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

[Christoph Hellwig]

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 <h...@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