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-rw-r--r--fs/fscache/io.c116
1 files changed, 116 insertions, 0 deletions
diff --git a/fs/fscache/io.c b/fs/fscache/io.c
new file mode 100644
index 000000000000..8ecc1141802f
--- /dev/null
+++ b/fs/fscache/io.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Cache data I/O routines
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define FSCACHE_DEBUG_LEVEL PAGE
+#include <linux/module.h>
+#define FSCACHE_USE_NEW_IO_API
+#include <linux/fscache-cache.h>
+#include <linux/slab.h>
+#include <linux/netfs.h>
+#include "internal.h"
+
+/*
+ * Start a cache read operation.
+ * - we return:
+ * -ENOMEM - out of memory, some pages may be being read
+ * -ERESTARTSYS - interrupted, some pages may be being read
+ * -ENOBUFS - no backing object or space available in which to cache any
+ * pages not being read
+ * -ENODATA - no data available in the backing object for some or all of
+ * the pages
+ * 0 - dispatched a read on all pages
+ */
+int __fscache_begin_read_operation(struct netfs_read_request *rreq,
+ struct fscache_cookie *cookie)
+{
+ struct fscache_retrieval *op;
+ struct fscache_object *object;
+ bool wake_cookie = false;
+ int ret;
+
+ _enter("rr=%08x", rreq->debug_id);
+
+ fscache_stat(&fscache_n_retrievals);
+
+ if (hlist_empty(&cookie->backing_objects))
+ goto nobufs;
+
+ if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
+ _leave(" = -ENOBUFS [invalidating]");
+ return -ENOBUFS;
+ }
+
+ ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
+
+ if (fscache_wait_for_deferred_lookup(cookie) < 0)
+ return -ERESTARTSYS;
+
+ op = fscache_alloc_retrieval(cookie, NULL, NULL, NULL);
+ if (!op)
+ return -ENOMEM;
+ trace_fscache_page_op(cookie, NULL, &op->op, fscache_page_op_retr_multi);
+
+ spin_lock(&cookie->lock);
+
+ if (!fscache_cookie_enabled(cookie) ||
+ hlist_empty(&cookie->backing_objects))
+ goto nobufs_unlock;
+ object = hlist_entry(cookie->backing_objects.first,
+ struct fscache_object, cookie_link);
+
+ __fscache_use_cookie(cookie);
+ atomic_inc(&object->n_reads);
+ __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
+
+ if (fscache_submit_op(object, &op->op) < 0)
+ goto nobufs_unlock_dec;
+ spin_unlock(&cookie->lock);
+
+ fscache_stat(&fscache_n_retrieval_ops);
+
+ /* we wait for the operation to become active, and then process it
+ * *here*, in this thread, and not in the thread pool */
+ ret = fscache_wait_for_operation_activation(
+ object, &op->op,
+ __fscache_stat(&fscache_n_retrieval_op_waits),
+ __fscache_stat(&fscache_n_retrievals_object_dead));
+ if (ret < 0)
+ goto error;
+
+ /* ask the cache to honour the operation */
+ ret = object->cache->ops->begin_read_operation(rreq, op);
+
+error:
+ if (ret == -ENOMEM)
+ fscache_stat(&fscache_n_retrievals_nomem);
+ else if (ret == -ERESTARTSYS)
+ fscache_stat(&fscache_n_retrievals_intr);
+ else if (ret == -ENODATA)
+ fscache_stat(&fscache_n_retrievals_nodata);
+ else if (ret < 0)
+ fscache_stat(&fscache_n_retrievals_nobufs);
+ else
+ fscache_stat(&fscache_n_retrievals_ok);
+
+ fscache_put_retrieval(op);
+ _leave(" = %d", ret);
+ return ret;
+
+nobufs_unlock_dec:
+ atomic_dec(&object->n_reads);
+ wake_cookie = __fscache_unuse_cookie(cookie);
+nobufs_unlock:
+ spin_unlock(&cookie->lock);
+ fscache_put_retrieval(op);
+ if (wake_cookie)
+ __fscache_wake_unused_cookie(cookie);
+nobufs:
+ fscache_stat(&fscache_n_retrievals_nobufs);
+ _leave(" = -ENOBUFS");
+ return -ENOBUFS;
+}
+EXPORT_SYMBOL(__fscache_begin_read_operation);