[PATCH v2 05/10] erofs: add big physical cluster definition

From: Gao Xiang
Date: Wed Mar 31 2021 - 23:37:39 EST


From: Gao Xiang <hsiangkao@xxxxxxxxxx>

Big pcluster indicates the size of compressed data for each physical
pcluster is no longer fixed as block size, but could be more than 1
block (more accurately, 1 logical pcluster)

When big pcluster feature is enabled for head0/1, delta0 of the 1st
non-head lcluster index will keep block count of this pcluster in
lcluster size instead of 1. Or, the compressed size of pcluster
should be 1 lcluster if pcluster has no non-head lcluster index.

Also note that BIG_PCLUSTER feature reuses COMPR_CFGS feature since
it depends on COMPR_CFGS and will be released together.

Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
---
fs/erofs/erofs_fs.h | 19 +++++++++++++++----
fs/erofs/internal.h | 1 +
2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h
index 76777673eb63..ecc3a0ea0bc4 100644
--- a/fs/erofs/erofs_fs.h
+++ b/fs/erofs/erofs_fs.h
@@ -19,6 +19,7 @@
*/
#define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING 0x00000001
#define EROFS_FEATURE_INCOMPAT_COMPR_CFGS 0x00000002
+#define EROFS_FEATURE_INCOMPAT_BIG_PCLUSTER 0x00000002
#define EROFS_ALL_FEATURE_INCOMPAT EROFS_FEATURE_INCOMPAT_LZ4_0PADDING

#define EROFS_SB_EXTSLOT_SIZE 16
@@ -214,17 +215,20 @@ enum {
/* 14 bytes (+ length field = 16 bytes) */
struct z_erofs_lz4_cfgs {
__le16 max_distance;
- u8 reserved[12];
+ __le16 max_pclusterblks;
+ u8 reserved[10];
} __packed;

/*
* bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
* e.g. for 4k logical cluster size, 4B if compacted 2B is off;
* (4B) + 2B + (4B) if compacted 2B is on.
+ * bit 1 : HEAD1 big pcluster (0 - off; 1 - on)
+ * bit 2 : HEAD2 big pcluster (0 - off; 1 - on)
*/
-#define Z_EROFS_ADVISE_COMPACTED_2B_BIT 0
-
-#define Z_EROFS_ADVISE_COMPACTED_2B (1 << Z_EROFS_ADVISE_COMPACTED_2B_BIT)
+#define Z_EROFS_ADVISE_COMPACTED_2B 0x0001
+#define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002
+#define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004

struct z_erofs_map_header {
__le32 h_reserved1;
@@ -279,6 +283,13 @@ enum {
#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2
#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0

+/*
+ * D0_CBLKCNT will be marked _only_ at the 1st non-head lcluster to store the
+ * compressed block count of a compressed extent (in logical clusters, aka.
+ * block count of a pcluster).
+ */
+#define Z_EROFS_VLE_DI_D0_CBLKCNT (1 << 11)
+
struct z_erofs_vle_decompressed_index {
__le16 di_advise;
/* where to decompress in the head cluster */
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 06c294929069..c4b3938a7e56 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -230,6 +230,7 @@ static inline bool erofs_sb_has_##name(struct erofs_sb_info *sbi) \

EROFS_FEATURE_FUNCS(lz4_0padding, incompat, INCOMPAT_LZ4_0PADDING)
EROFS_FEATURE_FUNCS(compr_cfgs, incompat, INCOMPAT_COMPR_CFGS)
+EROFS_FEATURE_FUNCS(big_pcluster, incompat, INCOMPAT_BIG_PCLUSTER)
EROFS_FEATURE_FUNCS(sb_chksum, compat, COMPAT_SB_CHKSUM)

/* atomic flag definitions */
--
2.20.1