1 files changed, 31 insertions, 3 deletions

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index ad932f670bb6..26f9aa57ff3c 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -125,6 +125,7 @@ struct erofs_sb_info {
 	struct erofs_sb_lz4_info lz4;
 #endif	/* CONFIG_EROFS_FS_ZIP */
 	struct inode *packed_inode;
+	struct inode *metabox_inode;
 	struct erofs_dev_context *devs;
 	u64 total_blocks;
 
@@ -148,6 +149,7 @@ struct erofs_sb_info {
 	/* what we really care is nid, rather than ino.. */
 	erofs_nid_t root_nid;
 	erofs_nid_t packed_nid;
+	erofs_nid_t metabox_nid;
 	/* used for statfs, f_files - f_favail */
 	u64 inos;
 
@@ -232,6 +234,23 @@ 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)
 
+static inline u64 erofs_nid_to_ino64(struct erofs_sb_info *sbi, erofs_nid_t nid)
+{
+	if (!erofs_sb_has_metabox(sbi))
+		return nid;
+
+	/*
+	 * When metadata compression is enabled, avoid generating excessively
+	 * large inode numbers for metadata-compressed inodes.  Shift NIDs in
+	 * the 31-62 bit range left by one and move the metabox flag to bit 31.
+	 *
+	 * Note: on-disk NIDs remain unchanged as they are primarily used for
+	 * compatibility with non-LFS 32-bit applications.
+	 */
+	return ((nid << 1) & GENMASK_ULL(63, 32)) | (nid & GENMASK(30, 0)) |
+		((nid >> EROFS_DIRENT_NID_METABOX_BIT) << 31);
+}
+
 /* atomic flag definitions */
 #define EROFS_I_EA_INITED_BIT	0
 #define EROFS_I_Z_INITED_BIT	1
@@ -281,12 +300,20 @@ struct erofs_inode {
 
 #define EROFS_I(ptr)	container_of(ptr, struct erofs_inode, vfs_inode)
 
+static inline bool erofs_inode_in_metabox(struct inode *inode)
+{
+	return EROFS_I(inode)->nid & BIT_ULL(EROFS_DIRENT_NID_METABOX_BIT);
+}
+
 static inline erofs_off_t erofs_iloc(struct inode *inode)
 {
 	struct erofs_sb_info *sbi = EROFS_I_SB(inode);
+	erofs_nid_t nid_lo = EROFS_I(inode)->nid & EROFS_DIRENT_NID_MASK;
 
+	if (erofs_inode_in_metabox(inode))
+		return nid_lo << sbi->islotbits;
 	return erofs_pos(inode->i_sb, sbi->meta_blkaddr) +
-		(EROFS_I(inode)->nid << sbi->islotbits);
+		(nid_lo << sbi->islotbits);
 }
 
 static inline unsigned int erofs_inode_version(unsigned int ifmt)
@@ -385,9 +412,10 @@ void *erofs_read_metadata(struct super_block *sb, struct erofs_buf *buf,
 void erofs_unmap_metabuf(struct erofs_buf *buf);
 void erofs_put_metabuf(struct erofs_buf *buf);
 void *erofs_bread(struct erofs_buf *buf, erofs_off_t offset, bool need_kmap);
-void erofs_init_metabuf(struct erofs_buf *buf, struct super_block *sb);
+int erofs_init_metabuf(struct erofs_buf *buf, struct super_block *sb,
+		       bool in_metabox);
 void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
-			 erofs_off_t offset);
+			 erofs_off_t offset, bool in_metabox);
 int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *dev);
 int erofs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		 u64 start, u64 len);