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erofs: fix encoded extents handling

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- The MSB 32 bits of `z_fragmentoff` are available only in extent
records of size >= 8B.

 - Use round_down() to calculate `lstart` as well as increase `pos`
   correspondingly for extent records of size == 8B.

Fixes: 1d191b4ca5 ("erofs: implement encoded extent metadata")
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250408114448.4040220-2-hsiangkao@linux.alibaba.com
This commit is contained in:
Gao Xiang
2025-04-08 19:44:48 +08:00
parent d385f15d5b
commit be45319c9f
1 changed files with 3 additions and 2 deletions
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5
fs/erofs/zmap.c
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@@ -559,7 +559,8 @@ static int z_erofs_map_blocks_ext(struct inode *inode,
pos += sizeof(__le64);
lstart = 0;
} else {
lstart = map->m_la >> vi->z_lclusterbits;
lstart = round_down(map->m_la, 1 << vi->z_lclusterbits);
pos += (lstart >> vi->z_lclusterbits) * recsz;
pa = EROFS_NULL_ADDR;
}
@@ -614,7 +615,7 @@ static int z_erofs_map_blocks_ext(struct inode *inode,
if (last && (vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER)) {
map->m_flags |= EROFS_MAP_MAPPED | EROFS_MAP_FRAGMENT;
vi->z_fragmentoff = map->m_plen;
if (recsz >= offsetof(struct z_erofs_extent, pstart_lo))
if (recsz > offsetof(struct z_erofs_extent, pstart_lo))
vi->z_fragmentoff |= map->m_pa << 32;
} else if (map->m_plen) {
map->m_flags |= EROFS_MAP_MAPPED |