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SubjectRe: [PATCH v11 7/8] xfs: Implement ->notify_failure() for XFS
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在 2022/3/30 14:00, Christoph Hellwig 写道:
>> @@ -1892,6 +1893,8 @@ xfs_free_buftarg(
>> list_lru_destroy(&btp->bt_lru);
>>
>> blkdev_issue_flush(btp->bt_bdev);
>> + if (btp->bt_daxdev)
>> + dax_unregister_holder(btp->bt_daxdev, btp->bt_mount);
>> fs_put_dax(btp->bt_daxdev);
>>
>> kmem_free(btp);
>> @@ -1939,6 +1942,7 @@ xfs_alloc_buftarg(
>> struct block_device *bdev)
>> {
>> xfs_buftarg_t *btp;
>> + int error;
>>
>> btp = kmem_zalloc(sizeof(*btp), KM_NOFS);
>>
>> @@ -1946,6 +1950,14 @@ xfs_alloc_buftarg(
>> btp->bt_dev = bdev->bd_dev;
>> btp->bt_bdev = bdev;
>> btp->bt_daxdev = fs_dax_get_by_bdev(bdev, &btp->bt_dax_part_off);
>> + if (btp->bt_daxdev) {
>> + error = dax_register_holder(btp->bt_daxdev, mp,
>> + &xfs_dax_holder_operations);
>> + if (error) {
>> + xfs_err(mp, "DAX device already in use?!");
>> + goto error_free;
>> + }
>> + }
>
> It seems to me that just passing the holder and holder ops to
> fs_dax_get_by_bdev and the holder to dax_unregister_holder would
> significantly simply the interface here.
>
> Dan, what do you think?
>
>> +#if IS_ENABLED(CONFIG_MEMORY_FAILURE) && IS_ENABLED(CONFIG_FS_DAX)
>
> No real need for the IS_ENABLED. Also any reason to even build this
> file if the options are not set? It seems like
> xfs_dax_holder_operations should just be defined to NULL and the
> whole file not supported if we can't support the functionality.

Got it. These two CONFIG seem not related for now. So, I think I
should wrap these code with #ifdef CONFIG_MEMORY_FAILURE here, and add
`xfs-$(CONFIG_FS_DAX) += xfs_notify_failure.o` in the makefile.

>
> Dan: not for this series, but is there any reason not to require
> MEMORY_FAILURE for DAX to start with?
>
>> +
>> + ddev_start = mp->m_ddev_targp->bt_dax_part_off;
>> + ddev_end = ddev_start +
>> + (mp->m_ddev_targp->bt_bdev->bd_nr_sectors << SECTOR_SHIFT) - 1;
>
> This should use bdev_nr_bytes.

OK.

>
> But didn't we say we don't want to support notifications on partitioned
> devices and thus don't actually need all this?
>
>> +
>> + /* Ignore the range out of filesystem area */
>> + if ((offset + len) < ddev_start)
>
> No need for the inner braces.
>
>> + if ((offset + len) > ddev_end)
>
> No need for the braces either.

Really no need? It is to make sure the range to be handled won't out of
the filesystem area. And make sure the @offset and @len are valid and
correct after subtract the bbdev_start.

>
>> diff --git a/fs/xfs/xfs_notify_failure.h b/fs/xfs/xfs_notify_failure.h
>> new file mode 100644
>> index 000000000000..76187b9620f9
>> --- /dev/null
>> +++ b/fs/xfs/xfs_notify_failure.h
>> @@ -0,0 +1,10 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) 2022 Fujitsu. All Rights Reserved.
>> + */
>> +#ifndef __XFS_NOTIFY_FAILURE_H__
>> +#define __XFS_NOTIFY_FAILURE_H__
>> +
>> +extern const struct dax_holder_operations xfs_dax_holder_operations;
>> +
>> +#endif /* __XFS_NOTIFY_FAILURE_H__ */
>
> Dowe really need a new header for this vs just sequeezing it into
> xfs_super.h or something like that?

Yes, I'll move it into xfs_super.h. The xfs_notify_failure.c was
splitted from xfs_super.c in the old patch. There is no need to create
a header file for only single line of code.

>
>> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
>> index e8f37bdc8354..b8de6ed2c888 100644
>> --- a/fs/xfs/xfs_super.c
>> +++ b/fs/xfs/xfs_super.c
>> @@ -353,6 +353,12 @@ xfs_setup_dax_always(
>> return -EINVAL;
>> }
>>
>> + if (xfs_has_reflink(mp) && !xfs_has_rmapbt(mp)) {
>> + xfs_alert(mp,
>> + "need rmapbt when both DAX and reflink enabled.");
>> + return -EINVAL;
>> + }
>
> Right now we can't even enable reflink with DAX yet, so adding this
> here seems premature - it should go into the patch allowing DAX+reflink.
>

Yes. I'll remove it for now.


--
Thanks,
Ruan.


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