From 81def6b9862764924a99ac1b680e73ac8c80ac64 Mon Sep 17 00:00:00 2001 From: Joern Engel Date: Sun, 28 Mar 2010 12:47:09 +0200 Subject: Simplify and fix pad_wbuf A comment in the old code read: /* The math in this function can surely use some love */ And indeed it did. In the case that area->a_used_bytes is exactly 4096 bytes below segment size it fell apart. pad_wbuf is now split into two helpers that are significantly less complicated. Signed-off-by: Joern Engel --- fs/logfs/segment.c | 52 ++++++++++++++++++++++++++++++---------------------- 1 file changed, 30 insertions(+), 22 deletions(-) (limited to 'fs/logfs') diff --git a/fs/logfs/segment.c b/fs/logfs/segment.c index 1a14f9910d5..ff9d7f3b4d3 100644 --- a/fs/logfs/segment.c +++ b/fs/logfs/segment.c @@ -93,49 +93,57 @@ void __logfs_buf_write(struct logfs_area *area, u64 ofs, void *buf, size_t len, } while (len); } -/* - * bdev_writeseg will write full pages. Memset the tail to prevent data leaks. - */ -static void pad_wbuf(struct logfs_area *area, int final) +static void pad_partial_page(struct logfs_area *area) { struct super_block *sb = area->a_sb; - struct logfs_super *super = logfs_super(sb); struct page *page; u64 ofs = dev_ofs(sb, area->a_segno, area->a_used_bytes); pgoff_t index = ofs >> PAGE_SHIFT; long offset = ofs & (PAGE_SIZE-1); u32 len = PAGE_SIZE - offset; - if (len == PAGE_SIZE) { - /* The math in this function can surely use some love */ - len = 0; - } - if (len) { - BUG_ON(area->a_used_bytes >= super->s_segsize); - - page = get_mapping_page(area->a_sb, index, 0); + if (len % PAGE_SIZE) { + page = get_mapping_page(sb, index, 0); BUG_ON(!page); /* FIXME: reserve a pool */ memset(page_address(page) + offset, 0xff, len); SetPagePrivate(page); page_cache_release(page); } +} - if (!final) - return; +static void pad_full_pages(struct logfs_area *area) +{ + struct super_block *sb = area->a_sb; + struct logfs_super *super = logfs_super(sb); + u64 ofs = dev_ofs(sb, area->a_segno, area->a_used_bytes); + u32 len = super->s_segsize - area->a_used_bytes; + pgoff_t index = PAGE_CACHE_ALIGN(ofs) >> PAGE_CACHE_SHIFT; + pgoff_t no_indizes = len >> PAGE_CACHE_SHIFT; + struct page *page; - area->a_used_bytes += len; - for ( ; area->a_used_bytes < super->s_segsize; - area->a_used_bytes += PAGE_SIZE) { - /* Memset another page */ - index++; - page = get_mapping_page(area->a_sb, index, 0); + while (no_indizes) { + page = get_mapping_page(sb, index, 0); BUG_ON(!page); /* FIXME: reserve a pool */ - memset(page_address(page), 0xff, PAGE_SIZE); + SetPageUptodate(page); + memset(page_address(page), 0xff, PAGE_CACHE_SIZE); SetPagePrivate(page); page_cache_release(page); + index++; + no_indizes--; } } +/* + * bdev_writeseg will write full pages. Memset the tail to prevent data leaks. + * Also make sure we allocate (and memset) all pages for final writeout. + */ +static void pad_wbuf(struct logfs_area *area, int final) +{ + pad_partial_page(area); + if (final) + pad_full_pages(area); +} + /* * We have to be careful with the alias tree. Since lookup is done by bix, * it needs to be normalized, so 14, 15, 16, etc. all match when dealing with -- cgit v1.2.3-18-g5258