Commit 93b856bb authored by Jeffle Xu's avatar Jeffle Xu Committed by Gao Xiang
Browse files

erofs: add fscache mode check helper 



Until then erofs is exactly blockdev based filesystem.

A new fscache-based mode is going to be introduced for erofs to support
scenarios where on-demand read semantics is needed, e.g. container
image distribution. In this case, erofs could be mounted from data blobs
through fscache.

Add a helper checking which mode erofs works in, and twist the code in
preparation for the upcoming fscache mode.

Signed-off-by: default avatarJeffle Xu <jefflexu@linux.alibaba.com>
Reviewed-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220425122143.56815-11-jefflexu@linux.alibaba.com


Acked-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
parent 94d78946

fs/erofs/internal.h

+5 −0
Original line number Diff line number Diff line
@@ -161,6 +161,11 @@ struct erofs_sb_info { 
#define set_opt(opt, option)	((opt)->mount_opt |= EROFS_MOUNT_##option)

#define test_opt(opt, option)	((opt)->mount_opt & EROFS_MOUNT_##option)



static inline bool erofs_is_fscache_mode(struct super_block *sb)

{

	return IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND) && !sb->s_bdev;

}



enum {

	EROFS_ZIP_CACHE_DISABLED,

	EROFS_ZIP_CACHE_READAHEAD,

fs/erofs/super.c

+29 −15
Original line number Diff line number Diff line
@@ -260,6 +260,7 @@ static int erofs_init_devices(struct super_block *sb, 
		}

		dis = ptr + erofs_blkoff(pos);



		if (!erofs_is_fscache_mode(sb)) {

			bdev = blkdev_get_by_path(dif->path,

						  FMODE_READ | FMODE_EXCL,

						  sb->s_type);
@@ -268,7 +269,10 @@ static int erofs_init_devices(struct super_block *sb, 
				break;

			}

			dif->bdev = bdev;

		dif->dax_dev = fs_dax_get_by_bdev(bdev, &dif->dax_part_off);

			dif->dax_dev = fs_dax_get_by_bdev(bdev,

							  &dif->dax_part_off);

		}



		dif->blocks = le32_to_cpu(dis->blocks);

		dif->mapped_blkaddr = le32_to_cpu(dis->mapped_blkaddr);

		sbi->total_blocks += dif->blocks;
@@ -625,21 +629,28 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc) 


	sb->s_magic = EROFS_SUPER_MAGIC;



	if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {

		erofs_err(sb, "failed to set erofs blksize");

		return -EINVAL;

	}



	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);

	if (!sbi)

		return -ENOMEM;



	sb->s_fs_info = sbi;

	sbi->opt = ctx->opt;

	sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->dax_part_off);

	sbi->devs = ctx->devs;

	ctx->devs = NULL;



	if (erofs_is_fscache_mode(sb)) {

		sb->s_blocksize = EROFS_BLKSIZ;

		sb->s_blocksize_bits = LOG_BLOCK_SIZE;

	} else {

		if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {

			erofs_err(sb, "failed to set erofs blksize");

			return -EINVAL;

		}



		sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev,

						  &sbi->dax_part_off);

	}



	err = erofs_read_superblock(sb);

	if (err)

		return err;
@@ -897,7 +908,10 @@ static int erofs_statfs(struct dentry *dentry, struct kstatfs *buf) 
{

	struct super_block *sb = dentry->d_sb;

	struct erofs_sb_info *sbi = EROFS_SB(sb);

	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

	u64 id = 0;



	if (!erofs_is_fscache_mode(sb))

		id = huge_encode_dev(sb->s_bdev->bd_dev);



	buf->f_type = sb->s_magic;

	buf->f_bsize = EROFS_BLKSIZ;