[PATCH 1/2] erofs-utils: lib: fix up compact indexes for block size < 4096

[PATCH 1/2] erofs-utils: lib: fix up compact indexes for block size < 4096

[Gao Xiang]

Previously, the block size always equaled to PAGE_SIZE in kernel,
therefore `lclusterbits` couldn't be less than 12.

Since sub-page compressed blocks are now considered, `lobits` for
a lcluster in each pack of compact indexes cannot always be
`lclusterbits` as before.  Otherwise, there is no enough room for
the special value `Z_EROFS_LI_D0_CBLKCNT`.

To support smaller block sizes, `lobits` for each compacted lcluster is
now calculated as:
   lobits = max(lclusterbits, ilog2(Z_EROFS_LI_D0_CBLKCNT) + 1)

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 lib/zmap.c | 32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)

diff --git a/lib/zmap.c b/lib/zmap.c
index 81fa22b..12eb426 100644
--- a/lib/zmap.c
+++ b/lib/zmap.c
@@ -197,29 +197,26 @@ static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 }
 
 static unsigned int decode_compactedbits(unsigned int lobits,
-					 unsigned int lomask,
 					 u8 *in, unsigned int pos, u8 *type)
 {
 	const unsigned int v = get_unaligned_le32(in + pos / 8) >> (pos & 7);
-	const unsigned int lo = v & lomask;
+	const unsigned int lo = v & ((1 << lobits) - 1);
 
 	*type = (v >> lobits) & 3;
 	return lo;
 }
 
-static int get_compacted_la_distance(unsigned int lclusterbits,
+static int get_compacted_la_distance(unsigned int lobits,
 				     unsigned int encodebits,
 				     unsigned int vcnt, u8 *in, int i)
 {
-	const unsigned int lomask = (1 << lclusterbits) - 1;
 	unsigned int lo, d1 = 0;
 	u8 type;
 
 	DBG_BUGON(i >= vcnt);
 
 	do {
-		lo = decode_compactedbits(lclusterbits, lomask,
-					  in, encodebits * i, &type);
+		lo = decode_compactedbits(lobits, in, encodebits * i, &type);
 
 		if (type != Z_EROFS_LCLUSTER_TYPE_NONHEAD)
 			return d1;
@@ -238,15 +235,14 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 {
 	struct erofs_inode *const vi = m->inode;
 	const unsigned int lclusterbits = vi->z_logical_clusterbits;
-	const unsigned int lomask = (1 << lclusterbits) - 1;
-	unsigned int vcnt, base, lo, encodebits, nblk, eofs;
+	unsigned int vcnt, base, lo, lobits, encodebits, nblk, eofs;
 	int i;
 	u8 *in, type;
 	bool big_pcluster;
 
 	if (1 << amortizedshift == 4 && lclusterbits <= 14)
 		vcnt = 2;
-	else if (1 << amortizedshift == 2 && lclusterbits == 12)
+	else if (1 << amortizedshift == 2 && lclusterbits <= 12)
 		vcnt = 16;
 	else
 		return -EOPNOTSUPP;
@@ -255,6 +251,7 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 	m->nextpackoff = round_down(pos, vcnt << amortizedshift) +
 			 (vcnt << amortizedshift);
 	big_pcluster = vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1;
+	lobits = max(lclusterbits, ilog2(Z_EROFS_LI_D0_CBLKCNT) + 1U);
 	encodebits = ((vcnt << amortizedshift) - sizeof(__le32)) * 8 / vcnt;
 	eofs = erofs_blkoff(vi->sbi, pos);
 	base = round_down(eofs, vcnt << amortizedshift);
@@ -262,15 +259,14 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 
 	i = (eofs - base) >> amortizedshift;
 
-	lo = decode_compactedbits(lclusterbits, lomask,
-				  in, encodebits * i, &type);
+	lo = decode_compactedbits(lobits, in, encodebits * i, &type);
 	m->type = type;
 	if (type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
 		m->clusterofs = 1 << lclusterbits;
 
 		/* figure out lookahead_distance: delta[1] if needed */
 		if (lookahead)
-			m->delta[1] = get_compacted_la_distance(lclusterbits,
+			m->delta[1] = get_compacted_la_distance(lobits,
 						encodebits, vcnt, in, i);
 		if (lo & Z_EROFS_LI_D0_CBLKCNT) {
 			if (!big_pcluster) {
@@ -289,8 +285,8 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 		 * of which lo saves delta[1] rather than delta[0].
 		 * Hence, get delta[0] by the previous lcluster indirectly.
 		 */
-		lo = decode_compactedbits(lclusterbits, lomask,
-					  in, encodebits * (i - 1), &type);
+		lo = decode_compactedbits(lobits, in,
+					  encodebits * (i - 1), &type);
 		if (type != Z_EROFS_LCLUSTER_TYPE_NONHEAD)
 			lo = 0;
 		else if (lo & Z_EROFS_LI_D0_CBLKCNT)
@@ -305,8 +301,8 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 		nblk = 1;
 		while (i > 0) {
 			--i;
-			lo = decode_compactedbits(lclusterbits, lomask,
-						  in, encodebits * i, &type);
+			lo = decode_compactedbits(lobits, in,
+						  encodebits * i, &type);
 			if (type == Z_EROFS_LCLUSTER_TYPE_NONHEAD)
 				i -= lo;
 
@@ -317,8 +313,8 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 		nblk = 0;
 		while (i > 0) {
 			--i;
-			lo = decode_compactedbits(lclusterbits, lomask,
-						  in, encodebits * i, &type);
+			lo = decode_compactedbits(lobits, in,
+						  encodebits * i, &type);
 			if (type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
 				if (lo & Z_EROFS_LI_D0_CBLKCNT) {
 					--i;
-- 
2.39.3

[PATCH 2/2] erofs-utils: mkfs: support compact indexes for smaller block sizes

[Gao Xiang]

This commit also adds mkfs support of compact indexes for smaller
block sizes (less than 4096).

