diff options
Diffstat (limited to 'mm/page-writeback.c')
| -rw-r--r-- | mm/page-writeback.c | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 4f51d0ac5043..55c2776ae699 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -652,18 +652,25 @@ static unsigned int bdi_min_ratio; int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) { + unsigned int delta; int ret = 0; spin_lock_bh(&bdi_lock); if (min_ratio > bdi->max_ratio) { ret = -EINVAL; } else { - min_ratio -= bdi->min_ratio; - if (bdi_min_ratio + min_ratio < 100) { - bdi_min_ratio += min_ratio; - bdi->min_ratio += min_ratio; + if (min_ratio < bdi->min_ratio) { + delta = bdi->min_ratio - min_ratio; + bdi_min_ratio -= delta; + bdi->min_ratio = min_ratio; } else { - ret = -EINVAL; + delta = min_ratio - bdi->min_ratio; + if (bdi_min_ratio + delta < 100) { + bdi_min_ratio += delta; + bdi->min_ratio = min_ratio; + } else { + ret = -EINVAL; + } } } spin_unlock_bh(&bdi_lock); @@ -2686,10 +2693,12 @@ EXPORT_SYMBOL(folio_redirty_for_writepage); * folio_mark_dirty - Mark a folio as being modified. * @folio: The folio. * - * For folios with a mapping this should be done with the folio lock held - * for the benefit of asynchronous memory errors who prefer a consistent - * dirty state. This rule can be broken in some special cases, - * but should be better not to. + * The folio may not be truncated while this function is running. + * Holding the folio lock is sufficient to prevent truncation, but some + * callers cannot acquire a sleeping lock. These callers instead hold + * the page table lock for a page table which contains at least one page + * in this folio. Truncation will block on the page table lock as it + * unmaps pages before removing the folio from its mapping. * * Return: True if the folio was newly dirtied, false if it was already dirty. */ |