On Tue, Nov 29, 2022 at 06:00:53PM +0800, Yue Hu wrote:
> From: Yue Hu <[email protected]>
> 
> Previously, there's no fragment deduplication when this feature is
> introduced. Let's support it now.
> 
> With this patch, for Linux 5.10.1 + 5.10.87 source code:
> 

Please add EROFS -T0 to retest 32 byte inode results.

Also add Squashfs + LZ4HC results as a comparison.

> [before]
>  32k pcluster + lz4hc,12 + fragment           454M
>  64k pcluster + lz4hc,12 + fragment           439M
> 128k pcluster + lz4hc,12 + fragment           431M
>  32k pcluster + lz4hc,12 + fragment + dedupe  376M
>  64k pcluster + lz4hc,12 + fragment + dedupe  384M
> 128k pcluster + lz4hc,12 + fragment + dedupe  399M
> 
> [after]
>  32k pcluster + lz4hc,12 + fragment           316M
>  64k pcluster + lz4hc,12 + fragment           300M
> 128k pcluster + lz4hc,12 + fragment           292M
>  32k pcluster + lz4hc,12 + fragment + dedupe  291M
>  64k pcluster + lz4hc,12 + fragment + dedupe  286M
> 128k pcluster + lz4hc,12 + fragment + dedupe  283M
> 
> Suggested-by: Gao Xiang <[email protected]>
> Signed-off-by: Yue Hu <[email protected]>
> ---
> v3: 
> - modify acrroding to Xiang's comments in v2
> - simplify the logic in vle_compress_one
> - fix the crash for 1MB pcluster
> 
> v2: mainly improve the logic in compression
> 
>  include/erofs/fragments.h |   3 +-
>  lib/compress.c            | 115 ++++++++++++++++++++----
>  lib/fragments.c           | 180 +++++++++++++++++++++++++++++++++++++-
>  3 files changed, 277 insertions(+), 21 deletions(-)
> 
> diff --git a/include/erofs/fragments.h b/include/erofs/fragments.h
> index 5444384..6c51fc9 100644
> --- a/include/erofs/fragments.h
> +++ b/include/erofs/fragments.h
> @@ -15,8 +15,9 @@ extern "C"
>  extern const char *frags_packedname;
>  #define EROFS_PACKED_INODE   frags_packedname
>  
> +int z_erofs_fragments_dedupe(struct erofs_inode *inode, int fd, u32 *crc);
>  int z_erofs_pack_fragments(struct erofs_inode *inode, void *data,
> -                        unsigned int len);
> +                        unsigned int len, u32 crc);

                                                ^ tofcrc

tail of file crc

>  struct erofs_inode *erofs_mkfs_build_fragments(void);
>  int erofs_fragments_init(void);
>  void erofs_fragments_exit(void);
> diff --git a/lib/compress.c b/lib/compress.c
> index 17b3213..7e01932 100644
> --- a/lib/compress.c
> +++ b/lib/compress.c
> @@ -33,6 +33,10 @@ struct z_erofs_vle_compress_ctx {
>       unsigned int head, tail;
>       erofs_blk_t blkaddr;            /* pointing to the next blkaddr */
>       u16 clusterofs;
> +
> +     u32 crc;

        tofcrc;

> +     unsigned int pclustersize;
> +     erofs_off_t remaining;
>  };
>  
>  #define Z_EROFS_LEGACY_MAP_HEADER_SIZE       \
> @@ -162,10 +166,10 @@ static void z_erofs_write_indexes(struct 
> z_erofs_vle_compress_ctx *ctx)
>       ctx->clusterofs = clusterofs + count;
>  }
>  
> -static int z_erofs_compress_dedupe(struct erofs_inode *inode,
> -                                struct z_erofs_vle_compress_ctx *ctx,
> +static int z_erofs_compress_dedupe(struct z_erofs_vle_compress_ctx *ctx,
>                                  unsigned int *len)
>  {
> +     struct erofs_inode *inode = ctx->inode;
>       int ret = 0;
>  
>       do {
> @@ -319,30 +323,62 @@ static void tryrecompress_trailing(void *in, unsigned 
> int *insize,
>       *compressedsize = ret;
>  }
>  
> -static int vle_compress_one(struct z_erofs_vle_compress_ctx *ctx,
> -                         bool final)
> +static void z_erofs_fragments_dedupe_update(struct z_erofs_vle_compress_ctx 
> *ctx,
> +                                         unsigned int *len)
> +{
> +     struct erofs_inode *inode = ctx->inode;
> +     const unsigned int remaining = ctx->remaining + *len;

please rename as "new_fragmentsize" for easy understanding.

