iomap: add the new iomap_iter model

[linux-2.6-microblaze.git] / fs / iomap / apply.c

diff --git a/fs/iomap/apply.c b/fs/iomap/apply.c
index 26ab656..e82647a 100644 (file)
--- a/fs/iomap/apply.c
+++ b/fs/iomap/apply.c
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2010 Red Hat, Inc.
- * Copyright (c) 2016-2018 Christoph Hellwig.
+ * Copyright (c) 2016-2021 Christoph Hellwig.
  */
 #include <linux/module.h>
 #include <linux/compiler.h>
@@ -97,3 +97,75 @@ out:
 
        return written ? written : ret;
 }
+
+static inline int iomap_iter_advance(struct iomap_iter *iter)
+{
+       /* handle the previous iteration (if any) */
+       if (iter->iomap.length) {
+               if (iter->processed <= 0)
+                       return iter->processed;
+               if (WARN_ON_ONCE(iter->processed > iomap_length(iter)))
+                       return -EIO;
+               iter->pos += iter->processed;
+               iter->len -= iter->processed;
+               if (!iter->len)
+                       return 0;
+       }
+
+       /* clear the state for the next iteration */
+       iter->processed = 0;
+       memset(&iter->iomap, 0, sizeof(iter->iomap));
+       memset(&iter->srcmap, 0, sizeof(iter->srcmap));
+       return 1;
+}
+
+static inline void iomap_iter_done(struct iomap_iter *iter)
+{
+       WARN_ON_ONCE(iter->iomap.offset > iter->pos);
+       WARN_ON_ONCE(iter->iomap.length == 0);
+       WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos);
+
+       trace_iomap_iter_dstmap(iter->inode, &iter->iomap);
+       if (iter->srcmap.type != IOMAP_HOLE)
+               trace_iomap_iter_srcmap(iter->inode, &iter->srcmap);
+}
+
+/**
+ * iomap_iter - iterate over a ranges in a file
+ * @iter: iteration structue
+ * @ops: iomap ops provided by the file system
+ *
+ * Iterate over filesystem-provided space mappings for the provided file range.
+ *
+ * This function handles cleanup of resources acquired for iteration when the
+ * filesystem indicates there are no more space mappings, which means that this
+ * function must be called in a loop that continues as long it returns a
+ * positive value.  If 0 or a negative value is returned, the caller must not
+ * return to the loop body.  Within a loop body, there are two ways to break out
+ * of the loop body:  leave @iter.processed unchanged, or set it to a negative
+ * errno.
+ */
+int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)
+{
+       int ret;
+
+       if (iter->iomap.length && ops->iomap_end) {
+               ret = ops->iomap_end(iter->inode, iter->pos, iomap_length(iter),
+                               iter->processed > 0 ? iter->processed : 0,
+                               iter->flags, &iter->iomap);
+               if (ret < 0 && !iter->processed)
+                       return ret;
+       }
+
+       trace_iomap_iter(iter, ops, _RET_IP_);
+       ret = iomap_iter_advance(iter);
+       if (ret <= 0)
+               return ret;
+
+       ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags,
+                              &iter->iomap, &iter->srcmap);
+       if (ret < 0)
+               return ret;
+       iomap_iter_done(iter);
+       return 1;
+}