1 files changed, 31 insertions, 43 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e1e111c8b08b..ac9554d71a46 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2846,7 +2846,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	u64 features;
 	u16 csum_type;
 	struct btrfs_key location;
-	struct buffer_head *bh;
 	struct btrfs_super_block *disk_super;
 	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 	struct btrfs_root *tree_root;
@@ -2887,9 +2886,9 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	/*
 	 * Read super block and check the signature bytes only
 	 */
-	bh = btrfs_read_dev_super(fs_devices->latest_bdev);
-	if (IS_ERR(bh)) {
-		err = PTR_ERR(bh);
+	disk_super = btrfs_read_dev_super(fs_devices->latest_bdev);
+	if (IS_ERR(disk_super)) {
+		err = PTR_ERR(disk_super);
 		goto fail_alloc;
 	}
 
@@ -2897,18 +2896,19 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	 * Verify the type first, if that or the the checksum value are
 	 * corrupted, we'll find out
 	 */
-	csum_type = btrfs_super_csum_type((struct btrfs_super_block *)bh->b_data);
+	csum_type = btrfs_super_csum_type(disk_super);
 	if (!btrfs_supported_super_csum(csum_type)) {
 		btrfs_err(fs_info, "unsupported checksum algorithm: %u",
 			  csum_type);
 		err = -EINVAL;
-		brelse(bh);
+		btrfs_release_disk_super(disk_super);
 		goto fail_alloc;
 	}
 
 	ret = btrfs_init_csum_hash(fs_info, csum_type);
 	if (ret) {
 		err = ret;
+		btrfs_release_disk_super(disk_super);
 		goto fail_alloc;
 	}
 
@@ -2916,10 +2916,10 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	 * We want to check superblock checksum, the type is stored inside.
 	 * Pass the whole disk block of size BTRFS_SUPER_INFO_SIZE (4k).
 	 */
-	if (btrfs_check_super_csum(fs_info, bh->b_data)) {
+	if (btrfs_check_super_csum(fs_info, (u8 *)disk_super)) {
 		btrfs_err(fs_info, "superblock checksum mismatch");
 		err = -EINVAL;
-		brelse(bh);
+		btrfs_release_disk_super(disk_super);
 		goto fail_alloc;
 	}
 
@@ -2928,8 +2928,8 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	 * following bytes up to INFO_SIZE, the checksum is calculated from
 	 * the whole block of INFO_SIZE
 	 */
-	memcpy(fs_info->super_copy, bh->b_data, sizeof(*fs_info->super_copy));
-	brelse(bh);
+	memcpy(fs_info->super_copy, disk_super, sizeof(*fs_info->super_copy));
+	btrfs_release_disk_super(disk_super);
 
 	disk_super = fs_info->super_copy;
 
@@ -3416,45 +3416,38 @@ static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate)
 	put_bh(bh);
 }
 
-int btrfs_read_dev_one_super(struct block_device *bdev, int copy_num,
-			struct buffer_head **bh_ret)
+struct btrfs_super_block *btrfs_read_dev_one_super(struct block_device *bdev,
+						   int copy_num)
 {
-	struct buffer_head *bh;
 	struct btrfs_super_block *super;
+	struct page *page;
 	u64 bytenr;
+	struct address_space *mapping = bdev->bd_inode->i_mapping;
 
 	bytenr = btrfs_sb_offset(copy_num);
 	if (bytenr + BTRFS_SUPER_INFO_SIZE >= i_size_read(bdev->bd_inode))
-		return -EINVAL;
+		return ERR_PTR(-EINVAL);
 
-	bh = __bread(bdev, bytenr / BTRFS_BDEV_BLOCKSIZE, BTRFS_SUPER_INFO_SIZE);
-	/*
-	 * If we fail to read from the underlying devices, as of now
-	 * the best option we have is to mark it EIO.
-	 */
-	if (!bh)
-		return -EIO;
+	page = read_cache_page_gfp(mapping, bytenr >> PAGE_SHIFT, GFP_NOFS);
+	if (IS_ERR(page))
+		return ERR_CAST(page);
 
-	super = (struct btrfs_super_block *)bh->b_data;
+	super = page_address(page);
 	if (btrfs_super_bytenr(super) != bytenr ||
 		    btrfs_super_magic(super) != BTRFS_MAGIC) {
-		brelse(bh);
-		return -EINVAL;
+		btrfs_release_disk_super(super);
+		return ERR_PTR(-EINVAL);
 	}
 
-	*bh_ret = bh;
-	return 0;
+	return super;
 }
 
 
-struct buffer_head *btrfs_read_dev_super(struct block_device *bdev)
+struct btrfs_super_block *btrfs_read_dev_super(struct block_device *bdev)
 {
-	struct buffer_head *bh;
-	struct buffer_head *latest = NULL;
-	struct btrfs_super_block *super;
+	struct btrfs_super_block *super, *latest = NULL;
 	int i;
 	u64 transid = 0;
-	int ret = -EINVAL;
 
 	/* we would like to check all the supers, but that would make
 	 * a btrfs mount succeed after a mkfs from a different FS.
@@ -3462,25 +3455,20 @@ struct buffer_head *btrfs_read_dev_super(struct block_device *bdev)
 	 * later supers, using BTRFS_SUPER_MIRROR_MAX instead
 	 */
 	for (i = 0; i < 1; i++) {
-		ret = btrfs_read_dev_one_super(bdev, i, &bh);
-		if (ret)
+		super = btrfs_read_dev_one_super(bdev, i);
+		if (IS_ERR(super))
 			continue;
 
-		super = (struct btrfs_super_block *)bh->b_data;
-
 		if (!latest || btrfs_super_generation(super) > transid) {
-			brelse(latest);
-			latest = bh;
+			if (latest)
+				btrfs_release_disk_super(super);
+
+			latest = super;
 			transid = btrfs_super_generation(super);
-		} else {
-			brelse(bh);
 		}
 	}
 
-	if (!latest)
-		return ERR_PTR(ret);
-
-	return latest;
+	return super;
 }
 
 /*