On Tue, Aug 29 2017, Zhilong Liu wrote:
> Hi, Neil;
> Thanks for your pointing and sorry for the incorrect dmesg for last
> mail.
>
> Here update the pure steps and paste the dmesg.
>
> ENV:
> OS: 4.13-rc7 upstream
> linux-apta:~/mdadm-test # df -T /mnt/
> Filesystem Type 1K-blocks Used Available Use% Mounted on
> /dev/sda2 ext4 44248848 24416952 18778472 57% /
>
> Reproduce: 100%
>
> Steps:
> linux-apta:~/mdadm-test # ./mdadm -CR /dev/md0 -l1 -b /mnt/3 -n2 -x1
> /dev/loop[0-2] --force
> mdadm: Note: this array has metadata at the start and
> may not be suitable as a boot device. If you plan to
> store '/boot' on this device please ensure that
> your boot-loader understands md/v1.x metadata, or use
> --metadata=0.90
> mdadm: Defaulting to version 1.2 metadata
> mdadm: array /dev/md0 started.
> linux-apta:~/mdadm-test # cat /proc/mdstat
> Personalities : [raid1]
> md0 : active raid1 loop2[2](S) loop1[1] loop0[0]
> 18944 blocks super 1.2 [2/2] [UU]
> bitmap: 3/3 pages [12KB], 4KB chunk, file: /mnt/3
>
> unused devices: <none>
> linux-apta:~/mdadm-test # dmesg -c
> [ 181.378209] md/raid1:md0: not clean -- starting background reconstruction
> [ 181.378211] md/raid1:md0: active with 2 out of 2 mirrors
> [ 181.379354] md0: detected capacity change from 0 to 19398656
> [ 181.379773] md: resync of RAID array md0
> [ 190.396162] md: md0: resync done.
>
> linux-apta:~/mdadm-test # ./mdadm --grow /dev/md0 --size 128
> Segmentation fault
> linux-apta:~/mdadm-test # cat /sys/block/md0/md/component_size
> 18944 "here is incorrect also."
> linux-apta:~/mdadm-test # dmesg -c
> [ 208.027505] ------------[ cut here ]------------
> [ 208.027508] kernel BUG at drivers/md/bitmap.c:298!
Thanks. Less confusing now.
The problem is that when the bitmap is resized, new pages are allocated
to store the on-disk copy, but these are not read from the file, the
contents are set from the in-memory bitmap.
So read_page() isn't called and particularly
bh = alloc_page_buffers(page, 1<<inode->i_blkbits, 0);
...
attach_page_buffers(page, bh);
doesn't happen.
Maybe something like this will work.
Can you test it?
Thanks,
NeilBrown
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 40f3cd7eab0f..52fe93fa4598 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -368,12 +368,7 @@ static int read_page(struct file *file, unsigned long index,
pr_debug("read bitmap file (%dB @ %llu)\n", (int)PAGE_SIZE,
(unsigned long long)index << PAGE_SHIFT);
- bh = alloc_page_buffers(page, 1<<inode->i_blkbits, 0);
- if (!bh) {
- ret = -ENOMEM;
- goto out;
- }
- attach_page_buffers(page, bh);
+ bh = page_buffers(page);
block = index << (PAGE_SHIFT - inode->i_blkbits);
while (bh) {
if (count == 0)
@@ -771,12 +766,18 @@ static inline struct page *filemap_get_page(struct bitmap_storage *store,
}
static int bitmap_storage_alloc(struct bitmap_storage *store,
- unsigned long chunks, int with_super,
+ unsigned long chunks,
+ struct file *file,
+ int with_super,
int slot_number)
{
int pnum, offset = 0;
unsigned long num_pages;
unsigned long bytes;
+ struct inode *inode = NULL;
+
+ if (file)
+ inode = file_inode(file);
bytes = DIV_ROUND_UP(chunks, 8);
if (with_super)
@@ -804,12 +805,21 @@ static int bitmap_storage_alloc(struct bitmap_storage *store,
}
for ( ; pnum < num_pages; pnum++) {
- store->filemap[pnum] = alloc_page(GFP_KERNEL|__GFP_ZERO);
- if (!store->filemap[pnum]) {
+ struct page *p = alloc_page(GFP_KERNEL|__GFP_ZERO);
+ store->filemap[pnum] = p;
+ if (!p) {
store->file_pages = pnum;
return -ENOMEM;
}
- store->filemap[pnum]->index = pnum + offset;
+ if (inode) {
+ struct buffer_head *bh;
+ bh = alloc_page_buffers(p, 1 << inode->i_blkbits, 0);
+ if (bh)
+ attach_page_buffers(p, bh);
+ else
+ return -ENOMEM;
+ }
+ p->index = pnum + offset;
}
store->file_pages = pnum;
@@ -2091,7 +2101,7 @@ int bitmap_resize(struct bitmap *bitmap, sector_t blocks,
chunks = DIV_ROUND_UP_SECTOR_T(blocks, 1 << chunkshift);
memset(&store, 0, sizeof(store));
if (bitmap->mddev->bitmap_info.offset || bitmap->mddev->bitmap_info.file)
- ret = bitmap_storage_alloc(&store, chunks,
+ ret = bitmap_storage_alloc(&store, chunks, bitmap->mddev->bitmap_info.file,
!bitmap->mddev->bitmap_info.external,
mddev_is_clustered(bitmap->mddev)
? bitmap->cluster_slot : 0);
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