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erofs: add fscache mode check helper

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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 <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220425122143.56815-11-jefflexu@linux.alibaba.com
Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
This commit is contained in:
Jeffle Xu 2022-04-25 20:21:32 +08:00 committed by Gao Xiang
parent 94d7894670
commit 93b856bb5f
2 changed files with 34 additions and 15 deletions
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5
fs/erofs/internal.h
View File

@ -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,

44
fs/erofs/super.c
View File

@ -260,15 +260,19 @@ 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;
@ -625,21 +629,28 @@ 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;
@ -897,7 +908,10 @@ 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;