exportfs: move most of reconnect_path to helper function
Also replace 3 easily-confused three-letter acronyms by more helpful
variable names.
Just cleanup, no change in functionality, with one exception: the
dentry_connected() check in the "out_reconnected" case will now only
check the ancestors of the current dentry instead of checking all the
way from target_dir. Since we've already verified connectivity up to
this dentry, that should be sufficient.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index d8ba88a..d32ead9 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -126,6 +126,86 @@
}
/*
+ * Reconnect a directory dentry with its parent.
+ *
+ * This can return a dentry, or NULL, or an error.
+ *
+ * In the first case the returned dentry is the parent of the given
+ * dentry, and may itself need to be reconnected to its parent.
+ *
+ * In the NULL case, a concurrent VFS operation has either renamed or
+ * removed this directory. The concurrent operation has reconnected our
+ * dentry, so we no longer need to.
+ */
+static struct dentry *reconnect_one(struct vfsmount *mnt,
+ struct dentry *dentry, char *nbuf)
+{
+ struct dentry *parent;
+ struct dentry *tmp;
+ int err;
+
+ parent = ERR_PTR(-EACCES);
+ mutex_lock(&dentry->d_inode->i_mutex);
+ if (mnt->mnt_sb->s_export_op->get_parent)
+ parent = mnt->mnt_sb->s_export_op->get_parent(dentry);
+ mutex_unlock(&dentry->d_inode->i_mutex);
+
+ if (IS_ERR(parent)) {
+ dprintk("%s: get_parent of %ld failed, err %d\n",
+ __func__, dentry->d_inode->i_ino, PTR_ERR(parent));
+ return parent;
+ }
+
+ dprintk("%s: find name of %lu in %lu\n", __func__,
+ dentry->d_inode->i_ino, parent->d_inode->i_ino);
+ err = exportfs_get_name(mnt, parent, nbuf, dentry);
+ if (err == -ENOENT)
+ goto out_reconnected;
+ if (err)
+ goto out_err;
+ dprintk("%s: found name: %s\n", __func__, nbuf);
+ mutex_lock(&parent->d_inode->i_mutex);
+ tmp = lookup_one_len(nbuf, parent, strlen(nbuf));
+ mutex_unlock(&parent->d_inode->i_mutex);
+ if (IS_ERR(tmp)) {
+ dprintk("%s: lookup failed: %d\n", __func__, PTR_ERR(tmp));
+ goto out_err;
+ }
+ if (tmp != dentry) {
+ dput(tmp);
+ goto out_reconnected;
+ }
+ dput(tmp);
+ if (IS_ROOT(dentry)) {
+ err = -ESTALE;
+ goto out_err;
+ }
+ return parent;
+
+out_err:
+ dput(parent);
+ return ERR_PTR(err);
+out_reconnected:
+ dput(parent);
+ /*
+ * Someone must have renamed our entry into another parent, in
+ * which case it has been reconnected by the rename.
+ *
+ * Or someone removed it entirely, in which case filehandle
+ * lookup will succeed but the directory is now IS_DEAD and
+ * subsequent operations on it will fail.
+ *
+ * Alternatively, maybe there was no race at all, and the
+ * filesystem is just corrupt and gave us a parent that doesn't
+ * actually contain any entry pointing to this inode. So,
+ * double check that this worked and return -ESTALE if not:
+ */
+ if (!dentry_connected(dentry))
+ return ERR_PTR(-ESTALE);
+ return NULL;
+}
+
+/*
* Make sure target_dir is fully connected to the dentry tree.
*
* On successful return, DCACHE_DISCONNECTED will be cleared on
@@ -158,76 +238,19 @@
dput(pd);
break;
} else {
+ struct dentry *parent;
/*
* We have hit the top of a disconnected path, try to
* find parent and connect.
- *
- * Racing with some other process renaming a directory
- * isn't much of a problem here. If someone renames
- * the directory, it will end up properly connected,
- * which is what we want
- *
- * Getting the parent can't be supported generically,
- * the locking is too icky.
- *
- * Instead we just return EACCES. If server reboots
- * or inodes get flushed, you lose
*/
- struct dentry *ppd = ERR_PTR(-EACCES);
- struct dentry *npd;
-
- mutex_lock(&pd->d_inode->i_mutex);
- if (mnt->mnt_sb->s_export_op->get_parent)
- ppd = mnt->mnt_sb->s_export_op->get_parent(pd);
- mutex_unlock(&pd->d_inode->i_mutex);
-
- if (IS_ERR(ppd)) {
- err = PTR_ERR(ppd);
- dprintk("%s: get_parent of %ld failed, err %d\n",
- __func__, pd->d_inode->i_ino, err);
- dput(pd);
- break;
- }
-
- dprintk("%s: find name of %lu in %lu\n", __func__,
- pd->d_inode->i_ino, ppd->d_inode->i_ino);
- err = exportfs_get_name(mnt, ppd, nbuf, pd);
- if (err) {
- dput(ppd);
- dput(pd);
- if (err == -ENOENT)
- /* some race between get_parent and
- * get_name?
- */
- goto out_reconnected;
- break;
- }
- dprintk("%s: found name: %s\n", __func__, nbuf);
- mutex_lock(&ppd->d_inode->i_mutex);
- npd = lookup_one_len(nbuf, ppd, strlen(nbuf));
- mutex_unlock(&ppd->d_inode->i_mutex);
- if (IS_ERR(npd)) {
- err = PTR_ERR(npd);
- dprintk("%s: lookup failed: %d\n",
- __func__, err);
- dput(ppd);
- dput(pd);
- break;
- }
- /* we didn't really want npd, we really wanted
- * a side-effect of the lookup.
- * hopefully, npd == pd, though it isn't really
- * a problem if it isn't
- */
- dput(npd);
- dput(ppd);
- if (npd != pd)
+ parent = reconnect_one(mnt, pd, nbuf);
+ if (!parent)
goto out_reconnected;
- if (IS_ROOT(pd)) {
- /* something went wrong, we have to give up */
- dput(pd);
+ if (IS_ERR(parent)) {
+ err = PTR_ERR(parent);
break;
}
+ dput(parent);
}
dput(pd);
}
@@ -241,21 +264,6 @@
return 0;
out_reconnected:
- /*
- * Someone must have renamed our entry into another parent, in
- * which case it has been reconnected by the rename.
- *
- * Or someone removed it entirely, in which case filehandle
- * lookup will succeed but the directory is now IS_DEAD and
- * subsequent operations on it will fail.
- *
- * Alternatively, maybe there was no race at all, and the
- * filesystem is just corrupt and gave us a parent that doesn't
- * actually contain any entry pointing to this inode. So,
- * double check that this worked and return -ESTALE if not:
- */
- if (!dentry_connected(target_dir))
- return -ESTALE;
clear_disconnected(target_dir);
return 0;
}