> +
> +     DBG_BUGON(!inode->fragment_size);
> +
> +     /* try to close the gap if it gets larger (should be rare) */
> +     if (inode->fragment_size < remaining) {
> +             ctx->pclustersize = roundup(remaining - inode->fragment_size,
> +                                         EROFS_BLKSIZ);
> +             return;
> +     }
> +
> +     inode->fragmentoff += inode->fragment_size - remaining;
> +     inode->fragment_size = remaining;
> +
> +     erofs_dbg("Reducing fragment size to %u at %lu",
> +               inode->fragment_size, inode->fragmentoff);
> +
> +     /* it's ending */
> +     ctx->head += remaining;
> +     ctx->remaining = 0;
> +     *len = 0;
> +}
> +
> +static int vle_compress_one(struct z_erofs_vle_compress_ctx *ctx, bool fixup)
>  {
>       static char dstbuf[EROFS_CONFIG_COMPR_MAX_SZ + EROFS_BLKSIZ];
>       struct erofs_inode *inode = ctx->inode;
>       char *const dst = dstbuf + EROFS_BLKSIZ;
>       struct erofs_compress *const h = &compresshandle;
>       unsigned int len = ctx->tail - ctx->head;
> +     bool final = !ctx->remaining;
>       int ret;
>  
>       while (len) {
> -             unsigned int pclustersize =
> -                     z_erofs_get_max_pclusterblks(inode) * EROFS_BLKSIZ;
>               bool may_inline = (cfg.c_ztailpacking && final);
>               bool may_packing = (cfg.c_fragments && final &&
>                                  !erofs_is_packed_inode(inode));

                bool may_xxxx = fixup;

>  
> -             if (z_erofs_compress_dedupe(inode, ctx, &len) && !final)
> +             if (z_erofs_compress_dedupe(ctx, &len) && !final)
>                       break;
>  
> -             if (len <= pclustersize) {
> +             if (len <= ctx->pclustersize) {
>                       if (!final || !len)
>                               break;
>                       if (may_packing) {
> +                             if (inode->fragment_size && !fixup) {
> +                                     ctx->remaining = inode->fragment_size;
> +                                     ctx->pclustersize =
> +                                             roundup(len, EROFS_BLKSIZ);
> +                                     ctx->e.length = 0;
> +                                     return -EAGAIN;
> +                             }
>                               ctx->e.length = len;
>                               goto frag_packing;
>                       }
> @@ -353,7 +389,7 @@ static int vle_compress_one(struct 
> z_erofs_vle_compress_ctx *ctx,
>               ctx->e.length = min(len,
>                               cfg.c_max_decompressed_extent_bytes);
>               ret = erofs_compress_destsize(h, ctx->queue + ctx->head,
> -                             &ctx->e.length, dst, pclustersize,
> +                             &ctx->e.length, dst, ctx->pclustersize,
>                               !(final && len == ctx->e.length));
>               if (ret <= 0) {
>                       if (ret != -EAGAIN) {
> @@ -385,11 +421,12 @@ nocompression:
>                       ctx->e.compressedblks = 1;
>                       ctx->e.raw = true;
>               } else if (may_packing && len == ctx->e.length &&
> -                        ret < pclustersize) {
> +                        ret < ctx->pclustersize && (!inode->fragment_size ||
> +                        fixup)) {
>  frag_packing:
>                       ret = z_erofs_pack_fragments(inode,
>                                                    ctx->queue + ctx->head,
> -                                                  len);
> +                                                  len, ctx->crc);
>                       if (ret < 0)
>                               return ret;
>                       ctx->e.compressedblks = 0; /* indicate a fragment */

                        may_xxxx = false;

