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[dm-devel] [PATCH] block: factor out bio_check_eod()



End of device check is done twice in __generic_make_request() and it's
fully inlined each time.  Factor out bio_check_eod().

This is taken from Jens' zero-length barrier patch.

Signed-off-by: Tejun Heo <htejun gmail com>
Cc: Jens Axboe <jens axboe oracle com>
---
 block/ll_rw_blk.c |   63 ++++++++++++++++++++++++++++--------------------------
 1 file changed, 33 insertions(+), 30 deletions(-)

Index: work/block/ll_rw_blk.c
===================================================================
--- work.orig/block/ll_rw_blk.c
+++ work/block/ll_rw_blk.c
@@ -3094,6 +3094,35 @@ static inline int should_fail_request(st
 
 #endif /* CONFIG_FAIL_MAKE_REQUEST */
 
+/*
+ * Check whether this bio extends beyond the end of the device.
+ */
+static int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
+{
+	sector_t maxsector;
+
+	if (!nr_sectors)
+		return 0;
+
+	/* Test device or partition size, when known. */
+	maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
+	if (maxsector) {
+		sector_t sector = bio->bi_sector;
+
+		if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
+			/*
+			 * This may well happen - the kernel calls bread()
+			 * without checking the size of the device, e.g., when
+			 * mounting a device.
+			 */
+			handle_bad_sector(bio);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
 /**
  * generic_make_request: hand a buffer to its device driver for I/O
  * @bio:  The bio describing the location in memory and on the device.
@@ -3121,27 +3150,14 @@ static inline int should_fail_request(st
 static inline void __generic_make_request(struct bio *bio)
 {
 	request_queue_t *q;
-	sector_t maxsector;
 	sector_t old_sector;
 	int ret, nr_sectors = bio_sectors(bio);
 	dev_t old_dev;
 
 	might_sleep();
-	/* Test device or partition size, when known. */
-	maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
-	if (maxsector) {
-		sector_t sector = bio->bi_sector;
 
-		if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
-			/*
-			 * This may well happen - the kernel calls bread()
-			 * without checking the size of the device, e.g., when
-			 * mounting a device.
-			 */
-			handle_bad_sector(bio);
-			goto end_io;
-		}
-	}
+	if (bio_check_eod(bio, nr_sectors))
+		goto end_io;
 
 	/*
 	 * Resolve the mapping until finished. (drivers are
@@ -3197,21 +3213,8 @@ end_io:
 		old_sector = bio->bi_sector;
 		old_dev = bio->bi_bdev->bd_dev;
 
-		maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
-		if (maxsector) {
-			sector_t sector = bio->bi_sector;
-
-			if (maxsector < nr_sectors ||
-					maxsector - nr_sectors < sector) {
-				/*
-				 * This may well happen - partitions are not
-				 * checked to make sure they are within the size
-				 * of the whole device.
-				 */
-				handle_bad_sector(bio);
-				goto end_io;
-			}
-		}
+		if (bio_check_eod(bio, nr_sectors))
+			goto end_io;
 
 		ret = q->make_request_fn(q, bio);
 	} while (ret);


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