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erofs: improve LZ4 error strings

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Just like what was done for other algorithms, let's propagate detailed
error reasons for LZ4 instead of just -EFSCORRUPTED to users:

 "corrupted compressed data":
    the compressed data is malformed or
      destination buffer is not large enough

 "unexpected end of stream":
    the compressed stream ends normally, but without producing enough
    decompressed data.

 "compressed data start not found":
    can be returned by z_erofs_fixup_insize().

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
This commit is contained in:
Gao Xiang 2025-12-19 14:43:36 +08:00
parent 43ac93b543
commit 48df6d1bc9
1 changed files with 20 additions and 22 deletions
Download patch file Download diff file Expand all files Collapse all files

42
fs/erofs/decompressor.c
View file

@ -195,26 +195,25 @@ const char *z_erofs_fixup_insize(struct z_erofs_decompress_req *rq,
return NULL;
}
static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq, u8 *dst)
static const char *__z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
u8 *dst)
{
bool support_0padding = false, may_inplace = false;
bool zeropadded = erofs_sb_has_zero_padding(EROFS_SB(rq->sb));
bool may_inplace = false;
unsigned int inputmargin;
u8 *out, *headpage, *src;
const char *reason;
int ret, maptype;
DBG_BUGON(*rq->in == NULL);
headpage = kmap_local_page(*rq->in);
/* LZ4 decompression inplace is only safe if zero_padding is enabled */
if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
support_0padding = true;
if (zeropadded) {
reason = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
min_t(unsigned int, rq->inputsize,
rq->sb->s_blocksize - rq->pageofs_in));
if (reason) {
kunmap_local(headpage);
return IS_ERR(reason) ? PTR_ERR(reason) : -EFSCORRUPTED;
return reason;
}
may_inplace = !((rq->pageofs_in + rq->inputsize) &
(rq->sb->s_blocksize - 1));
@ -224,26 +223,24 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq, u8 *dst
src = z_erofs_lz4_handle_overlap(rq, headpage, dst, &inputmargin,
&maptype, may_inplace);
if (IS_ERR(src))
return PTR_ERR(src);
return ERR_CAST(src);
out = dst + rq->pageofs_out;
/* legacy format could compress extra data in a pcluster. */
if (rq->partial_decoding || !support_0padding)
if (rq->partial_decoding || !zeropadded)
ret = LZ4_decompress_safe_partial(src + inputmargin, out,
rq->inputsize, rq->outputsize, rq->outputsize);
else
ret = LZ4_decompress_safe(src + inputmargin, out,
rq->inputsize, rq->outputsize);
if (ret == rq->outputsize)
reason = NULL;
else if (ret < 0)
reason = "corrupted compressed data";
else
reason = "unexpected end of stream";
if (ret != rq->outputsize) {
if (ret >= 0)
memset(out + ret, 0, rq->outputsize - ret);
ret = -EFSCORRUPTED;
} else {
ret = 0;
}
if (maptype == 0) {
if (!maptype) {
kunmap_local(headpage);
} else if (maptype == 1) {
vm_unmap_ram(src, rq->inpages);
@ -251,15 +248,16 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq, u8 *dst
z_erofs_put_gbuf(src);
} else if (maptype != 3) {
DBG_BUGON(1);
return -EFAULT;
return ERR_PTR(-EFAULT);
}
return ret;
return reason;
}
static const char *z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
struct page **pagepool)
{
unsigned int dst_maptype;
const char *reason;
void *dst;
int ret;
@ -283,12 +281,12 @@ static const char *z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
dst_maptype = 2;
}
}
ret = z_erofs_lz4_decompress_mem(rq, dst);
reason = __z_erofs_lz4_decompress(rq, dst);
if (!dst_maptype)
kunmap_local(dst);
else if (dst_maptype == 2)
vm_unmap_ram(dst, rq->outpages);
return ERR_PTR(ret);
return reason;
}
static const char *z_erofs_transform_plain(struct z_erofs_decompress_req *rq,