[PATCH 2/2] erofs-utils: mkfs: add `--inode-digest-xattr` option
Hongbo Li
lihongbo22 at huawei.com
Tue Dec 30 00:06:10 AEDT 2025
Hi Xiang,
On 2025/12/29 15:49, Gao Xiang wrote:
> Based on the original Hongbo's version [1], it enables storing the
> SHA-256 digest of each inode as an extended attribute, in preparation
> for the upcoming page cache sharing feature.
>
> Example usage:
> $ mkfs.erofs --inode-digest-xattr=trusted.erofs.fingerprint [-zlz4hc] foo.erofs foo/
>
> Co-developed-by: Hongbo Li <lihongbo22 at huawei.com>
> [1] https://lore.kernel.org/r/20251118015849.228939-1-lihongbo22@huawei.com
> Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>
> ---
> include/erofs/internal.h | 2 ++
> include/erofs/xattr.h | 2 ++
> include/erofs_fs.h | 4 +++-
> lib/inode.c | 44 ++++++++++++++++++++++++++++++++++++++--
> lib/super.c | 13 ++++++++++--
> lib/xattr.c | 14 ++++++++++++-
> mkfs/main.c | 27 ++++++++++++++++++++----
> 7 files changed, 96 insertions(+), 10 deletions(-)
>
> diff --git a/include/erofs/internal.h b/include/erofs/internal.h
> index 62594b877151..5798f10e89c2 100644
> --- a/include/erofs/internal.h
> +++ b/include/erofs/internal.h
> @@ -130,6 +130,7 @@ struct erofs_sb_info {
>
> u32 xattr_prefix_start;
> u8 xattr_prefix_count;
> + u8 ishare_xattr_prefix_id;
> struct erofs_xattr_prefix_item *xattr_prefixes;
>
> struct erofs_vfile bdev;
> @@ -189,6 +190,7 @@ EROFS_FEATURE_FUNCS(metabox, incompat, INCOMPAT_METABOX)
> EROFS_FEATURE_FUNCS(sb_chksum, compat, COMPAT_SB_CHKSUM)
> EROFS_FEATURE_FUNCS(xattr_filter, compat, COMPAT_XATTR_FILTER)
> EROFS_FEATURE_FUNCS(plain_xattr_pfx, compat, COMPAT_PLAIN_XATTR_PFX)
> +EROFS_FEATURE_FUNCS(ishare_xattrs, compat, COMPAT_ISHARE_XATTRS)
>
> #define EROFS_I_EA_INITED_BIT 0
> #define EROFS_I_Z_INITED_BIT 1
> diff --git a/include/erofs/xattr.h b/include/erofs/xattr.h
> index 941bed778956..96546364f316 100644
> --- a/include/erofs/xattr.h
> +++ b/include/erofs/xattr.h
> @@ -33,6 +33,8 @@ char *erofs_export_xattr_ibody(struct erofs_inode *inode);
> int erofs_load_shared_xattrs_from_path(struct erofs_sb_info *sbi, const char *path,
> long inlinexattr_tolerance);
> int erofs_xattr_insert_name_prefix(const char *prefix);
> +int erofs_xattr_set_ishare_prefix(struct erofs_sb_info *sbi,
> + const char *prefix);
> void erofs_xattr_cleanup_name_prefixes(void);
> int erofs_xattr_flush_name_prefixes(struct erofs_importer *im, bool plain);
> int erofs_xattr_prefixes_init(struct erofs_sb_info *sbi);
> diff --git a/include/erofs_fs.h b/include/erofs_fs.h
> index 887f37faba59..8b0d155f8c4c 100644
> --- a/include/erofs_fs.h
> +++ b/include/erofs_fs.h
> @@ -17,6 +17,7 @@
> #define EROFS_FEATURE_COMPAT_MTIME 0x00000002
> #define EROFS_FEATURE_COMPAT_XATTR_FILTER 0x00000004
> #define EROFS_FEATURE_COMPAT_PLAIN_XATTR_PFX 0x00000010
> +#define EROFS_FEATURE_COMPAT_ISHARE_XATTRS 0x00000020
>
> /*
> * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should
> @@ -82,7 +83,8 @@ struct erofs_super_block {
> __le32 xattr_prefix_start; /* start of long xattr prefixes */
> __le64 packed_nid; /* nid of the special packed inode */
> __u8 xattr_filter_reserved; /* reserved for xattr name filter */
> - __u8 reserved[3];
> + __u8 ishare_xattr_prefix_id;
> + __u8 reserved[2];
