netfs: Move pinning-for-writeback from fscache to netfs

Move the resource pinning-for-writeback from fscache code to netfslib code.
This is used to keep a cache backing object pinned whilst we have dirty
pages on the netfs inode in the pagecache such that VM writeback will be
able to reach it.

Whilst we're at it, switch the parameters of netfs_unpin_writeback() to
match ->write_inode() so that it can be used for that directly.

Note that this mechanism could be more generically useful than that for
network filesystems.  Quite often they have to keep around other resources
(e.g. authentication tokens or network connections) until the writeback is
complete.

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

5 files changed, 3 insertions, 24 deletions

diff --git a/fs/afs/file.c b/fs/afs/file.c
index 8c17e37c2e59..9142fda7dbd6 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -55,7 +55,7 @@ const struct inode_operations afs_file_inode_operations = {
 const struct address_space_operations afs_file_aops = {
 	.read_folio	= netfs_read_folio,
 	.readahead	= netfs_readahead,
-	.dirty_folio	= afs_dirty_folio,
+	.dirty_folio	= netfs_dirty_folio,
 	.launder_folio	= afs_launder_folio,
 	.release_folio	= afs_release_folio,
 	.invalidate_folio = afs_invalidate_folio,
@@ -386,12 +386,6 @@ const struct netfs_request_ops afs_req_ops = {
 	.issue_read		= afs_issue_read,
 };
 
-int afs_write_inode(struct inode *inode, struct writeback_control *wbc)
-{
-	fscache_unpin_writeback(wbc, afs_vnode_cache(AFS_FS_I(inode)));
-	return 0;
-}
-
 /*
  * Adjust the dirty region of the page on truncation or full invalidation,
  * getting rid of the markers altogether if the region is entirely invalidated.
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 78efc9719349..6f375f0cf650 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -823,7 +823,7 @@ void afs_evict_inode(struct inode *inode)
 	truncate_inode_pages_final(&inode->i_data);
 
 	afs_set_cache_aux(vnode, &aux);
-	fscache_clear_inode_writeback(afs_vnode_cache(vnode), inode, &aux);
+	netfs_clear_inode_writeback(inode, &aux);
 	clear_inode(inode);
 
 	while (!list_empty(&vnode->wb_keys)) {
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 7385d62c8cf5..b77797559e27 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -1073,7 +1073,6 @@ extern int afs_release(struct inode *, struct file *);
 extern int afs_fetch_data(struct afs_vnode *, struct afs_read *);
 extern struct afs_read *afs_alloc_read(gfp_t);
 extern void afs_put_read(struct afs_read *);
-extern int afs_write_inode(struct inode *, struct writeback_control *);
 
 static inline struct afs_read *afs_get_read(struct afs_read *req)
 {
@@ -1522,11 +1521,6 @@ extern int afs_check_volume_status(struct afs_volume *, struct afs_operation *);
 /*
  * write.c
  */
-#ifdef CONFIG_AFS_FSCACHE
-bool afs_dirty_folio(struct address_space *, struct folio *);
-#else
-#define afs_dirty_folio filemap_dirty_folio
-#endif
 extern int afs_write_begin(struct file *file, struct address_space *mapping,
 			loff_t pos, unsigned len,
 			struct page **pagep, void **fsdata);
diff --git a/fs/afs/super.c b/fs/afs/super.c
index a01a0fb2cdbb..4f1b0492f1c5 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -55,7 +55,7 @@ int afs_net_id;
 static const struct super_operations afs_super_ops = {
 	.statfs		= afs_statfs,
 	.alloc_inode	= afs_alloc_inode,
-	.write_inode	= afs_write_inode,
+	.write_inode	= netfs_unpin_writeback,
 	.drop_inode	= afs_drop_inode,
 	.destroy_inode	= afs_destroy_inode,
 	.free_inode	= afs_free_inode,
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 4a168781936b..e40cf8e7543a 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -23,15 +23,6 @@ static void afs_write_to_cache(struct afs_vnode *vnode, loff_t start, size_t len
 			       loff_t i_size, bool caching);
 
 #ifdef CONFIG_AFS_FSCACHE
-/*
- * Mark a page as having been made dirty and thus needing writeback.  We also
- * need to pin the cache object to write back to.
- */
-bool afs_dirty_folio(struct address_space *mapping, struct folio *folio)
-{
-	return fscache_dirty_folio(mapping, folio,
-				afs_vnode_cache(AFS_FS_I(mapping->host)));
-}
 static void afs_folio_start_fscache(bool caching, struct folio *folio)
 {
 	if (caching)