> @@ -425,6 +462,21 @@ frag_packing:
>                       DBG_BUGON(ctx->e.compressedblks * EROFS_BLKSIZ >=
>                                 ctx->e.length);
>  
> +                     /*
> +                      * Try to recompress a litte more if there's space left
> +                      * for fragment deduplication.
> +                      */
> +                     if (may_packing && len == ctx->e.length && tailused &&
> +                         ctx->tail < sizeof(ctx->queue)) {
> +                             DBG_BUGON(!inode->fragment_size);
> +
> +                             ctx->remaining = inode->fragment_size;
> +                             ctx->pclustersize =
> +                                     ctx->e.compressedblks * EROFS_BLKSIZ;
> +                             ctx->e.length = 0;
> +                             return -EAGAIN;
> +                     }
> +
>                       /* zero out garbage trailing data for non-0padding */
>                       if (!erofs_sb_has_lz4_0padding())
>                               memset(dst + ret, 0,
> @@ -454,6 +506,9 @@ frag_packing:
>               ctx->head += ctx->e.length;
>               len -= ctx->e.length;
>  
> +             if (fixup && ctx->e.compressedblks)

                if (may_xxxx)

> +                     z_erofs_fragments_dedupe_update(ctx, &len);
> +
>               if (!final && ctx->head >= EROFS_CONFIG_COMPR_MAX_SZ) {
>                       const unsigned int qh_aligned =
>                               round_down(ctx->head, EROFS_BLKSIZ);
> @@ -736,10 +791,9 @@ int erofs_write_compressed_file(struct erofs_inode 
> *inode, int fd)
>  {
>       struct erofs_buffer_head *bh;
>       static struct z_erofs_vle_compress_ctx ctx;
> -     erofs_off_t remaining;
>       erofs_blk_t blkaddr, compressed_blocks;
>       unsigned int legacymetasize;
> -     int ret;
> +     int ret = 0;
>       u8 *compressmeta = malloc(vle_compressmeta_capacity(inode->i_size));
>  
>       if (!compressmeta)
> @@ -775,6 +829,16 @@ int erofs_write_compressed_file(struct erofs_inode 
> *inode, int fd)
>       inode->idata_size = 0;
>       inode->fragment_size = 0;
>  
> +     /*
> +      * Dedupe fragments before compression to avoid writing duplicate parts
> +      * into packed inode.
> +      */
> +     if (cfg.c_fragments && !erofs_is_packed_inode(inode)) {
> +             ret = z_erofs_fragments_dedupe(inode, fd, &ctx.crc);
> +             if (ret < 0)
> +                     goto err_bdrop;
> +     }
> +
>       blkaddr = erofs_mapbh(bh->block);       /* start_blkaddr */
>       ctx.inode = inode;
>       ctx.blkaddr = blkaddr;
> @@ -782,22 +846,25 @@ int erofs_write_compressed_file(struct erofs_inode 
> *inode, int fd)
>       ctx.head = ctx.tail = 0;
>       ctx.clusterofs = 0;
>       ctx.e.length = 0;
> -     remaining = inode->i_size;
> +     ctx.e.compressedblks = 0;
> +     ctx.pclustersize = z_erofs_get_max_pclusterblks(inode) * EROFS_BLKSIZ;
> +     ctx.remaining = inode->i_size - inode->fragment_size;
>  
> -     while (remaining) {
> -             const u64 readcount = min_t(u64, remaining,
> +     while (ctx.remaining) {
> +             const u64 readcount = min_t(u64, ctx.remaining,
>                                           sizeof(ctx.queue) - ctx.tail);
> +             bool fixup = ret < 0;

        drop this one;

>  
>               ret = read(fd, ctx.queue + ctx.tail, readcount);
>               if (ret != readcount) {
>                       ret = -errno;
>                       goto err_bdrop;
>               }
> -             remaining -= readcount;
> +             ctx.remaining -= readcount;
>               ctx.tail += readcount;
>  
> -             ret = vle_compress_one(&ctx, !remaining);

                                             ret == -EAGAIN

> -             if (ret)
> +             ret = vle_compress_one(&ctx, fixup);
> +             if (ret && ret != -EAGAIN)
>                       goto err_free_idata;
>       }
>       DBG_BUGON(ctx.head != ctx.tail);
> @@ -807,6 +874,16 @@ int erofs_write_compressed_file(struct erofs_inode 
> *inode, int fd)
>       DBG_BUGON(compressed_blocks < !!inode->idata_size);
>       compressed_blocks -= !!inode->idata_size;
>  
> +     if (inode->fragment_size && ctx.e.compressedblks) {

why not moving into z_erofs_fragments_dedupe_update()?

