[PATCH] erofs-utils: fix the erofs_io_pread and erofs_io_pwrite

[Hongzhen Luo]

When `vf->ops` is not null, `vf->ops->pread` returns the
number of bytes successfully read, which is inconsistent
with the semantics of `erofs_io_pread`. Similar situation
occurs in `erofs_io_pwrite`. This fixes this issue.

Signed-off-by: Hongzhen Luo <hongzhen at linux.alibaba.com>
---
 lib/io.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/lib/io.c b/lib/io.c
index c523f00..52a74dc 100644
--- a/lib/io.c
+++ b/lib/io.c
@@ -34,15 +34,18 @@ ssize_t erofs_io_pwrite(struct erofs_vfile *vf, const void *buf,
 	if (unlikely(cfg.c_dry_run))
 		return 0;
 
-	if (vf->ops)
-		return vf->ops->pwrite(vf, buf, pos, len);
-
 	pos += vf->offset;
 	do {
 #ifdef HAVE_PWRITE64
-		ret = pwrite64(vf->fd, buf, len, (off64_t)pos);
+		if (vf->ops)
+			ret = vf->ops->pwrite(vf, buf, pos, len);
+		else
+			ret = pwrite64(vf->fd, buf, len, (off64_t)pos);
 #else
-		ret = pwrite(vf->fd, buf, len, (off_t)pos);
+		if (vf->ops)
+			ret = vf->ops->pwrite(vf, buf, pos, len);
+		else
+			ret = pwrite(vf->fd, buf, len, (off_t)pos);
 #endif
 		if (ret <= 0) {
 			erofs_err("failed to write: %s", strerror(errno));
@@ -130,15 +133,18 @@ ssize_t erofs_io_pread(struct erofs_vfile *vf, void *buf, u64 pos, size_t len)
 	if (unlikely(cfg.c_dry_run))
 		return 0;
 
-	if (vf->ops)
-		return vf->ops->pread(vf, buf, pos, len);
-
 	pos += vf->offset;
 	do {
 #ifdef HAVE_PREAD64
-		ret = pread64(vf->fd, buf, len, (off64_t)pos);
+		if (vf->ops)
+			ret = vf->ops->pread(vf, buf, pos, len);
+		else
+			ret = pread64(vf->fd, buf, len, (off64_t)pos);
 #else
-		ret = pread(vf->fd, buf, len, (off_t)pos);
+		if (vf->ops)
+			ret = vf->ops->pread(vf, buf, pos, len);
+		else
+			ret = pread(vf->fd, buf, len, (off_t)pos);
 #endif
 		if (ret <= 0) {
 			if (!ret) {
-- 
2.39.3