[PATCH 1/4] erofs: improve decompression error reporting

[PATCH 1/4] erofs: improve decompression error reporting

[Gao Xiang]

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@linux.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

[PATCH 2/4] erofs: improve Zstd, LZMA and DEFLATE error strings

[Gao Xiang]

Enable better, more detailed, and unique error reporting.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/erofs/decompressor_deflate.c | 16 ++++++++++------
 fs/erofs/decompressor_lzma.c    |  7 +++++--
 fs/erofs/decompressor_zstd.c    |  8 +++++---
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/fs/erofs/decompressor_deflate.c b/fs/erofs/decompressor_deflate.c
index e9c4b740ef89..46cc1fd19bce 100644
--- a/fs/erofs/decompressor_deflate.c
+++ b/fs/erofs/decompressor_deflate.c
@@ -97,12 +97,13 @@ static int z_erofs_load_deflate_config(struct super_block *sb,
 	return -ENOMEM;
 }
 
-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)
 {
 	struct super_block *sb = rq->sb;
 	struct z_erofs_stream_dctx dctx = { .rq = rq, .no = -1, .ni = 0 };
 	struct z_erofs_deflate *strm;
+	const char *reason = NULL;
 	int zerr, err;
 
 	/* 1. get the exact DEFLATE compressed size */
@@ -111,7 +112,7 @@ static int __z_erofs_deflate_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 DEFLATE context */
@@ -129,7 +130,7 @@ static int __z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
 	/* 3. multi-call decompress */
 	zerr = zlib_inflateInit2(&strm->z, -MAX_WBITS);
 	if (zerr != Z_OK) {
-		err = -EIO;
+		err = -EINVAL;
 		goto failed_zinit;
 	}
 
@@ -157,6 +158,9 @@ static int __z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
 				break;
 			if (zerr == Z_STREAM_END && !rq->outputsize)
 				break;
+			reason = (zerr == Z_DATA_ERROR ?
+				"corrupted compressed data" :
+				"unexpected end of stream");
 			err = -EFSCORRUPTED;
 			break;
 		}
@@ -173,7 +177,7 @@ static int __z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
 	z_erofs_deflate_head = strm;
 	spin_unlock(&z_erofs_deflate_lock);
 	wake_up(&z_erofs_deflate_wq);
-	return err;
+	return reason ?: ERR_PTR(err);
 }
 
 static const char *z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
@@ -189,7 +193,7 @@ static const char *z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
 
 	}
 #endif
-	return ERR_PTR(__z_erofs_deflate_decompress(rq, pgpl));
+	return __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 7784ced90145..98a8c22cdbde 100644
--- a/fs/erofs/decompressor_lzma.c
+++ b/fs/erofs/decompressor_lzma.c
@@ -154,6 +154,7 @@ static const char *z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
 	struct xz_buf buf = {};
 	struct z_erofs_lzma *strm;
 	enum xz_ret xz_err;
+	const char *reason = NULL;
 	int err;
 
 	/* 1. get the exact LZMA compressed size */
@@ -207,7 +208,9 @@ static const char *z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
 		if (xz_err != XZ_OK) {
 			if (xz_err == XZ_STREAM_END && !rq->outputsize)
 				break;
-			err = -EFSCORRUPTED;
+			reason = (xz_err == XZ_DATA_ERROR ?
+				"corrupted compressed data" :
+				"unexpected end of stream");
 			break;
 		}
 	} while (1);
@@ -221,7 +224,7 @@ static const char *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_PTR(err);
+	return reason ?: 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 50fadff89cbc..aff6825cacde 100644
--- a/fs/erofs/decompressor_zstd.c
+++ b/fs/erofs/decompressor_zstd.c
@@ -143,6 +143,7 @@ static const char *z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
 	zstd_in_buffer in_buf = { NULL, 0, 0 };
 	zstd_out_buffer out_buf = { NULL, 0, 0 };
 	struct z_erofs_zstd *strm;
+	const char *reason = NULL;
 	zstd_dstream *stream;
 	int zerr, err;
 
@@ -161,7 +162,7 @@ static const char *z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
 	/* 3. multi-call decompress */
 	stream = zstd_init_dstream(z_erofs_zstd_max_dictsize, strm->wksp, strm->wkspsz);
 	if (!stream) {
-		err = -EIO;
+		err = -ENOMEM;
 		goto failed_zinit;
 	}
 
