[RFC PATCH 20/53] fscache: Add a function to begin an cache op from a netfslib request
From: David Howells
Date: Fri Oct 13 2023 - 12:07:58 EST
Add a function to begin an cache read or write operation from a netfslib
I/O request. This function can then be pointed to directly by the network
filesystem's netfs_request_ops::begin_cache_operation op pointer.
Ideally, netfslib would just call into fscache directly, but that would
cause dependency cycles as fscache calls into netfslib directly.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Jeff Layton <jlayton@xxxxxxxxxx>
cc: linux-cachefs@xxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx
cc: linux-mm@xxxxxxxxx
---
fs/9p/vfs_addr.c | 18 ++----------------
fs/afs/file.c | 14 +-------------
fs/ceph/addr.c | 2 +-
fs/ceph/cache.h | 12 ------------
fs/fscache/io.c | 42 +++++++++++++++++++++++++++++++++++++++++
include/linux/fscache.h | 6 ++++++
6 files changed, 52 insertions(+), 42 deletions(-)
diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index 18a666c43e4a..516572bad412 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -17,6 +17,7 @@
#include <linux/swap.h>
#include <linux/uio.h>
#include <linux/netfs.h>
+#include <linux/fscache.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
@@ -82,25 +83,10 @@ static void v9fs_free_request(struct netfs_io_request *rreq)
p9_fid_put(fid);
}
-/**
- * v9fs_begin_cache_operation - Begin a cache operation for a read
- * @rreq: The read request
- */
-static int v9fs_begin_cache_operation(struct netfs_io_request *rreq)
-{
-#ifdef CONFIG_9P_FSCACHE
- struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(rreq->inode));
-
- return fscache_begin_read_operation(&rreq->cache_resources, cookie);
-#else
- return -ENOBUFS;
-#endif
-}
-
const struct netfs_request_ops v9fs_req_ops = {
.init_request = v9fs_init_request,
.free_request = v9fs_free_request,
- .begin_cache_operation = v9fs_begin_cache_operation,
+ .begin_cache_operation = fscache_begin_cache_operation,
.issue_read = v9fs_issue_read,
};
diff --git a/fs/afs/file.c b/fs/afs/file.c
index 3e39a2ebcad6..5bb78d874292 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -360,18 +360,6 @@ static int afs_init_request(struct netfs_io_request *rreq, struct file *file)
return 0;
}
-static int afs_begin_cache_operation(struct netfs_io_request *rreq)
-{
-#ifdef CONFIG_AFS_FSCACHE
- struct afs_vnode *vnode = AFS_FS_I(rreq->inode);
-
- return fscache_begin_read_operation(&rreq->cache_resources,
- afs_vnode_cache(vnode));
-#else
- return -ENOBUFS;
-#endif
-}
-
static int afs_check_write_begin(struct file *file, loff_t pos, unsigned len,
struct folio **foliop, void **_fsdata)
{
@@ -388,7 +376,7 @@ static void afs_free_request(struct netfs_io_request *rreq)
const struct netfs_request_ops afs_req_ops = {
.init_request = afs_init_request,
.free_request = afs_free_request,
- .begin_cache_operation = afs_begin_cache_operation,
+ .begin_cache_operation = fscache_begin_cache_operation,
.check_write_begin = afs_check_write_begin,
.issue_read = afs_issue_read,
};
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 92a5ddcd9a76..4841b06df78c 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -488,7 +488,7 @@ static void ceph_netfs_free_request(struct netfs_io_request *rreq)
const struct netfs_request_ops ceph_netfs_ops = {
.init_request = ceph_init_request,
.free_request = ceph_netfs_free_request,
- .begin_cache_operation = ceph_begin_cache_operation,
