[RFC PATCH 23/36] cifs: Clean up mid->callback_data and kill off mid->creator
From: David Howells
Date: Tue May 19 2026 - 06:33:52 EST
We shouldn't really be pinning a task_struct on the mid_q_struct. Better
to provide a wait queue there and have the waiter wait on it. For
synchronous operations, this allows them to remove themselves from it once
this is absorbed into smb_message and smb_message is generated higher up
the stack. This also gets rid of one of the uses of mid->callback_data.
We can also get rid of the need for callback_data for the Echo command
callback by passing a server pointer down into ->callback() from the
callers (all of which have it available). This can also be used in the
Read and Write callbacks.
We then only need the callback_data for the Read and Write commands - and
in both cases, it points to a cifs_io_subrequest struct. So replace
callback_data with a specifically typed pointer in a union that other users
can be added to as the need arises.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Steve French <sfrench@xxxxxxxxx>
cc: Paulo Alcantara <pc@xxxxxxxxxxxxx>
cc: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
cc: Tom Talpey <tom@xxxxxxxxxx>
cc: linux-cifs@xxxxxxxxxxxxxxx
cc: netfs@xxxxxxxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx
---
fs/smb/client/cifs_debug.c | 3 +--
fs/smb/client/cifsglob.h | 11 ++++++++---
fs/smb/client/cifssmb.c | 7 ++-----
fs/smb/client/smb1debug.c | 7 ++++---
fs/smb/client/smb2ops.c | 5 +++--
fs/smb/client/smb2pdu.c | 9 ++++-----
fs/smb/client/smb2transport.c | 6 ------
fs/smb/client/transport.c | 7 +++----
8 files changed, 25 insertions(+), 30 deletions(-)
diff --git a/fs/smb/client/cifs_debug.c b/fs/smb/client/cifs_debug.c
index 47dadab67440..0e3e790bbdbc 100644
--- a/fs/smb/client/cifs_debug.c
+++ b/fs/smb/client/cifs_debug.c
@@ -659,11 +659,10 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
chan_server->conn_id);
spin_lock(&chan_server->mid_queue_lock);
list_for_each_entry(smb, &chan_server->pending_mid_q, qhead) {
- seq_printf(m, "\n\t\tState: %d com: %d pid: %d cbdata: %p mid %llu",
+ seq_printf(m, "\n\t\tState: %d com: %d pid: %d mid %llu",
smb->mid_state,
le16_to_cpu(smb->command),
smb->pid,
- smb->callback_data,
smb->mid);
}
spin_unlock(&chan_server->mid_queue_lock);
diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 6b90f17ae0fa..3a2f684cede9 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -1636,7 +1636,8 @@ static inline void cifs_stats_bytes_read(struct cifs_tcon *tcon,
* - it will be called by cifsd, with no locks held
* - the mid will be removed from any lists
*/
-typedef void (*mid_callback_t)(struct TCP_Server_Info *srv, struct smb_message *smb);
+typedef void (*mid_callback_t)(struct TCP_Server_Info *server,
+ struct smb_message *smb);
/*
* Definition of an SMB request message to be transmitted. These may be
@@ -1668,12 +1669,18 @@ struct smb_message {
struct smb_message *next; /* Next message in compound */
struct cifs_credits credits; /* Credit requirements for this message */
void *request; /* Pointer to request message body */
+ wait_queue_head_t waitq; /* Wait queue for message events */
refcount_t ref;
unsigned int debug_id; /* Debugging ID for tracing */
bool sensitive; /* Request contains sensitive data */
bool cancelled; /* T if cancelled */
unsigned int sr_flags; /* Flags passed to send_recv() */
+ /* PDU-type specific data */
+ union {
+ struct cifs_io_subrequest *subreq; /* Read/write subrequest */
+ };
+
/* Queue state */
struct list_head qhead; /* mids waiting on reply from this server */
__u64 mid; /* multiplex id */
@@ -1687,8 +1694,6 @@ struct smb_message {
unsigned long when_received; /* when demux complete (taken off wire) */
#endif
