netfs: Extend the netfs_io_*request structs to handle writes

Modify the netfs_io_request struct to act as a point around which writes
can be coordinated.  It represents and pins a range of pages that need
writing and a list of regions of dirty data in that range of pages.

If RMW is required, the original data can be downloaded into the bounce
buffer, decrypted if necessary, the modifications made, then the modified
data can be reencrypted/recompressed and sent back to the server.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org

4 files changed, 27 insertions, 4 deletions

diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
index b908c7e0a901..2bf2e82b2ad7 100644
--- a/fs/netfs/internal.h
+++ b/fs/netfs/internal.h
@@ -110,6 +110,12 @@ extern atomic_t netfs_n_rh_write_begin;
 extern atomic_t netfs_n_rh_write_done;
 extern atomic_t netfs_n_rh_write_failed;
 extern atomic_t netfs_n_rh_write_zskip;
+extern atomic_t netfs_n_wh_upload;
+extern atomic_t netfs_n_wh_upload_done;
+extern atomic_t netfs_n_wh_upload_failed;
+extern atomic_t netfs_n_wh_write;
+extern atomic_t netfs_n_wh_write_done;
+extern atomic_t netfs_n_wh_write_failed;
 
 int netfs_stats_show(struct seq_file *m, void *v);
 
diff --git a/fs/netfs/main.c b/fs/netfs/main.c
index 97ce1436615b..ab6cac110676 100644
--- a/fs/netfs/main.c
+++ b/fs/netfs/main.c
@@ -25,10 +25,11 @@ MODULE_PARM_DESC(netfs_debug, "Netfs support debugging mask");
 LIST_HEAD(netfs_io_requests);
 DEFINE_SPINLOCK(netfs_proc_lock);
 
-static const char *netfs_origins[] = {
+static const char *netfs_origins[nr__netfs_io_origin] = {
 	[NETFS_READAHEAD]	= "RA",
 	[NETFS_READPAGE]	= "RP",
 	[NETFS_READ_FOR_WRITE]	= "RW",
+	[NETFS_WRITEBACK]	= "WB",
 };
 
 /*
diff --git a/fs/netfs/objects.c b/fs/netfs/objects.c
index 4df5e5eeada6..65a17dd4ab49 100644
--- a/fs/netfs/objects.c
+++ b/fs/netfs/objects.c
@@ -20,6 +20,7 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
 	struct inode *inode = file ? file_inode(file) : mapping->host;
 	struct netfs_inode *ctx = netfs_inode(inode);
 	struct netfs_io_request *rreq;
+	bool cached = netfs_is_cache_enabled(ctx);
 	int ret;
 
 	rreq = kzalloc(ctx->ops->io_request_size ?: sizeof(struct netfs_io_request),
@@ -37,7 +38,10 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
 	rreq->debug_id	= atomic_inc_return(&debug_ids);
 	INIT_LIST_HEAD(&rreq->subrequests);
 	refcount_set(&rreq->ref, 1);
+
 	__set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
+	if (cached)
+		__set_bit(NETFS_RREQ_WRITE_TO_CACHE, &rreq->flags);
 	if (rreq->netfs_ops->init_request) {
 		ret = rreq->netfs_ops->init_request(rreq, file);
 		if (ret < 0) {
@@ -46,6 +50,7 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
 		}
 	}
 
+	trace_netfs_rreq_ref(rreq->debug_id, 1, netfs_rreq_trace_new);
 	netfs_proc_add_rreq(rreq);
 	netfs_stat(&netfs_n_rh_rreq);
 	return rreq;
@@ -129,6 +134,7 @@ struct netfs_io_subrequest *netfs_alloc_subrequest(struct netfs_io_request *rreq
 			 sizeof(struct netfs_io_subrequest),
 			 GFP_KERNEL);
 	if (subreq) {
+		INIT_WORK(&subreq->work, NULL);
 		INIT_LIST_HEAD(&subreq->rreq_link);
 		refcount_set(&subreq->ref, 2);
 		subreq->rreq = rreq;
diff --git a/fs/netfs/stats.c b/fs/netfs/stats.c
index 6025dc485f7e..c1f85cd595a4 100644
--- a/fs/netfs/stats.c
+++ b/fs/netfs/stats.c
@@ -27,6 +27,12 @@ atomic_t netfs_n_rh_write_begin;
 atomic_t netfs_n_rh_write_done;
 atomic_t netfs_n_rh_write_failed;
 atomic_t netfs_n_rh_write_zskip;
+atomic_t netfs_n_wh_upload;
+atomic_t netfs_n_wh_upload_done;
+atomic_t netfs_n_wh_upload_failed;
+atomic_t netfs_n_wh_write;
+atomic_t netfs_n_wh_write_done;
+atomic_t netfs_n_wh_write_failed;
 
 int netfs_stats_show(struct seq_file *m, void *v)
 {
@@ -50,10 +56,14 @@ int netfs_stats_show(struct seq_file *m, void *v)
 		   atomic_read(&netfs_n_rh_read),
 		   atomic_read(&netfs_n_rh_read_done),
 		   atomic_read(&netfs_n_rh_read_failed));
+	seq_printf(m, "Netfs  : UL=%u us=%u uf=%u\n",
+		   atomic_read(&netfs_n_wh_upload),
+		   atomic_read(&netfs_n_wh_upload_done),
+		   atomic_read(&netfs_n_wh_upload_failed));
 	seq_printf(m, "Netfs  : WR=%u ws=%u wf=%u\n",
-		   atomic_read(&netfs_n_rh_write),
-		   atomic_read(&netfs_n_rh_write_done),
-		   atomic_read(&netfs_n_rh_write_failed));
+		   atomic_read(&netfs_n_wh_write),
+		   atomic_read(&netfs_n_wh_write_done),
+		   atomic_read(&netfs_n_wh_write_failed));
 	return fscache_stats_show(m);
 }
 EXPORT_SYMBOL(netfs_stats_show);