Until then erofs is exactly blockdev based filesystem.
A new fscache-based mode is going to be introduced for erofs to support
scenarios where on-demand read semantics is needed, e.g. container
image distribution. In this case, erofs could be mounted from data blobs
through fscache.
Add a helper checking which mode erofs works in, and twist the code in
preparation for the upcoming fscache mode.
Signed-off-by: Jeffle Xu <[email protected]>
Reviewed-by: Gao Xiang <[email protected]>
---
fs/erofs/internal.h | 5 +++++
fs/erofs/super.c | 44 +++++++++++++++++++++++++++++---------------
2 files changed, 34 insertions(+), 15 deletions(-)
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index fe9564e5091e..05a97533b1e9 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -161,6 +161,11 @@ struct erofs_sb_info {
#define set_opt(opt, option) ((opt)->mount_opt |= EROFS_MOUNT_##option)
#define test_opt(opt, option) ((opt)->mount_opt & EROFS_MOUNT_##option)
+static inline bool erofs_is_fscache_mode(struct super_block *sb)
+{
+ return IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND) && !sb->s_bdev;
+}
+
enum {
EROFS_ZIP_CACHE_DISABLED,
EROFS_ZIP_CACHE_READAHEAD,
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 0c4b41130c2f..724d5ff0d78c 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -259,15 +259,19 @@ static int erofs_init_devices(struct super_block *sb,
}
dis = ptr + erofs_blkoff(pos);
- bdev = blkdev_get_by_path(dif->path,
- FMODE_READ | FMODE_EXCL,
- sb->s_type);
- if (IS_ERR(bdev)) {
- err = PTR_ERR(bdev);
- break;
+ if (!erofs_is_fscache_mode(sb)) {
+ bdev = blkdev_get_by_path(dif->path,
+ FMODE_READ | FMODE_EXCL,
+ sb->s_type);
+ if (IS_ERR(bdev)) {
+ err = PTR_ERR(bdev);
+ break;
+ }
+ dif->bdev = bdev;
+ dif->dax_dev = fs_dax_get_by_bdev(bdev,
+ &dif->dax_part_off);
}
- dif->bdev = bdev;
- dif->dax_dev = fs_dax_get_by_bdev(bdev, &dif->dax_part_off);
+
dif->blocks = le32_to_cpu(dis->blocks);
dif->mapped_blkaddr = le32_to_cpu(dis->mapped_blkaddr);
sbi->total_blocks += dif->blocks;
@@ -586,21 +590,28 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
sb->s_magic = EROFS_SUPER_MAGIC;
- if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {
- erofs_err(sb, "failed to set erofs blksize");
- return -EINVAL;
- }
-
sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
if (!sbi)
return -ENOMEM;
sb->s_fs_info = sbi;
sbi->opt = ctx->opt;
- sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->dax_part_off);
sbi->devs = ctx->devs;
ctx->devs = NULL;
+ if (erofs_is_fscache_mode(sb)) {
+ sb->s_blocksize = EROFS_BLKSIZ;
+ sb->s_blocksize_bits = LOG_BLOCK_SIZE;
+ } else {
+ if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {
+ erofs_err(sb, "failed to set erofs blksize");
+ return -EINVAL;
+ }
+
+ sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev,
+ &sbi->dax_part_off);
+ }
+
err = erofs_read_superblock(sb);
if (err)
return err;
@@ -857,7 +868,10 @@ static int erofs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct super_block *sb = dentry->d_sb;
struct erofs_sb_info *sbi = EROFS_SB(sb);
- u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
+ u64 id = 0;
+
+ if (!erofs_is_fscache_mode(sb))
+ id = huge_encode_dev(sb->s_bdev->bd_dev);
buf->f_type = sb->s_magic;
buf->f_bsize = EROFS_BLKSIZ;
--
2.27.0