@@ -191,7 +192,8 @@ static const char *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))))) {
-			err = -EFSCORRUPTED;
+			reason = zstd_is_error(zerr) ? zstd_get_error_name(zerr) :
+					"unexpected end of stream";
 			break;
 		}
 	} while (rq->outputsize + dctx.avail_out);
@@ -206,7 +208,7 @@ static const char *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_PTR(err);
+	return reason ?: ERR_PTR(err);
 }
 
 const struct z_erofs_decompressor z_erofs_zstd_decomp = {
-- 
2.43.5

[PATCH 3/4] erofs: enable error reporting for z_erofs_stream_switch_bufs()

[Gao Xiang]

Enable propagation of detailed errors to callers.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/erofs/compress.h             |  4 ++--
 fs/erofs/decompressor.c         | 23 +++++++++--------------
 fs/erofs/decompressor_deflate.c |  4 ++--
 fs/erofs/decompressor_lzma.c    |  6 +++---
 fs/erofs/decompressor_zstd.c    |  4 ++--
 5 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/fs/erofs/compress.h b/fs/erofs/compress.h
index 1ee4ad934c1f..91dbc8bb5ddf 100644
--- a/fs/erofs/compress.h
+++ b/fs/erofs/compress.h
@@ -70,8 +70,8 @@ struct z_erofs_stream_dctx {
 	bool bounced;			/* is the bounce buffer used now? */
 };
 
-int z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx, void **dst,
-			       void **src, struct page **pgpl);
+const char *z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx,
+				void **dst, void **src, struct page **pgpl);
 int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
 			 unsigned int padbufsize);
 int __init z_erofs_init_decompressor(void);
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index f9d29f43666f..638b5f87bd0c 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -342,19 +342,16 @@ static const char *z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
 	return NULL;
 }
 
-int z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx, void **dst,
-			       void **src, struct page **pgpl)
+const char *z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx,
+				void **dst, void **src, struct page **pgpl)
 {
 	struct z_erofs_decompress_req *rq = dctx->rq;
-	struct super_block *sb = rq->sb;
 	struct page **pgo, *tmppage;
 	unsigned int j;
 
 	if (!dctx->avail_out) {
-		if (++dctx->no >= rq->outpages || !rq->outputsize) {
-			erofs_err(sb, "insufficient space for decompressed data");
-			return -EFSCORRUPTED;
-		}
+		if (++dctx->no >= rq->outpages || !rq->outputsize)
+			return "insufficient space for decompressed data";
 
 		if (dctx->kout)
 			kunmap_local(dctx->kout);
@@ -365,7 +362,7 @@ int z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx, void **dst,
 			*pgo = erofs_allocpage(pgpl, rq->gfp);
 			if (!*pgo) {
 				dctx->kout = NULL;
-				return -ENOMEM;
+				return ERR_PTR(-ENOMEM);
 			}
 			set_page_private(*pgo, Z_EROFS_SHORTLIVED_PAGE);
 		}
@@ -379,10 +376,8 @@ int z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx, void **dst,
 	}
 
 	if (dctx->inbuf_pos == dctx->inbuf_sz && rq->inputsize) {
-		if (++dctx->ni >= rq->inpages) {
-			erofs_err(sb, "invalid compressed data");
-			return -EFSCORRUPTED;
-		}
+		if (++dctx->ni >= rq->inpages)
+			return "invalid compressed data";
 		if (dctx->kout) /* unlike kmap(), take care of the orders */
 			kunmap_local(dctx->kout);
 		kunmap_local(dctx->kin);
@@ -417,12 +412,12 @@ int z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx, void **dst,
 			continue;
 		tmppage = erofs_allocpage(pgpl, rq->gfp);
 		if (!tmppage)
-			return -ENOMEM;
+			return ERR_PTR(-ENOMEM);
 		set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE);
 		copy_highpage(tmppage, rq->in[j]);
 		rq->in[j] = tmppage;
 	}
-	return 0;
+	return NULL;
 }
 
