erofs-utils: lib: merge consecutive chunks if possible

Since EROFS chunk size can be configured on a per-file basis,
let's generate indexes with the best chunk size.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230724170646.22281-3-hsiangkao@linux.alibaba.com

diff --git a/include/erofs/defs.h b/include/erofs/defs.h
index 44af557b19d611820d967021b3d01377e5429faf..20f97413b6a24b4e70c09ed4d9cf0834931c8d91 100644 (file)
--- a/include/erofs/defs.h
+++ b/include/erofs/defs.h
@@ -286,6 +286,11 @@ static inline unsigned int fls_long(unsigned long x)
        return x ? sizeof(x) * 8 - __builtin_clz(x) : 0;
 }
 
+static inline unsigned long lowbit(unsigned long n)
+{
+       return n & -n;
+}
+
 /**
  * __roundup_pow_of_two() - round up to nearest power of two
  * @n: value to round up

diff --git a/lib/blobchunk.c b/lib/blobchunk.c
index 4619057e4b49f7906268504f995533b3def5f49b..4e4295eb317ff9bcb738ae2186404c244434f07e 100644 (file)
--- a/lib/blobchunk.c
+++ b/lib/blobchunk.c
@@ -179,13 +179,47 @@ int erofs_blob_write_chunk_indexes(struct erofs_inode *inode,
        return dev_write(inode->sbi, inode->chunkindexes, off, inode->extent_isize);
 }
 
+int erofs_blob_mergechunks(struct erofs_inode *inode, unsigned int chunkbits,
+                          unsigned int new_chunkbits)
+{
+       struct erofs_sb_info *sbi = inode->sbi;
+       unsigned int dst, src, unit, count;
+
+       if (new_chunkbits - sbi->blkszbits > EROFS_CHUNK_FORMAT_BLKBITS_MASK)
+               new_chunkbits = EROFS_CHUNK_FORMAT_BLKBITS_MASK + sbi->blkszbits;
+       if (chunkbits >= new_chunkbits)         /* no need to merge */
+               goto out;
+
+       if (inode->u.chunkformat & EROFS_CHUNK_FORMAT_INDEXES)
+               unit = sizeof(struct erofs_inode_chunk_index);
+       else
+               unit = EROFS_BLOCK_MAP_ENTRY_SIZE;
+
+       count = round_up(inode->i_size, 1ULL << new_chunkbits) >> new_chunkbits;
+       for (dst = src = 0; dst < count; ++dst) {
+               *((void **)inode->chunkindexes + dst) =
+                       *((void **)inode->chunkindexes + src);
+               src += 1U << (new_chunkbits - chunkbits);
+       }
+
+       DBG_BUGON(count * unit >= inode->extent_isize);
+       inode->extent_isize = count * unit;
+       chunkbits = new_chunkbits;
+out:
+       inode->u.chunkformat = (chunkbits - sbi->blkszbits) |
+               (inode->u.chunkformat & ~EROFS_CHUNK_FORMAT_BLKBITS_MASK);
+       return 0;
+}
+
 int erofs_blob_write_chunked_file(struct erofs_inode *inode, int fd)
 {
        struct erofs_sb_info *sbi = inode->sbi;
        unsigned int chunkbits = cfg.c_chunkbits;
        unsigned int count, unit;
+       struct erofs_blobchunk *chunk, *lastch;
        struct erofs_inode_chunk_index *idx;
        erofs_off_t pos, len, chunksize;
+       erofs_blk_t lb, minextblks;
        u8 *chunkdata;
        int ret;
 
@@ -201,10 +235,9 @@ int erofs_blob_write_chunked_file(struct erofs_inode *inode, int fd)
                chunkbits = EROFS_CHUNK_FORMAT_BLKBITS_MASK + sbi->blkszbits;
        chunksize = 1ULL << chunkbits;
        count = DIV_ROUND_UP(inode->i_size, chunksize);
-       inode->u.chunkformat |= chunkbits - sbi->blkszbits;
+
        if (multidev)
                inode->u.chunkformat |= EROFS_CHUNK_FORMAT_INDEXES;
-
        if (inode->u.chunkformat & EROFS_CHUNK_FORMAT_INDEXES)
                unit = sizeof(struct erofs_inode_chunk_index);
        else
@@ -222,8 +255,9 @@ int erofs_blob_write_chunked_file(struct erofs_inode *inode, int fd)
        }
        idx = inode->chunkindexes;
 
+       lastch = NULL;
+       minextblks = BLK_ROUND_UP(sbi, inode->i_size);
        for (pos = 0; pos < inode->i_size; pos += len) {
-               struct erofs_blobchunk *chunk;
 #ifdef SEEK_DATA
                off_t offset = lseek(fd, pos, SEEK_DATA);
 
@@ -247,6 +281,7 @@ int erofs_blob_write_chunked_file(struct erofs_inode *inode, int fd)
                                pos += chunksize;
                        } while (pos < offset);
                        DBG_BUGON(pos != offset);
+                       lastch = NULL;
                        continue;
                }
 #endif
@@ -263,11 +298,21 @@ int erofs_blob_write_chunked_file(struct erofs_inode *inode, int fd)
                        ret = PTR_ERR(chunk);
                        goto err;
                }
+
+               if (lastch && (lastch->device_id != chunk->device_id ||
+                   erofs_pos(sbi, lastch->blkaddr) + lastch->chunksize !=
+                   erofs_pos(sbi, chunk->blkaddr))) {
+                       lb = lowbit(pos >> sbi->blkszbits);
+                       if (lb && lb < minextblks)
+                               minextblks = lb;
+               }
                *(void **)idx++ = chunk;
+               lastch = chunk;
        }
        inode->datalayout = EROFS_INODE_CHUNK_BASED;
        free(chunkdata);
-       return 0;
+       return erofs_blob_mergechunks(inode, chunkbits,
+                                     ilog2(minextblks) + sbi->blkszbits);
 err:
        free(inode->chunkindexes);
        inode->chunkindexes = NULL;