fscache/cachefiles used to serve as a local cache for remote fs.
This patch set introduces a new use case, in which local read-only
fs could implement demand read with fscache.
Thus 'type' field is used to distinguish which mode netfs API works in.
Besides, in demand-read case, local fs using fscache for demand-read
can't offer and also doesn't need the file handle of the netfs file. The
input folio of netfs_readpage() is may not a page cache inside the
address space of the netfs file, and may be just a temporary page
containing the data. What netfs API needs to do is just move data from
backing file the the input folio. Thus buffer the folio in 'struct
netfs_read_request'.
Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
---
include/linux/netfs.h | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index b46c39d98bbd..638ea5d63869 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -148,6 +148,11 @@ struct netfs_read_subrequest {
#define NETFS_SREQ_NO_PROGRESS 4 /* Set if we didn't manage to read any data */
};
+enum netfs_read_request_type {
+ NETFS_TYPE_CACHE,
+ NETFS_TYPE_DEMAND,
+};
+
/*
* Descriptor for a read helper request. This is used to make multiple I/O
* requests on a variety of sources and then stitch the result together.
@@ -156,6 +161,7 @@ struct netfs_read_request {
struct work_struct work;
struct inode *inode; /* The file being accessed */
struct address_space *mapping; /* The mapping being accessed */
+ struct folio *folio;
struct netfs_cache_resources cache_resources;
struct list_head subrequests; /* Requests to fetch I/O from disk or net */
void *netfs_priv; /* Private data for the netfs */
@@ -177,6 +183,7 @@ struct netfs_read_request {
#define NETFS_RREQ_FAILED 4 /* The request failed */
#define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes */
const struct netfs_read_request_ops *netfs_ops;
+ enum netfs_read_request_type type;
};
/*
--
2.27.0
