erofs: introduce z_erofs_fixup_insize
To prepare for the upcoming ztailpacking feature, introduce
z_erofs_fixup_insize() and pageofs_in to wrap up the process
to get the exact compressed size via zero padding.
Link: https://lore.kernel.org/r/20211228054604.114518-3-hsiangkao@linux.alibaba.com
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index ebb478a..9281491 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -184,6 +184,24 @@ static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx,
return src;
}
+/*
+ * Get the exact inputsize with zero_padding feature.
+ * - For LZ4, it should work if zero_padding feature is on (5.3+);
+ * - For MicroLZMA, it'd be enabled all the time.
+ */
+int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
+ unsigned int padbufsize)
+{
+ const char *padend;
+
+ padend = memchr_inv(padbuf, 0, padbufsize);
+ if (!padend)
+ return -EFSCORRUPTED;
+ rq->inputsize -= padend - padbuf;
+ rq->pageofs_in += padend - padbuf;
+ return 0;
+}
+
static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx,
u8 *out)
{
@@ -198,21 +216,19 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx,
inputmargin = 0;
support_0padding = false;
- /* decompression inplace is only safe when zero_padding is enabled */
+ /* LZ4 decompression inplace is only safe if zero_padding is enabled */
if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
support_0padding = true;
-
- while (!headpage[inputmargin & ~PAGE_MASK])
- if (!(++inputmargin & ~PAGE_MASK))
- break;
-
- if (inputmargin >= rq->inputsize) {
+ ret = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
+ min_t(unsigned int, rq->inputsize,
+ EROFS_BLKSIZ - rq->pageofs_in));
+ if (ret) {
kunmap_atomic(headpage);
- return -EIO;
+ return ret;
}
}
- rq->inputsize -= inputmargin;
+ inputmargin = rq->pageofs_in;
src = z_erofs_lz4_handle_overlap(ctx, headpage, &inputmargin,
&maptype, support_0padding);
if (IS_ERR(src))
