Commit 4afe6b8d authored by Al Viro's avatar Al Viro Committed by Gao Xiang
Browse files

erofs: don't round offset down for erofs_read_metabuf() 



There's only one place where struct z_erofs_maprecorder ->kaddr is
used not in the same function that has assigned it -
the value read in unpack_compacted_index() gets calculated in
z_erofs_load_compact_lcluster().  With minor massage we can switch
to storing it with offset in block already added.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20240425195944.GE1031757@ZenIV


Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
parent 076d965e

fs/erofs/zmap.c

+8 −8
Original line number Diff line number Diff line
@@ -34,13 +34,13 @@ static int z_erofs_load_full_lcluster(struct z_erofs_maprecorder *m, 
	unsigned int advise;



	m->kaddr = erofs_read_metabuf(&m->map->buf, inode->i_sb,

				      erofs_pos(inode->i_sb, erofs_blknr(inode->i_sb, pos)), EROFS_KMAP);

				      pos, EROFS_KMAP);

	if (IS_ERR(m->kaddr))

		return PTR_ERR(m->kaddr);



	m->nextpackoff = pos + sizeof(struct z_erofs_lcluster_index);

	m->lcn = lcn;

	di = m->kaddr + erofs_blkoff(inode->i_sb, pos);

	di = m->kaddr;



	advise = le16_to_cpu(di->di_advise);

	m->type = advise & Z_EROFS_LI_LCLUSTER_TYPE_MASK;
@@ -109,7 +109,7 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, 
{

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

	const unsigned int lclusterbits = vi->z_logical_clusterbits;

	unsigned int vcnt, base, lo, lobits, encodebits, nblk, eofs;

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

	int i;

	u8 *in, type;

	bool big_pcluster;
@@ -127,11 +127,11 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, 
	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(m->inode->i_sb, pos);

	base = round_down(eofs, vcnt << amortizedshift);

	in = m->kaddr + base;

	bytes = pos & ((vcnt << amortizedshift) - 1);



	i = (eofs - base) >> amortizedshift;

	in = m->kaddr - bytes;



	i = bytes >> amortizedshift;



	lo = decode_compactedbits(lobits, in, encodebits * i, &type);

	m->type = type;
@@ -256,7 +256,7 @@ static int z_erofs_load_compact_lcluster(struct z_erofs_maprecorder *m, 
out:

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

	m->kaddr = erofs_read_metabuf(&m->map->buf, inode->i_sb,

				      erofs_pos(inode->i_sb, erofs_blknr(inode->i_sb, pos)), EROFS_KMAP);

				      pos, EROFS_KMAP);

	if (IS_ERR(m->kaddr))

		return PTR_ERR(m->kaddr);

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