Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6:
  cifs: guard against hardlinking directories

2 files changed, 20 insertions, 2 deletions

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index ecf0ffbe2b64..0c2fd17439c8 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -502,6 +502,7 @@ struct dfs_info3_param {
 #define CIFS_FATTR_DFS_REFERRAL         0x1
 #define CIFS_FATTR_DELETE_PENDING       0x2
 #define CIFS_FATTR_NEED_REVAL           0x4
+#define CIFS_FATTR_INO_COLLISION        0x8
 
 struct cifs_fattr {
         u32             cf_flags;
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 35ec11716213..29b9ea244c81 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -715,6 +715,16 @@ cifs_find_inode(struct inode *inode, void *opaque)
         if (CIFS_I(inode)->uniqueid != fattr->cf_uniqueid)
                 return 0;
 
+        /*
+         * uh oh -- it's a directory. We can't use it since hardlinked dirs are
+         * verboten. Disable serverino and return it as if it were found, the
+         * caller can discard it, generate a uniqueid and retry the find
+         */
+        if (S_ISDIR(inode->i_mode) && !list_empty(&inode->i_dentry)) {
+                fattr->cf_flags |= CIFS_FATTR_INO_COLLISION;
+                cifs_autodisable_serverino(CIFS_SB(inode->i_sb));
+        }
+
         return 1;
 }
 
@@ -734,15 +744,22 @@ cifs_iget(struct super_block *sb, struct cifs_fattr *fattr)
         unsigned long hash;
         struct inode *inode;
 
+retry_iget5_locked:
         cFYI(1, ("looking for uniqueid=%llu", fattr->cf_uniqueid));
 
         /* hash down to 32-bits on 32-bit arch */
         hash = cifs_uniqueid_to_ino_t(fattr->cf_uniqueid);
 
         inode = iget5_locked(sb, hash, cifs_find_inode, cifs_init_inode, fattr);
-
-        /* we have fattrs in hand, update the inode */
         if (inode) {
+                /* was there a problematic inode number collision? */
+                if (fattr->cf_flags & CIFS_FATTR_INO_COLLISION) {
+                        iput(inode);
+                        fattr->cf_uniqueid = iunique(sb, ROOT_I);
+                        fattr->cf_flags &= ~CIFS_FATTR_INO_COLLISION;
+                        goto retry_iget5_locked;
+                }
+
                 cifs_fattr_to_inode(inode, fattr);
                 if (sb->s_flags & MS_NOATIME)
                         inode->i_flags |= S_NOATIME | S_NOCMTIME;