btrfs: Implement find_first_clear_extent_bit (45bfcfc1) · Commits · 戴 / test

fs/btrfs/extent_io.c

+73 −0

Original line number	Diff line number	Diff line
		@@ -1542,6 +1542,79 @@ out:
		return ret;
		}

		/**
		* find_first_clear_extent_bit - finds the first range that has @bits not set
		* and that starts after @start
		*
		* @tree - the tree to search
		* @start - the offset at/after which the found extent should start
		* @start_ret - records the beginning of the range
		* @end_ret - records the end of the range (inclusive)
		* @bits - the set of bits which must be unset
		*
		* Since unallocated range is also considered one which doesn't have the bits
		* set it's possible that @end_ret contains -1, this happens in case the range
		* spans (last_range_end, end of device]. In this case it's up to the caller to
		* trim @end_ret to the appropriate size.
		*/
		void find_first_clear_extent_bit(struct extent_io_tree *tree, u64 start,
		u64 start_ret, u64 end_ret, unsigned bits)
		{
		struct extent_state *state;
		struct rb_node node, prev = NULL, *next;

		spin_lock(&tree->lock);

		/* Find first extent with bits cleared */
		while (1) {
		node = __etree_search(tree, start, &next, &prev, NULL, NULL);
		if (!node) {
		node = next;
		if (!node) {
		/*
		* We are past the last allocated chunk,
		* set start at the end of the last extent. The
		* device alloc tree should never be empty so
		* prev is always set.
		*/
		ASSERT(prev);
		state = rb_entry(prev, struct extent_state, rb_node);
		*start_ret = state->end + 1;
		*end_ret = -1;
		goto out;
		}
		}
		state = rb_entry(node, struct extent_state, rb_node);
		if (in_range(start, state->start, state->end - state->start + 1) &&
		(state->state & bits)) {
		start = state->end + 1;
		} else {
		*start_ret = start;
		break;
		}
		}

		/*
		* Find the longest stretch from start until an entry which has the
		* bits set
		*/
		while (1) {
		state = rb_entry(node, struct extent_state, rb_node);
		if (state->end >= start && !(state->state & bits)) {
		*end_ret = state->end;
		} else {
		*end_ret = state->start - 1;
		break;
		}

		node = rb_next(node);
		if (!node)
		break;
		}
		out:
		spin_unlock(&tree->lock);
		}

		/*
		* find a contiguous range of bytes in the file marked as delalloc, not
		* more than 'max_bytes'. start and end are used to return the range,

fs/btrfs/extent_io.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -403,6 +403,8 @@ static inline int set_extent_uptodate(struct extent_io_tree *tree, u64 start,
		int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
		u64 start_ret, u64 end_ret, unsigned bits,
		struct extent_state **cached_state);
		void find_first_clear_extent_bit(struct extent_io_tree *tree, u64 start,
		u64 start_ret, u64 end_ret, unsigned bits);
		int extent_invalidatepage(struct extent_io_tree *tree,
		struct page *page, unsigned long offset);
		int extent_write_full_page(struct page page, struct writeback_control wbc);

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