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md/bitmap: don't set max_write_behind if there is no write mostly device

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[ Upstream commit 8c13ab115b577bd09097b9d77916732e97e31b7b ]

We shouldn't set it since write behind IO should only happen to write
mostly device.

Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Signed-off-by: Song Liu <songliubraving@fb.com>
Stable-dep-of: 44abfa6a95df ("md/md-bitmap: hold 'reconfig_mutex' in backlog_store()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Guoqing Jiang 2021-10-17 21:50:17 +08:00 committed by Greg Kroah-Hartman
parent a8f8c4e728
commit 630be0110e
1 changed files with 19 additions and 0 deletions
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19
drivers/md/md-bitmap.c
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@ -2480,11 +2480,30 @@ backlog_store(struct mddev *mddev, const char *buf, size_t len)
{
unsigned long backlog;
unsigned long old_mwb = mddev->bitmap_info.max_write_behind;
struct md_rdev *rdev;
bool has_write_mostly = false;
int rv = kstrtoul(buf, 10, &backlog);
if (rv)
return rv;
if (backlog > COUNTER_MAX)
return -EINVAL;
/*
* Without write mostly device, it doesn't make sense to set
* backlog for max_write_behind.
*/
rdev_for_each(rdev, mddev) {
if (test_bit(WriteMostly, &rdev->flags)) {
has_write_mostly = true;
break;
}
}
if (!has_write_mostly) {
pr_warn_ratelimited("%s: can't set backlog, no write mostly device available\n",
mdname(mddev));
return -EINVAL;
}
mddev->bitmap_info.max_write_behind = backlog;
if (!backlog && mddev->wb_info_pool) {
/* wb_info_pool is not needed if backlog is zero */