[PATCH 15/17] gfs2: use bdev_rw_virt in gfs2_read_super

[Christoph Hellwig <hch@lst.de>]

Switch gfs2_read_super to allocate the superblock buffer using kmalloc
which falls back to the page allocator for PAGE_SIZE allocation but
gives us a kernel virtual address and then use bdev_rw_virt to perform
the synchronous read into it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/gfs2/ops_fstype.c | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index e83d293c3614..7c1014ba7ac7 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -226,28 +226,22 @@ static void gfs2_sb_in(struct gfs2_sbd *sdp, const struct gfs2_sb *str)
 
 static int gfs2_read_super(struct gfs2_sbd *sdp, sector_t sector, int silent)
 {
-	struct super_block *sb = sdp->sd_vfs;
-	struct page *page;
-	struct bio_vec bvec;
-	struct bio bio;
+	struct gfs2_sb *sb;
 	int err;
 
-	page = alloc_page(GFP_KERNEL);
-	if (unlikely(!page))
+	sb = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (unlikely(!sb))
 		return -ENOMEM;
-
-	bio_init(&bio, sb->s_bdev, &bvec, 1, REQ_OP_READ | REQ_META);
-	bio.bi_iter.bi_sector = sector * (sb->s_blocksize >> 9);
-	__bio_add_page(&bio, page, PAGE_SIZE, 0);
-
-	err = submit_bio_wait(&bio);
+	err = bdev_rw_virt(sdp->sd_vfs->s_bdev,
+			sector * (sdp->sd_vfs->s_blocksize >> 9), sb, PAGE_SIZE,
+			REQ_OP_READ | REQ_META);
 	if (err) {
 		pr_warn("error %d reading superblock\n", err);
-		__free_page(page);
+		kfree(sb);
 		return err;
 	}
-	gfs2_sb_in(sdp, page_address(page));
-	__free_page(page);
+	gfs2_sb_in(sdp, sb);
+	kfree(sb);
 	return gfs2_check_sb(sdp, silent);
 }
 
-- 
2.47.2