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Message-ID: <20251127073122.2542542-1-hsiangkao@linux.alibaba.com>
Date: Thu, 27 Nov 2025 15:31:19 +0800
From: Gao Xiang <hsiangkao@...ux.alibaba.com>
To: linux-erofs@...ts.ozlabs.org
Cc: LKML <linux-kernel@...r.kernel.org>,
Gao Xiang <hsiangkao@...ux.alibaba.com>
Subject: [PATCH 1/4] erofs: improve decompression error reporting
Change the return type of decompress() from `int` to `const char *` to
provide more informative error diagnostics:
- A NULL return indicates successful decompression;
- If IS_ERR(ptr) is true, the return value encodes a standard negative
errno (e.g., -ENOMEM, -EOPNOTSUPP) identifying the specific error;
- Otherwise, a non-NULL return points to a human-readable error string,
and the corresponding error code should be treated as -EFSCORRUPTED.
Signed-off-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
---
fs/erofs/compress.h | 4 ++--
fs/erofs/decompressor.c | 20 +++++++++-----------
fs/erofs/decompressor_deflate.c | 10 ++++------
fs/erofs/decompressor_lzma.c | 10 ++++------
fs/erofs/decompressor_zstd.c | 12 ++++--------
fs/erofs/zdata.c | 21 +++++++++++++++++----
6 files changed, 40 insertions(+), 37 deletions(-)
diff --git a/fs/erofs/compress.h b/fs/erofs/compress.h
index 510e922c5193..1ee4ad934c1f 100644
--- a/fs/erofs/compress.h
+++ b/fs/erofs/compress.h
@@ -23,8 +23,8 @@ struct z_erofs_decompress_req {
struct z_erofs_decompressor {
int (*config)(struct super_block *sb, struct erofs_super_block *dsb,
void *data, int size);
- int (*decompress)(struct z_erofs_decompress_req *rq,
- struct page **pagepool);
+ const char *(*decompress)(struct z_erofs_decompress_req *rq,
+ struct page **pagepool);
int (*init)(void);
void (*exit)(void);
char *name;
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 2f4cef67cf64..f9d29f43666f 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -235,8 +235,6 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq, u8 *dst
rq->inputsize, rq->outputsize);
if (ret != rq->outputsize) {
- erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
- ret, rq->inputsize, inputmargin, rq->outputsize);
if (ret >= 0)
memset(out + ret, 0, rq->outputsize - ret);
ret = -EFSCORRUPTED;
@@ -257,8 +255,8 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq, u8 *dst
return ret;
}
-static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
- struct page **pagepool)
+static const char *z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
+ struct page **pagepool)
{
unsigned int dst_maptype;
void *dst;
@@ -273,14 +271,14 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
/* general decoding path which can be used for all cases */
ret = z_erofs_lz4_prepare_dstpages(rq, pagepool);
if (ret < 0)
- return ret;
+ return ERR_PTR(ret);
if (ret > 0) {
dst = page_address(*rq->out);
dst_maptype = 1;
} else {
dst = erofs_vm_map_ram(rq->out, rq->outpages);
if (!dst)
- return -ENOMEM;
+ return ERR_PTR(-ENOMEM);
dst_maptype = 2;
}
}
@@ -289,11 +287,11 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
kunmap_local(dst);
else if (dst_maptype == 2)
vm_unmap_ram(dst, rq->outpages);
- return ret;
+ return ERR_PTR(ret);
}
-static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
- struct page **pagepool)
+static const char *z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
+ struct page **pagepool)
{
const unsigned int nrpages_in = rq->inpages, nrpages_out = rq->outpages;
const unsigned int bs = rq->sb->s_blocksize;
@@ -301,7 +299,7 @@ static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
u8 *kin;
if (rq->outputsize > rq->inputsize)
- return -EOPNOTSUPP;
+ return ERR_PTR(-EOPNOTSUPP);
if (rq->alg == Z_EROFS_COMPRESSION_INTERLACED) {
cur = bs - (rq->pageofs_out & (bs - 1));
pi = (rq->pageofs_in + rq->inputsize - cur) & ~PAGE_MASK;
@@ -341,7 +339,7 @@ static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
kunmap_local(kin);
}
DBG_BUGON(ni > nrpages_in);
- return 0;
+ return NULL;
}
int z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx, void **dst,
diff --git a/fs/erofs/decompressor_deflate.c b/fs/erofs/decompressor_deflate.c
index 6909b2d529c7..e9c4b740ef89 100644
--- a/fs/erofs/decompressor_deflate.c
+++ b/fs/erofs/decompressor_deflate.c
@@ -157,8 +157,6 @@ static int __z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
break;
if (zerr == Z_STREAM_END && !rq->outputsize)
break;
- erofs_err(sb, "failed to decompress %d in[%u] out[%u]",
- zerr, rq->inputsize, rq->outputsize);
err = -EFSCORRUPTED;
break;
}
@@ -178,8 +176,8 @@ static int __z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
return err;
}
-static int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
- struct page **pgpl)
+static const char *z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
+ struct page **pgpl)
{
#ifdef CONFIG_EROFS_FS_ZIP_ACCEL
int err;
@@ -187,11 +185,11 @@ static int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
if (!rq->partial_decoding) {
err = z_erofs_crypto_decompress(rq, pgpl);
if (err != -EOPNOTSUPP)
