On 2025/12/23 09:56, Hongbo Li wrote:
From: Hongzhen Luo <[email protected]>
When creating the EROFS image, users can specify the fingerprint name.
This is to prepare for the upcoming inode page cache share.
Signed-off-by: Hongzhen Luo <[email protected]>
Signed-off-by: Hongbo Li <[email protected]>
---
fs/erofs/Kconfig | 9 +++++++++
fs/erofs/erofs_fs.h | 5 +++--
fs/erofs/internal.h | 2 ++
fs/erofs/super.c | 3 +++
fs/erofs/xattr.c | 13 +++++++++++++
5 files changed, 30 insertions(+), 2 deletions(-)
diff --git a/fs/erofs/Kconfig b/fs/erofs/Kconfig
index d81f3318417d..c88b6d0714a4 100644
--- a/fs/erofs/Kconfig
+++ b/fs/erofs/Kconfig
@@ -194,3 +194,12 @@ config EROFS_FS_PCPU_KTHREAD_HIPRI
at higher priority.
If unsure, say N.
+
+config EROFS_FS_PAGE_CACHE_SHARE
+ bool "EROFS page cache share support (experimental)"
+ depends on EROFS_FS && EROFS_FS_XATTR && !EROFS_FS_ONDEMAND
+ help
+ This enables page cache sharing among inodes with identical
+ content fingerprints on the same device.
`on the same device` seems ambiguous because of `device`.
maybe just `on the same machine`.
+
+ If unsure, say N.
diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h
index e24268acdd62..20515d2462af 100644
--- a/fs/erofs/erofs_fs.h
+++ b/fs/erofs/erofs_fs.h
@@ -17,7 +17,7 @@
#define EROFS_FEATURE_COMPAT_XATTR_FILTER 0x00000004
#define EROFS_FEATURE_COMPAT_SHARED_EA_IN_METABOX 0x00000008
#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
@@ -83,7 +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; /* indexes the ishare key in prefix
xattres */
+ __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/fs/erofs/internal.h b/fs/erofs/internal.h
index 98fe652aea33..99e2857173c3 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -134,6 +134,7 @@ struct erofs_sb_info {
u32 xattr_blkaddr;
u32 xattr_prefix_start;
u8 xattr_prefix_count;
+ u8 ishare_xattr_pfx;
struct erofs_xattr_prefix_item *xattr_prefixes;
unsigned int xattr_filter_reserved;
#endif
@@ -238,6 +239,7 @@ EROFS_FEATURE_FUNCS(sb_chksum, compat, COMPAT_SB_CHKSUM)
EROFS_FEATURE_FUNCS(xattr_filter, compat, COMPAT_XATTR_FILTER)
EROFS_FEATURE_FUNCS(shared_ea_in_metabox, compat, COMPAT_SHARED_EA_IN_METABOX)
EROFS_FEATURE_FUNCS(plain_xattr_pfx, compat, COMPAT_PLAIN_XATTR_PFX)
+EROFS_FEATURE_FUNCS(ishare_xattrs, compat, COMPAT_ISHARE_XATTRS)
static inline u64 erofs_nid_to_ino64(struct erofs_sb_info *sbi, erofs_nid_t nid)
{
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 2a44c4e5af4f..68480f10e69d 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -298,6 +298,9 @@ static int erofs_read_superblock(struct super_block *sb)
if (ret)
goto out;
}
+ if (erofs_sb_has_ishare_xattrs(sbi))
+ sbi->ishare_xattr_pfx =
+ dsb->ishare_xattr_prefix_id &
EROFS_XATTR_LONG_PREFIX_MASK;
Is it possible to move this one into erofs_xattr_prefixes_init()?
we could pass dsb into erofs_xattr_prefixes_init() too.
ret = -EINVAL;
sbi->feature_incompat = le32_to_cpu(dsb->feature_incompat);
diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index 396536d9a862..969e77efd038 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -519,6 +519,19 @@ int erofs_xattr_prefixes_init(struct super_block *sb)
}
erofs_put_metabuf(&buf);
+ if (!ret && erofs_sb_has_ishare_xattrs(sbi)) {
+ struct erofs_xattr_prefix_item *pf = pfs +
sbi->ishare_xattr_pfx;
+ struct erofs_xattr_long_prefix *newpfx;
then:
sbi->ishare_xattr_pfx =
dsb->ishare_xattr_prefix_id &
EROFS_XATTR_LONG_PREFIX_MASK;
...
Thanks,
Gao Xiang
