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Message-ID: <8742625e-8ae7-47a8-fd62-18c201c45a33@cn.fujitsu.com>
Date: Wed, 3 Feb 2021 09:51:37 +0800
From: Ruan Shiyang <ruansy.fnst@...fujitsu.com>
To: "Darrick J. Wong" <djwong@...nel.org>
CC: <linux-kernel@...r.kernel.org>, <linux-xfs@...r.kernel.org>,
<linux-nvdimm@...ts.01.org>, <linux-mm@...ck.org>,
<linux-fsdevel@...r.kernel.org>, <dm-devel@...hat.com>,
<darrick.wong@...cle.com>, <dan.j.williams@...el.com>,
<david@...morbit.com>, <hch@....de>, <agk@...hat.com>,
<snitzer@...hat.com>, <rgoldwyn@...e.de>, <qi.fuli@...itsu.com>,
<y-goto@...itsu.com>
Subject: Re: [PATCH RESEND v2 08/10] md: Implement ->corrupted_range()
On 2021/2/2 上午11:17, Darrick J. Wong wrote:
> On Fri, Jan 29, 2021 at 02:27:55PM +0800, Shiyang Ruan wrote:
>> With the support of ->rmap(), it is possible to obtain the superblock on
>> a mapped device.
>>
>> If a pmem device is used as one target of mapped device, we cannot
>> obtain its superblock directly. With the help of SYSFS, the mapped
>> device can be found on the target devices. So, we iterate the
>> bdev->bd_holder_disks to obtain its mapped device.
>>
>> Signed-off-by: Shiyang Ruan <ruansy.fnst@...fujitsu.com>
>> ---
>> drivers/md/dm.c | 61 +++++++++++++++++++++++++++++++++++++++++++
>> drivers/nvdimm/pmem.c | 11 +++-----
>> fs/block_dev.c | 42 ++++++++++++++++++++++++++++-
>
> I feel like this ^^^ part that implements the generic ability for a block
> device with a bad sector to notify whatever's holding onto it (fs, other
> block device) should be in patch 2. That's generic block layer code,
> and it's hard to tell (when you're looking at patch 2) what the bare
> function declaration in it is really supposed to do.
>
> Also, this patch is still difficult to review because it mixes device
> mapper, nvdimm, and block layer changes!
OK. I'll split this to make it looks simple.
>
>> include/linux/genhd.h | 2 ++
>> 4 files changed, 107 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
>> index 7bac564f3faa..31b0c340b695 100644
>> --- a/drivers/md/dm.c
>> +++ b/drivers/md/dm.c
>> @@ -507,6 +507,66 @@ static int dm_blk_report_zones(struct gendisk *disk, sector_t sector,
>> #define dm_blk_report_zones NULL
>> #endif /* CONFIG_BLK_DEV_ZONED */
>>
>> +struct corrupted_hit_info {
>> + struct block_device *bdev;
>> + sector_t offset;
>> +};
>> +
>> +static int dm_blk_corrupted_hit(struct dm_target *ti, struct dm_dev *dev,
>> + sector_t start, sector_t count, void *data)
>> +{
>> + struct corrupted_hit_info *bc = data;
>> +
>> + return bc->bdev == (void *)dev->bdev &&
>> + (start <= bc->offset && bc->offset < start + count);
>> +
>> +}
>> +
>> +struct corrupted_do_info {
>> + size_t length;
>> + void *data;
>> +};
>> +
>> +static int dm_blk_corrupted_do(struct dm_target *ti, struct block_device *bdev,
>> + sector_t disk_sect, void *data)
>> +{
>> + struct corrupted_do_info *bc = data;
>> + loff_t disk_off = to_bytes(disk_sect);
>> + loff_t bdev_off = to_bytes(disk_sect - get_start_sect(bdev));
>> +
>> + return bd_corrupted_range(bdev, disk_off, bdev_off, bc->length, bc->data);
>> +}
>> +
>> +static int dm_blk_corrupted_range(struct gendisk *disk,
>> + struct block_device *target_bdev,
>> + loff_t target_offset, size_t len, void *data)
>> +{
>> + struct mapped_device *md = disk->private_data;
>> + struct dm_table *map;
>> + struct dm_target *ti;
>> + sector_t target_sect = to_sector(target_offset);
>> + struct corrupted_hit_info hi = {target_bdev, target_sect};
>> + struct corrupted_do_info di = {len, data};
>> + int srcu_idx, i, rc = -ENODEV;
>> +
>> + map = dm_get_live_table(md, &srcu_idx);
>> + if (!map)
>> + return rc;
>> +
>> + for (i = 0; i < dm_table_get_num_targets(map); i++) {
>> + ti = dm_table_get_target(map, i);
>> + if (!(ti->type->iterate_devices && ti->type->rmap))
>> + continue;
>> + if (!ti->type->iterate_devices(ti, dm_blk_corrupted_hit, &hi))
>> + continue;
>> +
>> + rc = ti->type->rmap(ti, target_sect, dm_blk_corrupted_do, &di);
>
> Why is it necessary to call ->iterate_devices here?
->iterate_devices() here is to find out which target is the pmem device
which is corrupted now. Then call ->rmap() on this target. Other
targets will be ignored.
>
> If you pass the target_bdev, offset, and length to the dm-target's
> ->rmap function, it should be able to work backwards through its mapping
> logic to come up with all the LBA ranges of the mapped_device that
> are affected, and then it can call bd_corrupted_range on each of those
> reverse mappings.
>
> It would be helpful to have the changes to dm-linear.c in this patch
> too, since that's the only real implementation at this point.
