[PATCH 6.15 038/187] netfs: Fix copy-to-cache so that it performs collection with ceph+fscache

[PATCH 6.15 038/187] netfs: Fix copy-to-cache so that it performs collection with ceph+fscache

[Greg Kroah-Hartman]

6.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

commit 4c238e30774e3022a505fa54311273add7570f13 upstream.

The netfs copy-to-cache that is used by Ceph with local caching sets up a
new request to write data just read to the cache.  The request is started
and then left to look after itself whilst the app continues.  The request
gets notified by the backing fs upon completion of the async DIO write, but
then tries to wake up the app because NETFS_RREQ_OFFLOAD_COLLECTION isn't
set - but the app isn't waiting there, and so the request just hangs.

Fix this by setting NETFS_RREQ_OFFLOAD_COLLECTION which causes the
notification from the backing filesystem to put the collection onto a work
queue instead.

Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item")
Reported-by: Max Kellermann <max.kellermann@ionos.com>
Link: https://lore.kernel.org/r/CAKPOu+8z_ijTLHdiCYGU_Uk7yYD=shxyGLwfe-L7AV3DhebS3w@mail.gmail.com/
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/20250711151005.2956810-2-dhowells@redhat.com
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: Viacheslav Dubeyko <slava@dubeyko.com>
cc: Alex Markuze <amarkuze@redhat.com>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: netfs@lists.linux.dev
cc: ceph-devel@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/netfs/read_pgpriv2.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/netfs/read_pgpriv2.c b/fs/netfs/read_pgpriv2.c
index 5bbe906a551d..080d2a6a51d9 100644
--- a/fs/netfs/read_pgpriv2.c
+++ b/fs/netfs/read_pgpriv2.c
@@ -110,6 +110,7 @@ static struct netfs_io_request *netfs_pgpriv2_begin_copy_to_cache(
 	if (!creq->io_streams[1].avail)
 		goto cancel_put;
 
+	__set_bit(NETFS_RREQ_OFFLOAD_COLLECTION, &creq->flags);
 	trace_netfs_write(creq, netfs_write_trace_copy_to_cache);
 	netfs_stat(&netfs_n_wh_copy_to_cache);
 	rreq->copy_to_cache = creq;
-- 
2.50.1

[PATCH 6.15 039/187] netfs: Fix race between cache write completion and ALL_QUEUED being set

[Greg Kroah-Hartman]

6.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

commit 89635eae076cd8eaa5cb752f66538c9dc6c9fdc3 upstream.

When netfslib is issuing subrequests, the subrequests start processing
immediately and may complete before we reach the end of the issuing
function.  At the end of the issuing function we set NETFS_RREQ_ALL_QUEUED
to indicate to the collector that we aren't going to issue any more subreqs
and that it can do the final notifications and cleanup.

Now, this isn't a problem if the request is synchronous
(NETFS_RREQ_OFFLOAD_COLLECTION is unset) as the result collection will be
done in-thread and we're guaranteed an opportunity to run the collector.

However, if the request is asynchronous, collection is primarily triggered
by the termination of subrequests queuing it on a workqueue.  Now, a race
can occur here if the app thread sets ALL_QUEUED after the last subrequest
terminates.

This can happen most easily with the copy2cache code (as used by Ceph)
where, in the collection routine of a read request, an asynchronous write
request is spawned to copy data to the cache.  Folios are added to the
write request as they're unlocked, but there may be a delay before
ALL_QUEUED is set as the write subrequests may complete before we get
there.

If all the write subreqs have finished by the ALL_QUEUED point, no further
events happen and the collection never happens, leaving the request
hanging.

Fix this by queuing the collector after setting ALL_QUEUED.  This is a bit
heavy-handed and it may be sufficient to do it only if there are no extant
subreqs.

Also add a tracepoint to cross-reference both requests in a copy-to-request
operation and add a trace to the netfs_rreq tracepoint to indicate the
setting of ALL_QUEUED.

Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item")
Reported-by: Max Kellermann <max.kellermann@ionos.com>
Link: https://lore.kernel.org/r/CAKPOu+8z_ijTLHdiCYGU_Uk7yYD=shxyGLwfe-L7AV3DhebS3w@mail.gmail.com/
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/20250711151005.2956810-3-dhowells@redhat.com
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: Viacheslav Dubeyko <slava@dubeyko.com>
cc: Alex Markuze <amarkuze@redhat.com>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: netfs@lists.linux.dev
cc: ceph-devel@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/netfs/read_pgpriv2.c      |    4 ++++
 include/trace/events/netfs.h |   30 ++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

--- a/fs/netfs/read_pgpriv2.c
+++ b/fs/netfs/read_pgpriv2.c
@@ -111,6 +111,7 @@ static struct netfs_io_request *netfs_pg
 		goto cancel_put;
 
