Hi Yue,

On Wed, Nov 17, 2021 at 05:22:01PM +0800, Yue Hu via Linux-erofs wrote:
> Add tail-packing inline compressed data support for erofsfuse.
> 
> Signed-off-by: Yue Hu <[email protected]>

Sorry about long delay, I'm very busy in container use cases now.
I've checked your patch, some inlined comments below.

> ---
> v3:
> - remove z_idata_addr, add z_idata_headlcn instead of m_taillcn.
> - add bug_on for legacy if enable inline and disable big pcluster.
> - extract z_erofs_do_map_blocks() instead of added
>   z_erofs_map_tail_data_blocks() with similar logic.
> 
> v2:
> - add tail-packing information to inode and get it on first read.
> - update tail-packing checking logic.
> 
>  include/erofs/internal.h |   2 +
>  lib/decompress.c         |   3 -
>  lib/zmap.c               | 136 +++++++++++++++++++++++++++++++++------
>  3 files changed, 120 insertions(+), 21 deletions(-)
> 
> diff --git a/include/erofs/internal.h b/include/erofs/internal.h
> index 54e5939..5d1a44c 100644
> --- a/include/erofs/internal.h
> +++ b/include/erofs/internal.h
> @@ -172,6 +172,8 @@ struct erofs_inode {
>                       uint8_t  z_algorithmtype[2];
>                       uint8_t  z_logical_clusterbits;
>                       uint8_t  z_physical_clusterblks;
> +                     uint16_t z_idata_size;
> +                     uint32_t z_idata_headlcn;
>               };
>       };
>  #ifdef WITH_ANDROID
> diff --git a/lib/decompress.c b/lib/decompress.c
> index 6f4ecc2..806ac91 100644
> --- a/lib/decompress.c
> +++ b/lib/decompress.c
> @@ -71,9 +71,6 @@ out:
>  int z_erofs_decompress(struct z_erofs_decompress_req *rq)
>  {
>       if (rq->alg == Z_EROFS_COMPRESSION_SHIFTED) {
> -             if (rq->inputsize != EROFS_BLKSIZ)
> -                     return -EFSCORRUPTED;
> -

                if (rq->inputsize > EROFS_BLKSIZ)
                        return -EFSCORRUPTED;

>               DBG_BUGON(rq->decodedlength > EROFS_BLKSIZ);
>               DBG_BUGON(rq->decodedlength < rq->decodedskip);
>  
> diff --git a/lib/zmap.c b/lib/zmap.c
> index 458030b..42783e5 100644
> --- a/lib/zmap.c
> +++ b/lib/zmap.c
> @@ -10,6 +10,9 @@
>  #include "erofs/io.h"
>  #include "erofs/print.h"
>  
> +static int z_erofs_do_map_blocks(struct erofs_inode *vi,
> +                              struct erofs_map_blocks *map);
> +
>  int z_erofs_fill_inode(struct erofs_inode *vi)
>  {
>       if (!erofs_sb_has_big_pcluster() &&
> @@ -18,12 +21,69 @@ int z_erofs_fill_inode(struct erofs_inode *vi)
>               vi->z_algorithmtype[0] = 0;
>               vi->z_algorithmtype[1] = 0;
>               vi->z_logical_clusterbits = LOG_BLOCK_SIZE;
> +             vi->z_idata_size = 0;
>  
>               vi->flags |= EROFS_I_Z_INITED;
> +             DBG_BUGON(erofs_sb_has_tail_packing());
>       }
>       return 0;
>  }
>  
> +static erofs_off_t compacted_inline_data_addr(struct erofs_inode *vi,
> +                                           unsigned int totalidx)
> +{
> +     const erofs_off_t ebase = round_up(iloc(vi->nid) + vi->inode_isize +
> +                               vi->xattr_isize, 8) +
> +                               sizeof(struct z_erofs_map_header);
> +     unsigned int compacted_4b_initial, compacted_4b_end;
> +     unsigned int compacted_2b;
> +     erofs_off_t addr;
> +
> +     compacted_4b_initial = (32 - ebase % 32) / 4;
> +     if (compacted_4b_initial == 32 / 4)
> +             compacted_4b_initial = 0;
> +
> +     if (compacted_4b_initial > totalidx) {
> +             compacted_4b_initial = 0;
> +             compacted_2b = 0;
> +     } else if (vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B) {
> +             compacted_2b = rounddown(totalidx - compacted_4b_initial, 16);
> +     } else
> +             compacted_2b = 0;
> +
> +     compacted_4b_end = totalidx - compacted_4b_initial - compacted_2b;
> +
> +     addr = ebase + compacted_4b_initial * 4 + compacted_2b * 2;
> +     if (compacted_4b_end > 1)
> +             addr += (compacted_4b_end/2) * 8;
> +     if (compacted_4b_end % 2)
> +             addr += 8;
> +
> +     return addr;
> +}
> +
> +static erofs_off_t legacy_inline_data_addr(struct erofs_inode *vi,
> +                                        unsigned int totalidx)
> +{
> +     return Z_EROFS_VLE_LEGACY_INDEX_ALIGN(iloc(vi->nid) + vi->inode_isize +
> +                                           vi->xattr_isize) +
> +             totalidx * sizeof(struct z_erofs_vle_decompressed_index);
> +}
> +
> +static erofs_off_t z_erofs_inline_data_addr(struct erofs_inode *vi)
> +{
> +     const unsigned int datamode = vi->datalayout;
> +     const unsigned int totalidx = DIV_ROUND_UP(vi->i_size, EROFS_BLKSIZ);
> +
> +     if (datamode == EROFS_INODE_FLAT_COMPRESSION)
> +             return compacted_inline_data_addr(vi, totalidx);
> +
> +     if (datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY)
> +             return legacy_inline_data_addr(vi, totalidx);
> +
> +     return -EINVAL;
> +}

no need these three new functions if introducing
EROFS_GET_BLOCKS_FINDTAIL, see below..

