Messages in this thread Patch in this message | | | From | Gao Xiang <> | Subject | [PATCH v2 08/10] erofs: support parsing big pcluster compact indexes | Date | Thu, 1 Apr 2021 11:29:52 +0800 |
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From: Gao Xiang <hsiangkao@redhat.com>
Different from non-compact indexes, several lclusters are packed as the compact form at once and an unique base blkaddr is stored for each pack, so each lcluster index would take less space on avarage (e.g. 2 bytes for COMPACT_2B.) btw, that is also why BIG_PCLUSTER switch should be consistent for compact head0/1.
Prior to big pcluster, the size of all pclusters is 1 lcluster. Therefore, when a new HEAD lcluster was scanned, blkaddr would be bumped by 1 lcluster. However, that way doesn't work anymore for big pcluster since we actually don't know the compressed size of pclusters in advance (before reading CBLKCNT).
So, instead, let blkaddr of each pack be the first pcluster blkaddr with a valid CBLKCNT, in detail,
1) if CBLKCNT starts at the pack, this first valid pcluster is itself, e.g. _____________________________________________________________ |_CBLKCNT0_|_NONHEAD_| .. |_HEAD_|_CBLKCNT1_| ... |_HEAD_| ... ^ = blkaddr base ^ += CBLKCNT0 ^ += CBLKCNT1
2) if CBLKCNT doesn't start at the pack, the first valid pcluster is the next pcluster, e.g. _________________________________________________________ | NONHEAD_| .. |_HEAD_|_CBLKCNT0_| ... |_HEAD_|_HEAD_| ... ^ = blkaddr base ^ += CBLKCNT0 ^ += 1
When a CBLKCNT is found, blkaddr will be increased by CBLKCNT lclusters, or a new HEAD is found immediately, bump blkaddr by 1 instead (see the picture above.)
Also noted if CBLKCNT is the end of the pack, instead of storing delta1 (distance of the next HEAD lcluster) as normal NONHEADs, it still stores the compressed block count (delta0) since delta1 can be calculated indirectly but the block count can't.
Adjust decoding logic to fit big pcluster compact indexes as well.
Signed-off-by: Gao Xiang <hsiangkao@redhat.com> --- fs/erofs/zmap.c | 63 +++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 53 insertions(+), 10 deletions(-)
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index d34ff810cc15..545cd5989e6a 100644 --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -77,6 +77,13 @@ static int z_erofs_fill_inode_lazy(struct inode *inode) } vi->z_logical_clusterbits = LOG_BLOCK_SIZE + (h->h_clusterbits & 7); + if (vi->datalayout == EROFS_INODE_FLAT_COMPRESSION && + !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1) ^ + !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_2)) { + erofs_err(sb, "big pcluster head1/2 of compact indexes should be consistent for nid %llu", + vi->nid); + return -EFSCORRUPTED; + } /* paired with smp_mb() at the beginning of the function */ smp_mb(); set_bit(EROFS_I_Z_INITED_BIT, &vi->flags); @@ -207,6 +214,7 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, unsigned int vcnt, base, lo, encodebits, nblk; int i; u8 *in, type; + bool big_pcluster; if (1 << amortizedshift == 4) vcnt = 2; @@ -215,6 +223,7 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, else return -EOPNOTSUPP; + big_pcluster = vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1; encodebits = ((vcnt << amortizedshift) - sizeof(__le32)) * 8 / vcnt; base = round_down(eofs, vcnt << amortizedshift); in = m->kaddr + base; @@ -226,7 +235,15 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, m->type = type; if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) { m->clusterofs = 1 << lclusterbits; - if (i + 1 != vcnt) { + if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) { + if (!big_pcluster) { + DBG_BUGON(1); + return -EFSCORRUPTED; + } + m->compressedlcs = lo & ~Z_EROFS_VLE_DI_D0_CBLKCNT; + m->delta[0] = 1; + return 0; + } else if (i + 1 != (int)vcnt) { m->delta[0] = lo; return 0; } @@ -239,22 +256,48 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, in, encodebits * (i - 1), &type); if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) lo = 0; + else if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) + lo = 1; m->delta[0] = lo + 1; return 0; } m->clusterofs = lo; m->delta[0] = 0; /* figout out blkaddr (pblk) for HEAD lclusters */ - nblk = 1; - while (i > 0) { - --i; - lo = decode_compactedbits(lclusterbits, lomask, - in, encodebits * i, &type); - if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) - i -= lo; - - if (i >= 0) + if (!big_pcluster) { + nblk = 1; + while (i > 0) { + --i; + lo = decode_compactedbits(lclusterbits, lomask, + in, encodebits * i, &type); + if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) + i -= lo; + + if (i >= 0) + ++nblk; + } + } else { + nblk = 0; + while (i > 0) { + --i; + lo = decode_compactedbits(lclusterbits, lomask, + in, encodebits * i, &type); + if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) { + if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) { + --i; + nblk += lo & ~Z_EROFS_VLE_DI_D0_CBLKCNT; + continue; + } + /* bigpcluster shouldn't have plain d0 == 1 */ + if (lo <= 1) { + DBG_BUGON(1); + return -EFSCORRUPTED; + } + i -= lo - 2; + continue; + } ++nblk; + } } in += (vcnt << amortizedshift) - sizeof(__le32); m->pblk = le32_to_cpu(*(__le32 *)in) + nblk; -- 2.20.1
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