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Subject: Re: [PATCH v2] md: Kill usage of page->index
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To:     Guoqing Jiang <guoqing.jiang@linux.dev>,
        Kent Overstreet <kent.overstreet@gmail.com>
CC:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        akpm@linux-foundation.org, linux-raid@vger.kernel.org,
        linux-block@vger.kernel.org, axboe@kernel.dk,
        alexander.h.duyck@linux.intel.com
References: <20211013160034.3472923-1-kent.overstreet@gmail.com>
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From:   "heming.zhao@suse.com" <heming.zhao@suse.com>
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I agree Guoqing's comments.

In Documentation/driver-api/md/md-cluster.rst, there is a pic in "1. On-dis=
k format".
Which describes the layout of "sb+bitmap" area.

And even in non-cluster array, bitmap area more than 1 pages also needs ind=
ex/offset.
After the serial patches removing page->index, md layer should create a sim=
ilar
struct to manage it.

- Heming

On 10/15/21 11:01, Guoqing Jiang wrote:
>=20
>=20
> On 10/14/21 10:30 PM, Kent Overstreet wrote:
>> On Thu, Oct 14, 2021 at 04:58:46PM +0800,heming.zhao@suse.com=C2=A0 wrot=
e:
>>> Hello all,
>>>
>>> The page->index takes an important role for cluster-md module.
>>> i.e, a two-node HA env, node A bitmap may be managed in first 4K area, =
then
>>> node B bitmap is in 8K area (the second page). this patch removes the i=
ndex
>>> and fix/hardcode index with value 0, which will only operate first node=
 bitmap.
>>>
>>> If this serial patches are important and must be merged in mainline, we=
 should
>>> redesign code logic for the related code.
>>>
>>> Thanks,
>>> Heming
>> Can you look at and test the updated patch below? The more I look at the=
 md
>> bitmap code the more it scares me.
>>
>> -- >8 --
>> Subject: [PATCH] md: Kill usage of page->index
>>
>> As part of the struct page cleanups underway, we want to remove as much
>> usage of page->mapping and page->index as possible, as frequently they
>> are known from context - as they are here in the md bitmap code.
>>
>> Signed-off-by: Kent Overstreet<kent.overstreet@gmail.com>
>> ---
>> =C2=A0 drivers/md/md-bitmap.c | 49 ++++++++++++++++++++-----------------=
-----
>> =C2=A0 drivers/md/md-bitmap.h |=C2=A0 1 +
>> =C2=A0 2 files changed, 24 insertions(+), 26 deletions(-)
>>
>> diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
>> index e29c6298ef..316e4cd5a7 100644
>> --- a/drivers/md/md-bitmap.c
>> +++ b/drivers/md/md-bitmap.c
>> @@ -165,10 +165,8 @@ static int read_sb_page(struct mddev *mddev, loff_t=
 offset,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (sync_page_io(=
rdev, target,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 roundup(size, bdev_logical_block_size(=
rdev->bdev)),
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0 page, REQ_OP_READ, 0, true)) {
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 page=
->index =3D index;
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0 page, REQ_OP_READ, 0, true))
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 return 0;
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 return -EIO;
>> =C2=A0 }
>> @@ -209,7 +207,8 @@ static struct md_rdev *next_active_rdev(struct md_rd=
ev *rdev, struct mddev *mdde
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 return NULL;
>> =C2=A0 }
>> -static int write_sb_page(struct bitmap *bitmap, struct page *page, int =
wait)
>> +static int write_sb_page(struct bitmap *bitmap, struct page *page,
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0 unsigned long index, int wait)
>> =C2=A0 {
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct md_rdev *rdev;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct block_device *bdev;
>> @@ -224,7 +223,7 @@ static int write_sb_page(struct bitmap *bitmap, stru=
ct page *page, int wait)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bdev =3D (rdev->m=
eta_bdev) ? rdev->meta_bdev : rdev->bdev;
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (page->index =3D=3D store=
->file_pages-1) {
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (index =3D=3D store->file=
_pages-1) {
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 int last_page_size =3D store->bytes & (PAGE_SIZE-1);
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 if (last_page_size =3D=3D 0)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 last_page_size =3D PAGE_SIZE;
>> @@ -236,8 +235,7 @@ static int write_sb_page(struct bitmap *bitmap, stru=
ct page *page, int wait)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (mddev->extern=
al) {
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 /* Bitmap could be anywhere. */
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (=
rdev->sb_start + offset + (page->index
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * (PAGE_SIZE/512))
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (=
rdev->sb_start + offset + index * PAGE_SECTORS
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 > rdev->data_offset
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 &&
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 rdev->sb_start + offset
>> @@ -247,7 +245,7 @@ static int write_sb_page(struct bitmap *bitmap, stru=
ct page *page, int wait)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } else if (offset=
 < 0) {
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 /* DATA=C2=A0 BITMAP METADATA=C2=A0 */
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 if (offset
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0 + (long)(page->index * (PAGE_SIZE/512))
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0 + (long)(index * PAGE_SECTORS)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 + size/512 > 0)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* bitmap runs in to metadata */
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 goto bad_alignment;
>> @@ -259,7 +257,7 @@ static int write_sb_page(struct bitmap *bitmap, stru=
ct page *page, int wait)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 /* METADATA BITMAP DATA */
