[PATCH 2/2] erofs-utils: lib: fix direct S3 writes to blob devices

[Gao Xiang <xiang@kernel.org>]

From: Yifan Zhao <yifan.yfzhao@foxmail.com>

Direct S3 writes target the primary device and may leave the selected
blob device shorter than its allocated extent.

Write objects at device-relative offsets on the selected device.
and extend it to the final block boundary.

Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Yifan Zhao <yifan.yfzhao@foxmail.com>
Signed-off-by: Gao Xiang <xiang@kernel.org>
---
 lib/remotes/s3.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/lib/remotes/s3.c b/lib/remotes/s3.c
index 56ab808..01dd1ff 100644
--- a/lib/remotes/s3.c
+++ b/lib/remotes/s3.c
@@ -1054,15 +1054,19 @@ static int s3erofs_remote_getobject(struct erofs_importer *im,
 
 	resp.pos = 0;
 	if (!sbi->available_compr_algs && im->params->no_datainline) {
+		unsigned int device_id = im->params->ddev_id_def;
+
 		inode->datalayout = EROFS_INODE_FLAT_PLAIN;
 		inode->idata_size = 0;
 		ret = erofs_allocate_inode_bh_data(inode,
 				DIV_ROUND_UP(inode->i_size, 1U << sbi->blkszbits),
-				im->params->ddev_id_def);
+				device_id);
 		if (ret)
 			return ret;
-		resp.vf = &sbi->bdev;
-		resp.pos = erofs_pos(inode->sbi, inode->u.i_blkaddr);
+
+		resp.vf = device_id ?
+			sbi->devs[device_id - 1].bmgr->vf : &sbi->bdev;
+		resp.pos = erofs_pos(sbi, erofs_inode_dev_baddr(inode));
 		inode->datasource = EROFS_INODE_DATA_SOURCE_NONE;
 	} else {
 		if (!inode->i_diskbuf) {
@@ -1179,7 +1183,7 @@ int s3erofs_build_trees(struct erofs_importer *im, struct erofs_s3 *s3,
 		ret = __erofs_fill_inode(im, inode, &st, obj->key);
 		if (!ret && S_ISREG(inode->i_mode)) {
 			inode->i_size = obj->size;
-			if (fillzero)
+			if (fillzero || !inode->i_size)
 				ret = erofs_write_zero_inode(inode);
 			else
 				ret = s3erofs_remote_getobject(im, s3, inode,
-- 
2.47.3