Commit 0a05ad21 authored by Paulo Alcantara's avatar Paulo Alcantara Committed by Steve French
Browse files

smb: client: refresh referral without acquiring refpath_lock 



Avoid refreshing DFS referral with refpath_lock acquired as the I/O
could block for a while due to a potentially disconnected or slow DFS
root server and then making other threads - that use same @server and
don't require a DFS root server - unable to make any progress.

Cc: stable@vger.kernel.org # 6.4+
Signed-off-by: default avatarPaulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 062a7f0f

fs/smb/client/dfs_cache.c

+24 −20
Original line number Diff line number Diff line
@@ -1172,8 +1172,8 @@ static bool is_ses_good(struct cifs_ses *ses) 
	return ret;

}



/* Refresh dfs referral of tcon and mark it for reconnect if needed */

static int __refresh_tcon(const char *path, struct cifs_ses *ses, bool force_refresh)

/* Refresh dfs referral of @ses and mark it for reconnect if needed */

static void __refresh_ses_referral(struct cifs_ses *ses, bool force_refresh)

{

	struct TCP_Server_Info *server = ses->server;

	DFS_CACHE_TGT_LIST(old_tl);
@@ -1181,10 +1181,21 @@ static int __refresh_tcon(const char *path, struct cifs_ses *ses, bool force_ref 
	bool needs_refresh = false;

	struct cache_entry *ce;

	unsigned int xid;

	char *path = NULL;

	int rc = 0;



	xid = get_xid();



	mutex_lock(&server->refpath_lock);

	if (server->leaf_fullpath) {

		path = kstrdup(server->leaf_fullpath + 1, GFP_ATOMIC);

		if (!path)

			rc = -ENOMEM;

	}

	mutex_unlock(&server->refpath_lock);

	if (!path)

		goto out;



	down_read(&htable_rw_lock);

	ce = lookup_cache_entry(path);

	needs_refresh = force_refresh || IS_ERR(ce) || cache_entry_expired(ce);
@@ -1218,19 +1229,17 @@ static int __refresh_tcon(const char *path, struct cifs_ses *ses, bool force_ref 
	free_xid(xid);

	dfs_cache_free_tgts(&old_tl);

	dfs_cache_free_tgts(&new_tl);

	return rc;

	kfree(path);

}



static int refresh_tcon(struct cifs_tcon *tcon, bool force_refresh)

static inline void refresh_ses_referral(struct cifs_ses *ses)

{

	struct TCP_Server_Info *server = tcon->ses->server;

	struct cifs_ses *ses = tcon->ses;

	__refresh_ses_referral(ses, false);

}



	mutex_lock(&server->refpath_lock);

	if (server->leaf_fullpath)

		__refresh_tcon(server->leaf_fullpath + 1, ses, force_refresh);

	mutex_unlock(&server->refpath_lock);

	return 0;

static inline void force_refresh_ses_referral(struct cifs_ses *ses)

{

	__refresh_ses_referral(ses, true);

}



/**
@@ -1271,25 +1280,20 @@ int dfs_cache_remount_fs(struct cifs_sb_info *cifs_sb) 
	 */

	cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;



	return refresh_tcon(tcon, true);

	force_refresh_ses_referral(tcon->ses);

	return 0;

}



/* Refresh all DFS referrals related to DFS tcon */

void dfs_cache_refresh(struct work_struct *work)

{

	struct TCP_Server_Info *server;

	struct cifs_tcon *tcon;

	struct cifs_ses *ses;



	tcon = container_of(work, struct cifs_tcon, dfs_cache_work.work);



	for (ses = tcon->ses; ses; ses = ses->dfs_root_ses) {

		server = ses->server;

		mutex_lock(&server->refpath_lock);

		if (server->leaf_fullpath)

			__refresh_tcon(server->leaf_fullpath + 1, ses, false);

		mutex_unlock(&server->refpath_lock);

	}

	for (ses = tcon->ses; ses; ses = ses->dfs_root_ses)

		refresh_ses_referral(ses);



	queue_delayed_work(dfscache_wq, &tcon->dfs_cache_work,

			   atomic_read(&dfs_cache_ttl) * HZ);