mid_callback_t callback; /* call completion callback */
- void *callback_data; /* general purpose pointer for callback */
- struct task_struct *creator;
int mid_state; /* wish this were enum but can not pass to wait_event */
int mid_rc; /* rc for MID_RC */
unsigned int optype; /* operation type */
diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
index ca6410e1f39e..e36828359f67 100644
--- a/fs/smb/client/cifssmb.c
+++ b/fs/smb/client/cifssmb.c
@@ -737,7 +737,6 @@ CIFSSMBEcho(struct TCP_Server_Info *server)
smb->request = req;
smb->total_len = in_len;
smb->callback = cifs_echo_callback;
- smb->callback_data = server;
rc = cifs_call_async(server, smb, CIFS_NON_BLOCKING | CIFS_ECHO_OP, NULL);
if (rc)
@@ -1428,7 +1427,7 @@ CIFS_open(const unsigned int xid, struct cifs_open_parms *oparms, int *oplock,
static void
cifs_readv_callback(struct TCP_Server_Info *server, struct smb_message *smb)
{
- struct cifs_io_subrequest *rdata = smb->callback_data;
+ struct cifs_io_subrequest *rdata = smb->subreq;
struct netfs_inode *ictx = netfs_inode(rdata->rreq->inode);
struct cifs_tcon *tcon = tlink_tcon(rdata->req->cfile->tlink);
struct inode *inode = &ictx->inode;
@@ -1595,7 +1594,6 @@ cifs_async_readv(struct cifs_io_subrequest *rdata)
smb->request = req;
smb->total_len = in_len;
smb->callback = cifs_readv_callback;
- smb->callback_data = rdata;
smb->copy_to_bufs = true;
iov_iter_bvec_queue(&smb->response_iter, ITER_DEST,
@@ -1860,7 +1858,7 @@ CIFSSMBWrite(const unsigned int xid, struct cifs_io_parms *io_parms,
static void
cifs_writev_callback(struct TCP_Server_Info *server, struct smb_message *smb)
{
- struct cifs_io_subrequest *wdata = smb->callback_data;
+ struct cifs_io_subrequest *wdata = smb->subreq;
struct cifs_tcon *tcon = tlink_tcon(wdata->req->cfile->tlink);
WRITE_RSP *rsp = (WRITE_RSP *)smb->response;
struct cifs_credits credits = {
@@ -1975,7 +1973,6 @@ cifs_async_writev(struct cifs_io_subrequest *wdata)
smb->total_len = in_len + 1;
smb->total_len += wdata->subreq.len;
smb->callback = cifs_writev_callback;
- smb->callback_data = wdata;
iov_iter_bvec_queue(&smb->rqst.rq_iter, ITER_DEST,
wdata->subreq.content.bvecq, wdata->subreq.content.slot,
diff --git a/fs/smb/client/smb1debug.c b/fs/smb/client/smb1debug.c
index 048fe6303bc1..6eb87852bce7 100644
--- a/fs/smb/client/smb1debug.c
+++ b/fs/smb/client/smb1debug.c
@@ -40,11 +40,12 @@ void cifs_dump_mids(struct TCP_Server_Info *server)
.data_offset = smb->resp_data_offset,
};
- cifs_dbg(VFS, "State: %d Cmd: %d Pid: %d Cbdata: %p Mid %llu\n",
+ cifs_dbg(VFS, "State: %d Cmd: %x Pid: %d R=%x[%x] Mid %llu\n",
smb->mid_state,
- le16_to_cpu(smb->command),
+ le32_to_cpu(smb->command),
smb->pid,
- smb->callback_data,
+ smb->subreq ? smb->subreq->rreq->debug_id : 0,
+ smb->subreq ? smb->subreq->subreq.debug_index : 0,
smb->mid);
#ifdef CONFIG_CIFS_STATS2
cifs_dbg(VFS, "IsLarge: %d buf: %p time rcv: %ld now: %ld\n",
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 0aaefe901fbd..b655c0f626f5 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -485,11 +485,12 @@ void smb2_dump_mids(struct TCP_Server_Info *server)
.data_offset = smb->resp_data_offset,
};
- cifs_dbg(VFS, "State: %d Cmd: %d Pid: %d Cbdata: %p Mid %llu\n",
+ cifs_dbg(VFS, "State: %d Cmd: %d Pid: %d R=%x[%x] Mid %llu\n",
smb->mid_state,
smb->command,
smb->pid,
- smb->callback_data,
+ smb->subreq ? smb->subreq->rreq->debug_id : 0,
+ smb->subreq ? smb->subreq->subreq.debug_index : 0,
smb->mid);
#ifdef CONFIG_CIFS_STATS2
cifs_dbg(VFS, "IsLarge: %d buf: %p time rcv: %ld now: %ld\n",
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index 2a234df2fad5..f4ea7256b09d 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -4386,7 +4386,6 @@ SMB2_echo(struct TCP_Server_Info *server)
smb->request = req;