>
>> + break;
>> + }
>> +
>> + dm_put_live_table(md, srcu_idx);
>> + return rc;
>> +}
>> +
>> static int dm_prepare_ioctl(struct mapped_device *md, int *srcu_idx,
>> struct block_device **bdev)
>> {
>> @@ -3062,6 +3122,7 @@ static const struct block_device_operations dm_blk_dops = {
>> .getgeo = dm_blk_getgeo,
>> .report_zones = dm_blk_report_zones,
>> .pr_ops = &dm_pr_ops,
>> + .corrupted_range = dm_blk_corrupted_range,
>> .owner = THIS_MODULE
>> };
>>
>> diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
>> index 501959947d48..3d9f4ccbbd9e 100644
>> --- a/drivers/nvdimm/pmem.c
>> +++ b/drivers/nvdimm/pmem.c
>> @@ -256,21 +256,16 @@ static int pmem_rw_page(struct block_device *bdev, sector_t sector,
>> static int pmem_corrupted_range(struct gendisk *disk, struct block_device *bdev,
>> loff_t disk_offset, size_t len, void *data)
>> {
>> - struct super_block *sb;
>> loff_t bdev_offset;
>> sector_t disk_sector = disk_offset >> SECTOR_SHIFT;
>> - int rc = 0;
>> + int rc = -ENODEV;
>>
>> bdev = bdget_disk_sector(disk, disk_sector);
>> if (!bdev)
>> - return -ENODEV;
>> + return rc;
>>
>> bdev_offset = (disk_sector - get_start_sect(bdev)) << SECTOR_SHIFT;
>> - sb = get_super(bdev);
>> - if (sb && sb->s_op->corrupted_range) {
>> - rc = sb->s_op->corrupted_range(sb, bdev, bdev_offset, len, data);
>> - drop_super(sb);
>> - }
>> + rc = bd_corrupted_range(bdev, bdev_offset, bdev_offset, len, data);
>>
>> bdput(bdev);
>> return rc;
>> diff --git a/fs/block_dev.c b/fs/block_dev.c
>> index 3b8963e228a1..3cc2b2911e3a 100644
>> --- a/fs/block_dev.c
>> +++ b/fs/block_dev.c
>> @@ -1079,6 +1079,27 @@ struct bd_holder_disk {
>> int refcnt;
>> };
>>
>> +static int bd_disk_holder_corrupted_range(struct block_device *bdev, loff_t off,
>> + size_t len, void *data)
>> +{
>> + struct bd_holder_disk *holder;
>> + struct gendisk *disk;
>> + int rc = 0;
>> +
>> + if (list_empty(&(bdev->bd_holder_disks)))
>> + return -ENODEV;
>> +
>> + list_for_each_entry(holder, &bdev->bd_holder_disks, list) {
>> + disk = holder->disk;
>> + if (disk->fops->corrupted_range) {
>> + rc = disk->fops->corrupted_range(disk, bdev, off, len, data);
>> + if (rc != -ENODEV)
>> + break;
>> + }
>> + }
>> + return rc;
>> +}
>> +
>> static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
>> struct gendisk *disk)
>> {
>> @@ -1212,7 +1233,26 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
>> mutex_unlock(&bdev->bd_mutex);
>> }
>> EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
>> -#endif
>> +#endif /* CONFIG_SYSFS */
>> +
>> +int bd_corrupted_range(struct block_device *bdev, loff_t disk_off,
>> + loff_t bdev_off, size_t len, void *data)
>> +{
>> + struct super_block *sb = get_super(bdev);
>> + int rc = -EOPNOTSUPP;
>> +
>> + if (!sb) {
>> +#ifdef CONFIG_SYSFS
>> + rc = bd_disk_holder_corrupted_range(bdev, disk_off, len, data);
>> +#endif /* CONFIG_SYSFS */
>
> Normal kernel convention is that you'd provide a empty shell for the
> CONFIG_SYSFS=n case, e.g.
>
> #ifdef CONFIG_SYSFS
> int bd_corrupted_range(...) {
> /* real code */
> }
> #else
> static inline bd_corrupted_range(...) { return -EOPNOTSUPP; }
> #endif
>
> so that you don't have preprocessor directives making this function
> choppy.
I'll fix it.
--
Thanks,
Ruan Shiyang.
>
> --D
>
>> + return rc;
>> + } else if (sb->s_op->corrupted_range)
>> + rc = sb->s_op->corrupted_range(sb, bdev, bdev_off, len, data);
>> + drop_super(sb);
>> +
>> + return rc;
>> +}
>> +EXPORT_SYMBOL(bd_corrupted_range);
>>
>> static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
>>
>> diff --git a/include/linux/genhd.h b/include/linux/genhd.h
>> index 4da480798955..996f91b08d48 100644
>> --- a/include/linux/genhd.h
>> +++ b/include/linux/genhd.h
>> @@ -315,6 +315,8 @@ void unregister_blkdev(unsigned int major, const char *name);
>> bool bdev_check_media_change(struct block_device *bdev);
>> int __invalidate_device(struct block_device *bdev, bool kill_dirty);
>> void set_capacity(struct gendisk *disk, sector_t size);
>> +int bd_corrupted_range(struct block_device *bdev, loff_t disk_off,
>> + loff_t bdev_off, size_t len, void *data);
>>
>> /* for drivers/char/raw.c: */
>> int blkdev_ioctl(struct block_device *, fmode_t, unsigned, unsigned long);
>> --
>> 2.30.0
>>
>>
>>
>
>
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