[PATCH 8/9] iomap: move the main iteration code into a separate file

Darrick J. Wong
2019-07-15T18:00:25Z

From: Darrick J. Wong <darrick.wong@oracle.com>

Move the main iteration code into a separate file so that we can group
related functions in a single file instead of having a single enormous
source file.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/Makefile | 1 -
fs/iomap.c | 91 -----------------------------------------------------
fs/iomap/Makefile | 1 +
fs/iomap/apply.c | 76 ++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 77 insertions(+), 92 deletions(-)
delete mode 100644 fs/iomap.c
create mode 100644 fs/iomap/apply.c

diff --git a/fs/Makefile b/fs/Makefile
index 8e61bdf9f330..d60089fd689b 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -52,7 +52,6 @@ obj-$(CONFIG_COREDUMP) += coredump.o
obj-$(CONFIG_SYSCTL) += drop_caches.o

obj-$(CONFIG_FHANDLE) += fhandle.o
-obj-$(CONFIG_FS_IOMAP) += iomap.o
obj-y += iomap/

obj-y += quota/
diff --git a/fs/iomap.c b/fs/iomap.c
deleted file mode 100644
index 88a3144351a9..000000000000
--- a/fs/iomap.c
+++ /dev/null
@@ -1,91 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Copyright (C) 2010 Red Hat, Inc.
- * Copyright (c) 2016-2018 Christoph Hellwig.
- */
-#include <linux/module.h>
-#include <linux/compiler.h>
-#include <linux/fs.h>
-#include <linux/iomap.h>
-#include <linux/uaccess.h>
-#include <linux/gfp.h>
-#include <linux/migrate.h>
-#include <linux/mm.h>
-#include <linux/mm_inline.h>
-#include <linux/swap.h>
-#include <linux/pagemap.h>
-#include <linux/pagevec.h>
-#include <linux/file.h>
-#include <linux/uio.h>
-#include <linux/backing-dev.h>
-#include <linux/buffer_head.h>
-#include <linux/task_io_accounting_ops.h>
-#include <linux/dax.h>
-#include <linux/sched/signal.h>
-
-#include "internal.h"
-
-/*
- * Execute a iomap write on a segment of the mapping that spans a
- * contiguous range of pages that have identical block mapping state.
- *
- * This avoids the need to map pages individually, do individual allocations
- * for each page and most importantly avoid the need for filesystem specific
- * locking per page. Instead, all the operations are amortised over the entire
- * range of pages. It is assumed that the filesystems will lock whatever
- * resources they require in the iomap_begin call, and release them in the
- * iomap_end call.
- */
-loff_t
-iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
- const struct iomap_ops *ops, void *data, iomap_actor_t actor)
-{
- struct iomap iomap = { 0 };
- loff_t written = 0, ret;
-
- /*
- * Need to map a range from start position for length bytes. This can
- * span multiple pages - it is only guaranteed to return a range of a
- * single type of pages (e.g. all into a hole, all mapped or all
- * unwritten). Failure at this point has nothing to undo.
- *
- * If allocation is required for this range, reserve the space now so
- * that the allocation is guaranteed to succeed later on. Once we copy
- * the data into the page cache pages, then we cannot fail otherwise we
- * expose transient stale data. If the reserve fails, we can safely
- * back out at this point as there is nothing to undo.
- */
- ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
- if (ret)
- return ret;
- if (WARN_ON(iomap.offset > pos))
- return -EIO;
- if (WARN_ON(iomap.length == 0))
- return -EIO;
-
- /*
- * Cut down the length to the one actually provided by the filesystem,
- * as it might not be able to give us the whole size that we requested.
- */
- if (iomap.offset + iomap.length < pos + length)
- length = iomap.offset + iomap.length - pos;
-
- /*
- * Now that we have guaranteed that the space allocation will succeed.
- * we can do the copy-in page by page without having to worry about
- * failures exposing transient data.
- */
- written = actor(inode, pos, length, data, &iomap);
-
- /*
- * Now the data has been copied, commit the range we've copied. This
- * should not fail unless the filesystem has had a fatal error.
- */
- if (ops->iomap_end) {
- ret = ops->iomap_end(inode, pos, length,
- written > 0 ? written : 0,
- flags, &iomap);
- }
-
- return written ? written : ret;
-}
diff --git a/fs/iomap/Makefile b/fs/iomap/Makefile
index 04cbeed44248..d8112f386415 100644
--- a/fs/iomap/Makefile
+++ b/fs/iomap/Makefile
@@ -9,6 +9,7 @@ ccflags-y += -I $(srctree)/$(src)/..
obj-$(CONFIG_FS_IOMAP) += iomap.o

iomap-y += \
+ apply.o \
direct-io.o \
buffered-io.o \
fiemap.o \
diff --git a/fs/iomap/apply.c b/fs/iomap/apply.c
new file mode 100644
index 000000000000..844e56612dd2
--- /dev/null
+++ b/fs/iomap/apply.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2010 Red Hat, Inc.
+ * Copyright (c) 2016-2018 Christoph Hellwig.
+ */
+#include <linux/module.h>
+#include <linux/compiler.h>
+#include <linux/fs.h>
+#include <linux/iomap.h>
+
+#include "internal.h"
+
+/*
+ * Execute a iomap write on a segment of the mapping that spans a
+ * contiguous range of pages that have identical block mapping state.
+ *
+ * This avoids the need to map pages individually, do individual allocations
+ * for each page and most importantly avoid the need for filesystem specific
+ * locking per page. Instead, all the operations are amortised over the entire
+ * range of pages. It is assumed that the filesystems will lock whatever
+ * resources they require in the iomap_begin call, and release them in the
+ * iomap_end call.
+ */
+loff_t
+iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
+ const struct iomap_ops *ops, void *data, iomap_actor_t actor)
+{
+ struct iomap iomap = { 0 };
+ loff_t written = 0, ret;
+
+ /*
+ * Need to map a range from start position for length bytes. This can
+ * span multiple pages - it is only guaranteed to return a range of a
+ * single type of pages (e.g. all into a hole, all mapped or all
+ * unwritten). Failure at this point has nothing to undo.
+ *
+ * If allocation is required for this range, reserve the space now so
+ * that the allocation is guaranteed to succeed later on. Once we copy
+ * the data into the page cache pages, then we cannot fail otherwise we
+ * expose transient stale data. If the reserve fails, we can safely
+ * back out at this point as there is nothing to undo.
+ */
+ ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
+ if (ret)
+ return ret;
+ if (WARN_ON(iomap.offset > pos))
+ return -EIO;
+ if (WARN_ON(iomap.length == 0))
+ return -EIO;
+
+ /*
+ * Cut down the length to the one actually provided by the filesystem,
+ * as it might not be able to give us the whole size that we requested.
+ */
+ if (iomap.offset + iomap.length < pos + length)
+ length = iomap.offset + iomap.length - pos;
+
+ /*
+ * Now that we have guaranteed that the space allocation will succeed.
+ * we can do the copy-in page by page without having to worry about
+ * failures exposing transient data.
+ */
+ written = actor(inode, pos, length, data, &iomap);
+
+ /*
+ * Now the data has been copied, commit the range we've copied. This
+ * should not fail unless the filesystem has had a fatal error.
+ */
+ if (ops->iomap_end) {
+ ret = ops->iomap_end(inode, pos, length,
+ written > 0 ? written : 0,
+ flags, &iomap);
+ }
+
+ return written ? written : ret;
+}