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-rw-r--r--fs/iomap/seek.c104
1 files changed, 104 insertions, 0 deletions
diff --git a/fs/iomap/seek.c b/fs/iomap/seek.c
new file mode 100644
index 000000000..a845c012b
--- /dev/null
+++ b/fs/iomap/seek.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017 Red Hat, Inc.
+ * Copyright (c) 2018-2021 Christoph Hellwig.
+ */
+#include <linux/module.h>
+#include <linux/compiler.h>
+#include <linux/fs.h>
+#include <linux/iomap.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+
+static loff_t iomap_seek_hole_iter(const struct iomap_iter *iter,
+ loff_t *hole_pos)
+{
+ loff_t length = iomap_length(iter);
+
+ switch (iter->iomap.type) {
+ case IOMAP_UNWRITTEN:
+ *hole_pos = mapping_seek_hole_data(iter->inode->i_mapping,
+ iter->pos, iter->pos + length, SEEK_HOLE);
+ if (*hole_pos == iter->pos + length)
+ return length;
+ return 0;
+ case IOMAP_HOLE:
+ *hole_pos = iter->pos;
+ return 0;
+ default:
+ return length;
+ }
+}
+
+loff_t
+iomap_seek_hole(struct inode *inode, loff_t pos, const struct iomap_ops *ops)
+{
+ loff_t size = i_size_read(inode);
+ struct iomap_iter iter = {
+ .inode = inode,
+ .pos = pos,
+ .flags = IOMAP_REPORT,
+ };
+ int ret;
+
+ /* Nothing to be found before or beyond the end of the file. */
+ if (pos < 0 || pos >= size)
+ return -ENXIO;
+
+ iter.len = size - pos;
+ while ((ret = iomap_iter(&iter, ops)) > 0)
+ iter.processed = iomap_seek_hole_iter(&iter, &pos);
+ if (ret < 0)
+ return ret;
+ if (iter.len) /* found hole before EOF */
+ return pos;
+ return size;
+}
+EXPORT_SYMBOL_GPL(iomap_seek_hole);
+
+static loff_t iomap_seek_data_iter(const struct iomap_iter *iter,
+ loff_t *hole_pos)
+{
+ loff_t length = iomap_length(iter);
+
+ switch (iter->iomap.type) {
+ case IOMAP_HOLE:
+ return length;
+ case IOMAP_UNWRITTEN:
+ *hole_pos = mapping_seek_hole_data(iter->inode->i_mapping,
+ iter->pos, iter->pos + length, SEEK_DATA);
+ if (*hole_pos < 0)
+ return length;
+ return 0;
+ default:
+ *hole_pos = iter->pos;
+ return 0;
+ }
+}
+
+loff_t
+iomap_seek_data(struct inode *inode, loff_t pos, const struct iomap_ops *ops)
+{
+ loff_t size = i_size_read(inode);
+ struct iomap_iter iter = {
+ .inode = inode,
+ .pos = pos,
+ .flags = IOMAP_REPORT,
+ };
+ int ret;
+
+ /* Nothing to be found before or beyond the end of the file. */
+ if (pos < 0 || pos >= size)
+ return -ENXIO;
+
+ iter.len = size - pos;
+ while ((ret = iomap_iter(&iter, ops)) > 0)
+ iter.processed = iomap_seek_data_iter(&iter, &pos);
+ if (ret < 0)
+ return ret;
+ if (iter.len) /* found data before EOF */
+ return pos;
+ /* We've reached the end of the file without finding data */
+ return -ENXIO;
+}
+EXPORT_SYMBOL_GPL(iomap_seek_data);