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From: David Howells <dhowells@redhat.com>
To: Christian Brauner <christian@brauner.io>,
	Jeff Layton <jlayton@kernel.org>,
	Gao Xiang <hsiangkao@linux.alibaba.com>,
	Dominique Martinet <asmadeus@codewreck.org>
Cc: David Howells <dhowells@redhat.com>,
	Matthew Wilcox <willy@infradead.org>,
	Steve French <smfrench@gmail.com>,
	Marc Dionne <marc.dionne@auristor.com>,
	Paulo Alcantara <pc@manguebit.com>,
	Shyam Prasad N <sprasad@microsoft.com>,
	Tom Talpey <tom@talpey.com>,
	Eric Van Hensbergen <ericvh@kernel.org>,
	Ilya Dryomov <idryomov@gmail.com>,
	netfs@lists.linux.dev,
	linux-cachefs@redhat.com,
	linux-afs@lists.infradead.org,
	linux-cifs@vger.kernel.org,
	linux-nfs@vger.kernel.org,
	ceph-devel@vger.kernel.org,
	v9fs@lists.linux.dev,
	linux-erofs@lists.ozlabs.org,
	linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org,
	netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v2 22/22] netfs, afs: Use writeback retry to deal with alternate keys
Date: Tue, 30 Apr 2024 15:00:53 +0100
Message-ID: <20240430140056.261997-23-dhowells@redhat.com>
In-Reply-To: <20240430140056.261997-1-dhowells@redhat.com>
References: <20240430140056.261997-1-dhowells@redhat.com>
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Use a hook in the new writeback code's retry algorithm to rotate the keys
once all the outstanding subreqs have failed rather than doing it
separately on each subreq.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
---

Notes:
    Changes
    =======
    ver #2)
     - Change a comma ending a statement to a semicolon.

 fs/afs/file.c            |   1 +
 fs/afs/internal.h        |   1 +
 fs/afs/write.c           | 191 +++++++++++++++++++--------------------
 fs/netfs/write_collect.c |   9 +-
 include/linux/netfs.h    |   2 +
 5 files changed, 104 insertions(+), 100 deletions(-)

diff --git a/fs/afs/file.c b/fs/afs/file.c
index 8f983e3ecae7..c3f0c45ae9a9 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -368,6 +368,7 @@ static int afs_check_write_begin(struct file *file, loff_t pos, unsigned len,
 static void afs_free_request(struct netfs_io_request *rreq)
 {
 	key_put(rreq->netfs_priv);
+	afs_put_wb_key(rreq->netfs_priv2);
 }
 
 static void afs_update_i_size(struct inode *inode, loff_t new_i_size)
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 887245f9336d..6e1d3c4daf72 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -1601,6 +1601,7 @@ extern int afs_check_volume_status(struct afs_volume *, struct afs_operation *);
 void afs_prepare_write(struct netfs_io_subrequest *subreq);
 void afs_issue_write(struct netfs_io_subrequest *subreq);
 void afs_begin_writeback(struct netfs_io_request *wreq);
+void afs_retry_request(struct netfs_io_request *wreq, struct netfs_io_stream *stream);
 extern int afs_writepages(struct address_space *, struct writeback_control *);
 extern int afs_fsync(struct file *, loff_t, loff_t, int);
 extern vm_fault_t afs_page_mkwrite(struct vm_fault *vmf);
diff --git a/fs/afs/write.c b/fs/afs/write.c
index b8505a8b622a..e959640694c2 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -29,43 +29,39 @@ static void afs_pages_written_back(struct afs_vnode *vnode, loff_t start, unsign
 
 /*
  * Find a key to use for the writeback.  We cached the keys used to author the
- * writes on the vnode.  *_wbk will contain the last writeback key used or NULL
- * and we need to start from there if it's set.
+ * writes on the vnode.  wreq->netfs_priv2 will contain the last writeback key
+ * record used or NULL and we need to start from there if it's set.
+ * wreq->netfs_priv will be set to the key itself or NULL.
  */
-static int afs_get_writeback_key(struct afs_vnode *vnode,
-				 struct afs_wb_key **_wbk)
+static void afs_get_writeback_key(struct netfs_io_request *wreq)
 {
-	struct afs_wb_key *wbk = NULL;
-	struct list_head *p;
-	int ret = -ENOKEY, ret2;
+	struct afs_wb_key *wbk, *old = wreq->netfs_priv2;
+	struct afs_vnode *vnode = AFS_FS_I(wreq->inode);
+
+	key_put(wreq->netfs_priv);
+	wreq->netfs_priv = NULL;
+	wreq->netfs_priv2 = NULL;
 
 	spin_lock(&vnode->wb_lock);
-	if (*_wbk)
-		p = (*_wbk)->vnode_link.next;
+	if (old)
+		wbk = list_next_entry(old, vnode_link);
 	else
-		p = vnode->wb_keys.next;
+		wbk = list_first_entry(&vnode->wb_keys, struct afs_wb_key, vnode_link);
 
