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erofs: fix up compacted indexes for block size < 4096

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

Since sub-page compressed blocks are now considered, `lobits` for
a lcluster in each pack 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)

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20231206091057.87027-4-hsiangkao@linux.alibaba.com
This commit is contained in:
Gao Xiang 2023-12-06 17:10:55 +08:00
parent 54ed3fdd66
commit 8d2517aaee
1 changed files with 14 additions and 18 deletions
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32
fs/erofs/zmap.c
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@ -82,29 +82,26 @@ static int z_erofs_load_full_lcluster(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;
@ -123,15 +120,14 @@ 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;
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;
@ -140,6 +136,7 @@ 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(m->inode->i_sb, pos);
base = round_down(eofs, vcnt << amortizedshift);
@ -147,15 +144,14 @@ 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) {
@ -174,8 +170,8 @@ 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)
@ -190,8 +186,8 @@ 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;
@ -202,8 +198,8 @@ 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;