ext4: add a function merging extents right and left (197217a5) · Commits · 戴 / test

fs/ext4/extents.c

+36 −29

Original line number	Diff line number	Diff line
		@@ -1563,7 +1563,7 @@ ext4_can_extents_be_merged(struct inode inode, struct ext4_extent ex1,
		* Returns 0 if the extents (ex and ex+1) were _not_ merged and returns
		* 1 if they got merged.
		*/
		static int ext4_ext_try_to_merge(struct inode *inode,
		static int ext4_ext_try_to_merge_right(struct inode *inode,
		struct ext4_ext_path *path,
		struct ext4_extent *ex)
		{
		@@ -1602,6 +1602,31 @@ static int ext4_ext_try_to_merge(struct inode *inode,
		return merge_done;
		}

		/*
		* This function tries to merge the @ex extent to neighbours in the tree.
		* return 1 if merge left else 0.
		*/
		static int ext4_ext_try_to_merge(struct inode *inode,
		struct ext4_ext_path *path,
		struct ext4_extent *ex) {
		struct ext4_extent_header *eh;
		unsigned int depth;
		int merge_done = 0;
		int ret = 0;

		depth = ext_depth(inode);
		BUG_ON(path[depth].p_hdr == NULL);
		eh = path[depth].p_hdr;

		if (ex > EXT_FIRST_EXTENT(eh))
		merge_done = ext4_ext_try_to_merge_right(inode, path, ex - 1);

		if (!merge_done)
		ret = ext4_ext_try_to_merge_right(inode, path, ex);

		return ret;
		}

		/*
		* check if a portion of the "newext" extent overlaps with an
		* existing extent.
		@@ -3039,6 +3064,7 @@ fix_extent_len:
		ext4_ext_dirty(handle, inode, path + depth);
		return err;
		}

		static int ext4_convert_unwritten_extents_endio(handle_t *handle,
		struct inode *inode,
		struct ext4_ext_path *path)
		@@ -3047,46 +3073,27 @@ static int ext4_convert_unwritten_extents_endio(handle_t *handle,
		struct ext4_extent_header *eh;
		int depth;
		int err = 0;
		int ret = 0;

		depth = ext_depth(inode);
		eh = path[depth].p_hdr;
		ex = path[depth].p_ext;

		ext_debug("ext4_convert_unwritten_extents_endio: inode %lu, logical"
		"block %llu, max_blocks %u\n", inode->i_ino,
		(unsigned long long)le32_to_cpu(ex->ee_block),
		ext4_ext_get_actual_len(ex));

		err = ext4_ext_get_access(handle, inode, path + depth);
		if (err)
		goto out;
		/* first mark the extent as initialized */
		ext4_ext_mark_initialized(ex);

		/*
		* We have to see if it can be merged with the extent
		* on the left.
		*/
		if (ex > EXT_FIRST_EXTENT(eh)) {
		/*
		* To merge left, pass "ex - 1" to try_to_merge(),
		* since it merges towards right _only_.
		/* note: ext4_ext_correct_indexes() isn't needed here because
		* borders are not changed
		*/
		ret = ext4_ext_try_to_merge(inode, path, ex - 1);
		if (ret) {
		err = ext4_ext_correct_indexes(handle, inode, path);
		if (err)
		goto out;
		depth = ext_depth(inode);
		ex--;
		}
		}
		/*
		* Try to Merge towards right.
		*/
		ret = ext4_ext_try_to_merge(inode, path, ex);
		if (ret) {
		err = ext4_ext_correct_indexes(handle, inode, path);
		if (err)
		goto out;
		depth = ext_depth(inode);
		}
		ext4_ext_try_to_merge(inode, path, ex);

		/* Mark modified extent as dirty */
		err = ext4_ext_dirty(handle, inode, path + depth);
		out:

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