 	__set_bit(NETFS_RREQ_OFFLOAD_COLLECTION, &creq->flags);
+	trace_netfs_copy2cache(rreq, creq);
 	trace_netfs_write(creq, netfs_write_trace_copy_to_cache);
 	netfs_stat(&netfs_n_wh_copy_to_cache);
 	rreq->copy_to_cache = creq;
@@ -155,6 +156,9 @@ void netfs_pgpriv2_end_copy_to_cache(str
 	netfs_issue_write(creq, &creq->io_streams[1]);
 	smp_wmb(); /* Write lists before ALL_QUEUED. */
 	set_bit(NETFS_RREQ_ALL_QUEUED, &creq->flags);
+	trace_netfs_rreq(rreq, netfs_rreq_trace_end_copy_to_cache);
+	if (list_empty_careful(&creq->io_streams[1].subrequests))
+		netfs_wake_collector(creq);
 
 	netfs_put_request(creq, netfs_rreq_trace_put_return);
 	creq->copy_to_cache = NULL;
--- a/include/trace/events/netfs.h
+++ b/include/trace/events/netfs.h
@@ -55,6 +55,7 @@
 	EM(netfs_rreq_trace_complete,		"COMPLET")	\
 	EM(netfs_rreq_trace_dirty,		"DIRTY  ")	\
 	EM(netfs_rreq_trace_done,		"DONE   ")	\
+	EM(netfs_rreq_trace_end_copy_to_cache,	"END-C2C")	\
 	EM(netfs_rreq_trace_free,		"FREE   ")	\
 	EM(netfs_rreq_trace_recollect,		"RECLLCT")	\
 	EM(netfs_rreq_trace_redirty,		"REDIRTY")	\
@@ -550,6 +551,35 @@ TRACE_EVENT(netfs_write,
 		      __entry->start, __entry->start + __entry->len - 1)
 	    );
 
+TRACE_EVENT(netfs_copy2cache,
+	    TP_PROTO(const struct netfs_io_request *rreq,
+		     const struct netfs_io_request *creq),
+
+	    TP_ARGS(rreq, creq),
+
+	    TP_STRUCT__entry(
+		    __field(unsigned int,		rreq)
+		    __field(unsigned int,		creq)
+		    __field(unsigned int,		cookie)
+		    __field(unsigned int,		ino)
+			     ),
+
+	    TP_fast_assign(
+		    struct netfs_inode *__ctx = netfs_inode(rreq->inode);
+		    struct fscache_cookie *__cookie = netfs_i_cookie(__ctx);
+		    __entry->rreq	= rreq->debug_id;
+		    __entry->creq	= creq->debug_id;
+		    __entry->cookie	= __cookie ? __cookie->debug_id : 0;
+		    __entry->ino	= rreq->inode->i_ino;
+			   ),
+
+	    TP_printk("R=%08x CR=%08x c=%08x i=%x ",
+		      __entry->rreq,
+		      __entry->creq,
+		      __entry->cookie,
+		      __entry->ino)
+	    );
+
 TRACE_EVENT(netfs_collect,
 	    TP_PROTO(const struct netfs_io_request *wreq),
 

[PATCH 6.15 181/187] cifs: Fix the smbd_response slab to allow usercopy

[Greg Kroah-Hartman]

6.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

commit 43e7e284fc77b710d899569360ea46fa3374ae22 upstream.

The handling of received data in the smbdirect client code involves using
copy_to_iter() to copy data from the smbd_reponse struct's packet trailer
to a folioq buffer provided by netfslib that encapsulates a chunk of
pagecache.

If, however, CONFIG_HARDENED_USERCOPY=y, this will result in the checks
then performed in copy_to_iter() oopsing with something like the following:

 CIFS: Attempting to mount //172.31.9.1/test
 CIFS: VFS: RDMA transport established
 usercopy: Kernel memory exposure attempt detected from SLUB object 'smbd_response_0000000091e24ea1' (offset 81, size 63)!
 ------------[ cut here ]------------
 kernel BUG at mm/usercopy.c:102!
 ...
 RIP: 0010:usercopy_abort+0x6c/0x80
 ...
 Call Trace:
  <TASK>
  __check_heap_object+0xe3/0x120
  __check_object_size+0x4dc/0x6d0
  smbd_recv+0x77f/0xfe0 [cifs]
  cifs_readv_from_socket+0x276/0x8f0 [cifs]
  cifs_read_from_socket+0xcd/0x120 [cifs]
  cifs_demultiplex_thread+0x7e9/0x2d50 [cifs]
  kthread+0x396/0x830
  ret_from_fork+0x2b8/0x3b0
  ret_from_fork_asm+0x1a/0x30

The problem is that the smbd_response slab's packet field isn't marked as
being permitted for usercopy.

