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 <joern@logfs.org>
diff --git a/fs/logfs/segment.c b/fs/logfs/segment.c
index 1a14f99..ff9d7f3 100644
--- a/fs/logfs/segment.c
+++ b/fs/logfs/segment.c
@@ -93,50 +93,58 @@
} 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
* indirect blocks. So always use it through accessor functions.