PM / Hibernate: Separate block_io

Move block I/O operations to a separate file. It is because it will
be used later not only by the swap writer.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 103 insertions, 0 deletions

diff --git a/kernel/power/block_io.c b/kernel/power/block_io.c
new file mode 100644
index 000000000000..2a2f8aed8e59
--- /dev/null
+++ b/kernel/power/block_io.c
@@ -0,0 +1,103 @@
+/*
+ * This file provides functions for block I/O operations on swap/file.
+ *
+ * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@ucw.cz>
+ * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/bio.h>
+#include <linux/kernel.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+
+#include "power.h"
+
+/**
+ *      submit - submit BIO request.
+ *      @rw:    READ or WRITE.
+ *      @off    physical offset of page.
+ *      @page:  page we're reading or writing.
+ *      @bio_chain: list of pending biod (for async reading)
+ *
+ *      Straight from the textbook - allocate and initialize the bio.
+ *      If we're reading, make sure the page is marked as dirty.
+ *      Then submit it and, if @bio_chain == NULL, wait.
+ */
+static int submit(int rw, struct block_device *bdev, sector_t sector,
+                struct page *page, struct bio **bio_chain)
+{
+        const int bio_rw = rw | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG);
+        struct bio *bio;
+
+        bio = bio_alloc(__GFP_WAIT | __GFP_HIGH, 1);
+        bio->bi_sector = sector;
+        bio->bi_bdev = bdev;
+        bio->bi_end_io = end_swap_bio_read;
+
+        if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
+                printk(KERN_ERR "PM: Adding page to bio failed at %ld\n",
+                        sector);
+                bio_put(bio);
+                return -EFAULT;
+        }
+
+        lock_page(page);
+        bio_get(bio);
+
+        if (bio_chain == NULL) {
+                submit_bio(bio_rw, bio);
+                wait_on_page_locked(page);
+                if (rw == READ)
+                        bio_set_pages_dirty(bio);
+                bio_put(bio);
+        } else {
+                if (rw == READ)
+                        get_page(page); /* These pages are freed later */
+                bio->bi_private = *bio_chain;
+                *bio_chain = bio;
+                submit_bio(bio_rw, bio);
+        }
+        return 0;
+}
+
+int hib_bio_read_page(pgoff_t page_off, void *addr, struct bio **bio_chain)
+{
+        return submit(READ, hib_resume_bdev, page_off * (PAGE_SIZE >> 9),
+                        virt_to_page(addr), bio_chain);
+}
+
+int hib_bio_write_page(pgoff_t page_off, void *addr, struct bio **bio_chain)
+{
+        return submit(WRITE, hib_resume_bdev, page_off * (PAGE_SIZE >> 9),
+                        virt_to_page(addr), bio_chain);
+}
+
+int hib_wait_on_bio_chain(struct bio **bio_chain)
+{
+        struct bio *bio;
+        struct bio *next_bio;
+        int ret = 0;
+
+        if (bio_chain == NULL)
+                return 0;
+
+        bio = *bio_chain;
+        if (bio == NULL)
+                return 0;
+        while (bio) {
+                struct page *page;
+
+                next_bio = bio->bi_private;
+                page = bio->bi_io_vec[0].bv_page;
+                wait_on_page_locked(page);
+                if (!PageUptodate(page) || PageError(page))
+                        ret = -EIO;
+                put_page(page);
+                bio_put(bio);
+                bio = next_bio;
+        }
+        *bio_chain = NULL;
+        return ret;
+}