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

Christoph Hellwig
2025-04-22T14:27:32Z

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