Until then erofs is exactly blockdev based filesystem. In other using
scenarios (e.g. container image), erofs needs to run upon files.
This patch introduces a new nodev mode, in which erofs could be mounted
from a bootstrap blob file containing the complete erofs image.
The following patch will introduce a new mount option "uuid", by which
users could specify the bootstrap blob file.
Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
---
fs/erofs/data.c | 13 ++++++++---
fs/erofs/internal.h | 1 +
fs/erofs/super.c | 56 +++++++++++++++++++++++++++++++++------------
3 files changed, 53 insertions(+), 17 deletions(-)
diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 477aaff0c832..61fa431d0713 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -11,11 +11,18 @@
struct page *erofs_get_meta_page(struct super_block *sb, erofs_blk_t blkaddr)
{
- struct address_space *const mapping = sb->s_bdev->bd_inode->i_mapping;
+ struct address_space *mapping;
struct page *page;
- page = read_cache_page_gfp(mapping, blkaddr,
- mapping_gfp_constraint(mapping, ~__GFP_FS));
+ if (sb->s_bdev) {
+ mapping = sb->s_bdev->bd_inode->i_mapping;
+ page = read_cache_page_gfp(mapping, blkaddr,
+ mapping_gfp_constraint(mapping, ~__GFP_FS));
+ } else {
+ /* TODO: data path in nodev mode */
+ page = ERR_PTR(-EINVAL);
+ }
+
/* should already be PageUptodate */
if (!IS_ERR(page))
lock_page(page);
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 45fb6f5d11b5..c9ee8c247202 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -67,6 +67,7 @@ struct erofs_mount_opts {
unsigned int max_sync_decompress_pages;
#endif
unsigned int mount_opt;
+ char *uuid;
};
struct erofs_dev_context {
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 6a969b1e0ee6..80c00c34eafc 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -304,15 +304,19 @@ 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);
- goto err_out;
+ if (sb->s_bdev) {
+ bdev = blkdev_get_by_path(dif->path,
+ FMODE_READ | FMODE_EXCL,
+ sb->s_type);
+ if (IS_ERR(bdev)) {
+ err = PTR_ERR(bdev);
+ goto err_out;
+ }
+ dif->bdev = bdev;
+ dif->dax_dev = fs_dax_get_by_bdev(bdev);
+ } else {
+ /* TODO: multi devs in nodev mode */
}
- dif->bdev = bdev;
- dif->dax_dev = fs_dax_get_by_bdev(bdev);
dif->blocks = le32_to_cpu(dis->blocks);
dif->mapped_blkaddr = le32_to_cpu(dis->mapped_blkaddr);
sbi->total_blocks += dif->blocks;
@@ -337,7 +341,11 @@ static int erofs_read_superblock(struct super_block *sb)
void *data;
int ret;
- page = read_mapping_page(sb->s_bdev->bd_inode->i_mapping, 0, NULL);
+ /* TODO: metadata path in nodev mode */
+ if (sb->s_bdev)
+ page = read_mapping_page(sb->s_bdev->bd_inode->i_mapping, 0, NULL);
+ else
+ page = ERR_PTR(-EOPNOTSUPP);
if (IS_ERR(page)) {
erofs_err(sb, "cannot read erofs superblock");
return PTR_ERR(page);
@@ -633,9 +641,12 @@ 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)) {
+ if (sb->s_bdev && !sb_set_blocksize(sb, EROFS_BLKSIZ)) {
erofs_err(sb, "failed to set erofs blksize");
return -EINVAL;
+ } else {
+ sb->s_blocksize = EROFS_BLKSIZ;
+ sb->s_blocksize_bits = LOG_BLOCK_SIZE;
}
sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
@@ -644,16 +655,22 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
sb->s_fs_info = sbi;
sbi->opt = ctx->opt;
- sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev);
sbi->devs = ctx->devs;
ctx->devs = NULL;
+ if (sb->s_bdev)
+ sbi->dax_dev = fs_dax_get_by_bdev(sb->s_bdev);
+ else
+ sbi->dax_dev = NULL;
+
err = erofs_read_superblock(sb);
if (err)
return err;
if (test_opt(&sbi->opt, DAX_ALWAYS) &&
- !dax_supported(sbi->dax_dev, sb->s_bdev, EROFS_BLKSIZ, 0, bdev_nr_sectors(sb->s_bdev))) {
+ (!sbi->dax_dev ||
+ !dax_supported(sbi->dax_dev, sb->s_bdev, EROFS_BLKSIZ, 0,
+ bdev_nr_sectors(sb->s_bdev)))) {
errorfc(fc, "DAX unsupported by block device. Turning off DAX.");
clear_opt(&sbi->opt, DAX_ALWAYS);
}
@@ -701,6 +718,10 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
static int erofs_fc_get_tree(struct fs_context *fc)
{
+ struct erofs_fs_context *ctx = fc->fs_private;
+
+ if (ctx->opt.uuid)
+ return get_tree_nodev(fc, erofs_fc_fill_super);
return get_tree_bdev(fc, erofs_fc_fill_super);
}
@@ -789,7 +810,10 @@ static void erofs_kill_sb(struct super_block *sb)
WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);
- kill_block_super(sb);
+ if (sb->s_bdev)
+ kill_block_super(sb);
+ else
+ generic_shutdown_super(sb);
sbi = EROFS_SB(sb);
if (!sbi)
@@ -889,7 +913,11 @@ 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;
+
+ /* TODO: fsid in nodev mode */
+ if (sb->s_bdev)
+ id = huge_encode_dev(sb->s_bdev->bd_dev);
buf->f_type = sb->s_magic;
buf->f_bsize = EROFS_BLKSIZ;
--
2.27.0