 const struct z_erofs_decompressor *z_erofs_decomp[] = {
diff --git a/fs/erofs/decompressor_deflate.c b/fs/erofs/decompressor_deflate.c
index 46cc1fd19bce..afc73abd8db5 100644
--- a/fs/erofs/decompressor_deflate.c
+++ b/fs/erofs/decompressor_deflate.c
@@ -144,10 +144,10 @@ static const char *__z_erofs_deflate_decompress(struct z_erofs_decompress_req *r
 	while (1) {
 		dctx.avail_out = strm->z.avail_out;
 		dctx.inbuf_sz = strm->z.avail_in;
-		err = z_erofs_stream_switch_bufs(&dctx,
+		reason = z_erofs_stream_switch_bufs(&dctx,
 					(void **)&strm->z.next_out,
 					(void **)&strm->z.next_in, pgpl);
-		if (err)
+		if (reason)
 			break;
 		strm->z.avail_out = dctx.avail_out;
 		strm->z.avail_in = dctx.inbuf_sz;
diff --git a/fs/erofs/decompressor_lzma.c b/fs/erofs/decompressor_lzma.c
index 98a8c22cdbde..0161f3375efd 100644
--- a/fs/erofs/decompressor_lzma.c
+++ b/fs/erofs/decompressor_lzma.c
@@ -189,9 +189,9 @@ static const char *z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
 		dctx.avail_out = buf.out_size - buf.out_pos;
 		dctx.inbuf_sz = buf.in_size;
 		dctx.inbuf_pos = buf.in_pos;
-		err = z_erofs_stream_switch_bufs(&dctx, (void **)&buf.out,
-						 (void **)&buf.in, pgpl);
-		if (err)
+		reason = z_erofs_stream_switch_bufs(&dctx, (void **)&buf.out,
+						    (void **)&buf.in, pgpl);
+		if (reason)
 			break;
 
 		if (buf.out_size == buf.out_pos) {
diff --git a/fs/erofs/decompressor_zstd.c b/fs/erofs/decompressor_zstd.c
index aff6825cacde..ae51faeb504d 100644
--- a/fs/erofs/decompressor_zstd.c
+++ b/fs/erofs/decompressor_zstd.c
@@ -175,9 +175,9 @@ static const char *z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
 	do {
 		dctx.inbuf_sz = in_buf.size;
 		dctx.inbuf_pos = in_buf.pos;
-		err = z_erofs_stream_switch_bufs(&dctx, &out_buf.dst,
+		reason = z_erofs_stream_switch_bufs(&dctx, &out_buf.dst,
 						 (void **)&in_buf.src, pgpl);
-		if (err)
+		if (reason)
 			break;
 
 		if (out_buf.size == out_buf.pos) {
-- 
2.43.5

[PATCH 4/4] erofs: enable error reporting for z_erofs_fixup_insize()

[Gao Xiang]

Enable propagation of detailed errors to callers.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/erofs/compress.h             |  4 ++--
 fs/erofs/decompressor.c         | 19 ++++++++++---------
 fs/erofs/decompressor_crypto.c  |  7 ++++---
 fs/erofs/decompressor_deflate.c | 19 +++++++++----------
 fs/erofs/decompressor_lzma.c    | 11 +++++------
 fs/erofs/decompressor_zstd.c    | 14 +++++++-------
 6 files changed, 37 insertions(+), 37 deletions(-)

diff --git a/fs/erofs/compress.h b/fs/erofs/compress.h
index 91dbc8bb5ddf..84c8e52581f4 100644
--- a/fs/erofs/compress.h
+++ b/fs/erofs/compress.h
@@ -72,8 +72,8 @@ struct z_erofs_stream_dctx {
 
 const char *z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx,
 				void **dst, void **src, struct page **pgpl);
-int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
-			 unsigned int padbufsize);
+const char *z_erofs_fixup_insize(struct z_erofs_decompress_req *rq,
+				 const char *padbuf, unsigned int padbufsize);
 int __init z_erofs_init_decompressor(void);
 void z_erofs_exit_decompressor(void);
 int z_erofs_crypto_decompress(struct z_erofs_decompress_req *rq,
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 638b5f87bd0c..eb20b4a30430 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -178,18 +178,18 @@ static void *z_erofs_lz4_handle_overlap(const struct z_erofs_decompress_req *rq,
 }
 