- return err;
+ return ERR_PTR(err);
}
#endif
- return __z_erofs_deflate_decompress(rq, pgpl);
+ return ERR_PTR(__z_erofs_deflate_decompress(rq, pgpl));
}
const struct z_erofs_decompressor z_erofs_deflate_decomp = {
diff --git a/fs/erofs/decompressor_lzma.c b/fs/erofs/decompressor_lzma.c
index 832cffb83a66..7784ced90145 100644
--- a/fs/erofs/decompressor_lzma.c
+++ b/fs/erofs/decompressor_lzma.c
@@ -146,8 +146,8 @@ static int z_erofs_load_lzma_config(struct super_block *sb,
return err;
}
-static int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
- struct page **pgpl)
+static const char *z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
+ struct page **pgpl)
{
struct super_block *sb = rq->sb;
struct z_erofs_stream_dctx dctx = { .rq = rq, .no = -1, .ni = 0 };
@@ -162,7 +162,7 @@ static int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
min(rq->inputsize, sb->s_blocksize - rq->pageofs_in));
if (err) {
kunmap_local(dctx.kin);
- return err;
+ return ERR_PTR(err);
}
/* 2. get an available lzma context */
@@ -207,8 +207,6 @@ static int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
if (xz_err != XZ_OK) {
if (xz_err == XZ_STREAM_END && !rq->outputsize)
break;
- erofs_err(sb, "failed to decompress %d in[%u] out[%u]",
- xz_err, rq->inputsize, rq->outputsize);
err = -EFSCORRUPTED;
break;
}
@@ -223,7 +221,7 @@ static int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
z_erofs_lzma_head = strm;
spin_unlock(&z_erofs_lzma_lock);
wake_up(&z_erofs_lzma_wq);
- return err;
+ return ERR_PTR(err);
}
const struct z_erofs_decompressor z_erofs_lzma_decomp = {
diff --git a/fs/erofs/decompressor_zstd.c b/fs/erofs/decompressor_zstd.c
index e38d93bb2104..50fadff89cbc 100644
--- a/fs/erofs/decompressor_zstd.c
+++ b/fs/erofs/decompressor_zstd.c
@@ -135,8 +135,8 @@ static int z_erofs_load_zstd_config(struct super_block *sb,
return strm ? -ENOMEM : 0;
}
-static int z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
- struct page **pgpl)
+static const char *z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
+ struct page **pgpl)
{
struct super_block *sb = rq->sb;
struct z_erofs_stream_dctx dctx = { .rq = rq, .no = -1, .ni = 0 };
@@ -152,7 +152,7 @@ static int z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
min(rq->inputsize, sb->s_blocksize - rq->pageofs_in));
if (err) {
kunmap_local(dctx.kin);
- return err;
+ return ERR_PTR(err);
}
/* 2. get an available ZSTD context */
@@ -191,10 +191,6 @@ static int z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
if (zstd_is_error(zerr) ||
((rq->outputsize + dctx.avail_out) && (!zerr || (zerr > 0 &&
!(rq->inputsize + in_buf.size - in_buf.pos))))) {
- erofs_err(sb, "failed to decompress in[%u] out[%u]: %s",
- rq->inputsize, rq->outputsize,
- zstd_is_error(zerr) ? zstd_get_error_name(zerr) :
- "unexpected end of stream");
err = -EFSCORRUPTED;
break;
}
@@ -210,7 +206,7 @@ static int z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
z_erofs_zstd_head = strm;
spin_unlock(&z_erofs_zstd_lock);
wake_up(&z_erofs_zstd_wq);
- return err;
+ return ERR_PTR(err);
}
const struct z_erofs_decompressor z_erofs_zstd_decomp = {
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index bc80cfe482f7..461a929e0825 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1267,12 +1267,13 @@ static int z_erofs_decompress_pcluster(struct z_erofs_backend *be, int err)
struct erofs_sb_info *const sbi = EROFS_SB(be->sb);
struct z_erofs_pcluster *pcl = be->pcl;
unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
- const struct z_erofs_decompressor *decomp =
+ const struct z_erofs_decompressor *alg =
z_erofs_decomp[pcl->algorithmformat];
+ bool try_free = true;
int i, j, jtop, err2;
struct page *page;
bool overlapped;
- bool try_free = true;
+ const char *reason;
mutex_lock(&pcl->lock);
be->nr_pages = PAGE_ALIGN(pcl->length + pcl->pageofs_out) >> PAGE_SHIFT;
@@ -1304,8 +1305,8 @@ static int z_erofs_decompress_pcluster(struct z_erofs_backend *be, int err)
err2 = z_erofs_parse_in_bvecs(be, &overlapped);
if (err2)
err = err2;
- if (!err)
- err = decomp->decompress(&(struct z_erofs_decompress_req) {
+ if (!err) {
+ reason = alg->decompress(&(struct z_erofs_decompress_req) {
.sb = be->sb,
.in = be->compressed_pages,
.out = be->decompressed_pages,
@@ -1322,6 +1323,18 @@ static int z_erofs_decompress_pcluster(struct z_erofs_backend *be, int err)
.gfp = pcl->besteffort ? GFP_KERNEL :
GFP_NOWAIT | __GFP_NORETRY
}, be->pagepool);
+ if (IS_ERR(reason)) {
+ erofs_err(be->sb, "failed to decompress (%s) %ld @ pa %llu size %u => %u",
+ alg->name, PTR_ERR(reason), pcl->pos,
+ pcl->pclustersize, pcl->length);
+ err = PTR_ERR(reason);
+ } else if (unlikely(reason)) {
+ erofs_err(be->sb, "failed to decompress (%s) %s @ pa %llu size %u => %u",
+ alg->name, reason, pcl->pos,
+ pcl->pclustersize, pcl->length);
+ err = -EFSCORRUPTED;
+ }
+ }
/* must handle all compressed pages before actual file pages */
if (pcl->from_meta) {
--
2.43.5
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