return new;
}
-struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
- u64 start)
+struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
+ u64 start, unsigned long len)
{
struct extent_buffer *eb;
- unsigned long len;
unsigned long num_pages;
unsigned long i;
- if (!fs_info) {
- /*
- * Called only from tests that don't always have a fs_info
- * available, but we know that nodesize is 4096
- */
- len = 4096;
- } else {
- len = fs_info->tree_root->nodesize;
- }
- num_pages = num_extent_pages(0, len);
+ num_pages = num_extent_pages(start, len);
eb = __alloc_extent_buffer(fs_info, start, len);
if (!eb)
return NULL;
}
+struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
+ u64 start)
+{
+ unsigned long len;
+
+ if (!fs_info) {
+ /*
+ * Called only from tests that don't always have a fs_info
+ * available, but we know that nodesize is 4096
+ */
+ len = 4096;
+ } else {
+ len = fs_info->tree_root->nodesize;
+ }
+
+ return __alloc_dummy_extent_buffer(fs_info, start, len);
+}
+
static void check_buffer_tree_ref(struct extent_buffer *eb)
{
int refs;
}
}
+/*
+ * The extent buffer bitmap operations are done with byte granularity because
+ * bitmap items are not guaranteed to be aligned to a word and therefore a
+ * single word in a bitmap may straddle two pages in the extent buffer.
+ */
+#define BIT_BYTE(nr) ((nr) / BITS_PER_BYTE)
+#define BYTE_MASK ((1 << BITS_PER_BYTE) - 1)
+#define BITMAP_FIRST_BYTE_MASK(start) \
+ ((BYTE_MASK << ((start) & (BITS_PER_BYTE - 1))) & BYTE_MASK)
+#define BITMAP_LAST_BYTE_MASK(nbits) \
+ (BYTE_MASK >> (-(nbits) & (BITS_PER_BYTE - 1)))
+
+/*
+ * eb_bitmap_offset() - calculate the page and offset of the byte containing the
+ * given bit number
+ * @eb: the extent buffer
+ * @start: offset of the bitmap item in the extent buffer
+ * @nr: bit number
+ * @page_index: return index of the page in the extent buffer that contains the
+ * given bit number
+ * @page_offset: return offset into the page given by page_index
+ *
+ * This helper hides the ugliness of finding the byte in an extent buffer which
+ * contains a given bit.
+ */
+static inline void eb_bitmap_offset(struct extent_buffer *eb,
+ unsigned long start, unsigned long nr,
+ unsigned long *page_index,
+ size_t *page_offset)
+{
+ size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
+ size_t byte_offset = BIT_BYTE(nr);
+ size_t offset;
+
+ /*
+ * The byte we want is the offset of the extent buffer + the offset of
+ * the bitmap item in the extent buffer + the offset of the byte in the
+ * bitmap item.
+ */
+ offset = start_offset + start + byte_offset;
+
+ *page_index = offset >> PAGE_CACHE_SHIFT;
+ *page_offset = offset & (PAGE_CACHE_SIZE - 1);
+}
+
+/**
+ * extent_buffer_test_bit - determine whether a bit in a bitmap item is set
+ * @eb: the extent buffer
+ * @start: offset of the bitmap item in the extent buffer
+ * @nr: bit number to test
+ */
+int extent_buffer_test_bit(struct extent_buffer *eb, unsigned long start,
+ unsigned long nr)
+{
+ char *kaddr;
+ struct page *page;
+ unsigned long i;
+ size_t offset;
+
+ eb_bitmap_offset(eb, start, nr, &i, &offset);
+ page = eb->pages[i];
+ WARN_ON(!PageUptodate(page));
+ kaddr = page_address(page);
+ return 1U & (kaddr[offset] >> (nr & (BITS_PER_BYTE - 1)));
+}
+
+/**
+ * extent_buffer_bitmap_set - set an area of a bitmap
+ * @eb: the extent buffer
+ * @start: offset of the bitmap item in the extent buffer
+ * @pos: bit number of the first bit
+ * @len: number of bits to set
+ */
+void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start,
+ unsigned long pos, unsigned long len)
+{
+ char *kaddr;
+ struct page *page;
+ unsigned long i;
+ size_t offset;
+ const unsigned int size = pos + len;
+ int bits_to_set = BITS_PER_BYTE - (pos % BITS_PER_BYTE);
+ unsigned int mask_to_set = BITMAP_FIRST_BYTE_MASK(pos);
+
+ eb_bitmap_offset(eb, start, pos, &i, &offset);
+ page = eb->pages[i];
+ WARN_ON(!PageUptodate(page));
+ kaddr = page_address(page);
+
+ while (len >= bits_to_set) {
+ kaddr[offset] |= mask_to_set;
+ len -= bits_to_set;
+ bits_to_set = BITS_PER_BYTE;
+ mask_to_set = ~0U;
+ if (++offset >= PAGE_CACHE_SIZE && len > 0) {
+ offset = 0;
+ page = eb->pages[++i];
+ WARN_ON(!PageUptodate(page));
+ kaddr = page_address(page);
+ }
+ }
+ if (len) {
+ mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
+ kaddr[offset] |= mask_to_set;
+ }
+}
+
+
+/**
+ * extent_buffer_bitmap_clear - clear an area of a bitmap
+ * @eb: the extent buffer
+ * @start: offset of the bitmap item in the extent buffer
+ * @pos: bit number of the first bit
+ * @len: number of bits to clear
+ */
+void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start,
+ unsigned long pos, unsigned long len)
+{
+ char *kaddr;
+ struct page *page;
+ unsigned long i;
+ size_t offset;
+ const unsigned int size = pos + len;
+ int bits_to_clear = BITS_PER_BYTE - (pos % BITS_PER_BYTE);
+ unsigned int mask_to_clear = BITMAP_FIRST_BYTE_MASK(pos);
+
+ eb_bitmap_offset(eb, start, pos, &i, &offset);
+ page = eb->pages[i];
+ WARN_ON(!PageUptodate(page));
+ kaddr = page_address(page);
+
+ while (len >= bits_to_clear) {
+ kaddr[offset] &= ~mask_to_clear;
+ len -= bits_to_clear;
+ bits_to_clear = BITS_PER_BYTE;
+ mask_to_clear = ~0U;
+ if (++offset >= PAGE_CACHE_SIZE && len > 0) {
+ offset = 0;
+ page = eb->pages[++i];
+ WARN_ON(!PageUptodate(page));
+ kaddr = page_address(page);
+ }
+ }
+ if (len) {
+ mask_to_clear &= BITMAP_LAST_BYTE_MASK(size);
+ kaddr[offset] &= ~mask_to_clear;
+ }
+}
+
static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len)
{
unsigned long distance = (src > dst) ? src - dst : dst - src;
projects / linux-drm-fsl-dcu.git / blobdiff