 /*
- * 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.
+ * Get the exact on-disk size of the compressed data:
+ *  - For LZ4, it should apply if the zero_padding feature is on (5.3+);
+ *  - For others, zero_padding is enabled all the time.
  */
-int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
-			 unsigned int padbufsize)
+const char *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;
+		return "compressed data start not found";
 	rq->inputsize -= padend - padbuf;
 	rq->pageofs_in += padend - padbuf;
 	return 0;
@@ -200,6 +200,7 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq, u8 *dst
 	bool support_0padding = false, may_inplace = false;
 	unsigned int inputmargin;
 	u8 *out, *headpage, *src;
+	const char *reason;
 	int ret, maptype;
 
 	DBG_BUGON(*rq->in == NULL);
@@ -208,12 +209,12 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq, u8 *dst
 	/* LZ4 decompression inplace is only safe if zero_padding is enabled */
 	if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
 		support_0padding = true;
-		ret = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
+		reason = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
 				min_t(unsigned int, rq->inputsize,
 				      rq->sb->s_blocksize - rq->pageofs_in));
-		if (ret) {
+		if (reason) {
 			kunmap_local(headpage);
-			return ret;
+			return IS_ERR(reason) ? PTR_ERR(reason) : -EFSCORRUPTED;
 		}
 		may_inplace = !((rq->pageofs_in + rq->inputsize) &
 				(rq->sb->s_blocksize - 1));
diff --git a/fs/erofs/decompressor_crypto.c b/fs/erofs/decompressor_crypto.c
index 97b77ab64432..5ef6f71d3b7f 100644
--- a/fs/erofs/decompressor_crypto.c
+++ b/fs/erofs/decompressor_crypto.c
@@ -9,16 +9,17 @@ static int __z_erofs_crypto_decompress(struct z_erofs_decompress_req *rq,
 	struct sg_table st_src, st_dst;
 	struct acomp_req *req;
 	struct crypto_wait wait;
+	const char *reason;
 	u8 *headpage;
 	int ret;
 
 	headpage = kmap_local_page(*rq->in);
-	ret = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
+	reason = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
 				min_t(unsigned int, rq->inputsize,
 				      rq->sb->s_blocksize - rq->pageofs_in));
 	kunmap_local(headpage);
-	if (ret)
-		return ret;
+	if (reason)
+		return IS_ERR(reason) ? PTR_ERR(reason) : -EFSCORRUPTED;
 
 	req = acomp_request_alloc(tfm);
 	if (!req)
diff --git a/fs/erofs/decompressor_deflate.c b/fs/erofs/decompressor_deflate.c
index afc73abd8db5..3fb73000ed27 100644
--- a/fs/erofs/decompressor_deflate.c
+++ b/fs/erofs/decompressor_deflate.c
@@ -103,16 +103,16 @@ static const char *__z_erofs_deflate_decompress(struct z_erofs_decompress_req *r
 	struct super_block *sb = rq->sb;
 	struct z_erofs_stream_dctx dctx = { .rq = rq, .no = -1, .ni = 0 };
 	struct z_erofs_deflate *strm;
-	const char *reason = NULL;
-	int zerr, err;
+	const char *reason;
+	int zerr;
 
 	/* 1. get the exact DEFLATE compressed size */
 	dctx.kin = kmap_local_page(*rq->in);
-	err = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
+	reason = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
 			min(rq->inputsize, sb->s_blocksize - rq->pageofs_in));
-	if (err) {
+	if (reason) {
 		kunmap_local(dctx.kin);
-		return ERR_PTR(err);
+		return reason;
 	}
 
 	/* 2. get an available DEFLATE context */
@@ -130,7 +130,7 @@ static const char *__z_erofs_deflate_decompress(struct z_erofs_decompress_req *r
 	/* 3. multi-call decompress */
 	zerr = zlib_inflateInit2(&strm->z, -MAX_WBITS);
 	if (zerr != Z_OK) {
-		err = -EINVAL;
+		reason = ERR_PTR(-EINVAL);
 		goto failed_zinit;
 	}
 
