Commit 1d191b4c authored by Gao Xiang's avatar Gao Xiang
Browse files

erofs: implement encoded extent metadata 



Implement the extent metadata parsing described in the previous commit.
For 16-byte and 32-byte extent records, currently it is just a trivial
binary search without considering the last access footprint, but it can
be optimized for better sequential performance later.

Tail fragments are supported, but ztailpacking feature is not
for simplicity.

Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
Acked-by: default avatarChao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20250310095459.2620647-9-hsiangkao@linux.alibaba.com
parent efb2aef5

fs/erofs/internal.h

+4 −1
Original line number Diff line number Diff line
@@ -263,7 +263,10 @@ struct erofs_inode { 
			unsigned short z_advise;

			unsigned char  z_algorithmtype[2];

			unsigned char  z_lclusterbits;

			unsigned long  z_tailextent_headlcn;

			union {

				u64    z_tailextent_headlcn;

				u64    z_extents;

			};

			erofs_off_t    z_fragmentoff;

			unsigned short z_idata_size;

		};

fs/erofs/zmap.c

+131 −11
Original line number Diff line number Diff line
@@ -391,7 +391,7 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m) 
	return 0;

}



static int z_erofs_do_map_blocks(struct inode *inode,

static int z_erofs_map_blocks_fo(struct inode *inode,

				 struct erofs_map_blocks *map, int flags)

{

	struct erofs_inode *vi = EROFS_I(inode);
@@ -409,6 +409,14 @@ static int z_erofs_do_map_blocks(struct inode *inode, 
	unsigned long long ofs, end;



	ofs = flags & EROFS_GET_BLOCKS_FINDTAIL ? inode->i_size - 1 : map->m_la;

	if (fragment && !(flags & EROFS_GET_BLOCKS_FINDTAIL) &&

	    !vi->z_tailextent_headlcn) {

		map->m_la = 0;

		map->m_llen = inode->i_size;

		map->m_flags = EROFS_MAP_MAPPED |

			EROFS_MAP_FULL_MAPPED | EROFS_MAP_FRAGMENT;

		return 0;

	}

	initial_lcn = ofs >> lclusterbits;

	endoff = ofs & ((1 << lclusterbits) - 1);
@@ -526,6 +534,115 @@ static int z_erofs_do_map_blocks(struct inode *inode, 
	return err;

}



static int z_erofs_map_blocks_ext(struct inode *inode,

				  struct erofs_map_blocks *map, int flags)

{

	struct erofs_inode *vi = EROFS_I(inode);

	struct super_block *sb = inode->i_sb;

	bool interlaced = vi->z_advise & Z_EROFS_ADVISE_INTERLACED_PCLUSTER;

	unsigned int recsz = z_erofs_extent_recsize(vi->z_advise);

	erofs_off_t pos = round_up(Z_EROFS_MAP_HEADER_END(erofs_iloc(inode) +

				   vi->inode_isize + vi->xattr_isize), recsz);

	erofs_off_t lend = inode->i_size;

	erofs_off_t l, r, mid, pa, la, lstart;

	struct z_erofs_extent *ext;

	unsigned int fmt;

	bool last;



	map->m_flags = 0;

	if (recsz <= offsetof(struct z_erofs_extent, pstart_hi)) {

		if (recsz <= offsetof(struct z_erofs_extent, pstart_lo)) {

			ext = erofs_read_metabuf(&map->buf, sb, pos, true);

			if (IS_ERR(ext))

				return PTR_ERR(ext);

			pa = le64_to_cpu(*(__le64 *)ext);

			pos += sizeof(__le64);

			lstart = 0;

		} else {

			lstart = map->m_la >> vi->z_lclusterbits;

			pa = EROFS_NULL_ADDR;

		}



		for (; lstart <= map->m_la; lstart += 1 << vi->z_lclusterbits) {

			ext = erofs_read_metabuf(&map->buf, sb, pos, true);

			if (IS_ERR(ext))

				return PTR_ERR(ext);

			map->m_plen = le32_to_cpu(ext->plen);

			if (pa != EROFS_NULL_ADDR) {

				map->m_pa = pa;

				pa += map->m_plen & Z_EROFS_EXTENT_PLEN_MASK;

			} else {

				map->m_pa = le32_to_cpu(ext->pstart_lo);

			}

			pos += recsz;

		}

		last = (lstart >= round_up(lend, 1 << vi->z_lclusterbits));

		lend = min(lstart, lend);

		lstart -= 1 << vi->z_lclusterbits;

