From d174b8079ff3ed526c067969893ae910887c478e Mon Sep 17 00:00:00 2001
From: Yehuda Sadeh <yehuda@hq.newdream.net>
Date: Tue, 14 Oct 2008 12:34:18 -0700
Subject: [PATCH] kclient: fix race condition

---
 src/kernel/dir.c        |  2 +-
 src/kernel/inode.c      | 11 +++++++++--
 src/kernel/mds_client.c | 11 +++++++++--
 src/kernel/super.h      |  3 ++-
 4 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/src/kernel/dir.c b/src/kernel/dir.c
index b0c2256f93e1b..f15c24816f1f8 100644
--- a/src/kernel/dir.c
+++ b/src/kernel/dir.c
@@ -153,7 +153,7 @@ nextfrag:
 		int op = ceph_snap(inode) == CEPH_SNAPDIR ?
 			CEPH_MDS_OP_LSSNAP:CEPH_MDS_OP_READDIR;
 
-		frag = ceph_choose_frag(ceph_inode(inode), frag, 0);
+		frag = ceph_choose_frag(ceph_inode(inode), frag, 0, 0);
 
 		/* query mds */
 		dout(10, "dir_readdir querying mds for ino %llx.%llx frag %x\n",
diff --git a/src/kernel/inode.c b/src/kernel/inode.c
index 732c2ecfe4735..f7fccb6a5f776 100644
--- a/src/kernel/inode.c
+++ b/src/kernel/inode.c
@@ -133,13 +133,17 @@ out:
 }
 
 __u32 ceph_choose_frag(struct ceph_inode_info *ci, u32 v,
-		       struct ceph_inode_frag **pfrag)
+		       struct ceph_inode_frag *pfrag,
+		       int *found)
 {
 	u32 t = frag_make(0, 0);
 	struct ceph_inode_frag *frag;
 	unsigned nway, i;
 	u32 n;
 
+	if (found)
+		*found = 0;
+
 	mutex_lock(&ci->i_fragtree_mutex);
 	while (1) {
 		WARN_ON(!frag_contains_value(t, v));
@@ -148,7 +152,10 @@ __u32 ceph_choose_frag(struct ceph_inode_info *ci, u32 v,
 			break; /* t is a leaf */
 		if (frag->split_by == 0) {
 			if (pfrag)
-				*pfrag = frag;
+				memcpy(pfrag, frag, sizeof(struct ceph_inode_frag));
+
+			if (found)
+				*found = 1;
 			break;
 		}
 
diff --git a/src/kernel/mds_client.c b/src/kernel/mds_client.c
index a4253a608ce20..efb670ac05a50 100644
--- a/src/kernel/mds_client.c
+++ b/src/kernel/mds_client.c
@@ -486,9 +486,15 @@ static int choose_mds(struct ceph_mds_client *mdsc,
 		if (is_hash &&
 		    dentry->d_inode &&
 		    S_ISDIR(dentry->d_inode->i_mode)) {
+			int found;
 			ci = ceph_inode(dentry->d_inode);
-			ceph_choose_frag(ci, hash, &frag);
-			if (frag) {
+			frag = kmalloc(sizeof(struct ceph_inode_frag), GFP_KERNEL);
+
+			if (!frag)
+				return -ENOMEM;
+
+			ceph_choose_frag(ci, hash, frag, &found);
+			if (found) {
 				/* avoid hitting dir replicas on dir
 				 * auth delegation point.. mds will
 				 * likely forward anyway to avoid
@@ -518,6 +524,7 @@ static int choose_mds(struct ceph_mds_client *mdsc,
 					return mds;
 				}
 			}
+			kfree(frag);
 		}
 		if (IS_ROOT(dentry))
 			break;
diff --git a/src/kernel/super.h b/src/kernel/super.h
index d4ad676ed0028..a4769a56e7198 100644
--- a/src/kernel/super.h
+++ b/src/kernel/super.h
@@ -322,7 +322,8 @@ __ceph_find_frag(struct ceph_inode_info *ci, u32 f)
 }
 
 extern __u32 ceph_choose_frag(struct ceph_inode_info *ci, u32 v,
-			      struct ceph_inode_frag **pfrag);
+			      struct ceph_inode_frag *pfrag,
+			      int *found);
 
 struct ceph_dentry_info {
 	struct dentry *dentry;
-- 
2.39.5