[PATCH] hfsplus: fix cross-page bio requests

[Sergei Antonov <saproj@gmail.com>]

Function hfsplus_submit_bio() did not work when the passed buffer spanned
over more than one page. That was because bio_alloc() is passed 1 as a number
of vectors but more than one vector were added inside the 'while' loop.
It periodically caused a mount error when the volume header could not be read.

This patch modifies the code so that only one vector is used. It works for
multiple pages too. Also adds a return code check after bio_alloc().

Cc: Anton Altaparmakov <aia21@cam.ac.uk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vyacheslav Dubeyko <slava@dubeyko.com>
Cc: Hin-Tak Leung <htl10@users.sourceforge.net>
Cc: Sougata Santra <sougata@tuxera.com>
Signed-off-by: Sergei Antonov <saproj@gmail.com>
---
 fs/hfsplus/wrapper.c | 29 ++++++++++-------------------
 1 file changed, 10 insertions(+), 19 deletions(-)

diff --git a/fs/hfsplus/wrapper.c b/fs/hfsplus/wrapper.c
index cc62356..e245faa 100644
--- a/fs/hfsplus/wrapper.c
+++ b/fs/hfsplus/wrapper.c
@@ -62,29 +62,20 @@ int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
 	offset = start & (io_size - 1);
 	sector &= ~((io_size >> HFSPLUS_SECTOR_SHIFT) - 1);
 
-	bio = bio_alloc(GFP_NOIO, 1);
-	bio->bi_iter.bi_sector = sector;
-	bio->bi_bdev = sb->s_bdev;
-
 	if (!(rw & WRITE) && data)
 		*data = (u8 *)buf + offset;
 
-	while (io_size > 0) {
-		unsigned int page_offset = offset_in_page(buf);
-		unsigned int len = min_t(unsigned int, PAGE_SIZE - page_offset,
-					 io_size);
-
-		ret = bio_add_page(bio, virt_to_page(buf), len, page_offset);
-		if (ret != len) {
-			ret = -EIO;
-			goto out;
-		}
-		io_size -= len;
-		buf = (u8 *)buf + len;
-	}
-
+	bio = bio_alloc(GFP_NOIO, 1);
+	if (!bio)
+		return -ENOMEM;
+	bio->bi_iter.bi_sector = sector;
+	bio->bi_bdev = sb->s_bdev;
+	bio->bi_vcnt = 1;
+	bio->bi_iter.bi_size = io_size;
+	bio->bi_io_vec[0].bv_page = virt_to_page(buf);
+	bio->bi_io_vec[0].bv_offset = offset_in_page(buf);
+	bio->bi_io_vec[0].bv_len = io_size;
 	ret = submit_bio_wait(rw, bio);
-out:
 	bio_put(bio);
 	return ret < 0 ? ret : 0;
 }
-- 
2.3.0