From: Andrew Morton <akpm@osdl.org>
Date: Sun, 30 Oct 2005 23:03:15 +0000 (-0800)
Subject: [PATCH] __bread oops fix
X-Git-Tag: v2.6.15-rc1~59^2~15^2~43
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a3e713b5fdd0e54c2e3c8909ccde2a98839e3a52;p=linux-2.6

[PATCH] __bread oops fix

If a filesystem passes an idiotic blocksize into bread(), __getblk_slow() will
warn and will return NULL.  We have a report (from Hubert Tonneau
<hubert.tonneau@fullpliant.org>) of isofs_fill_super() doing this (passing in
a silly block size) against an unplugged CDROM drive.

But a couple of __getblk_slow() callers forgot to check for the NULL bh, hence
oops.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/fs/buffer.c b/fs/buffer.c
index 75cac9ada0..35fa34977e 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1478,8 +1478,10 @@ EXPORT_SYMBOL(__getblk);
 void __breadahead(struct block_device *bdev, sector_t block, int size)
 {
 	struct buffer_head *bh = __getblk(bdev, block, size);
-	ll_rw_block(READA, 1, &bh);
-	brelse(bh);
+	if (likely(bh)) {
+		ll_rw_block(READA, 1, &bh);
+		brelse(bh);
+	}
 }
 EXPORT_SYMBOL(__breadahead);
 
@@ -1497,7 +1499,7 @@ __bread(struct block_device *bdev, sector_t block, int size)
 {
 	struct buffer_head *bh = __getblk(bdev, block, size);
 
-	if (!buffer_uptodate(bh))
+	if (likely(bh) && !buffer_uptodate(bh))
 		bh = __bread_slow(bh);
 	return bh;
 }