> __le32 build_time; /* seconds added to epoch for mkfs time */
> __le64 rootnid_8b; /* (48BIT on) nid of root directory */
> __le64 reserved2;
> diff --git a/lib/inode.c b/lib/inode.c
> index 1d08e39317c0..c6085a52281a 100644
> --- a/lib/inode.c
> +++ b/lib/inode.c
> @@ -31,6 +31,7 @@
> #include "liberofs_metabox.h"
> #include "liberofs_private.h"
> #include "liberofs_rebuild.h"
> +#include "sha256.h"
>
> static inline bool erofs_is_special_identifier(const char *path)
> {
> @@ -1879,6 +1880,37 @@ static int erofs_prepare_dir_inode(struct erofs_importer *im,
> return 0;
> }
>
> +static int erofs_set_inode_fingerprint(struct erofs_inode *inode, int fd,
> + erofs_off_t pos)
> +{
> + u8 ishare_xattr_prefix_id = inode->sbi->ishare_xattr_prefix_id;
> + erofs_off_t remaining = inode->i_size;
> + struct erofs_vfile vf = { .fd = fd };
> + struct sha256_state md;
> + u8 out[32 + sizeof("sha256:") - 1];
> + int ret;
> +
> + if (!ishare_xattr_prefix_id)
> + return 0;
> + erofs_sha256_init(&md);
> + do {
> + u8 buf[32768];
> +
> + ret = erofs_io_pread(&vf, buf,
> + min_t(u64, remaining, sizeof(buf)), pos);
> + if (ret < 0)
> + return ret;
> + if (ret > 0)
> + erofs_sha256_process(&md, buf, ret);
> + remaining -= ret;
> + pos += ret;
> + } while (remaining);
> + erofs_sha256_done(&md, out + sizeof("sha256:") - 1);
> + memcpy(out, "sha256:", sizeof("sha256:") - 1);
> + return erofs_setxattr(inode, ishare_xattr_prefix_id, "",
> + out, sizeof(out));
> +}
> +
> static int erofs_mkfs_begin_nondirectory(struct erofs_importer *im,
> struct erofs_inode *inode)
> {
> @@ -1899,9 +1931,16 @@ static int erofs_mkfs_begin_nondirectory(struct erofs_importer *im,
> return -errno;
> __erofs_fallthrough;
> default:
> - break;
> + goto out;
We should keep use break here to set inode fingerprint in following step.
Another is that, here we use "erofs_set_inode_fingerprint" to hook the
fingerprint xattr in inode->xattrs, but the "erofs_prepare_xattr_ibody"
has calculated the xattr_size before. So should we move the
"erofs_prepare_xattr_ibody" later so that to make sure the fingerprint
xattr is set?
Thanks,
Hongbo
> + }
> +
> + if (S_ISREG(inode->i_mode) && inode->i_size) {
> + ret = erofs_set_inode_fingerprint(inode, ctx.fd, ctx.fpos);
> + if (ret < 0)
> + return ret;
> }
> - if (ctx.fd >= 0 && cfg.c_compr_opts[0].alg &&
> +
> + if (cfg.c_compr_opts[0].alg &&
> erofs_file_is_compressible(im, inode)) {
> ctx.ictx = erofs_prepare_compressed_file(im, inode);
> if (IS_ERR(ctx.ictx))
> @@ -1913,6 +1952,7 @@ static int erofs_mkfs_begin_nondirectory(struct erofs_importer *im,
> return ret;
> }
> }
> +out:
> return erofs_mkfs_go(im, EROFS_MKFS_JOB_NDIR, &ctx, sizeof(ctx));
> }
>
> diff --git a/lib/super.c b/lib/super.c
> index e54aff2d4ab7..a4837e5702ed 100644
> --- a/lib/super.c
> +++ b/lib/super.c
> @@ -146,7 +146,15 @@ int erofs_read_superblock(struct erofs_sb_info *sbi)
> sbi->build_time = le32_to_cpu(dsb->build_time);
>
> memcpy(&sbi->uuid, dsb->uuid, sizeof(dsb->uuid));
> -
> + if (erofs_sb_has_ishare_xattrs(sbi)) {
> + if (dsb->ishare_xattr_prefix_id >= sbi->xattr_prefix_count) {
> + erofs_err("invalid ishare xattr prefix id %d",
> + dsb->ishare_xattr_prefix_id);
> + return -EFSCORRUPTED;
> + }
> + sbi->ishare_xattr_prefix_id =
