kernel/linux.git/fs/cifs/dfs_cache.c, branch v5.15.213

cifs: Add tracing for the cifs_tcon struct refcounting

2026-07-24T13:51:59+00:00

[ Upstream commit afc23febd51c7e24361e3a9c09f3e892eb0a41ea ] Add tracing for the refcounting/lifecycle of the cifs_tcon struct, marking different events with different labels and giving each tcon its own debug ID so that the tracelines corresponding to individual tcons can be distinguished. This can be enabled with: echo 1 >/sys/kernel/debug/tracing/events/cifs/smb3_tcon_ref/enable Signed-off-by: David Howells Acked-by: Paulo Alcantara (Red Hat) cc: Shyam Prasad N cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Steve French Stable-dep-of: ec457f9afe5a ("smb: client: resolve SWN tcon from live registrations") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

cifs: fix return of uninitialized rc in dfs_cache_update_tgthint()

2023-02-06T06:59:00+00:00

[ Upstream commit d6a49e8c4ca4d399ed65ac219585187fc8c2e2b1 ] Fix this by initializing rc to 0 as cache_refresh_path() would not set it in case of success. Reported-by: kernel test robot Link: https://lore.kernel.org/all/202301190004.bEHvbKG6-lkp@intel.com/ Signed-off-by: Paulo Alcantara (SUSE) Signed-off-by: Steve French Signed-off-by: Sasha Levin

cifs: fix potential deadlock in cache_refresh_path()

2023-02-01T07:27:13+00:00

[ Upstream commit 9fb0db40513e27537fde63287aea920b60557a69 ] Avoid getting DFS referral from an exclusive lock in cache_refresh_path() because the tcon IPC used for getting the referral could be disconnected and thus causing a deadlock as shown below: task A task B ====== ====== cifs_demultiplex_thread() dfs_cache_find() cifs_handle_standard() cache_refresh_path() reconnect_dfs_server() down_write() dfs_cache_noreq_find() get_dfs_referral() down_read() <- deadlock smb2_get_dfs_refer() SMB2_ioctl() cifs_send_recv() compound_send_recv() wait_for_response() where task A cannot wake up task B because it is blocked on down_read() due to the exclusive lock held in cache_refresh_path() and therefore not being able to make progress. Fixes: c9f711039905 ("cifs: keep referral server sessions alive") Reviewed-by: Aurélien Aptel Signed-off-by: Paulo Alcantara (SUSE) Signed-off-by: Steve French Signed-off-by: Sasha Levin

cifs: support nested dfs links over reconnect

2022-12-02T16:40:59+00:00

[ Upstream commit c88f7dcd6d6429197fc2fd87b54a894ffcd48e8e ] Mounting a dfs link that has nested links was already supported at mount(2), so make it work over reconnect as well. Make the following case work: * mount //root/dfs/link /mnt -o ... - final share: /server/share * in server settings - change target folder of /root/dfs/link3 to /server/share2 - change target folder of /root/dfs/link2 to /root/dfs/link3 - change target folder of /root/dfs/link to /root/dfs/link2 * mount -o remount,... /mnt - refresh all dfs referrals - mark current connection for failover - cifs_reconnect() reconnects to root server - tree_connect() * checks that /root/dfs/link2 is a link, then chase it * checks that root/dfs/link3 is a link, then chase it * finally tree connect to /server/share2 If the mounted share is no longer accessible and a reconnect had been triggered, the client will retry it from both last referral path (/root/dfs/link3) and original referral path (/root/dfs/link). Any new referral paths found while chasing dfs links over reconnect, it will be updated to TCP_Server_Info::leaf_fullpath, accordingly. Signed-off-by: Paulo Alcantara (SUSE) Signed-off-by: Steve French Stable-dep-of: 1dcdf5f5b213 ("cifs: Fix connections leak when tlink setup failed") Signed-off-by: Sasha Levin

cifs: support share failover when remounting

2021-07-22T16:43:23+00:00

When remouting a DFS share, force a new DFS referral of the path and if the currently cached targets do not match any of the new targets or there was no cached targets, then mark it for reconnect. For example: $ mount //dom/dfs/link /mnt -o username=foo,password=bar $ ls /mnt oldfile.txt change target share of 'link' in server settings $ mount /mnt -o remount,username=foo,password=bar $ ls /mnt newfile.txt Signed-off-by: Paulo Alcantara (SUSE) Signed-off-by: Steve French

cifs: fix check of dfs interlinks

2021-06-21T02:28:17+00:00

Interlink is a special type of DFS link that resolves to a different DFS domain-based namespace. To determine whether it is an interlink or not, check if ReferralServers and StorageServers bits are set to 1 and 0 respectively in ReferralHeaderFlags, as specified in MS-DFSC 3.1.5.4.5 Determining Whether a Referral Response is an Interlink. Signed-off-by: Paulo Alcantara (SUSE) Reviewed-by: Aurelien Aptel Signed-off-by: Steve French

cifs: avoid starvation when refreshing dfs cache

2021-06-21T02:28:17+00:00

When refreshing the DFS cache, keep SMB2 IOCTL calls as much outside critical sections as possible and avoid read/write starvation when getting new DFS referrals by using broken or slow connections. Signed-off-by: Paulo Alcantara (SUSE) Reviewed-by: Aurelien Aptel Signed-off-by: Steve French

cifs: set a minimum of 2 minutes for refreshing dfs cache

2021-06-21T02:28:17+00:00

We don't want to refresh the dfs cache in very short intervals, so setting a minimum interval of 2 minutes is OK. If it needs to be refreshed immediately, one could have the cache cleared with $ echo 0 > /proc/fs/cifs/dfscache and then remounting the dfs share. Signed-off-by: Paulo Alcantara (SUSE) Reviewed-by: Aurelien Aptel Signed-off-by: Steve French

cifs: fix path comparison and hash calc

2021-06-21T02:28:17+00:00

Fix cache lookup and hash calculations when handling paths with different cases. Signed-off-by: Paulo Alcantara (SUSE) Reviewed-by: Aurelien Aptel Signed-off-by: Steve French

cifs: handle different charsets in dfs cache

2021-06-21T02:28:16+00:00

Convert all dfs paths to dfs cache's local codepage (@cache_cp) and avoid mixing them with different charsets. Signed-off-by: Paulo Alcantara (SUSE) Reviewed-by: Aurelien Aptel Signed-off-by: Steve French