Commit 2a810ea7 authored by Gao Xiang's avatar Gao Xiang
Browse files

erofs: simplify z_erofs_load_compact_lcluster() 



 - Get rid of unpack_compacted_index() and fold it into
   z_erofs_load_compact_lcluster();

 - Avoid a goto.

Reviewed-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250114034429.431408-1-hsiangkao@linux.alibaba.com
parent db902986

fs/erofs/zmap.c

+36 −53
Original line number Diff line number Diff line
@@ -97,17 +97,48 @@ static int get_compacted_la_distance(unsigned int lobits, 
	return d1;

}



static int unpack_compacted_index(struct z_erofs_maprecorder *m,

				  unsigned int amortizedshift,

				  erofs_off_t pos, bool lookahead)

static int z_erofs_load_compact_lcluster(struct z_erofs_maprecorder *m,

					 unsigned long lcn, bool lookahead)

{

	struct erofs_inode *const vi = EROFS_I(m->inode);

	struct inode *const inode = m->inode;

	struct erofs_inode *const vi = EROFS_I(inode);

	const erofs_off_t ebase = sizeof(struct z_erofs_map_header) +

		ALIGN(erofs_iloc(inode) + vi->inode_isize + vi->xattr_isize, 8);

	const unsigned int lclusterbits = vi->z_logical_clusterbits;

	const unsigned int totalidx = erofs_iblks(inode);

	unsigned int compacted_4b_initial, compacted_2b, amortizedshift;

	unsigned int vcnt, lo, lobits, encodebits, nblk, bytes;

	bool big_pcluster;

	bool big_pcluster = vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1;

	erofs_off_t pos;

	u8 *in, type;

	int i;



	if (lcn >= totalidx || lclusterbits > 14)

		return -EINVAL;



	m->lcn = lcn;

	/* used to align to 32-byte (compacted_2b) alignment */

	compacted_4b_initial = ((32 - ebase % 32) / 4) & 7;

	compacted_2b = 0;

	if ((vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B) &&

	    compacted_4b_initial < totalidx)

		compacted_2b = rounddown(totalidx - compacted_4b_initial, 16);



	pos = ebase;

	amortizedshift = 2;	/* compact_4b */

	if (lcn >= compacted_4b_initial) {

		pos += compacted_4b_initial * 4;

		lcn -= compacted_4b_initial;

		if (lcn < compacted_2b) {

			amortizedshift = 1;

		} else {

			pos += compacted_2b * 2;

			lcn -= compacted_2b;

		}

	}

	pos += lcn * (1 << amortizedshift);



	/* figure out the lcluster count in this pack */

	if (1 << amortizedshift == 4 && lclusterbits <= 14)

		vcnt = 2;

	else if (1 << amortizedshift == 2 && lclusterbits <= 12)
@@ -122,7 +153,6 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, 
	/* it doesn't equal to round_up(..) */

	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;

	bytes = pos & ((vcnt << amortizedshift) - 1);
@@ -207,53 +237,6 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, 
	return 0;

}



static int z_erofs_load_compact_lcluster(struct z_erofs_maprecorder *m,

					 unsigned long lcn, bool lookahead)

{

	struct inode *const inode = m->inode;

	struct erofs_inode *const vi = EROFS_I(inode);

	const erofs_off_t ebase = sizeof(struct z_erofs_map_header) +

		ALIGN(erofs_iloc(inode) + vi->inode_isize + vi->xattr_isize, 8);

	unsigned int totalidx = erofs_iblks(inode);

	unsigned int compacted_4b_initial, compacted_2b;

	unsigned int amortizedshift;

	erofs_off_t pos;



	if (lcn >= totalidx || vi->z_logical_clusterbits > 14)

		return -EINVAL;



	m->lcn = lcn;

	/* used to align to 32-byte (compacted_2b) alignment */

	compacted_4b_initial = (32 - ebase % 32) / 4;

	if (compacted_4b_initial == 32 / 4)

		compacted_4b_initial = 0;



	if ((vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B) &&

	    compacted_4b_initial < totalidx)

		compacted_2b = rounddown(totalidx - compacted_4b_initial, 16);

	else

		compacted_2b = 0;



	pos = ebase;

	if (lcn < compacted_4b_initial) {

		amortizedshift = 2;

		goto out;

	}

	pos += compacted_4b_initial * 4;

	lcn -= compacted_4b_initial;



	if (lcn < compacted_2b) {

		amortizedshift = 1;

		goto out;

	}

	pos += compacted_2b * 2;

	lcn -= compacted_2b;

	amortizedshift = 2;

out:

	pos += lcn * (1 << amortizedshift);

	return unpack_compacted_index(m, amortizedshift, pos, lookahead);

}



static int z_erofs_load_lcluster_from_disk(struct z_erofs_maprecorder *m,

					   unsigned int lcn, bool lookahead)

{