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erofs: refine z_erofs_get_extent_compressedlen()

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- Set `compressedblks = 1` directly for non-bigpcluster cases.  This
   simplifies the logic a bit since lcluster sizes larger than one block
   are unsupported and the details remain unclear.

 - For Z_EROFS_LCLUSTER_TYPE_PLAIN pclusters, avoid assuming
   `compressedblks = 1` by default.  Instead, check if
   Z_EROFS_ADVISE_BIG_PCLUSTER_2 is set.

It basically has no impact to existing valid images, but it's useful to
find the gap to prepare for large PLAIN pclusters.

Link: https://lore.kernel.org/r/20250123090109.973463-1-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
This commit is contained in:
Gao Xiang 2025-01-23 17:01:09 +08:00
parent 6e2c2342e2
commit 8f9530aeeb
1 changed files with 16 additions and 20 deletions
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36
fs/erofs/zmap.c
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@ -294,27 +294,23 @@ err_bogus:
static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
unsigned int initial_lcn)
{
struct super_block *sb = m->inode->i_sb;
struct erofs_inode *const vi = EROFS_I(m->inode);
struct erofs_map_blocks *const map = m->map;
const unsigned int lclusterbits = vi->z_logical_clusterbits;
unsigned long lcn;
struct inode *inode = m->inode;
struct super_block *sb = inode->i_sb;
struct erofs_inode *vi = EROFS_I(inode);
bool bigpcl1 = vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1;
bool bigpcl2 = vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_2;
unsigned long lcn = m->lcn + 1;
int err;
DBG_BUGON(m->type != Z_EROFS_LCLUSTER_TYPE_PLAIN &&
m->type != Z_EROFS_LCLUSTER_TYPE_HEAD1 &&
m->type != Z_EROFS_LCLUSTER_TYPE_HEAD2);
DBG_BUGON(m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD);
DBG_BUGON(m->type != m->headtype);
if (m->headtype == Z_EROFS_LCLUSTER_TYPE_PLAIN ||
((m->headtype == Z_EROFS_LCLUSTER_TYPE_HEAD1) &&
!(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1)) ||
((m->headtype == Z_EROFS_LCLUSTER_TYPE_HEAD2) &&
!(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_2))) {
map->m_plen = 1ULL << lclusterbits;
return 0;
}
lcn = m->lcn + 1;
if ((m->headtype == Z_EROFS_LCLUSTER_TYPE_HEAD1 && !bigpcl1) ||
((m->headtype == Z_EROFS_LCLUSTER_TYPE_PLAIN ||
m->headtype == Z_EROFS_LCLUSTER_TYPE_HEAD2) && !bigpcl2) ||
(lcn << vi->z_logical_clusterbits) >= inode->i_size)
m->compressedblks = 1;
if (m->compressedblks)
goto out;
@ -339,9 +335,9 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
case Z_EROFS_LCLUSTER_TYPE_HEAD2:
/*
* if the 1st NONHEAD lcluster is actually PLAIN or HEAD type
* rather than CBLKCNT, it's a 1 lcluster-sized pcluster.
* rather than CBLKCNT, it's a 1 block-sized pcluster.
*/
m->compressedblks = 1 << (lclusterbits - sb->s_blocksize_bits);
m->compressedblks = 1;
break;
case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
if (m->delta[0] != 1)
@ -356,7 +352,7 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
return -EFSCORRUPTED;
}
out:
map->m_plen = erofs_pos(sb, m->compressedblks);
m->map->m_plen = erofs_pos(sb, m->compressedblks);
return 0;
err_bonus_cblkcnt:
erofs_err(sb, "bogus CBLKCNT @ lcn %lu of nid %llu", lcn, vi->nid);