NFS: Stop sillyname renames and unmounts from racing

The following patch stops sillyname renames and umounts from racing. I have a test script does the following:
1) start nfs server
2) mount loopback
3) open file in background
4) remove file
5) stop nfs server
6) kill -9 process which has file open
7) restart nfs server
8) umount looback mount.

After umount I got the "VFS: Busy inodes after unmount" message because the processing of the rename has not finished.

Below is a patch that the uses the new silly_count mechanism to synchronize sillyname processing and umounts. The patch introduces a nfs_put_super() routine that waits until the nfsi->silly_count count is zero.

Comments?

steved.

Author: Steve Dickson <[email protected]>
Date:   Wed Oct 31 12:19:26 2007 -0400

Close a unlink/sillyname rename and umount race by added a nfs_put_super routine that will run through all the inode currently on the super block, waiting for those that are in the middle of a sillyname rename or removal.

This patch stop the infamous "VFS: Busy inodes after unmount... " warning during umounts.

index ed35383..da9034a 100644
@@ -81,6 +81,7 @@ static struct hlist_head *inode_hashtable __read_mostly;
   * the i_state of an inode while it is in use..
   */
  DEFINE_SPINLOCK(inode_lock);
+EXPORT_SYMBOL_GPL(inode_lock);
 
  /*
   * iprune_mutex provides exclusion between the kswapd or try_to_free_pages

index fa517ae..2ac3c34 100644
@@ -48,6 +48,7 @@
  #include <linux/nfs_xdr.h>
  #include <linux/magic.h>
  #include <linux/parser.h>
+#include <linux/writeback.h>
 
  #include <asm/system.h>
  #include <asm/uaccess.h>

@@ -202,6 +203,7 @@ static int nfs_get_sb(struct file_system_type *, 

int, const char *, void *, stru
static int nfs_xdev_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
static void nfs_kill_super(struct super_block *);
+static void nfs_put_super(struct super_block *);

static struct file_system_type nfs_fs_type = {
.owner = THIS_MODULE,
@@ -223,6 +225,7 @@ static const struct super_operations nfs_sops = {
.alloc_inode = nfs_alloc_inode,
.destroy_inode = nfs_destroy_inode,
.write_inode = nfs_write_inode,
+ .put_super = nfs_put_super,
.statfs = nfs_statfs,
.clear_inode = nfs_clear_inode,
.umount_begin = nfs_umount_begin,
@@ -1767,6 +1770,30 @@ static void nfs4_kill_super(struct super_block *sb)
nfs_free_server(server);
}

+void nfs_put_super(struct super_block *sb)
+{
+ struct inode *inode;
+ struct nfs_inode *nfsi;
+ /*
+ * Make sure there are no outstanding renames
+ */
+relock:
+ spin_lock(&inode_lock);
+ list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+ nfsi = NFS_I(inode);
+ if (atomic_read(&nfsi->silly_count) > 0) {
+ /* Keep this inode around during the wait */
+ atomic_inc(&inode->i_count);
+ spin_unlock(&inode_lock);
+ wait_event(nfsi->waitqueue,
+ atomic_read(&nfsi->silly_count) == 1);
+ iput(inode);
+ goto relock;
+ }
+ }
+ spin_unlock(&inode_lock);
+}
+
/*
* Clone an NFS4 server record on xdev traversal (FSID-change) */

-------------------------------------------------------------------------
This SF.net email is sponsored by: Splunk Inc.
Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/
_______________________________________________
NFS maillist - [email protected]
https://lists.sourceforge.net/lists/listinfo/nfs