Re: [PATCH 5/9] iomap: Support arbitrarily many blocks per page

Size the uptodate array dynamically to support larger pages in the page cache. With a 64kB page, we're only saving 8 bytes per page today, but with a 2MB maximum page size, we'd have to allocate more than 4kB per page. Add a few debugging assertions. Signed-off-by: Matthew Wilcox (Oracle) <willy(a)infradead.org&gt; --- fs/iomap/buffered-io.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index dbf9572dabe9..844e95cacea8 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -22,18 +22,19 @@ #include "../internal.h" /* - * Structure allocated for each page when block size < PAGE_SIZE to track + * Structure allocated for each page when block size < page size to track * sub-page uptodate status and I/O completions. */ struct iomap_page { atomic_t read_count; atomic_t write_count; spinlock_t uptodate_lock; - DECLARE_BITMAP(uptodate, PAGE_SIZE / 512); + unsigned long uptodate[]; }; static inline struct iomap_page *to_iomap_page(struct page *page) { + VM_BUG_ON_PGFLAGS(PageTail(page), page); if (page_has_private(page)) return (struct iomap_page *)page_private(page); return NULL;