From 0c6a18c75b54e9045df5284d1cd5d65afcdfe34d Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Wed, 6 Dec 2023 17:10:55 +0800 Subject: [PATCH] BACKPORT: FROMGIT: erofs: fix up compacted indexes for block size < 4096 Previously, the block size always equaled to PAGE_SIZE, therefore `lclusterbits` couldn't be less than 12. Since sub-page compressed blocks are now considered, `lobits` for a lcluster in each pack cannot always be `lclusterbits` as before. Otherwise, there is no enough room for the special value `Z_EROFS_VLE_DI_D0_CBLKCNT`. To support smaller block sizes, `lobits` for each compacted lcluster is now calculated as: lobits = max(lclusterbits, ilog2(Z_EROFS_VLE_DI_D0_CBLKCNT) + 1) Reviewed-by: Yue Hu Reviewed-by: Chao Yu Signed-off-by: Gao Xiang Link: https://lore.kernel.org/r/20231206091057.87027-4-hsiangkao@linux.alibaba.com Bug: 318378021 Change-Id: Iacd89e2b33ddf39ea40b90e88a2bf99bb5a83b31 (cherry picked from commit 8d2517aaeea3ab8651bb517bca8f3c8664d318ea https: //git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git dev) [dhavale: resolved conflicts in zmap.c due to older naming of constants and updated commit message also to use the older names] Signed-off-by: Sandeep Dhavale --- fs/erofs/zmap.c | 32 ++++++++++++++------------------ 1 file changed, 14 insertions(+), 18 deletions(-) diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index 8973ccad707d..f5d3ba39dd42 100644 --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -101,29 +101,26 @@ static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m, } static unsigned int decode_compactedbits(unsigned int lobits, - unsigned int lomask, u8 *in, unsigned int pos, u8 *type) { const unsigned int v = get_unaligned_le32(in + pos / 8) >> (pos & 7); - const unsigned int lo = v & lomask; + const unsigned int lo = v & ((1 << lobits) - 1); *type = (v >> lobits) & 3; return lo; } -static int get_compacted_la_distance(unsigned int lclusterbits, +static int get_compacted_la_distance(unsigned int lobits, unsigned int encodebits, unsigned int vcnt, u8 *in, int i) { - const unsigned int lomask = (1 << lclusterbits) - 1; unsigned int lo, d1 = 0; u8 type; DBG_BUGON(i >= vcnt); do { - lo = decode_compactedbits(lclusterbits, lomask, - in, encodebits * i, &type); + lo = decode_compactedbits(lobits, in, encodebits * i, &type); if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) return d1; @@ -142,15 +139,14 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, { struct erofs_inode *const vi = EROFS_I(m->inode); const unsigned int lclusterbits = vi->z_logical_clusterbits; - const unsigned int lomask = (1 << lclusterbits) - 1; - unsigned int vcnt, base, lo, encodebits, nblk, eofs; + unsigned int vcnt, base, lo, lobits, encodebits, nblk, eofs; int i; u8 *in, type; bool big_pcluster; if (1 << amortizedshift == 4 && lclusterbits <= 14) vcnt = 2; - else if (1 << amortizedshift == 2 && lclusterbits == 12) + else if (1 << amortizedshift == 2 && lclusterbits <= 12) vcnt = 16; else return -EOPNOTSUPP; @@ -159,6 +155,7 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, m->nextpackoff = round_down(pos, vcnt << amortizedshift) + (vcnt << amortizedshift); big_pcluster = vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1; + lobits = max(lclusterbits, ilog2(Z_EROFS_VLE_DI_D0_CBLKCNT) + 1U); encodebits = ((vcnt << amortizedshift) - sizeof(__le32)) * 8 / vcnt; eofs = erofs_blkoff(m->inode->i_sb, pos); base = round_down(eofs, vcnt << amortizedshift); @@ -166,15 +163,14 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, i = (eofs - base) >> amortizedshift; - lo = decode_compactedbits(lclusterbits, lomask, - in, encodebits * i, &type); + lo = decode_compactedbits(lobits, in, encodebits * i, &type); m->type = type; if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) { m->clusterofs = 1 << lclusterbits; /* figure out lookahead_distance: delta[1] if needed */ if (lookahead) - m->delta[1] = get_compacted_la_distance(lclusterbits, + m->delta[1] = get_compacted_la_distance(lobits, encodebits, vcnt, in, i); if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) { if (!big_pcluster) { @@ -193,8 +189,8 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, * of which lo saves delta[1] rather than delta[0]. * Hence, get delta[0] by the previous lcluster indirectly. */ - lo = decode_compactedbits(lclusterbits, lomask, - in, encodebits * (i - 1), &type); + lo = decode_compactedbits(lobits, in, + encodebits * (i - 1), &type); if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) lo = 0; else if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) @@ -209,8 +205,8 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, nblk = 1; while (i > 0) { --i; - lo = decode_compactedbits(lclusterbits, lomask, - in, encodebits * i, &type); + lo = decode_compactedbits(lobits, in, + encodebits * i, &type); if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) i -= lo; @@ -221,8 +217,8 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, nblk = 0; while (i > 0) { --i; - lo = decode_compactedbits(lclusterbits, lomask, - in, encodebits * i, &type); + lo = decode_compactedbits(lobits, in, + encodebits * i, &type); if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) { if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) { --i;