[PATCH v6 20/22] erofs: implement fscache-based data read for data blobs

[Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>]

Implements the data plane of reading data from data blob file over
fscache.

Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
---
 fs/erofs/data.c     |  3 +++
 fs/erofs/fscache.c  | 15 +++++++++++++--
 fs/erofs/internal.h |  1 +
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index b4571bea93d5..b9a05de3c3b2 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -206,6 +206,7 @@ int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
 	map->m_bdev = sb->s_bdev;
 	map->m_daxdev = EROFS_SB(sb)->dax_dev;
 	map->m_dax_part_off = EROFS_SB(sb)->dax_part_off;
+	map->m_fscache = EROFS_SB(sb)->bootstrap;
 
 	if (map->m_deviceid) {
 		down_read(&devs->rwsem);
@@ -217,6 +218,7 @@ int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
 		map->m_bdev = dif->bdev;
 		map->m_daxdev = dif->dax_dev;
 		map->m_dax_part_off = dif->dax_part_off;
+		map->m_fscache = dif->blob;
 		up_read(&devs->rwsem);
 	} else if (devs->extra_devices) {
 		down_read(&devs->rwsem);
@@ -234,6 +236,7 @@ int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
 				map->m_bdev = dif->bdev;
 				map->m_daxdev = dif->dax_dev;
 				map->m_dax_part_off = dif->dax_part_off;
+				map->m_fscache = dif->blob;
 				break;
 			}
 		}
diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index d75958470645..cbb39657615e 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -63,9 +63,20 @@ static int erofs_fscache_readpage_blob(struct file *data, struct page *page)
 static inline int erofs_fscache_get_map(struct erofs_map_blocks *map,
 					struct super_block *sb)
 {
-	struct erofs_sb_info *sbi = EROFS_SB(sb);
+	struct erofs_map_dev mdev;
+	int ret;
+
+	mdev = (struct erofs_map_dev) {
+		.m_deviceid = map->m_deviceid,
+		.m_pa = map->m_pa,
+	};
+
+	ret = erofs_map_dev(sb, &mdev);
+	if (ret)
+		return ret;
 
-	map->m_fscache	= sbi->bootstrap;
+	map->m_fscache	= mdev.m_fscache;
+	map->m_pa	= mdev.m_pa;
 	return 0;
 }
 
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 94a118caf580..cea08f12a2c3 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -487,6 +487,7 @@ struct erofs_map_dev {
 	struct block_device *m_bdev;
 	struct dax_device *m_daxdev;
 	u64 m_dax_part_off;
+	struct erofs_fscache *m_fscache;
 
 	erofs_off_t m_pa;
 	unsigned int m_deviceid;
-- 
2.27.0