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>

2 files changed, 44 insertions, 40 deletions

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 0b0a39d05ca6..d3bb8132a1aa 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -128,7 +128,8 @@ more:
         dentry = list_entry(p, struct dentry, d_u.d_child);
         di = ceph_dentry(dentry);
         while (1) {
-                dout(" p %p/%p d_subdirs %p/%p\n", p->prev, p->next,
+                dout(" p %p/%p %s d_subdirs %p/%p\n", p->prev, p->next,
+                     d_unhashed(dentry) ? "!hashed" : "hashed",
                      parent->d_subdirs.prev, parent->d_subdirs.next);
                 if (p == &parent->d_subdirs) {
                         fi->at_end = 1;
@@ -571,7 +572,6 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry,
                     !is_root_ceph_dentry(dir, dentry) &&
                     (ci->i_ceph_flags & CEPH_I_COMPLETE) &&
                     (__ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1))) {
-                        di->offset = ci->i_max_offset++;
                         spin_unlock(&dir->i_lock);
                         dout(" dir %p complete, -ENOENT\n", dir);
                         d_add(dentry, NULL);
@@ -984,8 +984,9 @@ static int ceph_d_revalidate(struct dentry *dentry, struct nameidata *nd)
 {
         struct inode *dir = dentry->d_parent->d_inode;
 
-        dout("d_revalidate %p '%.*s' inode %p\n", dentry,
-             dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
+        dout("d_revalidate %p '%.*s' inode %p offset %lld\n", dentry,
+             dentry->d_name.len, dentry->d_name.name, dentry->d_inode,
+             ceph_dentry(dentry)->offset);
 
         /* always trust cached snapped dentries, snapdir dentry */
         if (ceph_snap(dir) != CEPH_NOSNAP) {
@@ -1177,8 +1178,8 @@ void ceph_dentry_lru_touch(struct dentry *dn)
         struct ceph_dentry_info *di = ceph_dentry(dn);
         struct ceph_mds_client *mdsc;
 
-        dout("dentry_lru_touch %p %p '%.*s'\n", di, dn,
-             dn->d_name.len, dn->d_name.name);
+        dout("dentry_lru_touch %p %p '%.*s' (offset %lld)\n", di, dn,
+             dn->d_name.len, dn->d_name.name, di->offset);
         if (di) {
                 mdsc = &ceph_sb_to_client(dn->d_sb)->mdsc;
                 spin_lock(&mdsc->dentry_lru_lock);
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 */