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erofs: simplify z_erofs_load_compact_lcluster()

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

 - Avoid a goto.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250114034429.431408-1-hsiangkao@linux.alibaba.com
This commit is contained in:
Gao Xiang 2025-01-14 11:44:26 +08:00
parent db902986de
commit 2a810ea79c
1 changed files with 36 additions and 53 deletions
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89
fs/erofs/zmap.c
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@ -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)
{