[PATCH 2/2] erofs-utils: mkfs: add `--inode-digest-xattr` option
Gao Xiang
hsiangkao at linux.alibaba.com
Tue Dec 30 00:15:10 AEDT 2025
Hi Hongbo,
On 2025/12/29 21:06, Hongbo Li wrote:
> 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?
Yeah, thanks for catching this, I will refine another version later.
Thanks,
Gao Xiang
>
> 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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