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 lib/compress.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/lib/compress.c b/lib/compress.c
index 47f1c1d..61328ed 100644
--- a/lib/compress.c
+++ b/lib/compress.c
@@ -627,19 +627,20 @@ static void *write_compacted_indexes(u8 *out,
 				     struct z_erofs_compressindex_vec *cv,
 				     erofs_blk_t *blkaddr_ret,
 				     unsigned int destsize,
-				     unsigned int logical_clusterbits,
+				     unsigned int lclusterbits,
 				     bool final, bool *dummy_head,
 				     bool update_blkaddr)
 {
-	unsigned int vcnt, encodebits, pos, i, cblks;
+	unsigned int vcnt, lobits, encodebits, pos, i, cblks;
 	erofs_blk_t blkaddr;
 
 	if (destsize == 4)
 		vcnt = 2;
-	else if (destsize == 2 && logical_clusterbits == 12)
+	else if (destsize == 2 && lclusterbits <= 12)
 		vcnt = 16;
 	else
 		return ERR_PTR(-EINVAL);
+	lobits = max(lclusterbits, ilog2(Z_EROFS_LI_D0_CBLKCNT) + 1U);
 	encodebits = (vcnt * destsize * 8 - 32) / vcnt;
 	blkaddr = *blkaddr_ret;
 
@@ -656,7 +657,7 @@ static void *write_compacted_indexes(u8 *out,
 				*dummy_head = false;
 			} else if (i + 1 == vcnt) {
 				offset = min_t(u16, cv[i].u.delta[1],
-						(1 << logical_clusterbits) - 1);
+						(1 << lobits) - 1);
 			} else {
 				offset = cv[i].u.delta[0];
 			}
@@ -676,7 +677,7 @@ static void *write_compacted_indexes(u8 *out,
 				DBG_BUGON(cv[i].u.blkaddr);
 			}
 		}
-		v = (cv[i].clustertype << logical_clusterbits) | offset;
+		v = (cv[i].clustertype << lobits) | offset;
 		rem = pos & 7;
 		ch = out[pos / 8] & ((1 << rem) - 1);
 		out[pos / 8] = (v << rem) | ch;
@@ -711,7 +712,7 @@ int z_erofs_convert_to_compacted_format(struct erofs_inode *inode,
 	bool dummy_head;
 	bool big_pcluster = erofs_sb_has_big_pcluster(sbi);
 
-	if (logical_clusterbits < sbi->blkszbits || sbi->blkszbits < 12)
+	if (logical_clusterbits < sbi->blkszbits)
 		return -EINVAL;
 	if (logical_clusterbits > 14) {
 		erofs_err("compact format is unsupported for lcluster size %u",
@@ -720,7 +721,7 @@ int z_erofs_convert_to_compacted_format(struct erofs_inode *inode,
 	}
 
 	if (inode->z_advise & Z_EROFS_ADVISE_COMPACTED_2B) {
-		if (logical_clusterbits != 12) {
+		if (logical_clusterbits > 12) {
 			erofs_err("compact 2B is unsupported for lcluster size %u",
 				  1 << logical_clusterbits);
 			return -EINVAL;
-- 
2.39.3

Re: [PATCH 1/2] erofs-utils: lib: fix up compact indexes for block size < 4096

[Yue Hu]

On Thu, 23 Nov 2023 13:22:44 +0800
Gao Xiang <hsiangkao@linux.alibaba.com> wrote:

> Previously, the block size always equaled to PAGE_SIZE in kernel,
> therefore `lclusterbits` couldn't be less than 12.
> 
> Since sub-page compressed blocks are now considered, `lobits` for
> a lcluster in each pack of compact indexes cannot always be
> `lclusterbits` as before.  Otherwise, there is no enough room for
> the special value `Z_EROFS_LI_D0_CBLKCNT`.
> 
> To support smaller block sizes, `lobits` for each compacted lcluster is
> now calculated as:
>    lobits = max(lclusterbits, ilog2(Z_EROFS_LI_D0_CBLKCNT) + 1)
> 
> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Reviewed-by: Yue Hu <huyue2@coolpad.com>

Re: [PATCH 2/2] erofs-utils: mkfs: support compact indexes for smaller block sizes

[Yue Hu]

On Thu, 23 Nov 2023 13:22:45 +0800
Gao Xiang <hsiangkao@linux.alibaba.com> wrote:

> This commit also adds mkfs support of compact indexes for smaller
> block sizes (less than 4096).
> 
> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Reviewed-by: Yue Hu <huyue2@coolpad.com>