[PATCH 11/19] zonefs: use bdev_rw_virt in zonefs_read_super

Christoph Hellwig
2025-04-30T21:22:32Z

Switch zonefs_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>
Acked-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
fs/zonefs/super.c | 34 ++++++++++++----------------------
1 file changed, 12 insertions(+), 22 deletions(-)

diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
index faf1eb87895d..d165eb979f21 100644
--- a/fs/zonefs/super.c
+++ b/fs/zonefs/super.c
@@ -1111,28 +1111,19 @@ static int zonefs_read_super(struct super_block *sb)
struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
struct zonefs_super *super;
u32 crc, stored_crc;
- struct page *page;
- struct bio_vec bio_vec;
- struct bio bio;
int ret;

- page = alloc_page(GFP_KERNEL);
- if (!page)
+ super = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!super)
return -ENOMEM;

- bio_init(&bio, sb->s_bdev, &bio_vec, 1, REQ_OP_READ);
- bio.bi_iter.bi_sector = 0;
- __bio_add_page(&bio, page, PAGE_SIZE, 0);
-
- ret = submit_bio_wait(&bio);
+ ret = bdev_rw_virt(sb->s_bdev, 0, super, PAGE_SIZE, REQ_OP_READ);
if (ret)
- goto free_page;
-
- super = page_address(page);
+ goto free_super;

ret = -EINVAL;
if (le32_to_cpu(super->s_magic) != ZONEFS_MAGIC)
- goto free_page;
+ goto free_super;

stored_crc = le32_to_cpu(super->s_crc);
super->s_crc = 0;
@@ -1140,14 +1131,14 @@ static int zonefs_read_super(struct super_block *sb)
if (crc != stored_crc) {
zonefs_err(sb, "Invalid checksum (Expected 0x%08x, got 0x%08x)",
crc, stored_crc);
- goto free_page;
+ goto free_super;
}

sbi->s_features = le64_to_cpu(super->s_features);
if (sbi->s_features & ~ZONEFS_F_DEFINED_FEATURES) {
zonefs_err(sb, "Unknown features set 0x%llx\n",
sbi->s_features);
- goto free_page;
+ goto free_super;
}

if (sbi->s_features & ZONEFS_F_UID) {
@@ -1155,7 +1146,7 @@ static int zonefs_read_super(struct super_block *sb)
le32_to_cpu(super->s_uid));
if (!uid_valid(sbi->s_uid)) {
zonefs_err(sb, "Invalid UID feature\n");
- goto free_page;
+ goto free_super;
}
}

@@ -1164,7 +1155,7 @@ static int zonefs_read_super(struct super_block *sb)
le32_to_cpu(super->s_gid));
if (!gid_valid(sbi->s_gid)) {
zonefs_err(sb, "Invalid GID feature\n");
- goto free_page;
+ goto free_super;
}
}

@@ -1173,15 +1164,14 @@ static int zonefs_read_super(struct super_block *sb)

if (memchr_inv(super->s_reserved, 0, sizeof(super->s_reserved))) {
zonefs_err(sb, "Reserved area is being used\n");
- goto free_page;
+ goto free_super;
}

import_uuid(&sbi->s_uuid, super->s_uuid);
ret = 0;

-free_page:
- __free_page(page);
-
+free_super:
+ kfree(super);
return ret;
}

--
2.47.2