* Re: [PATCH] erofs: delimit inode_share cache key components
2026-09-07 7:24 [PATCH] erofs: delimit inode_share cache key components ChengyuZhu6
@ 2026-09-07 8:18 ` Gao Xiang
2026-09-07 8:33 ` [PATCH v2] " ChengyuZhu6
1 sibling, 0 replies; 4+ messages in thread
From: Gao Xiang @ 2026-09-07 8:18 UTC (permalink / raw)
To: ChengyuZhu6; +Cc: linux-erofs, xiang, Chengyu Zhu
Hi Chengyu,
On Mon, Sep 07, 2026 at 03:24:40PM +0800, ChengyuZhu6 wrote:
> From: Chengyu Zhu <hudsonzhu@tencent.com>
>
> The selected fingerprint xattr is treated as opaque and accepts any
> positive length up to the filesystem block size. Appending the domain ID
> directly to such a value leaves no boundary between the two key components
> if a different fingerprint length is used.
>
> Change the key encoding as follows:
>
> fingerprint || domain_id -> domain_id || '\0' || fingerprint
>
> Since a mount option string cannot contain NUL, this makes the in-memory
> tuple unambiguous without constraining fingerprint contents or changing
> the on-disk format.
>
> Signed-off-by: Chengyu Zhu <hudsonzhu@tencent.com>
Subject: erofs: delimit inode_share key components
Previously, inode_share keys are encoded as follows:
fingerprint || domain_id
It would be better to have a separator between fingerprint and domain_id
so that fingerprint won't be parsed as part of a domain_id.
Change the key encoding as follows:
domain_id || '\0' || fingerprint
Since domain_id is a NIL-terminated string, this makes the in-memory
key indices unambiguous.
> ---
> fs/erofs/xattr.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
> index df7ea019526d..17c640aca5f7 100644
> --- a/fs/erofs/xattr.c
> +++ b/fs/erofs/xattr.c
> @@ -621,6 +621,7 @@ int erofs_xattr_fill_inode_fingerprint(struct erofs_inode_fingerprint *fp,
> struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
> struct erofs_xattr_prefix_item *prefix;
> const char *infix;
> + size_t domainlen;
> int valuelen, base_index;
>
> if (!test_opt(&sbi->opt, INODE_SHARE))
> @@ -633,17 +634,19 @@ int erofs_xattr_fill_inode_fingerprint(struct erofs_inode_fingerprint *fp,
> valuelen = erofs_getxattr(inode, base_index, infix, NULL, 0);
> if (valuelen <= 0 || valuelen > (1 << sbi->blkszbits))
> return -EFSCORRUPTED;
> - fp->size = valuelen + (domain_id ? strlen(domain_id) : 0);
> + domain_id = domain_id ?: "";
> + domainlen = strlen(domain_id);
> + fp->size = domainlen + 1 + valuelen;
> fp->opaque = kmalloc(fp->size, GFP_KERNEL);
> if (!fp->opaque)
> return -ENOMEM;
> + memcpy(fp->opaque, domain_id, domainlen + 1);
> if (valuelen != erofs_getxattr(inode, base_index, infix,
> - fp->opaque, valuelen)) {
> + fp->opaque + domainlen + 1, valuelen)) {
> kfree(fp->opaque);
> fp->opaque = NULL;
> return -EFSCORRUPTED;
> }
> - memcpy(fp->opaque + valuelen, domain_id, fp->size - valuelen);
> return 0;
Can you apply the following diff? domain_id cannot be NULL so it was a
redundant check:
diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index 17c640aca5f7..57cfb7520782 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -620,9 +620,8 @@ int erofs_xattr_fill_inode_fingerprint(struct erofs_inode_fingerprint *fp,
{
struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
struct erofs_xattr_prefix_item *prefix;
+ int domainlen, valuelen, base_index;
const char *infix;
- size_t domainlen;
- int valuelen, base_index;
if (!test_opt(&sbi->opt, INODE_SHARE))
return -EOPNOTSUPP;
@@ -634,7 +633,6 @@ int erofs_xattr_fill_inode_fingerprint(struct erofs_inode_fingerprint *fp,
valuelen = erofs_getxattr(inode, base_index, infix, NULL, 0);
if (valuelen <= 0 || valuelen > (1 << sbi->blkszbits))
return -EFSCORRUPTED;
- domain_id = domain_id ?: "";
domainlen = strlen(domain_id);
fp->size = domainlen + 1 + valuelen;
fp->opaque = kmalloc(fp->size, GFP_KERNEL);
> }
> #endif
> --
> 2.51.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH v2] erofs: delimit inode_share cache key components
2026-09-07 7:24 [PATCH] erofs: delimit inode_share cache key components ChengyuZhu6
2026-09-07 8:18 ` Gao Xiang
@ 2026-09-07 8:33 ` ChengyuZhu6
2026-09-07 9:10 ` Gao Xiang
1 sibling, 1 reply; 4+ messages in thread
From: ChengyuZhu6 @ 2026-09-07 8:33 UTC (permalink / raw)
To: linux-erofs; +Cc: xiang, Chengyu Zhu
From: Chengyu Zhu <hudsonzhu@tencent.com>
Previously, inode_share keys were encoded as follows:
fingerprint || domain_id
It would be better to have a separator between the fingerprint and domain
ID so that the fingerprint won't be parsed as part of a domain ID.
Change the key encoding as follows:
domain_id || '\0' || fingerprint
Since domain_id is a NUL-terminated string, this makes the in-memory key
indices unambiguous.
Signed-off-by: Chengyu Zhu <hudsonzhu@tencent.com>
---
Changes since v1:
- Use int for domainlen and drop the redundant NULL domain_id handling.
fs/erofs/xattr.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index df7ea019526d..57cfb7520782 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -620,7 +620,7 @@ int erofs_xattr_fill_inode_fingerprint(struct erofs_inode_fingerprint *fp,
{
struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
struct erofs_xattr_prefix_item *prefix;
+ int domainlen, valuelen, base_index;
const char *infix;
- int valuelen, base_index;
if (!test_opt(&sbi->opt, INODE_SHARE))
@@ -633,17 +633,18 @@ int erofs_xattr_fill_inode_fingerprint(struct erofs_inode_fingerprint *fp,
valuelen = erofs_getxattr(inode, base_index, infix, NULL, 0);
if (valuelen <= 0 || valuelen > (1 << sbi->blkszbits))
return -EFSCORRUPTED;
- fp->size = valuelen + (domain_id ? strlen(domain_id) : 0);
+ domainlen = strlen(domain_id);
+ fp->size = domainlen + 1 + valuelen;
fp->opaque = kmalloc(fp->size, GFP_KERNEL);
if (!fp->opaque)
return -ENOMEM;
+ memcpy(fp->opaque, domain_id, domainlen + 1);
if (valuelen != erofs_getxattr(inode, base_index, infix,
- fp->opaque, valuelen)) {
+ fp->opaque + domainlen + 1, valuelen)) {
kfree(fp->opaque);
fp->opaque = NULL;
return -EFSCORRUPTED;
}
- memcpy(fp->opaque + valuelen, domain_id, fp->size - valuelen);
return 0;
}
#endif
--
2.51.0
^ permalink raw reply related [flat|nested] 4+ messages in thread