From: Jens Axboe <jens.axboe@oracle.com>
Date: Tue, 23 Oct 2007 18:35:58 +0000 (+0200)
Subject: [SG] Add debug check for page alignment
X-Git-Tag: v2.6.24-rc1~26
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=de26103de56a0c482ad21296eae9b06deefc8e62;p=linux-2.6

[SG] Add debug check for page alignment

Suggested by Boaz Harrosh <bharrosh@panasas.com>

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

diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 42daf5e152..df7ddcee7c 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -41,6 +41,11 @@ static inline void sg_set_page(struct scatterlist *sg, struct page *page)
 {
 	unsigned long page_link = sg->page_link & 0x3;
 
+	/*
+	 * In order for the low bit stealing approach to work, pages
+	 * must be aligned at a 32-bit boundary as a minimum.
+	 */
+	BUG_ON((unsigned long) page & 0x03);
 #ifdef CONFIG_DEBUG_SG
 	BUG_ON(sg->sg_magic != SG_MAGIC);
 #endif