Fix this by passing parameters to kmem_slab_create() to indicate that
copy_to_iter() is permitted from the packet region of the smbd_response
slab objects, less the header space.

Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Reported-by: Stefan Metzmacher <metze@samba.org>
Link: https://lore.kernel.org/r/acb7f612-df26-4e2a-a35d-7cd040f513e1@samba.org/
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Tested-by: Stefan Metzmacher <metze@samba.org>
cc: Paulo Alcantara <pc@manguebit.com>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/smb/client/smbdirect.c |   18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

--- a/fs/smb/client/smbdirect.c
+++ b/fs/smb/client/smbdirect.c
@@ -1452,6 +1452,9 @@ static int allocate_caches_and_workqueue
 	char name[MAX_NAME_LEN];
 	int rc;
 
+	if (WARN_ON_ONCE(sp->max_recv_size < sizeof(struct smbdirect_data_transfer)))
+		return -ENOMEM;
+
 	scnprintf(name, MAX_NAME_LEN, "smbd_request_%p", info);
 	info->request_cache =
 		kmem_cache_create(
@@ -1469,12 +1472,17 @@ static int allocate_caches_and_workqueue
 		goto out1;
 
 	scnprintf(name, MAX_NAME_LEN, "smbd_response_%p", info);
+
+	struct kmem_cache_args response_args = {
+		.align		= __alignof__(struct smbd_response),
+		.useroffset	= (offsetof(struct smbd_response, packet) +
+				   sizeof(struct smbdirect_data_transfer)),
+		.usersize	= sp->max_recv_size - sizeof(struct smbdirect_data_transfer),
+	};
 	info->response_cache =
-		kmem_cache_create(
-			name,
-			sizeof(struct smbd_response) +
-				sp->max_recv_size,
-			0, SLAB_HWCACHE_ALIGN, NULL);
+		kmem_cache_create(name,
+				  sizeof(struct smbd_response) + sp->max_recv_size,
+				  &response_args, SLAB_HWCACHE_ALIGN);
 	if (!info->response_cache)
 		goto out2;
 

[PATCH 6.15 182/187] cifs: Fix reading into an ITER_FOLIOQ from the smbdirect code

[Greg Kroah-Hartman]

6.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

commit 263debecb4aa7cec0a86487e6f409814f6194a21 upstream.

When performing a file read from RDMA, smbd_recv() prints an "Invalid msg
type 4" error and fails the I/O.  This is due to the switch-statement there
not handling the ITER_FOLIOQ handed down from netfslib.

Fix this by collapsing smbd_recv_buf() and smbd_recv_page() into
smbd_recv() and just using copy_to_iter() instead of memcpy().  This
future-proofs the function too, in case more ITER_* types are added.

Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Reported-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Tom Talpey <tom@talpey.com>
cc: Paulo Alcantara (Red Hat) <pc@manguebit.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/smb/client/smbdirect.c |  112 ++++++----------------------------------------
 1 file changed, 17 insertions(+), 95 deletions(-)

--- a/fs/smb/client/smbdirect.c
+++ b/fs/smb/client/smbdirect.c
@@ -1755,35 +1755,39 @@ try_again:
 }
 
 /*
- * Receive data from receive reassembly queue
+ * Receive data from the transport's receive reassembly queue
  * All the incoming data packets are placed in reassembly queue
- * buf: the buffer to read data into
+ * iter: the buffer to read data into
  * size: the length of data to read
  * return value: actual data read
- * Note: this implementation copies the data from reassebmly queue to receive
+ *
+ * Note: this implementation copies the data from reassembly queue to receive
  * buffers used by upper layer. This is not the optimal code path. A better way
  * to do it is to not have upper layer allocate its receive buffers but rather
  * borrow the buffer from reassembly queue, and return it after data is
  * consumed. But this will require more changes to upper layer code, and also
  * need to consider packet boundaries while they still being reassembled.
  */
-static int smbd_recv_buf(struct smbd_connection *info, char *buf,
-		unsigned int size)
+int smbd_recv(struct smbd_connection *info, struct msghdr *msg)
 {
 	struct smbdirect_socket *sc = &info->socket;
 	struct smbd_response *response;
 	struct smbdirect_data_transfer *data_transfer;
+	size_t size = iov_iter_count(&msg->msg_iter);
 	int to_copy, to_read, data_read, offset;
 	u32 data_length, remaining_data_length, data_offset;
 	int rc;
 