Thanks,
Gao Xiang

> +             z_erofs_write_indexes(&ctx);
> +
> +             inode->z_advise |= Z_EROFS_ADVISE_FRAGMENT_PCLUSTER;
> +             ctx.e.length = inode->fragment_size;
> +             ctx.e.compressedblks = 0;
> +             ctx.e.raw = true;
> +             ctx.e.partial = false;
> +             ctx.e.blkaddr = ctx.blkaddr;
> +     }
>       z_erofs_write_indexes(&ctx);
>       z_erofs_write_indexes_final(&ctx);
>       legacymetasize = ctx.metacur - compressmeta;
> diff --git a/lib/fragments.c b/lib/fragments.c
> index b8c37d5..48c133f 100644
> --- a/lib/fragments.c
> +++ b/lib/fragments.c
> @@ -10,14 +10,183 @@
>  #include "erofs/inode.h"
>  #include "erofs/compress.h"
>  #include "erofs/print.h"
> +#include "erofs/internal.h"
>  #include "erofs/fragments.h"
>  
> +struct erofs_fragment_dedupe_item {
> +     struct list_head        list;
> +     unsigned int            length, nr_dup;
> +     erofs_off_t             pos;
> +     u8                      data[];
> +};
> +
> +#define FRAGMENT_HASHTABLE_SIZE              65536
> +#define FRAGMENT_HASH(crc)           (crc & (FRAGMENT_HASHTABLE_SIZE - 1))
> +
> +static struct list_head dupli_frags[FRAGMENT_HASHTABLE_SIZE];
> +static unsigned int len_to_hash; /* the fragment length for crc32 hash */
> +
>  static FILE *packedfile;
>  const char *frags_packedname = "packed_file";
>  
> +static int z_erofs_fragments_dedupe_find(struct erofs_inode *inode, int fd,
> +                                      u32 crc)
> +{
> +     struct erofs_fragment_dedupe_item *cur, *di = NULL;
> +     struct list_head *head;
> +     u8 *data;
> +     unsigned int length;
> +     int ret;
> +
> +     head = &dupli_frags[FRAGMENT_HASH(crc)];
> +     if (list_empty(head))
> +             return 0;
> +
> +     /* XXX: no need to read so much for smaller? */
> +     if (inode->i_size < 2 * EROFS_CONFIG_COMPR_MAX_SZ)
> +             length = inode->i_size;
> +     else
> +             length = 2 * EROFS_CONFIG_COMPR_MAX_SZ;
> +
> +     data = malloc(length);
> +     if (!data)
> +             return -ENOMEM;
> +
> +     ret = lseek(fd, inode->i_size - length, SEEK_SET);
> +     if (ret == -1) {
> +             ret = -errno;
> +             goto out;
> +     }
> +
> +     ret = read(fd, data, length);
> +     if (ret != length) {
> +             ret = -errno;
> +             goto out;
> +     }
> +
> +     list_for_each_entry(cur, head, list) {
> +             unsigned int e1, e2, i = 0;
> +
> +             DBG_BUGON(cur->length < len_to_hash + 1);
> +             DBG_BUGON(length < len_to_hash + 1);
> +
> +             e1 = cur->length - len_to_hash - 1;
> +             e2 = length - len_to_hash - 1;
> +
> +             if (memcmp(cur->data + e1 + 1, data + e2 + 1, len_to_hash))
> +                     continue;
> +
> +             while (i <= min(e1, e2) && cur->data[e1 - i] == data[e2 - i])
> +                     i++;
> +
> +             if (i && (!di || i + len_to_hash > di->nr_dup)) {
> +                     cur->nr_dup = i + len_to_hash;
> +                     di = cur;
> +
> +                     /* full match */
> +                     if (i == min(e1, e2) + 1)
> +                             break;
> +             }
> +     }
> +     if (!di)
> +             goto out;
> +
> +     DBG_BUGON(di->length < di->nr_dup);
> +
> +     inode->fragment_size = di->nr_dup;
> +     inode->fragmentoff = di->pos + di->length - di->nr_dup;
> +