smb->total_len = total_len;
smb->callback = smb2_echo_callback;
- smb->callback_data = server;
req->hdr.CreditRequest = cpu_to_le16(1);
@@ -4629,7 +4628,7 @@ smb2_new_read_req(void **buf, unsigned int *total_len,
static void
smb2_readv_callback(struct TCP_Server_Info *server, struct smb_message *smb)
{
- struct cifs_io_subrequest *rdata = smb->callback_data;
+ struct cifs_io_subrequest *rdata = smb->subreq;
struct netfs_inode *ictx = netfs_inode(rdata->rreq->inode);
struct cifs_tcon *tcon = tlink_tcon(rdata->req->cfile->tlink);
struct smb2_hdr *shdr = smb->response;
@@ -4828,7 +4827,7 @@ smb2_async_readv(struct cifs_io_subrequest *rdata)
smb->request = buf;
smb->total_len = total_len;
smb->callback = smb2_readv_callback;
- smb->callback_data = rdata;
+ smb->subreq = rdata;
smb->copy_to_bufs = true;
iov_iter_bvec_queue(&smb->response_iter, ITER_DEST,
@@ -4981,7 +4980,7 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms,
static void
smb2_writev_callback(struct TCP_Server_Info *server, struct smb_message *smb)
{
- struct cifs_io_subrequest *wdata = smb->callback_data;
+ struct cifs_io_subrequest *wdata = smb->subreq;
struct cifs_tcon *tcon = tlink_tcon(wdata->req->cfile->tlink);
struct smb2_write_rsp *rsp = (struct smb2_write_rsp *)smb->response;
struct cifs_credits credits = {
@@ -5160,7 +5159,7 @@ smb2_async_writev(struct cifs_io_subrequest *wdata)
smb->request = req;
smb->total_len = total_len;
smb->callback = smb2_writev_callback;
- smb->callback_data = wdata;
+ smb->subreq = wdata;
iov_iter_bvec_queue(&smb->rqst.rq_iter, ITER_SOURCE,
wdata->subreq.content.bvecq, wdata->subreq.content.slot,
diff --git a/fs/smb/client/smb2transport.c b/fs/smb/client/smb2transport.c
index 73db90ab8a52..14ee09b33f2c 100644
--- a/fs/smb/client/smb2transport.c
+++ b/fs/smb/client/smb2transport.c
@@ -611,12 +611,6 @@ static void smb2_init_mid(struct smb_message *smb,
smb->credits_consumed = credits > 0 ? credits : 1;
- /*
- * The default is for the mid to be synchronous, so the
- * default callback just wakes up the current task.
- */
- smb->creator = get_task_struct(current);
-
atomic_inc(&mid_count);
trace_smb3_cmd_enter(le32_to_cpu(shdr->Id.SyncId.TreeId),
le64_to_cpu(shdr->SessionId),
diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c
index 0a7b2e7922cf..68536de2c1a0 100644
--- a/fs/smb/client/transport.c
+++ b/fs/smb/client/transport.c
@@ -53,8 +53,8 @@ struct smb_message *smb_message_alloc(enum smb_command_trace cmd, gfp_t gfp)
* callback just wakes up the current task.
*/
smb->callback = cifs_wake_up_task;
- smb->callback_data = current;
smb->mid_state = MID_REQUEST_ALLOCATED;
+ init_waitqueue_head(&smb->waitq);
trace_smb3_message(smb->debug_id, 1, (enum smb_message_trace)cmd);
}
return smb;
@@ -122,7 +122,7 @@ cifs_wake_up_task(struct TCP_Server_Info *server, struct smb_message *smb)
if (smb->mid_state == MID_RESPONSE_RECEIVED)
smb->mid_state = MID_RESPONSE_READY;
smb_see_message(smb, smb_message_trace_see_wake_up_task);
- wake_up_process(smb->callback_data);
+ wake_up_all(&smb->waitq);
}
static void smb_clear_mid(struct TCP_Server_Info *server, struct smb_message *smb)
@@ -199,7 +199,6 @@ static void smb_clear_mid(struct TCP_Server_Info *server, struct smb_message *sm
}
}
#endif
- put_task_struct(smb->creator);
}
static bool discard_message(struct TCP_Server_Info *server, struct smb_message *smb)
@@ -901,7 +900,7 @@ int wait_for_response(struct TCP_Server_Info *server, struct smb_message *smb)
if (smb->sr_flags & CIFS_INTERRUPTIBLE_WAIT)
sleep_state = TASK_INTERRUPTIBLE;
- error = wait_event_state(server->response_q,
+ error = wait_event_state(smb->waitq,
smb->mid_state != MID_REQUEST_SUBMITTED &&
smb->mid_state != MID_RESPONSE_RECEIVED,
(sleep_state | TASK_FREEZABLE_UNSAFE));