在 2025/8/1 15:03, Yu Kuai 写道:
From: Yu Kuai <yukuai3@xxxxxxxxxx>
Redundant data is used to enhance data fault tolerance, and the storage
method for redundant data vary depending on the RAID levels. And it's
important to maintain the consistency of redundant data.
Bitmap is used to record which data blocks have been synchronized and which
ones need to be resynchronized or recovered. Each bit in the bitmap
represents a segment of data in the array. When a bit is set, it indicates
that the multiple redundant copies of that data segment may not be
consistent. Data synchronization can be performed based on the bitmap after
power failure or readding a disk. If there is no bitmap, a full disk
synchronization is required.
This is a large patch, I've found a few minor issues so far.
And I'm still working through it.
[...]
+ [BitDirty] = {
+ [BitmapActionStartwrite] = BitNone,
+ [BitmapActionStartsync] = BitNone,
+ [BitmapActionEndsync] = BitNone,
+ [BitmapActionAbortsync] = BitNone,
+ [BitmapActionReload] = BitNeedSync,
+ [BitmapActionDaemon] = BitClean,
+ [BitmapActionDiscard] = BitUnwritten,
+ [BitmapActionStale] = BitNeedSync,
+ },
Bits becomes BitDirt during degraded remains BitDirty even after recovery
and re-write. Should we consider adjusting this state transition, or maybe
trigger the daemon after the recovery is complete?
[...]
+
+static int llbitmap_create(struct mddev *mddev)
+{
+ struct llbitmap *llbitmap;
+ int ret;
+
+ ret = llbitmap_check_support(mddev);
+ if (ret)
+ return ret;
+
+ llbitmap = kzalloc(sizeof(*llbitmap), GFP_KERNEL);
+ if (!llbitmap)
+ return -ENOMEM;
+
+ llbitmap->mddev = mddev;
+ llbitmap->io_size = bdev_logical_block_size(mddev->gendisk->part0);
+ llbitmap->blocks_per_page = PAGE_SIZE / llbitmap->io_size;
logical_block_size can > PAGE_SIZE, blocks_per_page is set to 0 which can
cause issues in later computations.
--
Thanks,
Nan