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 if (rdev->sb_start
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 + offset
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0 + page->index*(PAGE_SIZE/512) + size/512
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0 + index * PAGE_SECTORS + size/512
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 > rdev->data_offset)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* bitmap runs in to data */
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 goto bad_alignment;
>> @@ -268,7 +266,7 @@ static int write_sb_page(struct bitmap *bitmap, stru=
ct page *page, int wait)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 md_super_write(md=
dev, rdev,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 rdev->sb_start + offset
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 + page->index * (PAGE_SIZE/512),
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 + index * PAGE_SECTORS,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 size,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 page);
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
>> @@ -285,12 +283,13 @@ static void md_bitmap_file_kick(struct bitmap *bit=
map);
>> =C2=A0 /*
>> =C2=A0=C2=A0 * write out a page to a file
>> =C2=A0=C2=A0 */
>> -static void write_page(struct bitmap *bitmap, struct page *page, int wa=
it)
>> +static void write_page(struct bitmap *bitmap, struct page *page,
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0 unsigned long index, int wait)
>> =C2=A0 {
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct buffer_head *bh;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (bitmap->storage.file =3D=3D NULL) {
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 switch (write_sb_page(bitmap=
, page, wait)) {
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 switch (write_sb_page(bitmap=
, page, index, wait)) {
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 case -EINVAL:
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 set_bit(BITMAP_WRITE_ERROR, &bitmap->flags);
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
>> @@ -399,7 +398,6 @@ static int read_page(struct file *file, unsigned lon=
g index,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 blk_cur++;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bh =3D bh->b_this=
_page;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
>> -=C2=A0=C2=A0=C2=A0 page->index =3D index;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 wait_event(bitmap->write_wait,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
 atomic_read(&bitmap->pending_writes)=3D=3D0);
>> @@ -472,7 +470,7 @@ void md_bitmap_update_sb(struct bitmap *bitmap)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 sb->sectors_reserved =3D cpu_to_le32(bitm=
ap->mddev->
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bi=
tmap_info.space);
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 kunmap_atomic(sb);
>> -=C2=A0=C2=A0=C2=A0 write_page(bitmap, bitmap->storage.sb_page, 1);
>> +=C2=A0=C2=A0=C2=A0 write_page(bitmap, bitmap->storage.sb_page, bitmap->=
storage.sb_index, 1);
>=20
> I guess it is fine for sb_page now.
>=20
> [...]
>=20
>> @@ -1027,7 +1024,7 @@ void md_bitmap_unplug(struct bitmap *bitmap)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 "md bitmap_unplug");
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 }
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 clear_page_attr(bitmap, i, BITMAP_PAGE_PENDING);
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 writ=
e_page(bitmap, bitmap->storage.filemap[i], 0);
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 writ=
e_page(bitmap, bitmap->storage.filemap[i], i, 0);
>=20
> But for filemap page, I am not sure the above is correct.
>=20
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 writing =3D 1;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
>> @@ -1137,7 +1134,7 @@ static int md_bitmap_init_from_disk(struct bitmap =
*bitmap, sector_t start)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 memset(paddr + offset, 0xff,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 PA=
GE_SIZE - offset);
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 kunmap_atomic(paddr);
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0 write_page(bitmap, page, 1);
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0 write_page(bitmap, page, index, 1);
>=20
> Ditto.
>=20
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 ret =3D -EIO;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (test_bit(BITMAP_WRITE_ERROR,
>> @@ -1336,7 +1333,7 @@ void md_bitmap_daemon_work(struct mddev *mddev)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (bitmap->stora=
ge.filemap &&
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0 test_and_clear_page_attr(bitmap, j,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0 BITMAP_PAGE_NEEDWRITE)) {
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 writ=
e_page(bitmap, bitmap->storage.filemap[j], 0);
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 writ=
e_page(bitmap, bitmap->storage.filemap[j], j, 0);
>=20
> Ditto.
>=20
>=20
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
>> diff --git a/drivers/md/md-bitmap.h b/drivers/md/md-bitmap.h
>> index cfd7395de8..6e820eea32 100644
>> --- a/drivers/md/md-bitmap.h
>> +++ b/drivers/md/md-bitmap.h
>> @@ -207,6 +207,7 @@ struct bitmap {
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0 * w/ filemap pages */
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long fil=
e_pages;=C2=A0=C2=A0=C2=A0 /* number of pages in the file*/
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long byt=
es;=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* total bytes in the bitmap =
*/
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long sb_index;=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* sb page index */
>=20
> I guess it resolve the issue for sb_page, and we might need to do similar=
 things
> for filemap as well if I am not misunderstood.
>=20
> Thanks,
> Guoqing
>=20