On Wed, Apr 06, 2022 at 03:56:12PM +0800, Jeffle Xu wrote:
> Introduce 'fsid' mount option to enable on-demand read sementics, in
> which case, erofs will be mounted from data blobs. Users could specify
> the name of primary data blob by this mount option.
>
> Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
> ---
> fs/erofs/super.c | 48 ++++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 42 insertions(+), 6 deletions(-)
>
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index a5e4de60a0d8..292b4a70ce19 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -398,6 +398,7 @@ enum {
> Opt_dax,
> Opt_dax_enum,
> Opt_device,
> + Opt_fsid,
> Opt_err
> };
>
> @@ -422,6 +423,7 @@ static const struct fs_parameter_spec erofs_fs_parameters[] = {
> fsparam_flag("dax", Opt_dax),
> fsparam_enum("dax", Opt_dax_enum, erofs_dax_param_enums),
> fsparam_string("device", Opt_device),
> + fsparam_string("fsid", Opt_fsid),
> {}
> };
>
> @@ -517,6 +519,16 @@ static int erofs_fc_parse_param(struct fs_context *fc,
> }
> ++ctx->devs->extra_devices;
> break;
> + case Opt_fsid:
> +#ifdef CONFIG_EROFS_FS_ONDEMAND
> + kfree(ctx->opt.fsid);
> + ctx->opt.fsid = kstrdup(param->string, GFP_KERNEL);
> + if (!ctx->opt.fsid)
> + return -ENOMEM;
> +#else
> + errorfc(fc, "fsid option not supported");
> +#endif
> + break;
> default:
> return -ENOPARAM;
> }
> @@ -597,9 +609,14 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
> sb->s_maxbytes = MAX_LFS_FILESIZE;
> sb->s_op = &erofs_sops;
>
> - if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {
> - erofs_err(sb, "failed to set erofs blksize");
> - return -EINVAL;
> + 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 = kzalloc(sizeof(*sbi), GFP_KERNEL);
> @@ -608,7 +625,7 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>
> sb->s_fs_info = sbi;
> sbi->opt = ctx->opt;
> - sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->dax_part_off);
> + ctx->opt.fsid = NULL;
> sbi->devs = ctx->devs;
> ctx->devs = NULL;
>
> @@ -625,6 +642,8 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
> err = super_setup_bdi(sb);
> if (err)
> return err;
> + } else {
> + sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->dax_part_off);
It should go with the previous patch? And even over long line here.
Thanks,
Gao Xiang
> }
>
> err = erofs_read_superblock(sb);
> @@ -684,6 +703,11 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>
> static int erofs_fc_get_tree(struct fs_context *fc)
> {
> + struct erofs_fs_context *ctx = fc->fs_private;
> +
> + if (IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND) && ctx->opt.fsid)
> + return get_tree_nodev(fc, erofs_fc_fill_super);
> +
> return get_tree_bdev(fc, erofs_fc_fill_super);
> }
>
> @@ -733,6 +757,7 @@ static void erofs_fc_free(struct fs_context *fc)
> struct erofs_fs_context *ctx = fc->fs_private;
>
> erofs_free_dev_context(ctx->devs);
> + kfree(ctx->opt.fsid);
> kfree(ctx);
> }
>
> @@ -773,7 +798,10 @@ static void erofs_kill_sb(struct super_block *sb)
>
> WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);
>
> - kill_block_super(sb);
> + if (erofs_is_fscache_mode(sb))
> + generic_shutdown_super(sb);
> + else
> + kill_block_super(sb);
>
> sbi = EROFS_SB(sb);
> if (!sbi)
> @@ -783,6 +811,7 @@ static void erofs_kill_sb(struct super_block *sb)
> fs_put_dax(sbi->dax_dev);
> erofs_fscache_unregister_cookie(&sbi->s_fscache);
> erofs_fscache_unregister_fs(sb);
> + kfree(sbi->opt.fsid);
> kfree(sbi);
> sb->s_fs_info = NULL;
> }
> @@ -884,7 +913,10 @@ 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;
> @@ -929,6 +961,10 @@ static int erofs_show_options(struct seq_file *seq, struct dentry *root)
> seq_puts(seq, ",dax=always");
> if (test_opt(opt, DAX_NEVER))
> seq_puts(seq, ",dax=never");
> +#ifdef CONFIG_EROFS_FS_ONDEMAND
> + if (opt->fsid)
> + seq_printf(seq, ",fsid=%s", opt->fsid);
> +#endif
> return 0;
> }
>
> --
> 2.27.0
>
