diff options
| author |   Gao Xiang <hsiangkao@linux.alibaba.com> | 2022-03-11 02:27:42 +0800 |
|---|---|---|
| committer | Gao Xiang <hsiangkao@linux.alibaba.com> | 2022-03-17 00:08:48 +0800 |
| commit | ab474fccd04509db89fde8d3b28c39aa9a47db64 (patch) | |
| tree | f79c58458b64ed05bbb623ea10132efb399782d2 /fs/erofs | |
| parent | erofs: silence warnings related to impossible m_plen (diff) | |
| download | wireguard-linux-ab474fccd04509db89fde8d3b28c39aa9a47db64.tar.xz wireguard-linux-ab474fccd04509db89fde8d3b28c39aa9a47db64.zip | |
erofs: clean up z_erofs_extent_lookback
Avoid the unnecessary tail recursion since it can be converted into
a loop directly in order to prevent potential stack overflow.
It's a pretty straightforward conversion.
Link: https://lore.kernel.org/r/20220310182743.102365-1-hsiangkao@linux.alibaba.com
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Diffstat (limited to 'fs/erofs')
| -rw-r--r-- | fs/erofs/zmap.c | 67 |
1 files changed, 33 insertions, 34 deletions
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index b4059b9c3bac..572f0b8151ba 100644 --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -431,48 +431,47 @@ static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m, unsigned int lookback_distance) { 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 = m->lcn; - int err; - if (lcn < lookback_distance) { - erofs_err(m->inode->i_sb, - "bogus lookback distance @ nid %llu", vi->nid); - DBG_BUGON(1); - return -EFSCORRUPTED; - } + while (m->lcn >= lookback_distance) { + unsigned long lcn = m->lcn - lookback_distance; + int err; - /* load extent head logical cluster if needed */ - lcn -= lookback_distance; - err = z_erofs_load_cluster_from_disk(m, lcn, false); - if (err) - return err; + /* load extent head logical cluster if needed */ + err = z_erofs_load_cluster_from_disk(m, lcn, false); + if (err) + return err; - switch (m->type) { - case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD: - if (!m->delta[0]) { + switch (m->type) { + case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD: + if (!m->delta[0]) { + erofs_err(m->inode->i_sb, + "invalid lookback distance 0 @ nid %llu", + vi->nid); + DBG_BUGON(1); + return -EFSCORRUPTED; + } + lookback_distance = m->delta[0]; + continue; + case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN: + case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1: + case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2: + m->headtype = m->type; + m->map->m_la = (lcn << lclusterbits) | m->clusterofs; + return 0; + default: erofs_err(m->inode->i_sb, - "invalid lookback distance 0 @ nid %llu", - vi->nid); + "unknown type %u @ lcn %lu of nid %llu", + m->type, lcn, vi->nid); DBG_BUGON(1); - return -EFSCORRUPTED; + return -EOPNOTSUPP; } - return z_erofs_extent_lookback(m, m->delta[0]); - case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN: - case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1: - case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2: - m->headtype = m->type; - map->m_la = (lcn << lclusterbits) | m->clusterofs; - break; - default: - erofs_err(m->inode->i_sb, - "unknown type %u @ lcn %lu of nid %llu", - m->type, lcn, vi->nid); - DBG_BUGON(1); - return -EOPNOTSUPP; } - return 0; + + erofs_err(m->inode->i_sb, "bogus lookback distance @ nid %llu", + vi->nid); + DBG_BUGON(1); + return -EFSCORRUPTED; } static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m, |