1 files changed, 94 insertions, 167 deletions

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index 6a792a513d6b..3e794891cd91 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -11,257 +11,180 @@ static DEFINE_MUTEX(erofs_domain_cookies_lock);
 static LIST_HEAD(erofs_domain_list);
 static struct vfsmount *erofs_pseudo_mnt;
 
-static struct netfs_io_request *erofs_fscache_alloc_request(struct address_space *mapping,
+struct erofs_fscache_request {
+	struct netfs_cache_resources cache_resources;
+	struct address_space	*mapping;	/* The mapping being accessed */
+	loff_t			start;		/* Start position */
+	size_t			len;		/* Length of the request */
+	size_t			submitted;	/* Length of submitted */
+	short			error;		/* 0 or error that occurred */
+	refcount_t		ref;
+};
+
+static struct erofs_fscache_request *erofs_fscache_req_alloc(struct address_space *mapping,
 					     loff_t start, size_t len)
 {
-	struct netfs_io_request *rreq;
+	struct erofs_fscache_request *req;
 
-	rreq = kzalloc(sizeof(struct netfs_io_request), GFP_KERNEL);
-	if (!rreq)
+	req = kzalloc(sizeof(struct erofs_fscache_request), GFP_KERNEL);
+	if (!req)
 		return ERR_PTR(-ENOMEM);
 
-	rreq->start	= start;
-	rreq->len	= len;
-	rreq->mapping	= mapping;
-	rreq->inode	= mapping->host;
-	INIT_LIST_HEAD(&rreq->subrequests);
-	refcount_set(&rreq->ref, 1);
-	return rreq;
-}
-
-static void erofs_fscache_put_request(struct netfs_io_request *rreq)
-{
-	if (!refcount_dec_and_test(&rreq->ref))
-		return;
-	if (rreq->cache_resources.ops)
-		rreq->cache_resources.ops->end_operation(&rreq->cache_resources);
-	kfree(rreq);
-}
-
-static void erofs_fscache_put_subrequest(struct netfs_io_subrequest *subreq)
-{
-	if (!refcount_dec_and_test(&subreq->ref))
-		return;
-	erofs_fscache_put_request(subreq->rreq);
-	kfree(subreq);
-}
+	req->mapping = mapping;
+	req->start   = start;
+	req->len     = len;
+	refcount_set(&req->ref, 1);
 
-static void erofs_fscache_clear_subrequests(struct netfs_io_request *rreq)
-{
-	struct netfs_io_subrequest *subreq;
-
-	while (!list_empty(&rreq->subrequests)) {
-		subreq = list_first_entry(&rreq->subrequests,
-				struct netfs_io_subrequest, rreq_link);
-		list_del(&subreq->rreq_link);
-		erofs_fscache_put_subrequest(subreq);
-	}
+	return req;
 }
 
-static void erofs_fscache_rreq_unlock_folios(struct netfs_io_request *rreq)
+static void erofs_fscache_req_complete(struct erofs_fscache_request *req)
 {
-	struct netfs_io_subrequest *subreq;
 	struct folio *folio;
-	unsigned int iopos = 0;
-	pgoff_t start_page = rreq->start / PAGE_SIZE;
-	pgoff_t last_page = ((rreq->start + rreq->len) / PAGE_SIZE) - 1;
-	bool subreq_failed = false;
+	bool failed = req->error;
+	pgoff_t start_page = req->start / PAGE_SIZE;
+	pgoff_t last_page = ((req->start + req->len) / PAGE_SIZE) - 1;
 
-	XA_STATE(xas, &rreq->mapping->i_pages, start_page);
-
-	subreq = list_first_entry(&rreq->subrequests,
-				  struct netfs_io_subrequest, rreq_link);
-	subreq_failed = (subreq->error < 0);
+	XA_STATE(xas, &req->mapping->i_pages, start_page);
 
 	rcu_read_lock();
 	xas_for_each(&xas, folio, last_page) {
-		unsigned int pgpos, pgend;
-		bool pg_failed = false;
-
 		if (xas_retry(&xas, folio))
 			continue;
-
-		pgpos = (folio_index(folio) - start_page) * PAGE_SIZE;
-		pgend = pgpos + folio_size(folio);
-
-		for (;;) {
-			if (!subreq) {
-				pg_failed = true;
-				break;
-			}
-
-			pg_failed |= subreq_failed;
-			if (pgend < iopos + subreq->len)
-				break;
-
-			iopos += subreq->len;
-			if (!list_is_last(&subreq->rreq_link,
-					  &rreq->subrequests)) {
-				subreq = list_next_entry(subreq, rreq_link);
-				subreq_failed = (subreq->error < 0);
-			} else {
-				subreq = NULL;
-				subreq_failed = false;
-			}
-			if (pgend == iopos)
-				break;
-		}
-
-		if (!pg_failed)
+		if (!failed)
 			folio_mark_uptodate(folio);
-
 		folio_unlock(folio);
 	}
 	rcu_read_unlock();
+
+	if (req->cache_resources.ops)
+		req->cache_resources.ops->end_operation(&req->cache_resources);
+
+	kfree(req);
 }
 
