From: Gao Xiang <hsiang...@redhat.com>

When INCOMPAT_BIG_PCLUSTER sb feature is enabled, legacy compress indexes
will also have the same on-disk header compact indexes to keep per-file
configurations instead of leaving it zeroed.

If ADVISE_BIG_PCLUSTER is set for a file, CBLKCNT will be loaded for each
pcluster in this file by parsing 1st non-head lcluster.

Acked-by: Chao Yu <yuch...@huawei.com>
Signed-off-by: Gao Xiang <hsiang...@redhat.com>
---
 fs/erofs/zmap.c | 79 +++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 73 insertions(+), 6 deletions(-)

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 7fd6bd843471..6c0c47f68b75 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -11,8 +11,10 @@
 int z_erofs_fill_inode(struct inode *inode)
 {
        struct erofs_inode *const vi = EROFS_I(inode);
+       struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
 
-       if (vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY) {
+       if (!erofs_sb_has_big_pcluster(sbi) &&
+           vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY) {
                vi->z_advise = 0;
                vi->z_algorithmtype[0] = 0;
                vi->z_algorithmtype[1] = 0;
@@ -49,7 +51,8 @@ static int z_erofs_fill_inode_lazy(struct inode *inode)
        if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags))
                goto out_unlock;
 
-       DBG_BUGON(vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY);
+       DBG_BUGON(!erofs_sb_has_big_pcluster(EROFS_SB(sb)) &&
+                 vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY);
 
        pos = ALIGN(iloc(EROFS_SB(sb), vi->nid) + vi->inode_isize +
                    vi->xattr_isize, 8);
@@ -96,7 +99,7 @@ struct z_erofs_maprecorder {
        u8  type;
        u16 clusterofs;
        u16 delta[2];
-       erofs_blk_t pblk;
+       erofs_blk_t pblk, compressedlcs;
 };
 
 static int z_erofs_reload_indexes(struct z_erofs_maprecorder *m,
@@ -159,6 +162,15 @@ static int legacy_load_cluster_from_disk(struct 
z_erofs_maprecorder *m,
        case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
                m->clusterofs = 1 << vi->z_logical_clusterbits;
                m->delta[0] = le16_to_cpu(di->di_u.delta[0]);
+               if (m->delta[0] & Z_EROFS_VLE_DI_D0_CBLKCNT) {
+                       if (!(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1)) {
+                               DBG_BUGON(1);
+                               return -EFSCORRUPTED;
+                       }
+                       m->compressedlcs = m->delta[0] &
+                               ~Z_EROFS_VLE_DI_D0_CBLKCNT;
+                       m->delta[0] = 1;
+               }
                m->delta[1] = le16_to_cpu(di->di_u.delta[1]);
                break;
        case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
@@ -366,6 +378,58 @@ static int z_erofs_extent_lookback(struct 
z_erofs_maprecorder *m,
        return 0;
 }
 
+static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
+                                           unsigned int initial_lcn)
+{
+       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;
+       int err;
+
+       DBG_BUGON(m->type != Z_EROFS_VLE_CLUSTER_TYPE_PLAIN &&
+                 m->type != Z_EROFS_VLE_CLUSTER_TYPE_HEAD);
+       if (!(map->m_flags & EROFS_MAP_ZIPPED) ||
+           !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1)) {
+               map->m_plen = 1 << lclusterbits;
+               return 0;
+       }
+
+       lcn = m->lcn + 1;
+       if (m->compressedlcs)
+               goto out;
+       if (lcn == initial_lcn)
+               goto err_bonus_cblkcnt;
+
+       err = z_erofs_load_cluster_from_disk(m, lcn);
+       if (err)
+               return err;
+
+       switch (m->type) {
+       case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+               if (m->delta[0] != 1)
+                       goto err_bonus_cblkcnt;
+               if (m->compressedlcs)
+                       break;
+               fallthrough;
+       default:
+               erofs_err(m->inode->i_sb,
+                         "cannot found CBLKCNT @ lcn %lu of nid %llu",
+                         lcn, vi->nid);
+               DBG_BUGON(1);
+               return -EFSCORRUPTED;
+       }
+out:
+       map->m_plen = m->compressedlcs << lclusterbits;
+       return 0;
+err_bonus_cblkcnt:
+       erofs_err(m->inode->i_sb,
+                 "bogus CBLKCNT @ lcn %lu of nid %llu",
+                 lcn, vi->nid);
+       DBG_BUGON(1);
+       return -EFSCORRUPTED;
+}
+
 int z_erofs_map_blocks_iter(struct inode *inode,
                            struct erofs_map_blocks *map,
                            int flags)
@@ -377,6 +441,7 @@ int z_erofs_map_blocks_iter(struct inode *inode,
        };
        int err = 0;
        unsigned int lclusterbits, endoff;
+       unsigned long initial_lcn;
        unsigned long long ofs, end;
 
        trace_z_erofs_map_blocks_iter_enter(inode, map, flags);
@@ -395,10 +460,10 @@ int z_erofs_map_blocks_iter(struct inode *inode,
 
        lclusterbits = vi->z_logical_clusterbits;
        ofs = map->m_la;
-       m.lcn = ofs >> lclusterbits;
+       initial_lcn = ofs >> lclusterbits;
        endoff = ofs & ((1 << lclusterbits) - 1);
 
-       err = z_erofs_load_cluster_from_disk(&m, m.lcn);
+       err = z_erofs_load_cluster_from_disk(&m, initial_lcn);
        if (err)
                goto unmap_out;
 
@@ -442,10 +507,12 @@ int z_erofs_map_blocks_iter(struct inode *inode,
        }
 
        map->m_llen = end - map->m_la;
-       map->m_plen = 1 << lclusterbits;
        map->m_pa = blknr_to_addr(m.pblk);
        map->m_flags |= EROFS_MAP_MAPPED;
 
+       err = z_erofs_get_extent_compressedlen(&m, initial_lcn);
+       if (err)
+               goto out;
 unmap_out:
        if (m.kaddr)
                kunmap_atomic(m.kaddr);
-- 
2.20.1

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