-	while (p != &vnode->wb_keys) {
-		wbk = list_entry(p, struct afs_wb_key, vnode_link);
+	list_for_each_entry_from(wbk, &vnode->wb_keys, vnode_link) {
 		_debug("wbk %u", key_serial(wbk->key));
-		ret2 = key_validate(wbk->key);
-		if (ret2 == 0) {
+		if (key_validate(wbk->key) == 0) {
 			refcount_inc(&wbk->usage);
+			wreq->netfs_priv = key_get(wbk->key);
+			wreq->netfs_priv2 = wbk;
 			_debug("USE WB KEY %u", key_serial(wbk->key));
 			break;
 		}
-
-		wbk = NULL;
-		if (ret == -ENOKEY)
-			ret = ret2;
-		p = p->next;
 	}
 
 	spin_unlock(&vnode->wb_lock);
-	if (*_wbk)
-		afs_put_wb_key(*_wbk);
-	*_wbk = wbk;
-	return 0;
+
+	afs_put_wb_key(old);
 }
 
 static void afs_store_data_success(struct afs_operation *op)
@@ -88,72 +84,91 @@ static const struct afs_operation_ops afs_store_data_operation = {
 };
 
 /*
- * write to a file
+ * Prepare a subrequest to write to the server.  This sets the max_len
+ * parameter.
  */
-static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t pos)
+void afs_prepare_write(struct netfs_io_subrequest *subreq)
 {
+	//if (test_bit(NETFS_SREQ_RETRYING, &subreq->flags))
+	//	subreq->max_len = 512 * 1024;
+	//else
+	subreq->max_len = 256 * 1024 * 1024;
+}
+
+/*
+ * Issue a subrequest to write to the server.
+ */
+static void afs_issue_write_worker(struct work_struct *work)
+{
+	struct netfs_io_subrequest *subreq = container_of(work, struct netfs_io_subrequest, work);
+	struct netfs_io_request *wreq = subreq->rreq;
 	struct afs_operation *op;
-	struct afs_wb_key *wbk = NULL;
-	loff_t size = iov_iter_count(iter);
+	struct afs_vnode *vnode = AFS_FS_I(wreq->inode);
+	unsigned long long pos = subreq->start + subreq->transferred;
+	size_t len = subreq->len - subreq->transferred;
 	int ret = -ENOKEY;
 
-	_enter("%s{%llx:%llu.%u},%llx,%llx",
+	_enter("R=%x[%x],%s{%llx:%llu.%u},%llx,%zx",
+	       wreq->debug_id, subreq->debug_index,
 	       vnode->volume->name,
 	       vnode->fid.vid,
 	       vnode->fid.vnode,
 	       vnode->fid.unique,
-	       size, pos);
+	       pos, len);
 
-	ret = afs_get_writeback_key(vnode, &wbk);
-	if (ret) {
-		_leave(" = %d [no keys]", ret);
-		return ret;
-	}
+#if 0 // Error injection
+	if (subreq->debug_index == 3)
+		return netfs_write_subrequest_terminated(subreq, -ENOANO, false);
 
-	op = afs_alloc_operation(wbk->key, vnode->volume);
-	if (IS_ERR(op)) {
-		afs_put_wb_key(wbk);
-		return -ENOMEM;
+	if (!test_bit(NETFS_SREQ_RETRYING, &subreq->flags)) {
+		set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
+		return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);
 	}
+#endif
+
+	op = afs_alloc_operation(wreq->netfs_priv, vnode->volume);
+	if (IS_ERR(op))
+		return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);
 
 	afs_op_set_vnode(op, 0, vnode);
-	op->file[0].dv_delta = 1;
+	op->file[0].dv_delta	= 1;
 	op->file[0].modification = true;
-	op->store.pos = pos;
-	op->store.size = size;
-	op->flags |= AFS_OPERATION_UNINTR;
-	op->ops = &afs_store_data_operation;
+	op->store.pos		= pos;
+	op->store.size		= len;
+	op->flags		|= AFS_OPERATION_UNINTR;
+	op->ops			= &afs_store_data_operation;
 
-try_next_key:
 	afs_begin_vnode_operation(op);
 
-	op->store.write_iter = iter;
-	op->store.i_size = max(pos + size, vnode->netfs.remote_i_size);
-	op->mtime = inode_get_mtime(&vnode->netfs.inode);
+	op->store.write_iter	= &subreq->io_iter;
+	op->store.i_size	= umax(pos + len, vnode->netfs.remote_i_size);
+	op->mtime		= inode_get_mtime(&vnode->netfs.inode);
 
 	afs_wait_for_operation(op);
-
-	switch (afs_op_error(op)) {
+	ret = afs_put_operation(op);
+	switch (ret) {
 	case -EACCES:
 	case -EPERM:
 	case -ENOKEY:
 	case -EKEYEXPIRED:
 	case -EKEYREJECTED:
 	case -EKEYREVOKED:
-		_debug("next");
-
-		ret = afs_get_writeback_key(vnode, &wbk);
-		if (ret == 0) {
-			key_put(op->key);
-			op->key = key_get(wbk->key);
-			goto try_next_key;
-		}
+		/* If there are more keys we can try, use the retry algorithm
+		 * to rotate the keys.
+		 */
+		if (wreq->netfs_priv2)
+			set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
 		break;
 	}
 
