dout("set_dentry_offset %p %lld (%p %p)\n", dn, di->offset,
+             dn->d_u.d_child.prev, dn->d_u.d_child.next);
+        spin_unlock(&dn->d_lock);
+        spin_unlock(&dcache_lock);
+}
+
+/*
  * splice a dentry to an inode.
  * caller must hold directory i_mutex for this to be safe.
  *
@@ -816,6 +847,8 @@ static struct dentry *splice_dentry(struct dentry *dn, struct inode *in,
 {
         struct dentry *realdn;
 
+        BUG_ON(dn->d_inode);
+
         /* dn must be unhashed */
         if (!d_unhashed(dn))
                 d_drop(dn);
@@ -837,48 +870,17 @@ static struct dentry *splice_dentry(struct dentry *dn, struct inode *in,
                 dn = realdn;
         } else {
                 BUG_ON(!ceph_dentry(dn));
-
                 dout("dn %p attached to %p ino %llx.%llx\n",
                      dn, dn->d_inode, ceph_vinop(dn->d_inode));
         }
         if ((!prehash || *prehash) && d_unhashed(dn))
                 d_rehash(dn);
+        ceph_set_dentry_offset(dn);
 out:
         return dn;
 }
 
 /*
- * Set dentry's directory position based on the current dir's max, and
- * order it in d_subdirs, so that dcache_readdir behaves.
- */
-static void ceph_set_dentry_offset(struct dentry *dn)
-{
-        struct dentry *dir = dn->d_parent;
-        struct inode *inode = dn->d_parent->d_inode;
-        struct ceph_dentry_info *di;
-
-        BUG_ON(!inode);
-
-        di = ceph_dentry(dn);
-
-        spin_lock(&inode->i_lock);
-        if ((ceph_inode(inode)->i_ceph_flags & CEPH_I_COMPLETE) == 0) {
-                spin_unlock(&inode->i_lock);
-                return;
-        }
-        di->offset = ceph_inode(inode)->i_max_offset++;
-        spin_unlock(&inode->i_lock);
-
-        spin_lock(&dcache_lock);
-        spin_lock(&dn->d_lock);
-        list_move_tail(&dir->d_subdirs, &dn->d_u.d_child);
-        dout("set_dentry_offset %p %lld (%p %p)\n", dn, di->offset,
-             dn->d_u.d_child.prev, dn->d_u.d_child.next);
-        spin_unlock(&dn->d_lock);
-        spin_unlock(&dcache_lock);
-}
-
-/*
  * Incorporate results into the local cache.  This is either just
  * one inode, or a directory, dentry, and possibly linked-to inode (e.g.,
  * after a lookup).
@@ -1030,6 +1032,9 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
                         ceph_invalidate_dentry_lease(dn);
 
                         /* take overwritten dentry's readdir offset */
+                        dout("dn %p gets %p offset %lld (old offset %lld)\n",
+                             req->r_old_dentry, dn, ceph_dentry(dn)->offset,
+                             ceph_dentry(req->r_old_dentry)->offset);
                         ceph_dentry(req->r_old_dentry)->offset =
                                 ceph_dentry(dn)->offset;
 
@@ -1074,7 +1079,6 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
                                 goto done;
                         }
                         req->r_dentry = dn;  /* may have spliced */
-                        ceph_set_dentry_offset(dn);
                         igrab(in);
                 } else if (ceph_ino(in) == vino.ino &&
                            ceph_snap(in) == vino.snap) {
@@ -1117,7 +1121,6 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
                         err = PTR_ERR(dn);
                         goto done;
                 }
-                ceph_set_dentry_offset(dn);
                 req->r_dentry = dn;  /* may have spliced */
                 igrab(in);
                 rinfo->head->is_dentry = 1;  /* fool notrace handlers */