+	if (WARN_ON_ONCE(iov_iter_rw(&msg->msg_iter) == WRITE))
+		return -EINVAL; /* It's a bug in upper layer to get there */
+
 again:
 	/*
 	 * No need to hold the reassembly queue lock all the time as we are
 	 * the only one reading from the front of the queue. The transport
 	 * may add more entries to the back of the queue at the same time
 	 */
-	log_read(INFO, "size=%d info->reassembly_data_length=%d\n", size,
+	log_read(INFO, "size=%zd info->reassembly_data_length=%d\n", size,
 		info->reassembly_data_length);
 	if (info->reassembly_data_length >= size) {
 		int queue_length;
@@ -1821,7 +1825,10 @@ again:
 			if (response->first_segment && size == 4) {
 				unsigned int rfc1002_len =
 					data_length + remaining_data_length;
-				*((__be32 *)buf) = cpu_to_be32(rfc1002_len);
+				__be32 rfc1002_hdr = cpu_to_be32(rfc1002_len);
+				if (copy_to_iter(&rfc1002_hdr, sizeof(rfc1002_hdr),
+						 &msg->msg_iter) != sizeof(rfc1002_hdr))
+					return -EFAULT;
 				data_read = 4;
 				response->first_segment = false;
 				log_read(INFO, "returning rfc1002 length %d\n",
@@ -1830,10 +1837,9 @@ again:
 			}
 
 			to_copy = min_t(int, data_length - offset, to_read);
-			memcpy(
-				buf + data_read,
-				(char *)data_transfer + data_offset + offset,
-				to_copy);
+			if (copy_to_iter((char *)data_transfer + data_offset + offset,
+					 to_copy, &msg->msg_iter) != to_copy)
+				return -EFAULT;
 
 			/* move on to the next buffer? */
 			if (to_copy == data_length - offset) {
@@ -1899,90 +1905,6 @@ read_rfc1002_done:
 }
 
 /*
- * Receive a page from receive reassembly queue
- * page: the page to read data into
- * to_read: the length of data to read
- * return value: actual data read
- */
-static int smbd_recv_page(struct smbd_connection *info,
-		struct page *page, unsigned int page_offset,
-		unsigned int to_read)
-{
-	struct smbdirect_socket *sc = &info->socket;
-	int ret;
-	char *to_address;
-	void *page_address;
-
-	/* make sure we have the page ready for read */
-	ret = wait_event_interruptible(
-		info->wait_reassembly_queue,
-		info->reassembly_data_length >= to_read ||
-			sc->status != SMBDIRECT_SOCKET_CONNECTED);
-	if (ret)
-		return ret;
-
-	/* now we can read from reassembly queue and not sleep */
-	page_address = kmap_atomic(page);
-	to_address = (char *) page_address + page_offset;
-
-	log_read(INFO, "reading from page=%p address=%p to_read=%d\n",
-		page, to_address, to_read);
-
-	ret = smbd_recv_buf(info, to_address, to_read);
-	kunmap_atomic(page_address);
-
-	return ret;
-}
-
-/*
- * Receive data from transport
- * msg: a msghdr point to the buffer, can be ITER_KVEC or ITER_BVEC
- * return: total bytes read, or 0. SMB Direct will not do partial read.
- */
-int smbd_recv(struct smbd_connection *info, struct msghdr *msg)
-{
-	char *buf;
-	struct page *page;
-	unsigned int to_read, page_offset;
-	int rc;
-
-	if (iov_iter_rw(&msg->msg_iter) == WRITE) {
-		/* It's a bug in upper layer to get there */
-		cifs_dbg(VFS, "Invalid msg iter dir %u\n",
-			 iov_iter_rw(&msg->msg_iter));
-		rc = -EINVAL;
-		goto out;
-	}
-
-	switch (iov_iter_type(&msg->msg_iter)) {
-	case ITER_KVEC:
-		buf = msg->msg_iter.kvec->iov_base;
-		to_read = msg->msg_iter.kvec->iov_len;
-		rc = smbd_recv_buf(info, buf, to_read);
-		break;
-
-	case ITER_BVEC:
-		page = msg->msg_iter.bvec->bv_page;
-		page_offset = msg->msg_iter.bvec->bv_offset;
-		to_read = msg->msg_iter.bvec->bv_len;
-		rc = smbd_recv_page(info, page, page_offset, to_read);
-		break;
-
-	default:
-		/* It's a bug in upper layer to get there */
-		cifs_dbg(VFS, "Invalid msg type %d\n",
-			 iov_iter_type(&msg->msg_iter));
-		rc = -EINVAL;
-	}
-
-out:
-	/* SMBDirect will read it all or nothing */
-	if (rc > 0)
-		msg->msg_iter.count = 0;
-	return rc;
-}
-
-/*
  * Send data to transport
  * Each rqst is transported as a SMBDirect payload
  * rqst: the data to write