diff options
| -rw-r--r-- | fs/btrfs/inode.c | 76 |
1 files changed, 60 insertions, 16 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 1f7a280481e4..5b3ec93ff911 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -2189,6 +2189,7 @@ int btrfs_set_extent_delalloc(struct inode *inode, u64 start, u64 end, /* see btrfs_writepage_start_hook for details on why this is required */ struct btrfs_writepage_fixup { struct page *page; + struct inode *inode; struct btrfs_work work; }; @@ -2203,9 +2204,20 @@ static void btrfs_writepage_fixup_worker(struct btrfs_work *work) u64 page_start; u64 page_end; int ret = 0; + bool free_delalloc_space = true; fixup = container_of(work, struct btrfs_writepage_fixup, work); page = fixup->page; + inode = fixup->inode; + page_start = page_offset(page); + page_end = page_offset(page) + PAGE_SIZE - 1; + + /* + * This is similar to page_mkwrite, we need to reserve the space before + * we take the page lock. + */ + ret = btrfs_delalloc_reserve_space(inode, &data_reserved, page_start, + PAGE_SIZE); again: lock_page(page); @@ -2214,25 +2226,48 @@ again: * page->mapping may go NULL, but it shouldn't be moved to a different * address space. */ - if (!page->mapping || !PageDirty(page) || !PageChecked(page)) + if (!page->mapping || !PageDirty(page) || !PageChecked(page)) { + /* + * Unfortunately this is a little tricky, either + * + * 1) We got here and our page had already been dealt with and + * we reserved our space, thus ret == 0, so we need to just + * drop our space reservation and bail. This can happen the + * first time we come into the fixup worker, or could happen + * while waiting for the ordered extent. + * 2) Our page was already dealt with, but we happened to get an + * ENOSPC above from the btrfs_delalloc_reserve_space. In + * this case we obviously don't have anything to release, but + * because the page was already dealt with we don't want to + * mark the page with an error, so make sure we're resetting + * ret to 0. This is why we have this check _before_ the ret + * check, because we do not want to have a surprise ENOSPC + * when the page was already properly dealt with. + */ + if (!ret) { + btrfs_delalloc_release_extents(BTRFS_I(inode), + PAGE_SIZE); + btrfs_delalloc_release_space(inode, data_reserved, + page_start, PAGE_SIZE, + true); + } + ret = 0; goto out_page; + } /* - * We keep the PageChecked() bit set until we're done with the - * btrfs_start_ordered_extent() dance that we do below. That drops and - * retakes the page lock, so we don't want new fixup workers queued for - * this page during the churn. + * We can't mess with the page state unless it is locked, so now that + * it is locked bail if we failed to make our space reservation. */ - inode = page->mapping->host; - page_start = page_offset(page); - page_end = page_offset(page) + PAGE_SIZE - 1; + if (ret) + goto out_page; lock_extent_bits(&BTRFS_I(inode)->io_tree, page_start, page_end, &cached_state); /* already ordered? We're done */ if (PagePrivate2(page)) - goto out; + goto out_reserved; ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), page_start, PAGE_SIZE); @@ -2245,11 +2280,6 @@ again: goto again; } - ret = btrfs_delalloc_reserve_space(inode, &data_reserved, page_start, - PAGE_SIZE); - if (ret) - goto out; - ret = btrfs_set_extent_delalloc(inode, page_start, page_end, 0, &cached_state); if (ret) @@ -2263,12 +2293,12 @@ again: * The page was dirty when we started, nothing should have cleaned it. */ BUG_ON(!PageDirty(page)); + free_delalloc_space = false; out_reserved: btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE); - if (ret) + if (free_delalloc_space) btrfs_delalloc_release_space(inode, data_reserved, page_start, PAGE_SIZE, true); -out: unlock_extent_cached(&BTRFS_I(inode)->io_tree, page_start, page_end, &cached_state); out_page: @@ -2287,6 +2317,12 @@ out_page: put_page(page); kfree(fixup); extent_changeset_free(data_reserved); + /* + * As a precaution, do a delayed iput in case it would be the last iput + * that could need flushing space. Recursing back to fixup worker would + * deadlock. + */ + btrfs_add_delayed_iput(inode); } /* @@ -2324,10 +2360,18 @@ int btrfs_writepage_cow_fixup(struct page *page, u64 start, u64 end) if (!fixup) return -EAGAIN; + /* + * We are already holding a reference to this inode from + * write_cache_pages. We need to hold it because the space reservation + * takes place outside of the page lock, and we can't trust + * page->mapping outside of the page lock. + */ + ihold(inode); SetPageChecked(page); get_page(page); btrfs_init_work(&fixup->work, btrfs_writepage_fixup_worker, NULL, NULL); fixup->page = page; + fixup->inode = inode; btrfs_queue_work(fs_info->fixup_workers, &fixup->work); return -EAGAIN; |