> +     erofs_dbg("Dedupe %u fragment data at %lu", inode->fragment_size,
> +               inode->fragmentoff);
> +out:
> +     free(data);
> +     return ret;
> +}
> +
> +
> +int z_erofs_fragments_dedupe(struct erofs_inode *inode, int fd, u32 *crc_ret)
> +{
> +     u8 data_to_hash[len_to_hash];
> +     u32 crc;
> +     int ret;
> +
> +     if (inode->i_size <= len_to_hash)
> +             return 0;
> +
> +     ret = lseek(fd, inode->i_size - len_to_hash, SEEK_SET);
> +     if (ret == -1)
> +             return -errno;
> +
> +     ret = read(fd, data_to_hash, len_to_hash);
> +     if (ret != len_to_hash)
> +             return -errno;
> +
> +     crc = erofs_crc32c(~0, data_to_hash, len_to_hash);
> +     *crc_ret = crc;
> +
> +     ret = z_erofs_fragments_dedupe_find(inode, fd, crc);
> +     if (ret < 0)
> +             return ret;
> +
> +     ret = lseek(fd, 0, SEEK_SET);
> +     if (ret == -1)
> +             return -errno;
> +     return 0;
> +}
> +
> +static int z_erofs_fragments_dedupe_insert(void *data, unsigned int len,
> +                                        erofs_off_t pos, u32 crc)
> +{
> +     struct erofs_fragment_dedupe_item *di;
> +
> +     if (len <= len_to_hash)
> +             return 0;
> +
> +     di = malloc(sizeof(*di) + len);
> +     if (!di)
> +             return -ENOMEM;
> +
> +     memcpy(di->data, data, len);
> +     di->length = len;
> +     di->pos = pos;
> +     di->nr_dup = 0;
> +
> +     list_add_tail(&di->list, &dupli_frags[FRAGMENT_HASH(crc)]);
> +     return 0;
> +}
> +
> +static inline void z_erofs_fragments_dedupe_init(unsigned int clen)
> +{
> +     unsigned int i;
> +
> +     for (i = 0; i < FRAGMENT_HASHTABLE_SIZE; ++i)
> +             init_list_head(&dupli_frags[i]);
> +
> +     len_to_hash = clen;
> +}
> +
> +static void z_erofs_fragments_dedupe_exit(void)
> +{
> +     struct erofs_fragment_dedupe_item *di, *n;
> +     struct list_head *head;
> +     unsigned int i;
> +
> +     for (i = 0; i < FRAGMENT_HASHTABLE_SIZE; ++i) {
> +             head = &dupli_frags[i];
> +
> +             if (list_empty(head))
> +                     continue;
> +
> +             list_for_each_entry_safe(di, n, head, list)
> +                     free(di);
> +     }
> +}
> +
>  int z_erofs_pack_fragments(struct erofs_inode *inode, void *data,
> -                        unsigned int len)
> +                        unsigned int len, u32 crc)
>  {
> +     int ret;
> +
>       inode->z_advise |= Z_EROFS_ADVISE_FRAGMENT_PCLUSTER;
>       inode->fragmentoff = ftell(packedfile);
>       inode->fragment_size = len;
> @@ -35,6 +204,11 @@ int z_erofs_pack_fragments(struct erofs_inode *inode, 
> void *data,
>  
>       erofs_dbg("Recording %u fragment data at %lu", inode->fragment_size,
>                 inode->fragmentoff);
> +
> +     ret = z_erofs_fragments_dedupe_insert(data, len, inode->fragmentoff,
> +                                           crc);
> +     if (ret)
> +             return ret;
>       return len;
>  }
>  
> @@ -50,6 +224,8 @@ void erofs_fragments_exit(void)
>  {
>       if (packedfile)
>               fclose(packedfile);
> +
> +     z_erofs_fragments_dedupe_exit();
>  }
>  
>  int erofs_fragments_init(void)
> @@ -61,5 +237,7 @@ int erofs_fragments_init(void)
>  #endif
>       if (!packedfile)
>               return -ENOMEM;
> +
> +     z_erofs_fragments_dedupe_init(16);
>       return 0;
>  }
> -- 
> 2.17.1

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