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 stable@vger.kernel.org.

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 'stable@vger.kernel.org' --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 pc@manguebit.com 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: stable@vger.kernel.org # 6.4+ Signed-off-by: Paulo Alcantara (Red Hat) pc@manguebit.com Signed-off-by: Steve French stfrench@microsoft.com

diff --git a/fs/smb/client/dfs_cache.c b/fs/smb/client/dfs_cache.c index 0552a864ff08..11c8efecf7aa 100644 --- a/fs/smb/client/dfs_cache.c +++ b/fs/smb/client/dfs_cache.c @@ -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);