> +
>  static int z_erofs_fill_inode_lazy(struct erofs_inode *vi)
>  {
>       int ret;
> @@ -44,6 +104,7 @@ static int z_erofs_fill_inode_lazy(struct erofs_inode *vi)
>  
>       h = (struct z_erofs_map_header *)buf;
>       vi->z_advise = le16_to_cpu(h->h_advise);
> +     vi->z_idata_size = le16_to_cpu(h->h_idata_size);
>       vi->z_algorithmtype[0] = h->h_algorithmtype & 15;
>       vi->z_algorithmtype[1] = h->h_algorithmtype >> 4;
>  
> @@ -61,6 +122,16 @@ static int z_erofs_fill_inode_lazy(struct erofs_inode *vi)
>                         vi->nid * 1ULL);
>               return -EFSCORRUPTED;
>       }
> +
> +     if (vi->z_idata_size) {
> +             struct erofs_map_blocks map = { .m_la = vi->i_size - 1 };
> +
> +             ret = z_erofs_do_map_blocks(vi, &map);
> +             if (ret)
> +                     return ret;

How about introducing another mode called
EROFS_GET_BLOCKS_FINDTAIL

which implys .m_la = vi->i_size - 1 internally, so we won't need to
handle .m_la here.

> +             vi->z_idata_headlcn = map.m_la >> vi->z_logical_clusterbits;

Also updaing vi->z_idata_headlcn when EROFS_GET_BLOCKS_FINDTAIL.

> +     }
> +
>       vi->flags |= EROFS_I_Z_INITED;
>       return 0;
>  }
> @@ -374,7 +445,8 @@ static int z_erofs_extent_lookback(struct 
> z_erofs_maprecorder *m,
>  }
>  
>  static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
> -                                         unsigned int initial_lcn)
> +                                         unsigned int initial_lcn,
> +                                         bool idatamap)
>  {
>       struct erofs_inode *const vi = m->inode;
>       struct erofs_map_blocks *const map = m->map;
> @@ -384,6 +456,12 @@ static int z_erofs_get_extent_compressedlen(struct 
> z_erofs_maprecorder *m,
>  
>       DBG_BUGON(m->type != Z_EROFS_VLE_CLUSTER_TYPE_PLAIN &&
>                 m->type != Z_EROFS_VLE_CLUSTER_TYPE_HEAD);
> +
> +     if (idatamap) {
> +             map->m_plen = vi->z_idata_size;
> +             return 0;
> +     }
> +
>       if (!(map->m_flags & EROFS_MAP_ZIPPED) ||
>           !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1)) {
>               map->m_plen = 1 << lclusterbits;
> @@ -440,8 +518,8 @@ err_bonus_cblkcnt:
>       return -EFSCORRUPTED;
>  }
>  
> -int z_erofs_map_blocks_iter(struct erofs_inode *vi,
> -                         struct erofs_map_blocks *map)
> +static int z_erofs_do_map_blocks(struct erofs_inode *vi,
> +                              struct erofs_map_blocks *map)
>  {
>       struct z_erofs_maprecorder m = {
>               .inode = vi,
> @@ -452,18 +530,7 @@ int z_erofs_map_blocks_iter(struct erofs_inode *vi,
>       unsigned int lclusterbits, endoff;
>       unsigned long initial_lcn;
>       unsigned long long ofs, end;
> -
> -     /* when trying to read beyond EOF, leave it unmapped */
> -     if (map->m_la >= vi->i_size) {
> -             map->m_llen = map->m_la + 1 - vi->i_size;
> -             map->m_la = vi->i_size;
> -             map->m_flags = 0;
> -             goto out;
> -     }
> -
> -     err = z_erofs_fill_inode_lazy(vi);
> -     if (err)
> -             goto out;
> +     bool idatamap;
>  
>       lclusterbits = vi->z_logical_clusterbits;
>       ofs = map->m_la;
> @@ -510,19 +577,52 @@ int z_erofs_map_blocks_iter(struct erofs_inode *vi,
>               goto out;
>       }
>  
> +     /* check if mapping tail-packing data */
> +     idatamap = vi->z_idata_size && (ofs == vi->i_size - 1 ||
> +                m.lcn == vi->z_idata_headlcn);

better namin as `is_idata'...

I think no need to handle ofs == vi->i_size - 1 specially here
if EROFS_GET_BLOCKS_FINDTAIL is introduced...

> +
> +     /* need to trim tail-packing data if beyond file size */
>       map->m_llen = end - map->m_la;
> -     map->m_pa = blknr_to_addr(m.pblk);
> +     if (idatamap && end > vi->i_size)
> +             map->m_llen -= end - vi->i_size;

No need as well?

>  
> -     err = z_erofs_get_extent_compressedlen(&m, initial_lcn);
> +     if (idatamap && (vi->z_advise & Z_EROFS_ADVISE_INLINE_DATA)) {
> +             map->m_pa = z_erofs_inline_data_addr(vi);

How about setting another u32 z_idataoff when EROFS_GET_BLOCKS_FINDTAIL
so we won't need to introduce another calculate methods instead?

Thanks,
Gao Xiang

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