> + dsb->ishare_xattr_prefix_id | EROFS_XATTR_LONG_PREFIX;
> + }
> ret = z_erofs_parse_cfgs(sbi, dsb);
> if (ret)
> return ret;
> @@ -160,7 +168,6 @@ int erofs_read_superblock(struct erofs_sb_info *sbi)
> free(sbi->devs);
> sbi->devs = NULL;
> }
> -
> sbi->sb_valid = !ret;
> return ret;
> }
> @@ -206,6 +213,8 @@ int erofs_writesb(struct erofs_sb_info *sbi)
> .extra_devices = cpu_to_le16(sbi->extra_devices),
> .devt_slotoff = cpu_to_le16(sbi->devt_slotoff),
> .packed_nid = cpu_to_le64(sbi->packed_nid),
> + .ishare_xattr_prefix_id = sbi->ishare_xattr_prefix_id &
> + EROFS_XATTR_LONG_PREFIX_MASK,
> };
> char *buf;
> int ret;
> diff --git a/lib/xattr.c b/lib/xattr.c
> index b6b1a5e600fb..764aee3be3c3 100644
> --- a/lib/xattr.c
> +++ b/lib/xattr.c
> @@ -1495,9 +1495,21 @@ int erofs_xattr_insert_name_prefix(const char *prefix)
> }
>
> tnode->index = EROFS_XATTR_LONG_PREFIX | ea_prefix_count;
> - ea_prefix_count++;
> init_list_head(&tnode->list);
> list_add_tail(&tnode->list, &ea_name_prefixes);
> + return ea_prefix_count++;
> +}
> +
> +int erofs_xattr_set_ishare_prefix(struct erofs_sb_info *sbi,
> + const char *prefix)
> +{
> + int err;
> +
> + err = erofs_xattr_insert_name_prefix(prefix);
> + if (err < 0)
> + return err;
> + sbi->ishare_xattr_prefix_id = EROFS_XATTR_LONG_PREFIX | err;
> + erofs_sb_set_ishare_xattrs(sbi);
> return 0;
> }
>
> diff --git a/mkfs/main.c b/mkfs/main.c
> index aaa0300bca1b..7fd6e8419d44 100644
> --- a/mkfs/main.c
> +++ b/mkfs/main.c
> @@ -102,6 +102,7 @@ static struct option long_options[] = {
> #endif
> {"zD", optional_argument, NULL, 536},
> {"ZI", optional_argument, NULL, 537},
> + {"inode-digest-xattr", required_argument, NULL, 538},
> {0, 0, 0, 0},
> };
>
> @@ -1262,7 +1263,7 @@ static int mkfs_parse_options_cfg(struct erofs_importer_params *params,
> case 19:
> errno = 0;
> opt = erofs_xattr_insert_name_prefix(optarg);
> - if (opt) {
> + if (opt < 0) {
> erofs_err("failed to parse xattr name prefix: %s",
> erofs_strerror(opt));
> return opt;
> @@ -1424,6 +1425,14 @@ static int mkfs_parse_options_cfg(struct erofs_importer_params *params,
> else
> mkfscfg.inode_metazone = false;
> break;
> + case 538:
> + err = erofs_xattr_set_ishare_prefix(&g_sbi, optarg);
> + if (err < 0) {
> + erofs_err("failed to parse ishare name: %s",
> + erofs_strerror(err));
> + return err;
> + }
> + break;
> case 'V':
> version();
> exit(0);
> @@ -1878,9 +1887,12 @@ int main(int argc, char **argv)
> goto exit;
> }
>
> - if (cfg.c_extra_ea_name_prefixes)
> - erofs_xattr_flush_name_prefixes(&importer,
> - mkfs_plain_xattr_pfx);
> + err = erofs_xattr_flush_name_prefixes(&importer,
> + mkfs_plain_xattr_pfx);
> + if (err) {
> + erofs_err("failed to flush long xattr prefixes: %s",
> + erofs_strerror(err));
> + }
>
> root = erofs_new_inode(&g_sbi);
> if (IS_ERR(root)) {
> @@ -1888,6 +1900,13 @@ int main(int argc, char **argv)
> goto exit;
> }
> } else {
> + err = erofs_xattr_flush_name_prefixes(&importer,
> + mkfs_plain_xattr_pfx);
> + if (err) {
> + erofs_err("failed to flush long xattr prefixes: %s",
> + erofs_strerror(err));
> + }
> +
> root = erofs_rebuild_make_root(&g_sbi);
> if (IS_ERR(root)) {
> err = PTR_ERR(root);
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