From ee36a3b345c433a846effcdcfba437c2298eeda5 Mon Sep 17 00:00:00 2001 From: Shyam Prasad N Date: Mon, 29 Jan 2024 13:58:13 +0000 Subject: cifs: make sure that channel scaling is done only once Following a successful cifs_tree_connect, we have the code to scale up/down the number of channels in the session. However, it is not protected by a lock today. As a result, this code can be executed by several processes that select the same channel. The core functions handle this well, as they pick chan_lock. However, we've seen cases where smb2_reconnect throws some warnings. To fix that, this change introduces a flags bitmap inside the cifs_ses structure. A new flag type is used to ensure that only one process enters this section at any time. Signed-off-by: Shyam Prasad N Signed-off-by: Steve French --- fs/smb/client/cifsglob.h | 3 +++ fs/smb/client/smb2pdu.c | 20 +++++++++++++++++--- 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h index 16befff4cbb4..9093c507042f 100644 --- a/fs/smb/client/cifsglob.h +++ b/fs/smb/client/cifsglob.h @@ -1032,6 +1032,8 @@ struct cifs_chan { __u8 signkey[SMB3_SIGN_KEY_SIZE]; }; +#define CIFS_SES_FLAG_SCALE_CHANNELS (0x1) + /* * Session structure. One of these for each uid session with a particular host */ @@ -1064,6 +1066,7 @@ struct cifs_ses { enum securityEnum sectype; /* what security flavor was specified? */ bool sign; /* is signing required? */ bool domainAuto:1; + unsigned int flags; __u16 session_flags; __u8 smb3signingkey[SMB3_SIGN_KEY_SIZE]; __u8 smb3encryptionkey[SMB3_ENC_DEC_KEY_SIZE]; diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c index 86f6f35b7f32..6db54c6ef571 100644 --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -399,6 +399,15 @@ skip_sess_setup: goto out; } + spin_lock(&ses->ses_lock); + if (ses->flags & CIFS_SES_FLAG_SCALE_CHANNELS) { + spin_unlock(&ses->ses_lock); + mutex_unlock(&ses->session_mutex); + goto skip_add_channels; + } + ses->flags |= CIFS_SES_FLAG_SCALE_CHANNELS; + spin_unlock(&ses->ses_lock); + if (!rc && (server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) { mutex_unlock(&ses->session_mutex); @@ -428,17 +437,22 @@ skip_sess_setup: if (ses->chan_max > ses->chan_count && ses->iface_count && !SERVER_IS_CHAN(server)) { - if (ses->chan_count == 1) + if (ses->chan_count == 1) { cifs_server_dbg(VFS, "supports multichannel now\n"); + queue_delayed_work(cifsiod_wq, &tcon->query_interfaces, + (SMB_INTERFACE_POLL_INTERVAL * HZ)); + } cifs_try_adding_channels(ses); - queue_delayed_work(cifsiod_wq, &tcon->query_interfaces, - (SMB_INTERFACE_POLL_INTERVAL * HZ)); } } else { mutex_unlock(&ses->session_mutex); } + skip_add_channels: + spin_lock(&ses->ses_lock); + ses->flags &= ~CIFS_SES_FLAG_SCALE_CHANNELS; + spin_unlock(&ses->ses_lock); if (smb2_command != SMB2_INTERNAL_CMD) mod_delayed_work(cifsiod_wq, &server->reconnect, 0); -- cgit v1.2.3 From e77e15fa5eb1c830597c5ca53ea7af973bae2f78 Mon Sep 17 00:00:00 2001 From: Shyam Prasad N Date: Thu, 1 Feb 2024 11:15:26 +0000 Subject: cifs: avoid redundant calls to disable multichannel When the server reports query network interface info call as unsupported following a tree connect, it means that multichannel is unsupported, even if the server capabilities report otherwise. When this happens, cifs_chan_skip_or_disable is called to disable multichannel on the client. However, we only need to call this when multichannel is currently setup. Fixes: f591062bdbf4 ("cifs: handle servers that still advertise multichannel after disabling") Signed-off-by: Shyam Prasad N Signed-off-by: Steve French --- fs/smb/client/smb2pdu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c index 6db54c6ef571..e257b10bc820 100644 --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -419,7 +419,7 @@ skip_sess_setup: rc = SMB3_request_interfaces(xid, tcon, false); free_xid(xid); - if (rc == -EOPNOTSUPP) { + if (rc == -EOPNOTSUPP && ses->chan_count > 1) { /* * some servers like Azure SMB server do not advertise * that multichannel has been disabled with server -- cgit v1.2.3 From 88675b22d34e6e815ad4bde09c590ccb2d50c59d Mon Sep 17 00:00:00 2001 From: Shyam Prasad N Date: Thu, 1 Feb 2024 11:15:28 +0000 Subject: cifs: do not search for channel if server is terminating In order to scale down the channels, the following sequence of operations happen: 1. server struct is marked for terminate 2. the channel is deallocated in the ses->chans array 3. at a later point the cifsd thread actually terminates the server Between 2 and 3, there can be calls to find the channel for a server struct. When that happens, there can be an ugly warning that's logged. But this is expected. So this change does two things: 1. in cifs_ses_get_chan_index, if server->terminate is set, return 2. always make sure server->terminate