-	afs_put_wb_key(wbk);
-	_leave(" = %d", afs_op_error(op));
-	return afs_put_operation(op);
+	netfs_write_subrequest_terminated(subreq, ret < 0 ? ret : subreq->len, false);
+}
+
+void afs_issue_write(struct netfs_io_subrequest *subreq)
+{
+	subreq->work.func = afs_issue_write_worker;
+	if (!queue_work(system_unbound_wq, &subreq->work))
+		WARN_ON_ONCE(1);
 }
 
 /*
@@ -162,52 +177,32 @@ static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t
  */
 void afs_begin_writeback(struct netfs_io_request *wreq)
 {
+	afs_get_writeback_key(wreq);
 	wreq->io_streams[0].avail = true;
 }
 
 /*
- * Prepare a subrequest to write to the server.  This sets the max_len
- * parameter.
- */
-void afs_prepare_write(struct netfs_io_subrequest *subreq)
-{
-	//if (test_bit(NETFS_SREQ_RETRYING, &subreq->flags))
-	//	subreq->max_len = 512 * 1024;
-	//else
-	subreq->max_len = 256 * 1024 * 1024;
-}
-
-/*
- * Issue a subrequest to write to the server.
+ * Prepare to retry the writes in request.  Use this to try rotating the
+ * available writeback keys.
  */
-static void afs_issue_write_worker(struct work_struct *work)
+void afs_retry_request(struct netfs_io_request *wreq, struct netfs_io_stream *stream)
 {
-	struct netfs_io_subrequest *subreq = container_of(work, struct netfs_io_subrequest, work);
-	struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode);
-	ssize_t ret;
-
-	_enter("%x[%x],%zx",
-	       subreq->rreq->debug_id, subreq->debug_index, subreq->io_iter.count);
-
-#if 0 // Error injection
-	if (subreq->debug_index == 3)
-		return netfs_write_subrequest_terminated(subreq, -ENOANO, false);
+	struct netfs_io_subrequest *subreq =
+		list_first_entry(&stream->subrequests,
+				 struct netfs_io_subrequest, rreq_link);
 
-	if (!test_bit(NETFS_SREQ_RETRYING, &subreq->flags)) {
-		set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
-		return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);
+	switch (subreq->error) {
+	case -EACCES:
+	case -EPERM:
+	case -ENOKEY:
+	case -EKEYEXPIRED:
+	case -EKEYREJECTED:
+	case -EKEYREVOKED:
+		afs_get_writeback_key(wreq);
+		if (!wreq->netfs_priv)
+			stream->failed = true;
+		break;
 	}
-#endif
-
-	ret = afs_store_data(vnode, &subreq->io_iter, subreq->start);
-	netfs_write_subrequest_terminated(subreq, ret < 0 ? ret : subreq->len, false);
-}
-
-void afs_issue_write(struct netfs_io_subrequest *subreq)
-{
-	subreq->work.func = afs_issue_write_worker;
-	if (!queue_work(system_unbound_wq, &subreq->work))
-		WARN_ON_ONCE(1);
 }
 
 /*
diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c
index f14c08bf605d..60112e4b2c5e 100644
--- a/fs/netfs/write_collect.c
+++ b/fs/netfs/write_collect.c
@@ -163,6 +163,13 @@ static void netfs_retry_write_stream(struct netfs_io_request *wreq,
 
 	_enter("R=%x[%x:]", wreq->debug_id, stream->stream_nr);
 
+	if (list_empty(&stream->subrequests))
+		return;
+
+	if (stream->source == NETFS_UPLOAD_TO_SERVER &&
+	    wreq->netfs_ops->retry_request)
+		wreq->netfs_ops->retry_request(wreq, stream);
+
 	if (unlikely(stream->failed))
 		return;
 
@@ -182,8 +189,6 @@ static void netfs_retry_write_stream(struct netfs_io_request *wreq,
 		return;
 	}
 
-	if (list_empty(&stream->subrequests))
-		return;
 	next = stream->subrequests.next;
 
 	do {
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index c2ba364041b0..298552f5122c 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -235,6 +235,7 @@ struct netfs_io_request {
 	struct iov_iter		iter;		/* Unencrypted-side iterator */
 	struct iov_iter		io_iter;	/* I/O (Encrypted-side) iterator */
 	void			*netfs_priv;	/* Private data for the netfs */
+	void			*netfs_priv2;	/* Private data for the netfs */
 	struct bio_vec		*direct_bv;	/* DIO buffer list (when handling iovec-iter) */
 	unsigned int		direct_bv_count; /* Number of elements in direct_bv[] */
 	unsigned int		debug_id;
@@ -306,6 +307,7 @@ struct netfs_request_ops {
 	void (*begin_writeback)(struct netfs_io_request *wreq);
 	void (*prepare_write)(struct netfs_io_subrequest *subreq);
 	void (*issue_write)(struct netfs_io_subrequest *subreq);
+	void (*retry_request)(struct netfs_io_request *wreq, struct netfs_io_stream *stream);
 	void (*invalidate_cache)(struct netfs_io_request *wreq);
 };