	} else {

		lstart = lend;

		for (l = 0, r = vi->z_extents; l < r; ) {

			mid = l + (r - l) / 2;

			ext = erofs_read_metabuf(&map->buf, sb,

						 pos + mid * recsz, true);

			if (IS_ERR(ext))

				return PTR_ERR(ext);



			la = le32_to_cpu(ext->lstart_lo);

			pa = le32_to_cpu(ext->pstart_lo) |

				(u64)le32_to_cpu(ext->pstart_hi) << 32;

			if (recsz > offsetof(struct z_erofs_extent, lstart_hi))

				la |= (u64)le32_to_cpu(ext->lstart_hi) << 32;



			if (la > map->m_la) {

				r = mid;

				lend = la;

			} else {

				l = mid + 1;

				if (map->m_la == la)

					r = min(l + 1, r);

				lstart = la;

				map->m_plen = le32_to_cpu(ext->plen);

				map->m_pa = pa;

			}

		}

		last = (l >= vi->z_extents);

	}



	if (lstart < lend) {

		map->m_la = lstart;

		if (last && (vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER)) {

			map->m_flags |= EROFS_MAP_MAPPED | EROFS_MAP_FRAGMENT;

			vi->z_fragmentoff = map->m_plen;

			if (recsz >= offsetof(struct z_erofs_extent, pstart_lo))

				vi->z_fragmentoff |= map->m_pa << 32;

		} else if (map->m_plen) {

			map->m_flags |= EROFS_MAP_MAPPED |

				EROFS_MAP_FULL_MAPPED | EROFS_MAP_ENCODED;

			fmt = map->m_plen >> Z_EROFS_EXTENT_PLEN_FMT_BIT;

			if (fmt)

				map->m_algorithmformat = fmt - 1;

			else if (interlaced && !erofs_blkoff(sb, map->m_pa))

				map->m_algorithmformat =

					Z_EROFS_COMPRESSION_INTERLACED;

			else

				map->m_algorithmformat =

					Z_EROFS_COMPRESSION_SHIFTED;

			if (map->m_plen & Z_EROFS_EXTENT_PLEN_PARTIAL)

				map->m_flags |= EROFS_MAP_PARTIAL_REF;

			map->m_plen &= Z_EROFS_EXTENT_PLEN_MASK;

		}

	}

	map->m_llen = lend - map->m_la;

	if (!last && map->m_llen < sb->s_blocksize) {

		erofs_err(sb, "extent too small %llu @ offset %llu of nid %llu",

			  map->m_llen, map->m_la, vi->nid);

		DBG_BUGON(1);

		return -EFSCORRUPTED;

	}

	return 0;

}



static int z_erofs_fill_inode_lazy(struct inode *inode)

{

	struct erofs_inode *const vi = EROFS_I(inode);
@@ -570,6 +687,13 @@ static int z_erofs_fill_inode_lazy(struct inode *inode) 
	}

	vi->z_advise = le16_to_cpu(h->h_advise);

	vi->z_lclusterbits = sb->s_blocksize_bits + (h->h_clusterbits & 15);

	if (vi->datalayout == EROFS_INODE_COMPRESSED_FULL &&

	    (vi->z_advise & Z_EROFS_ADVISE_EXTENTS)) {

		vi->z_extents = le32_to_cpu(h->h_extents_lo) |

			((u64)le16_to_cpu(h->h_extents_hi) << 32);

		goto done;

	}



	vi->z_algorithmtype[0] = h->h_algorithmtype & 15;

	vi->z_algorithmtype[1] = h->h_algorithmtype >> 4;

	if (vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER)
@@ -609,7 +733,7 @@ static int z_erofs_fill_inode_lazy(struct inode *inode) 
			.buf = __EROFS_BUF_INITIALIZER

		};



		err = z_erofs_do_map_blocks(inode, &map,

		err = z_erofs_map_blocks_fo(inode, &map,

					    EROFS_GET_BLOCKS_FINDTAIL);

		erofs_put_metabuf(&map.buf);

		if (err < 0)
@@ -640,15 +764,11 @@ int z_erofs_map_blocks_iter(struct inode *inode, struct erofs_map_blocks *map, 
	} else {

		err = z_erofs_fill_inode_lazy(inode);

		if (!err) {

			if ((vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER) &&

			    !vi->z_tailextent_headlcn) {

				map->m_la = 0;

				map->m_llen = inode->i_size;

				map->m_flags = EROFS_MAP_MAPPED |

					EROFS_MAP_FULL_MAPPED | EROFS_MAP_FRAGMENT;

			} else {

				err = z_erofs_do_map_blocks(inode, map, flags);

			}

			if (vi->datalayout == EROFS_INODE_COMPRESSED_FULL &&

			    (vi->z_advise & Z_EROFS_ADVISE_EXTENTS))

				err = z_erofs_map_blocks_ext(inode, map, flags);

			else

				err = z_erofs_map_blocks_fo(inode, map, flags);

		}

		if (!err && (map->m_flags & EROFS_MAP_ENCODED) &&

		    unlikely(map->m_plen > Z_EROFS_PCLUSTER_MAX_SIZE ||