is set with chan_lock held Signed-off-by: Shyam Prasad N Signed-off-by: Steve French --- fs/smb/client/sess.c | 4 ++++ fs/smb/client/smb2pdu.c | 2 +- 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/smb/client/sess.c b/fs/smb/client/sess.c index cde81042bebd..3d2548c35c9d 100644 --- a/fs/smb/client/sess.c +++ b/fs/smb/client/sess.c @@ -75,6 +75,10 @@ cifs_ses_get_chan_index(struct cifs_ses *ses, { unsigned int i; + /* if the channel is waiting for termination */ + if (server->terminate) + return CIFS_INVAL_CHAN_INDEX; + for (i = 0; i < ses->chan_count; i++) { if (ses->chans[i].server == server) return i; diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c index e257b10bc820..c58fa44dd6b0 100644 --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -178,6 +178,7 @@ cifs_chan_skip_or_disable(struct cifs_ses *ses, } ses->chans[chan_index].server = NULL; + server->terminate = true; spin_unlock(&ses->chan_lock); /* @@ -188,7 +189,6 @@ cifs_chan_skip_or_disable(struct cifs_ses *ses, */ cifs_put_tcp_session(server, from_reconnect); - server->terminate = true; cifs_signal_cifsd_for_reconnect(server, false); /* mark primary server as needing reconnect */ -- cgit v1.2.3 From 6aac002bcfd554aff6d3ebb55e1660d078d70ab0 Mon Sep 17 00:00:00 2001 From: Shyam Prasad N Date: Thu, 1 Feb 2024 11:15:29 +0000 Subject: cifs: failure to add channel on iface should bump up weight After the interface selection policy change to do a weighted round robin, each iface maintains a weight_fulfilled. When the weight_fulfilled reaches the total weight for the iface, we know that the weights can be reset and ifaces can be allocated from scratch again. During channel allocation failures on a particular channel, weight_fulfilled is not incremented. If a few interfaces are inactive, we could end up in a situation where the active interfaces are all allocated for the total_weight, and inactive ones are all that remain. This can cause a situation where no more channels can be allocated further. This change fixes it by increasing weight_fulfilled, even when channel allocation failure happens. This could mean that if there are temporary failures in channel allocation, the iface weights may not strictly be adhered to. But that's still okay. Fixes: a6d8fb54a515 ("cifs: distribute channels across interfaces based on speed") Signed-off-by: Shyam Prasad N Signed-off-by: Steve French --- fs/smb/client/sess.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/smb/client/sess.c b/fs/smb/client/sess.c index 3d2548c35c9d..ed4bd88dd528 100644 --- a/fs/smb/client/sess.c +++ b/fs/smb/client/sess.c @@ -273,6 +273,8 @@ int cifs_try_adding_channels(struct cifs_ses *ses) &iface->sockaddr, rc); kref_put(&iface->refcount, release_iface); + /* failure to add chan should increase weight */ + iface->weight_fulfilled++; continue; } -- cgit v1.2.3 From 11d4d1dba3315f73d2d1d386f5bf4811a8241d45 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Mon, 29 Jan 2024 21:04:44 -0300 Subject: smb: client: increase number of PDUs allowed in a compound request With the introduction of SMB2_OP_QUERY_WSL_EA, the client may now send 5 commands in a single compound request in order to query xattrs from potential WSL reparse points, which should be fine as we currently allow up to 5 PDUs in a single compound request. However, if encryption is enabled (e.g. 'seal' mount option) or enforced by the server, current MAX_COMPOUND(5) won't be enough as we require an extra PDU for the transform header. Fix this by increasing MAX_COMPOUND to 7 and, while we're at it, add an WARN_ON_ONCE() and return -EIO instead of -ENOMEM in case we attempt to send a compound request that couldn't include the extra transform header. Signed-off-by: Paulo Alcantara Signed-off-by: Steve French --- fs/smb/client/cifsglob.h | 2 +- fs/smb/client/transport.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h index 9093c507042f..c86a72c9d9ec 100644 --- a/fs/smb/client/cifsglob.h +++ b/fs/smb/client/cifsglob.h @@ -87,7 +87,7 @@ #define SMB_INTERFACE_POLL_INTERVAL 600 /* maximum number of PDUs in one compound */ -#define MAX_COMPOUND 5 +#define MAX_COMPOUND 7 /* * Default number of credits to keep available for SMB3. diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c index e00278fcfa4f..994d70193432 100644 --- a/fs/smb/client/transport.c +++ b/fs/smb/client/transport.c @@ -435,8 +435,8 @@ smb_send_rqst(struct TCP_Server_Info *server, int num_rqst, if (!(flags & CIFS_TRANSFORM_REQ)) return __smb_send_rqst(server, num_rqst, rqst); - if (num_rqst > MAX_COMPOUND - 1) - return -ENOMEM; + if (WARN_ON_ONCE(num_rqst > MAX_COMPOUND - 1)) + return -EIO; if (!server->ops->init_transform_rq) { cifs_server_dbg(VFS, "Encryption requested but transform callback is missing\n"); -- cgit v1.2.3