@@ -161,12 +161,11 @@ static const char *__z_erofs_deflate_decompress(struct z_erofs_decompress_req *r
 			reason = (zerr == Z_DATA_ERROR ?
 				"corrupted compressed data" :
 				"unexpected end of stream");
-			err = -EFSCORRUPTED;
 			break;
 		}
 	}
-	if (zlib_inflateEnd(&strm->z) != Z_OK && !err)
-		err = -EIO;
+	if (zlib_inflateEnd(&strm->z) != Z_OK && !reason)
+		reason = ERR_PTR(-EIO);
 	if (dctx.kout)
 		kunmap_local(dctx.kout);
 failed_zinit:
@@ -177,7 +176,7 @@ static const char *__z_erofs_deflate_decompress(struct z_erofs_decompress_req *r
 	z_erofs_deflate_head = strm;
 	spin_unlock(&z_erofs_deflate_lock);
 	wake_up(&z_erofs_deflate_wq);
-	return reason ?: ERR_PTR(err);
+	return reason;
 }
 
 static const char *z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
diff --git a/fs/erofs/decompressor_lzma.c b/fs/erofs/decompressor_lzma.c
index 0161f3375efd..b4ea6978faae 100644
--- a/fs/erofs/decompressor_lzma.c
+++ b/fs/erofs/decompressor_lzma.c
@@ -154,16 +154,15 @@ static const char *z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
 	struct xz_buf buf = {};
 	struct z_erofs_lzma *strm;
 	enum xz_ret xz_err;
-	const char *reason = NULL;
-	int err;
+	const char *reason;
 
 	/* 1. get the exact LZMA compressed size */
 	dctx.kin = kmap_local_page(*rq->in);
-	err = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
+	reason = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
 			min(rq->inputsize, sb->s_blocksize - rq->pageofs_in));
-	if (err) {
+	if (reason) {
 		kunmap_local(dctx.kin);
-		return ERR_PTR(err);
+		return reason;
 	}
 
 	/* 2. get an available lzma context */
@@ -224,7 +223,7 @@ static const char *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 reason ?: ERR_PTR(err);
+	return reason;
 }
 
 const struct z_erofs_decompressor z_erofs_lzma_decomp = {
diff --git a/fs/erofs/decompressor_zstd.c b/fs/erofs/decompressor_zstd.c
index ae51faeb504d..beae49165c69 100644
--- a/fs/erofs/decompressor_zstd.c
+++ b/fs/erofs/decompressor_zstd.c
@@ -143,17 +143,17 @@ static const char *z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
 	zstd_in_buffer in_buf = { NULL, 0, 0 };
 	zstd_out_buffer out_buf = { NULL, 0, 0 };
 	struct z_erofs_zstd *strm;
-	const char *reason = NULL;
 	zstd_dstream *stream;
-	int zerr, err;
+	const char *reason;
+	int zerr;
 
 	/* 1. get the exact compressed size */
 	dctx.kin = kmap_local_page(*rq->in);
-	err = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
+	reason = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
 			min(rq->inputsize, sb->s_blocksize - rq->pageofs_in));
-	if (err) {
+	if (reason) {
 		kunmap_local(dctx.kin);
-		return ERR_PTR(err);
+		return reason;
 	}
 
 	/* 2. get an available ZSTD context */
@@ -162,7 +162,7 @@ static const char *z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
 	/* 3. multi-call decompress */
 	stream = zstd_init_dstream(z_erofs_zstd_max_dictsize, strm->wksp, strm->wkspsz);
 	if (!stream) {
-		err = -ENOMEM;
+		reason = ERR_PTR(-ENOMEM);
 		goto failed_zinit;
 	}
 
@@ -208,7 +208,7 @@ static const char *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 reason ?: ERR_PTR(err);
+	return reason;
 }
 
 const struct z_erofs_decompressor z_erofs_zstd_decomp = {
-- 
2.43.5

[PATCH v2 4/4] erofs: enable error reporting for z_erofs_fixup_insize()

[Gao Xiang]

From: Gao Xiang <hsiangkao@linux.alibaba.com>

Enable propagation of detailed errors to callers.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
v2:
 - fix sparse warning:
    "Using plain integer as NULL pointer"

 fs/erofs/compress.h             |  4 ++--
 fs/erofs/decompressor.c         | 21 +++++++++++----------
 fs/erofs/decompressor_crypto.c  |  7 ++++---
 fs/erofs/decompressor_deflate.c | 19 +++++++++----------
 fs/erofs/decompressor_lzma.c    | 11 +++++------
 fs/erofs/decompressor_zstd.c    | 14 +++++++-------
 6 files changed, 38 insertions(+), 38 deletions(-)

diff --git a/fs/erofs/compress.h b/fs/erofs/compress.h
index 91dbc8bb5ddf..84c8e52581f4 100644
--- a/fs/erofs/compress.h
+++ b/fs/erofs/compress.h
@@ -72,8 +72,8 @@ struct z_erofs_stream_dctx {
 
