From:   Jeffle Xu <jefflexu@linux.alibaba.com>
To:     dhowells@redhat.com, linux-cachefs@redhat.com, xiang@kernel.org,
        chao@kernel.org, linux-erofs@lists.ozlabs.org
Cc:     linux-fsdevel@vger.kernel.org, joseph.qi@linux.alibaba.com,
        bo.liu@linux.alibaba.com, tao.peng@linux.alibaba.com,
        gerry@linux.alibaba.com, eguan@linux.alibaba.com,
        linux-kernel@vger.kernel.org
Subject: [PATCH v1 05/23] netfs: add inode parameter to netfs_alloc_read_request()
Date:   Mon, 27 Dec 2021 20:54:26 +0800
Message-Id: <20211227125444.21187-6-jefflexu@linux.alibaba.com>
In-Reply-To: <20211227125444.21187-1-jefflexu@linux.alibaba.com>
References: <20211227125444.21187-1-jefflexu@linux.alibaba.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

When working as the local cache, the @file parameter of
netfs_alloc_read_request() represents the backed file inside netfs. It
is for two use: 1) we can derive the corresponding inode from file,
2) works as the argument for ops->init_rreq().

In the new introduced demand-read mode, netfs_readpage() will be called
by the upper fs to read from backing files. However in this new mode,
the backed file may not be opened, and thus the @file argument is NULL
in this case.

For netfs_readpage(), @file parameter represents the backed file inside
netfs, while @folio parameter represents one page cache inside the
address space of this backed file. We can still derive the inode from
the @folio parameter, even when @file parameter is NULL.

Thus refactor netfs_alloc_read_request() somewhat for this change.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
 fs/netfs/read_helper.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index 8c58cff420ba..ca84918b6b5d 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -39,7 +39,7 @@ static void netfs_put_subrequest(struct netfs_read_subrequest *subreq,
 
 static struct netfs_read_request *netfs_alloc_read_request(
 	const struct netfs_read_request_ops *ops, void *netfs_priv,
-	struct file *file)
+	struct inode *inode, struct file *file)
 {
 	static atomic_t debug_ids;
 	struct netfs_read_request *rreq;
@@ -48,7 +48,7 @@ static struct netfs_read_request *netfs_alloc_read_request(
 	if (rreq) {
 		rreq->netfs_ops	= ops;
 		rreq->netfs_priv = netfs_priv;
-		rreq->inode	= file_inode(file);
+		rreq->inode	= inode;
 		rreq->i_size	= i_size_read(rreq->inode);
 		rreq->debug_id	= atomic_inc_return(&debug_ids);
 		INIT_LIST_HEAD(&rreq->subrequests);
@@ -870,6 +870,7 @@ void netfs_readahead(struct readahead_control *ractl,
 		     void *netfs_priv)
 {
 	struct netfs_read_request *rreq;
+	struct inode *inode = file_inode(ractl->file);
 	unsigned int debug_index = 0;
 	int ret;
 
@@ -878,7 +879,7 @@ void netfs_readahead(struct readahead_control *ractl,
 	if (readahead_count(ractl) == 0)
 		goto cleanup;
 
-	rreq = netfs_alloc_read_request(ops, netfs_priv, ractl->file);
+	rreq = netfs_alloc_read_request(ops, netfs_priv, inode, ractl->file);
 	if (!rreq)
 		goto cleanup;
 	rreq->mapping	= ractl->mapping;
@@ -948,12 +949,13 @@ int netfs_readpage(struct file *file,
 		   void *netfs_priv)
 {
 	struct netfs_read_request *rreq;
+	struct inode *inode = folio_file_mapping(folio)->host;
 	unsigned int debug_index = 0;
 	int ret;
 
 	_enter("%lx", folio_index(folio));
 
-	rreq = netfs_alloc_read_request(ops, netfs_priv, file);
+	rreq = netfs_alloc_read_request(ops, netfs_priv, inode, file);
 	if (!rreq) {
 		if (netfs_priv)
 			ops->cleanup(folio_file_mapping(folio), netfs_priv);
@@ -1122,7 +1124,7 @@ int netfs_write_begin(struct file *file, struct address_space *mapping,
 	}
 
 	ret = -ENOMEM;
-	rreq = netfs_alloc_read_request(ops, netfs_priv, file);
+	rreq = netfs_alloc_read_request(ops, netfs_priv, inode, file);
 	if (!rreq)
 		goto error;
 	rreq->mapping		= folio_file_mapping(folio);
-- 
2.27.0