+ .begin_cache_operation = fscache_begin_cache_operation,
.issue_read = ceph_netfs_issue_read,
.expand_readahead = ceph_netfs_expand_readahead,
.clamp_length = ceph_netfs_clamp_length,
diff --git a/fs/ceph/cache.h b/fs/ceph/cache.h
index dc502daac49a..b804f1094764 100644
--- a/fs/ceph/cache.h
+++ b/fs/ceph/cache.h
@@ -57,13 +57,6 @@ static inline int ceph_fscache_dirty_folio(struct address_space *mapping,
return fscache_dirty_folio(mapping, folio, ceph_fscache_cookie(ci));
}
-static inline int ceph_begin_cache_operation(struct netfs_io_request *rreq)
-{
- struct fscache_cookie *cookie = ceph_fscache_cookie(ceph_inode(rreq->inode));
-
- return fscache_begin_read_operation(&rreq->cache_resources, cookie);
-}
-
static inline bool ceph_is_cache_enabled(struct inode *inode)
{
return fscache_cookie_enabled(ceph_fscache_cookie(ceph_inode(inode)));
@@ -135,11 +128,6 @@ static inline bool ceph_is_cache_enabled(struct inode *inode)
return false;
}
-static inline int ceph_begin_cache_operation(struct netfs_io_request *rreq)
-{
- return -ENOBUFS;
-}
-
static inline void ceph_fscache_note_page_release(struct inode *inode)
{
}
diff --git a/fs/fscache/io.c b/fs/fscache/io.c
index 0d2b8dec8f82..cb602dd651e6 100644
--- a/fs/fscache/io.c
+++ b/fs/fscache/io.c
@@ -158,6 +158,48 @@ int __fscache_begin_write_operation(struct netfs_cache_resources *cres,
}
EXPORT_SYMBOL(__fscache_begin_write_operation);
+/**
+ * fscache_begin_cache_operation - Begin a cache op for netfslib
+ * @rreq: The netfs request that wants to access the cache.
+ *
+ * Begin an I/O operation on behalf of the netfs helper library, read or write.
+ * @rreq indicates the netfs operation that wishes to access the cache.
+ *
+ * This is intended to be pointed to directly by the ->begin_cache_operation()
+ * netfs lib operation for the network filesystem.
+ *
+ * @cres->inval_counter is set from @cookie->inval_counter for comparison at
+ * the end of the operation. This allows invalidation during the operation to
+ * be detected by the caller.
+ *
+ * Returns:
+ * * 0 - Success
+ * * -ENOBUFS - No caching available
+ * * Other error code from the cache, such as -ENOMEM.
+ */
+int fscache_begin_cache_operation(struct netfs_io_request *rreq)
+{
+ struct netfs_inode *ctx = netfs_inode(rreq->inode);
+
+ switch (rreq->origin) {
+ case NETFS_READAHEAD:
+ case NETFS_READPAGE:
+ case NETFS_READ_FOR_WRITE:
+ return fscache_begin_operation(&rreq->cache_resources,
+ netfs_i_cookie(ctx),
+ FSCACHE_WANT_PARAMS,
+ fscache_access_io_read);
+ case NETFS_WRITEBACK:
+ return fscache_begin_operation(&rreq->cache_resources,
+ netfs_i_cookie(ctx),
+ FSCACHE_WANT_PARAMS,
+ fscache_access_io_write);
+ default:
+ return -ENOBUFS;
+ }
+}
+EXPORT_SYMBOL(fscache_begin_cache_operation);
+
/**
* fscache_dirty_folio - Mark folio dirty and pin a cache object for writeback
* @mapping: The mapping the folio belongs to.
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 8e312c8323a8..9c389adaf286 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -177,6 +177,12 @@ extern void __fscache_write_to_cache(struct fscache_cookie *, struct address_spa
bool);
extern void __fscache_clear_page_bits(struct address_space *, loff_t, size_t);
+#if __fscache_available
+extern int fscache_begin_cache_operation(struct netfs_io_request *rreq);
+#else
+#define fscache_begin_cache_operation NULL
+#endif
+
/**
* fscache_acquire_volume - Register a volume as desiring caching services
* @volume_key: An identification string for the volume