 const char *z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx,
 				void **dst, void **src, struct page **pgpl);
-int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
-			 unsigned int padbufsize);
+const char *z_erofs_fixup_insize(struct z_erofs_decompress_req *rq,
+				 const char *padbuf, unsigned int padbufsize);
 int __init z_erofs_init_decompressor(void);
 void z_erofs_exit_decompressor(void);
 int z_erofs_crypto_decompress(struct z_erofs_decompress_req *rq,
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 638b5f87bd0c..d5d090276391 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -178,21 +178,21 @@ static void *z_erofs_lz4_handle_overlap(const struct z_erofs_decompress_req *rq,
 }
 
 /*
- * 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.
+ * Get the exact on-disk size of the compressed data:
+ *  - For LZ4, it should apply if the zero_padding feature is on (5.3+);
+ *  - For others, zero_padding is enabled all the time.
  */
-int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
-			 unsigned int padbufsize)
+const char *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;
+		return "compressed data start not found";
 	rq->inputsize -= padend - padbuf;
 	rq->pageofs_in += padend - padbuf;
-	return 0;
+	return NULL;
 }
 
 static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq, u8 *dst)
@@ -200,6 +200,7 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq, u8 *dst
 	bool support_0padding = false, may_inplace = false;
 	unsigned int inputmargin;
 	u8 *out, *headpage, *src;
+	const char *reason;
 	int ret, maptype;
 
 	DBG_BUGON(*rq->in == NULL);
@@ -208,12 +209,12 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq, u8 *dst
 	/* LZ4 decompression inplace is only safe if zero_padding is enabled */
 	if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
 		support_0padding = true;
-		ret = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
+		reason = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
 				min_t(unsigned int, rq->inputsize,
 				      rq->sb->s_blocksize - rq->pageofs_in));
-		if (ret) {
+		if (reason) {
 			kunmap_local(headpage);
-			return ret;
+			return IS_ERR(reason) ? PTR_ERR(reason) : -EFSCORRUPTED;
 		}
 		may_inplace = !((rq->pageofs_in + rq->inputsize) &
 				(rq->sb->s_blocksize - 1));
diff --git a/fs/erofs/decompressor_crypto.c b/fs/erofs/decompressor_crypto.c
index 97b77ab64432..5ef6f71d3b7f 100644
--- a/fs/erofs/decompressor_crypto.c
+++ b/fs/erofs/decompressor_crypto.c
@@ -9,16 +9,17 @@ static int __z_erofs_crypto_decompress(struct z_erofs_decompress_req *rq,
 	struct sg_table st_src, st_dst;
 	struct acomp_req *req;
 	struct crypto_wait wait;
+	const char *reason;
 	u8 *headpage;
 	int ret;
 
 	headpage = kmap_local_page(*rq->in);
-	ret = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
+	reason = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
 				min_t(unsigned int, rq->inputsize,
 				      rq->sb->s_blocksize - rq->pageofs_in));
 	kunmap_local(headpage);
-	if (ret)
-		return ret;
+	if (reason)
+		return IS_ERR(reason) ? PTR_ERR(reason) : -EFSCORRUPTED;
 
 	req = acomp_request_alloc(tfm);
 	if (!req)
diff --git a/fs/erofs/decompressor_deflate.c b/fs/erofs/decompressor_deflate.c
index afc73abd8db5..3fb73000ed27 100644
--- a/fs/erofs/decompressor_deflate.c
+++ b/fs/erofs/decompressor_deflate.c
@@ -103,16 +103,16 @@ static const char *__z_erofs_deflate_decompress(struct z_erofs_decompress_req *r
 	struct super_block *sb = rq->sb;
 	struct z_erofs_stream_dctx dctx = { .rq = rq, .no = -1, .ni = 0 };
 	struct z_erofs_deflate *strm;
-	const char *reason = NULL;
-	int zerr, err;
+	const char *reason;
+	int zerr;
 
 	/* 1. get the exact DEFLATE compressed size */
 	dctx.kin = kmap_local_page(*rq->in);
-	err = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
+	reason = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
 			min(rq->inputsize, sb->s_blocksize - rq->pageofs_in));
-	if (err) {
+	if (reason) {
 		kunmap_local(dctx.kin);
-		return ERR_PTR(err);
+		return reason;
 	}
 
