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Message-ID: <1c8b966e-8208-e9c9-c75b-9ebf2a138059@bytedance.com>
Date: Wed, 1 Mar 2023 15:44:37 +0800
From: Jia Zhu <zhujia.zj@...edance.com>
To: Gao Xiang <hsiangkao@...ux.alibaba.com>, xiang@...nel.org,
chao@...nel.org, gerry@...ux.alibaba.com,
linux-erofs@...ts.ozlabs.org
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
jefflexu@...ux.alibaba.com, huyue2@...lpad.com,
Xin Yin <yinxin.x@...edance.com>
Subject: Re: Re: [PATCH] erofs: support for mounting a single block device
with multiple devices
在 2023/3/1 15:08, Gao Xiang 写道:
> Hi Jia,
>
> On 2023/3/1 15:04, Jia Zhu wrote:
>> In order to support mounting multi-layer container image as a block
>> device, add single block device with multiple devices feature for EROFS.
>
> In order to support mounting multi-blob container image as a single
> flattened block device, add flattened block device feature for EROFS.
>
Thanks, I would revise it.
>>
>> In this mode, all meta/data contents will be mapped into one block
>> address.
>> User could directly mount the block device by EROFS.
>>
>> Signed-off-by: Jia Zhu <zhujia.zj@...edance.com>
>> Reviewed-by: Xin Yin <yinxin.x@...edance.com>
>> ---
>> fs/erofs/data.c | 8 ++++++--
>> fs/erofs/super.c | 5 +++++
>> 2 files changed, 11 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/erofs/data.c b/fs/erofs/data.c
>> index e16545849ea7..870b1f7fe1d4 100644
>> --- a/fs/erofs/data.c
>> +++ b/fs/erofs/data.c
>> @@ -195,9 +195,9 @@ int erofs_map_dev(struct super_block *sb, struct
>> erofs_map_dev *map)
>> {
>> struct erofs_dev_context *devs = EROFS_SB(sb)->devs;
>> struct erofs_device_info *dif;
>> + bool flatdev = !!sb->s_bdev;
>
> I'd like to land it in sbi and set it in advance?
>
I'll revise that in next version.
> Also, did you test this patch?
I've tested the patch using the following steps mentioned by
https://github.com/dragonflyoss/image-service/pull/1111
1. Compose a (nbd)block device from an EROFS image.
2. mount -t erofs /dev/nbdx /mnt/
3. compare the md5sum between source dir and /mnt dir.
>
> Thanks,
> Gao Xiang
>
>
>> int id;
>> - /* primary device by default */
>> 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;
>> @@ -210,12 +210,16 @@ int erofs_map_dev(struct super_block *sb, struct
>> erofs_map_dev *map)
>> up_read(&devs->rwsem);
>> return -ENODEV;
>> }
>> + if (flatdev) {
>> + map->m_pa += blknr_to_addr(dif->mapped_blkaddr);
>> + map->m_deviceid = 0;
>> + }
>> map->m_bdev = dif->bdev;
>> map->m_daxdev = dif->dax_dev;
>> map->m_dax_part_off = dif->dax_part_off;
>> map->m_fscache = dif->fscache;
>> up_read(&devs->rwsem);
>> - } else if (devs->extra_devices) {
>> + } else if (devs->extra_devices && !flatdev) {
>> down_read(&devs->rwsem);
>> idr_for_each_entry(&devs->tree, dif, id) {
>> erofs_off_t startoff, length;
>> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
>> index 19b1ae79cec4..4f9725b0950c 100644
>> --- a/fs/erofs/super.c
>> +++ b/fs/erofs/super.c
>> @@ -226,6 +226,7 @@ static int erofs_init_device(struct erofs_buf
>> *buf, struct super_block *sb,
>> struct erofs_fscache *fscache;
>> struct erofs_deviceslot *dis;
>> struct block_device *bdev;
>> + bool flatdev = !!sb->s_bdev;
>> void *ptr;
>> ptr = erofs_read_metabuf(buf, sb, erofs_blknr(*pos), EROFS_KMAP);
>> @@ -248,6 +249,10 @@ static int erofs_init_device(struct erofs_buf
>> *buf, struct super_block *sb,
>> if (IS_ERR(fscache))
>> return PTR_ERR(fscache);
>> dif->fscache = fscache;
>> + } else if (flatdev) {
>> + dif->bdev = sb->s_bdev;
>> + dif->dax_dev = EROFS_SB(sb)->dax_dev;
>> + dif->dax_part_off = sbi->dax_part_off;
>> } else {
>> bdev = blkdev_get_by_path(dif->path, FMODE_READ | FMODE_EXCL,
>> sb->s_type);
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