[PATCH] swsusp: use block device offsets to identify swap locations

Make swsusp use block device offsets instead of swap offsets to identify swap
locations and make it use the same code paths for writing as well as for
reading data.

This allows us to use the same code for handling swap files and swap
partitions and to simplify the code, eg.  by dropping rw_swap_page_sync().

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 17 insertions, 45 deletions

diff --git a/mm/page_io.c b/mm/page_io.c
index d4840ec..dbffec0 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -147,48 +147,3 @@ int swap_readpage(struct file *file, struct page *page)
 out:
 	return ret;
 }
-
-#ifdef CONFIG_SOFTWARE_SUSPEND
-/*
- * A scruffy utility function to read or write an arbitrary swap page
- * and wait on the I/O.  The caller must have a ref on the page.
- *
- * We use end_swap_bio_read() even for writes, because it happens to do what
- * we want.
- */
-int rw_swap_page_sync(int rw, swp_entry_t entry, struct page *page,
-			struct bio **bio_chain)
-{
-	struct bio *bio;
-	int ret = 0;
-	int bio_rw;
-
-	lock_page(page);
-
-	bio = get_swap_bio(GFP_KERNEL, entry.val, page, end_swap_bio_read);
-	if (bio == NULL) {
-		unlock_page(page);
-		ret = -ENOMEM;
-		goto out;
-	}
-
-	bio_rw = rw;
-	if (!bio_chain)
-		bio_rw |= (1 << BIO_RW_SYNC);
-	if (bio_chain)
-		bio_get(bio);
-	submit_bio(bio_rw, bio);
-	if (bio_chain == NULL) {
-		wait_on_page_locked(page);
-
-		if (!PageUptodate(page) || PageError(page))
-			ret = -EIO;
-	}
-	if (bio_chain) {
-		bio->bi_private = *bio_chain;
-		*bio_chain = bio;
-	}
-out:
-	return ret;
-}
-#endif
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 2bfacba..5524236 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -945,6 +945,23 @@ sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset)
 	}
 }
 
+#ifdef CONFIG_SOFTWARE_SUSPEND
+/*
+ * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
+ * corresponding to given index in swap_info (swap type).
+ */
+sector_t swapdev_block(int swap_type, pgoff_t offset)
+{
+	struct swap_info_struct *sis;
+
+	if (swap_type >= nr_swapfiles)
+		return 0;
+
+	sis = swap_info + swap_type;
+	return (sis->flags & SWP_WRITEOK) ? map_swap_page(sis, offset) : 0;
+}
+#endif /* CONFIG_SOFTWARE_SUSPEND */
+
 /*
  * Free all of a swapdev's extent information
  */