 	/* 2. get an available DEFLATE context */
@@ -130,7 +130,7 @@ static const char *__z_erofs_deflate_decompress(struct z_erofs_decompress_req *r
 	/* 3. multi-call decompress */
 	zerr = zlib_inflateInit2(&strm->z, -MAX_WBITS);
 	if (zerr != Z_OK) {
-		err = -EINVAL;
+		reason = ERR_PTR(-EINVAL);
 		goto failed_zinit;
 	}
 
@@ -161,12 +161,11 @@ static const char *__z_erofs_deflate_decompress(struct z_erofs_decompress_req *r
 			reason = (zerr == Z_DATA_ERROR ?
 				"corrupted compressed data" :
 				"unexpected end of stream");
-			err = -EFSCORRUPTED;
 			break;
 		}
 	}
-	if (zlib_inflateEnd(&strm->z) != Z_OK && !err)
-		err = -EIO;
+	if (zlib_inflateEnd(&strm->z) != Z_OK && !reason)
+		reason = ERR_PTR(-EIO);
 	if (dctx.kout)
 		kunmap_local(dctx.kout);
 failed_zinit:
@@ -177,7 +176,7 @@ static const char *__z_erofs_deflate_decompress(struct z_erofs_decompress_req *r
 	z_erofs_deflate_head = strm;
 	spin_unlock(&z_erofs_deflate_lock);
 	wake_up(&z_erofs_deflate_wq);
-	return reason ?: ERR_PTR(err);
+	return reason;
 }
 
 static const char *z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
diff --git a/fs/erofs/decompressor_lzma.c b/fs/erofs/decompressor_lzma.c
index 0161f3375efd..b4ea6978faae 100644
--- a/fs/erofs/decompressor_lzma.c
+++ b/fs/erofs/decompressor_lzma.c
@@ -154,16 +154,15 @@ static const char *z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
 	struct xz_buf buf = {};
 	struct z_erofs_lzma *strm;
 	enum xz_ret xz_err;
-	const char *reason = NULL;
-	int err;
+	const char *reason;
 
 	/* 1. get the exact LZMA compressed size */
 	dctx.kin = kmap_local_page(*rq->in);
-	err = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
+	reason = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
 			min(rq->inputsize, sb->s_blocksize - rq->pageofs_in));
-	if (err) {
+	if (reason) {
 		kunmap_local(dctx.kin);
-		return ERR_PTR(err);
+		return reason;
 	}
 
 	/* 2. get an available lzma context */
@@ -224,7 +223,7 @@ static const char *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 reason ?: ERR_PTR(err);
+	return reason;
 }
 
 const struct z_erofs_decompressor z_erofs_lzma_decomp = {
diff --git a/fs/erofs/decompressor_zstd.c b/fs/erofs/decompressor_zstd.c
index ae51faeb504d..beae49165c69 100644
--- a/fs/erofs/decompressor_zstd.c
+++ b/fs/erofs/decompressor_zstd.c
@@ -143,17 +143,17 @@ static const char *z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
 	zstd_in_buffer in_buf = { NULL, 0, 0 };
 	zstd_out_buffer out_buf = { NULL, 0, 0 };
 	struct z_erofs_zstd *strm;
-	const char *reason = NULL;
 	zstd_dstream *stream;
-	int zerr, err;
+	const char *reason;
+	int zerr;
 
 	/* 1. get the exact compressed size */
 	dctx.kin = kmap_local_page(*rq->in);
-	err = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
+	reason = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
 			min(rq->inputsize, sb->s_blocksize - rq->pageofs_in));
-	if (err) {
+	if (reason) {
 		kunmap_local(dctx.kin);
-		return ERR_PTR(err);
+		return reason;
 	}
 
 	/* 2. get an available ZSTD context */
@@ -162,7 +162,7 @@ static const char *z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
 	/* 3. multi-call decompress */
 	stream = zstd_init_dstream(z_erofs_zstd_max_dictsize, strm->wksp, strm->wkspsz);
 	if (!stream) {
-		err = -ENOMEM;
+		reason = ERR_PTR(-ENOMEM);
 		goto failed_zinit;
 	}
 
@@ -208,7 +208,7 @@ static const char *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 reason ?: ERR_PTR(err);
+	return reason;
 }
 
 const struct z_erofs_decompressor z_erofs_zstd_decomp = {
-- 
2.30.2