-static void erofs_fscache_rreq_complete(struct netfs_io_request *rreq)
+static void erofs_fscache_req_put(struct erofs_fscache_request *req)
 {
-	erofs_fscache_rreq_unlock_folios(rreq);
-	erofs_fscache_clear_subrequests(rreq);
-	erofs_fscache_put_request(rreq);
+	if (refcount_dec_and_test(&req->ref))
+		erofs_fscache_req_complete(req);
 }
 
-static void erofc_fscache_subreq_complete(void *priv,
+static void erofs_fscache_subreq_complete(void *priv,
 		ssize_t transferred_or_error, bool was_async)
 {
-	struct netfs_io_subrequest *subreq = priv;
-	struct netfs_io_request *rreq = subreq->rreq;
+	struct erofs_fscache_request *req = priv;
 
 	if (IS_ERR_VALUE(transferred_or_error))
-		subreq->error = transferred_or_error;
-
-	if (atomic_dec_and_test(&rreq->nr_outstanding))
-		erofs_fscache_rreq_complete(rreq);
-
-	erofs_fscache_put_subrequest(subreq);
+		req->error = transferred_or_error;
+	erofs_fscache_req_put(req);
 }
 
 /*
- * Read data from fscache and fill the read data into page cache described by
- * @rreq, which shall be both aligned with PAGE_SIZE. @pstart describes
- * the start physical address in the cache file.
+ * Read data from fscache (cookie, pstart, len), and fill the read data into
+ * page cache described by (req->mapping, lstart, len). @pstart describeis the
+ * start physical address in the cache file.
  */
 static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,
-				struct netfs_io_request *rreq, loff_t pstart)
+		struct erofs_fscache_request *req, loff_t pstart, size_t len)
 {
 	enum netfs_io_source source;
-	struct super_block *sb = rreq->mapping->host->i_sb;
-	struct netfs_io_subrequest *subreq;
-	struct netfs_cache_resources *cres = &rreq->cache_resources;
+	struct super_block *sb = req->mapping->host->i_sb;
+	struct netfs_cache_resources *cres = &req->cache_resources;
 	struct iov_iter iter;
-	loff_t start = rreq->start;
-	size_t len = rreq->len;
+	loff_t lstart = req->start + req->submitted;
 	size_t done = 0;
 	int ret;
 
-	atomic_set(&rreq->nr_outstanding, 1);
+	DBG_BUGON(len > req->len - req->submitted);
 
 	ret = fscache_begin_read_operation(cres, cookie);
 	if (ret)
-		goto out;
+		return ret;
 
 	while (done < len) {
-		subreq = kzalloc(sizeof(struct netfs_io_subrequest),
-				 GFP_KERNEL);
-		if (subreq) {
-			INIT_LIST_HEAD(&subreq->rreq_link);
-			refcount_set(&subreq->ref, 2);
-			subreq->rreq = rreq;
-			refcount_inc(&rreq->ref);
-		} else {
-			ret = -ENOMEM;
-			goto out;
-		}
-
-		subreq->start = pstart + done;
-		subreq->len	=  len - done;
-		subreq->flags = 1 << NETFS_SREQ_ONDEMAND;
+		loff_t sstart = pstart + done;
+		size_t slen = len - done;
+		unsigned long flags = 1 << NETFS_SREQ_ONDEMAND;
 
-		list_add_tail(&subreq->rreq_link, &rreq->subrequests);
-
-		source = cres->ops->prepare_read(subreq, LLONG_MAX);
-		if (WARN_ON(subreq->len == 0))
+		source = cres->ops->prepare_ondemand_read(cres,
+				sstart, &slen, LLONG_MAX, &flags, 0);
+		if (WARN_ON(slen == 0))
 			source = NETFS_INVALID_READ;
 		if (source != NETFS_READ_FROM_CACHE) {
-			erofs_err(sb, "failed to fscache prepare_read (source %d)",
-				  source);
-			ret = -EIO;
-			subreq->error = ret;
-			erofs_fscache_put_subrequest(subreq);
-			goto out;
+			erofs_err(sb, "failed to fscache prepare_read (source %d)", source);
+			return -EIO;
 		}
 
