From: Jens Axboe <jens.axboe@oracle.com>
Date: Fri, 15 Aug 2008 08:56:11 +0000 (+0200)
Subject: block: make bi_phys_segments an unsigned int instead of short
X-Git-Tag: v2.6.28-rc1~733^2~108
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=5b99c2ffa980528a197f26c7d876cceeccce8dd5;p=linux-2.6-omap-h63xx.git

block: make bi_phys_segments an unsigned int instead of short

raid5 can overflow with more than 255 stripes, and we can increase it
to an int for free on both 32 and 64-bit archs due to the padding.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 05b22925cce..37e546528f9 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -102,17 +102,17 @@ const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
 #endif
 
 /*
- * We maintain a biased count of active stripes in the bottom 8 bits of
- * bi_phys_segments, and a count of processed stripes in the upper 8 bits
+ * We maintain a biased count of active stripes in the bottom 16 bits of
+ * bi_phys_segments, and a count of processed stripes in the upper 16 bits
  */
 static inline int raid5_bi_phys_segments(struct bio *bio)
 {
-	return bio->bi_phys_segments & 0xff;
+	return bio->bi_phys_segments & 0xffff;
 }
 
 static inline int raid5_bi_hw_segments(struct bio *bio)
 {
-	return (bio->bi_phys_segments >> 8) & 0xff;
+	return (bio->bi_phys_segments >> 16) & 0xffff;
 }
 
 static inline int raid5_dec_bi_phys_segments(struct bio *bio)
@@ -126,13 +126,13 @@ static inline int raid5_dec_bi_hw_segments(struct bio *bio)
 	unsigned short val = raid5_bi_hw_segments(bio);
 
 	--val;
-	bio->bi_phys_segments = (val << 8) | raid5_bi_phys_segments(bio);
+	bio->bi_phys_segments = (val << 16) | raid5_bi_phys_segments(bio);
 	return val;
 }
 
 static inline void raid5_set_bi_hw_segments(struct bio *bio, unsigned int cnt)
 {
-	bio->bi_phys_segments = raid5_bi_phys_segments(bio) || (cnt << 8);
+	bio->bi_phys_segments = raid5_bi_phys_segments(bio) || (cnt << 16);
 }
 
 static inline int raid6_next_disk(int disk, int raid_disks)
diff --git a/include/linux/bio.h b/include/linux/bio.h
index dfc3556d311..2c0c09034fd 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -75,7 +75,7 @@ struct bio {
 	/* Number of segments in this BIO after
 	 * physical address coalescing is performed.
 	 */
-	unsigned short		bi_phys_segments;
+	unsigned int		bi_phys_segments;
 
 	unsigned int		bi_size;	/* residual I/O count */