fs/9p: mitigate inode collisions

[linux-2.6-block.git] / fs / 9p / vfs_inode.c

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 47bd77199e20c83a3c7554d5dc592697080b7885..7a3308d776060e2e2565af09d358f2cf33416b6b 100644 (file)
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -364,7 +364,8 @@ void v9fs_evict_inode(struct inode *inode)
                clear_inode(inode);
 }
 
-struct inode *v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid)
+struct inode *
+v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid, bool new)
 {
        dev_t rdev;
        int retval;
@@ -376,8 +377,18 @@ struct inode *v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid)
        inode = iget_locked(sb, QID2INO(&fid->qid));
        if (unlikely(!inode))
                return ERR_PTR(-ENOMEM);
-       if (!(inode->i_state & I_NEW))
-               return inode;
+       if (!(inode->i_state & I_NEW)) {
+               if (!new) {
+                       goto done;
+               } else {
+                       p9_debug(P9_DEBUG_VFS, "WARNING: Inode collision %ld\n",
+                                               inode->i_ino);
+                       iput(inode);
+                       remove_inode_hash(inode);
+                       inode = iget_locked(sb, QID2INO(&fid->qid));
+                       WARN_ON(!(inode->i_state & I_NEW));
+               }
+       }
 
        /*
         * initialize the inode with the stat info
@@ -401,11 +412,11 @@ struct inode *v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid)
        v9fs_set_netfs_context(inode);
        v9fs_cache_inode_get_cookie(inode);
        unlock_new_inode(inode);
+done:
        return inode;
 error:
        iget_failed(inode);
        return ERR_PTR(retval);
-
 }
 
 /**
@@ -437,8 +448,15 @@ static int v9fs_at_to_dotl_flags(int flags)
  */
 static void v9fs_dec_count(struct inode *inode)
 {
-       if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2)
-               drop_nlink(inode);
+       if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2) {
+               if (inode->i_nlink) {
+                       drop_nlink(inode);
+               } else {
+                       p9_debug(P9_DEBUG_VFS,
+                                               "WARNING: unexpected i_nlink zero %d inode %ld\n",
+                                               inode->i_nlink, inode->i_ino);
+               }
+       }
 }
 
 /**
@@ -489,6 +507,9 @@ static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
                } else
                        v9fs_dec_count(inode);
 
+               if (inode->i_nlink <= 0)        /* no more refs unhash it */
+                       remove_inode_hash(inode);
+
                v9fs_invalidate_inode_attr(inode);
                v9fs_invalidate_inode_attr(dir);
 
@@ -554,7 +575,7 @@ v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
                /*
                 * instantiate inode and assign the unopened fid to the dentry
                 */
-               inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
+               inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb, true);
                if (IS_ERR(inode)) {
                        err = PTR_ERR(inode);
                        p9_debug(P9_DEBUG_VFS,
@@ -683,7 +704,7 @@ struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
        else if (IS_ERR(fid))
                inode = ERR_CAST(fid);
        else
-               inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
+               inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb, false);
        /*
         * If we had a rename on the server and a parallel lookup
         * for the new name, then make sure we instantiate with