-		atomic_inc(&rreq->nr_outstanding);
+		refcount_inc(&req->ref);
+		iov_iter_xarray(&iter, READ, &req->mapping->i_pages,
+				lstart + done, slen);
 
-		iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages,
-				start + done, subreq->len);
-
-		ret = fscache_read(cres, subreq->start, &iter,
-				   NETFS_READ_HOLE_FAIL,
-				   erofc_fscache_subreq_complete, subreq);
+		ret = fscache_read(cres, sstart, &iter, NETFS_READ_HOLE_FAIL,
+				   erofs_fscache_subreq_complete, req);
 		if (ret == -EIOCBQUEUED)
 			ret = 0;
 		if (ret) {
 			erofs_err(sb, "failed to fscache_read (ret %d)", ret);
-			goto out;
+			return ret;
 		}
 
-		done += subreq->len;
+		done += slen;
 	}
-out:
-	if (atomic_dec_and_test(&rreq->nr_outstanding))
-		erofs_fscache_rreq_complete(rreq);
-
-	return ret;
+	DBG_BUGON(done != len);
+	req->submitted += len;
+	return 0;
 }
 
 static int erofs_fscache_meta_read_folio(struct file *data, struct folio *folio)
 {
 	int ret;
 	struct super_block *sb = folio_mapping(folio)->host->i_sb;
-	struct netfs_io_request *rreq;
+	struct erofs_fscache_request *req;
 	struct erofs_map_dev mdev = {
 		.m_deviceid = 0,
 		.m_pa = folio_pos(folio),
 	};
 
 	ret = erofs_map_dev(sb, &mdev);
-	if (ret)
-		goto out;
+	if (ret) {
+		folio_unlock(folio);
+		return ret;
+	}
 
-	rreq = erofs_fscache_alloc_request(folio_mapping(folio),
+	req = erofs_fscache_req_alloc(folio_mapping(folio),
 				folio_pos(folio), folio_size(folio));
-	if (IS_ERR(rreq)) {
-		ret = PTR_ERR(rreq);
-		goto out;
+	if (IS_ERR(req)) {
+		folio_unlock(folio);
+		return PTR_ERR(req);
 	}
 
-	return erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
-				rreq, mdev.m_pa);
-out:
-	folio_unlock(folio);
+	ret = erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
+				req, mdev.m_pa, folio_size(folio));
+	if (ret)
+		req->error = ret;
+
+	erofs_fscache_req_put(req);
 	return ret;
 }
 
 /*
  * Read into page cache in the range described by (@pos, @len).
  *
- * On return, the caller is responsible for page unlocking if the output @unlock
- * is true, or the callee will take this responsibility through netfs_io_request
- * interface.
+ * On return, if the output @unlock is true, the caller is responsible for page
+ * unlocking; otherwise the callee will take this responsibility through request
+ * completion.
  *
  * The return value is the number of bytes successfully handled, or negative
  * error code on failure. The only exception is that, the length of the range
- * instead of the error code is returned on failure after netfs_io_request is
- * allocated, so that .readahead() could advance rac accordingly.
+ * instead of the error code is returned on failure after request is allocated,
+ * so that .readahead() could advance rac accordingly.
  */
 static int erofs_fscache_data_read(struct address_space *mapping,
 				   loff_t pos, size_t len, bool *unlock)
 {
 	struct inode *inode = mapping->host;
 	struct super_block *sb = inode->i_sb;
-	struct netfs_io_request *rreq;
+	struct erofs_fscache_request *req;
 	struct erofs_map_blocks map;
 	struct erofs_map_dev mdev;
 	struct iov_iter iter;
@@ -318,13 +241,17 @@ static int erofs_fscache_data_read(struct address_space *mapping,
 	if (ret)
 		return ret;
 
-	rreq = erofs_fscache_alloc_request(mapping, pos, count);
-	if (IS_ERR(rreq))
-		return PTR_ERR(rreq);
+	req = erofs_fscache_req_alloc(mapping, pos, count);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
 
 	*unlock = false;
-	erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
-			rreq, mdev.m_pa + (pos - map.m_la));
+	ret = erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
+			req, mdev.m_pa + (pos - map.m_la), count);
+	if (ret)
+		req->error = ret;
+
+	erofs_fscache_req_put(req);
 	return count;
 }