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FAILED: patch "[PATCH] smb: client: refresh referral without acquiring refpath_lock" failed to apply to 6.6-stable tree

PATCH [email protected] 1 participant 1 message Apr 8, 2024

Subsystems (2)
Stable branch SMB client (CIFS)
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Share & tools
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[email protected]

author maintainer
#0 lore raw

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 0a05ad21d77a188d06481c36d6016805a881bcc0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024040810-corporate-splinter-3a5f@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

0a05ad21d77a ("smb: client: refresh referral without acquiring refpath_lock") 062a7f0ff46e ("smb: client: guarantee refcounted children from parent session") d8392c203e84 ("smb3: show beginning time for per share stats")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0a05ad21d77a188d06481c36d6016805a881bcc0 Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <[email protected]>
Date: Mon, 1 Apr 2024 22:44:07 -0300
Subject: [PATCH] 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 [email protected] # 6.4+
Signed-off-by Paulo Alcantara (Red Hat) <[email protected]>
Signed-off-by Steve French <[email protected]>
fs/smb/client/dfs_cache.c +24 -20
index 0552a864ff08..11c8efecf7aa 100644
@@ -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);