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>
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@ -93,49 +93,57 @@ void __logfs_buf_write(struct logfs_area *area, u64 ofs, void *buf, size_t len,
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} while (len);
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}
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/*
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* bdev_writeseg will write full pages. Memset the tail to prevent data leaks.
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*/
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static void pad_wbuf(struct logfs_area *area, int final)
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static void pad_partial_page(struct logfs_area *area)
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{
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struct super_block *sb = area->a_sb;
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struct logfs_super *super = logfs_super(sb);
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struct page *page;
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u64 ofs = dev_ofs(sb, area->a_segno, area->a_used_bytes);
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pgoff_t index = ofs >> PAGE_SHIFT;
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long offset = ofs & (PAGE_SIZE-1);
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u32 len = PAGE_SIZE - offset;
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if (len == PAGE_SIZE) {
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/* The math in this function can surely use some love */
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len = 0;
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}
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if (len) {
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BUG_ON(area->a_used_bytes >= super->s_segsize);
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page = get_mapping_page(area->a_sb, index, 0);
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if (len % PAGE_SIZE) {
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page = get_mapping_page(sb, index, 0);
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BUG_ON(!page); /* FIXME: reserve a pool */
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memset(page_address(page) + offset, 0xff, len);
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SetPagePrivate(page);
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page_cache_release(page);
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}
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}
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if (!final)
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return;
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static void pad_full_pages(struct logfs_area *area)
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{
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struct super_block *sb = area->a_sb;
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struct logfs_super *super = logfs_super(sb);
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u64 ofs = dev_ofs(sb, area->a_segno, area->a_used_bytes);
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u32 len = super->s_segsize - area->a_used_bytes;
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pgoff_t index = PAGE_CACHE_ALIGN(ofs) >> PAGE_CACHE_SHIFT;
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pgoff_t no_indizes = len >> PAGE_CACHE_SHIFT;
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struct page *page;
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area->a_used_bytes += len;
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for ( ; area->a_used_bytes < super->s_segsize;
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area->a_used_bytes += PAGE_SIZE) {
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/* Memset another page */
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index++;
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page = get_mapping_page(area->a_sb, index, 0);
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while (no_indizes) {
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page = get_mapping_page(sb, index, 0);
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BUG_ON(!page); /* FIXME: reserve a pool */
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memset(page_address(page), 0xff, PAGE_SIZE);
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SetPageUptodate(page);
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memset(page_address(page), 0xff, PAGE_CACHE_SIZE);
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SetPagePrivate(page);
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page_cache_release(page);
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index++;
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no_indizes--;
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}
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}
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/*
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* bdev_writeseg will write full pages. Memset the tail to prevent data leaks.
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* Also make sure we allocate (and memset) all pages for final writeout.
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*/
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static void pad_wbuf(struct logfs_area *area, int final)
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{
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pad_partial_page(area);
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if (final)
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pad_full_pages(area);
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}
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/*
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* We have to be careful with the alias tree. Since lookup is done by bix,
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* it needs to be normalized, so 14, 15, 16, etc. all match when dealing with
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