md/bitmap: don't read page from device with Bitmap_sync

The device owns Bitmap_sync flag needs recovery
to become in sync, and read page from this type
device could get stale status.

Also add comments for Bitmap_sync bit per the
suggestion from Shaohua and Neil.

Previous disscussion can be found here:
https://marc.info/?t=149760428900004&r=1&w=2

Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
Guoqing Jiang 2017-07-04 11:20:30 +08:00 committed by Shaohua Li
parent af3c8d9850
commit 4aaf7694f8
2 changed files with 5 additions and 2 deletions

View File

@ -156,7 +156,8 @@ static int read_sb_page(struct mddev *mddev, loff_t offset,
rdev_for_each(rdev, mddev) {
if (! test_bit(In_sync, &rdev->flags)
|| test_bit(Faulty, &rdev->flags))
|| test_bit(Faulty, &rdev->flags)
|| test_bit(Bitmap_sync, &rdev->flags))
continue;
target = offset + index * (PAGE_SIZE/512);

View File

@ -134,7 +134,9 @@ enum flag_bits {
Faulty, /* device is known to have a fault */
In_sync, /* device is in_sync with rest of array */
Bitmap_sync, /* ..actually, not quite In_sync. Need a
* bitmap-based recovery to get fully in sync
* bitmap-based recovery to get fully in sync.
* The bit is only meaningful before device
* has been passed to pers->hot_add_disk.
*/
WriteMostly, /* Avoid reading if at all possible */
AutoDetected, /* added by auto-detect */