Commit a2c613b8 authored by Baokun Li's avatar Baokun Li Committed by Theodore Ts'o
Browse files

ext4: refactor ext4_swap_extents() to reuse extents path 



The ext4_find_extent() can update the extent path so it doesn't have to
allocate and free path repeatedly, thus reducing the consumption of memory
allocation and freeing in ext4_swap_extents().

Signed-off-by: default avatarBaokun Li <libaokun1@huawei.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarOjaswin Mujoo <ojaswin@linux.ibm.com>
Tested-by: default avatarOjaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/20240822023545.1994557-24-libaokun@huaweicloud.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 4191eefe

fs/ext4/extents.c

+22 −26
Original line number Diff line number Diff line
@@ -5663,25 +5663,21 @@ ext4_swap_extents(handle_t *handle, struct inode *inode1, 
		int e1_len, e2_len, len;

		int split = 0;



		path1 = ext4_find_extent(inode1, lblk1, NULL, EXT4_EX_NOCACHE);

		path1 = ext4_find_extent(inode1, lblk1, path1, EXT4_EX_NOCACHE);

		if (IS_ERR(path1)) {

			*erp = PTR_ERR(path1);

			path1 = NULL;

		finish:

			count = 0;

			goto repeat;

			goto errout;

		}

		path2 = ext4_find_extent(inode2, lblk2, NULL, EXT4_EX_NOCACHE);

		path2 = ext4_find_extent(inode2, lblk2, path2, EXT4_EX_NOCACHE);

		if (IS_ERR(path2)) {

			*erp = PTR_ERR(path2);

			path2 = NULL;

			goto finish;

			goto errout;

		}

		ex1 = path1[path1->p_depth].p_ext;

		ex2 = path2[path2->p_depth].p_ext;

		/* Do we have something to swap ? */

		if (unlikely(!ex2 || !ex1))

			goto finish;

			goto errout;



		e1_blk = le32_to_cpu(ex1->ee_block);

		e2_blk = le32_to_cpu(ex2->ee_block);
@@ -5703,7 +5699,7 @@ ext4_swap_extents(handle_t *handle, struct inode *inode1, 
				next2 = e2_blk;

			/* Do we have something to swap */

			if (next1 == EXT_MAX_BLOCKS || next2 == EXT_MAX_BLOCKS)

				goto finish;

				goto errout;

			/* Move to the rightest boundary */

			len = next1 - lblk1;

			if (len < next2 - lblk2)
@@ -5713,7 +5709,7 @@ ext4_swap_extents(handle_t *handle, struct inode *inode1, 
			lblk1 += len;

			lblk2 += len;

			count -= len;

			goto repeat;

			continue;

		}



		/* Prepare left boundary */
@@ -5723,7 +5719,7 @@ ext4_swap_extents(handle_t *handle, struct inode *inode1, 
							   path1, lblk1, 0);

			if (IS_ERR(path1)) {

				*erp = PTR_ERR(path1);

				goto finish;

				goto errout;

			}

		}

		if (e2_blk < lblk2) {
@@ -5732,13 +5728,13 @@ ext4_swap_extents(handle_t *handle, struct inode *inode1, 
							   path2, lblk2, 0);

			if (IS_ERR(path2)) {

				*erp = PTR_ERR(path2);

				goto finish;

				goto errout;

			}

		}

		/* ext4_split_extent_at() may result in leaf extent split,

		 * path must to be revalidated. */

		if (split)

			goto repeat;

			continue;



		/* Prepare right boundary */

		len = count;
@@ -5753,7 +5749,7 @@ ext4_swap_extents(handle_t *handle, struct inode *inode1, 
							path1, lblk1 + len, 0);

			if (IS_ERR(path1)) {

				*erp = PTR_ERR(path1);

				goto finish;

				goto errout;

			}

		}

		if (len != e2_len) {
@@ -5762,21 +5758,21 @@ ext4_swap_extents(handle_t *handle, struct inode *inode1, 
							path2, lblk2 + len, 0);

			if (IS_ERR(path2)) {

				*erp = PTR_ERR(path2);

				goto finish;

				goto errout;

			}

		}

		/* ext4_split_extent_at() may result in leaf extent split,

		 * path must to be revalidated. */

		if (split)

			goto repeat;

			continue;



		BUG_ON(e2_len != e1_len);

		*erp = ext4_ext_get_access(handle, inode1, path1 + path1->p_depth);

		if (unlikely(*erp))

			goto finish;

			goto errout;

		*erp = ext4_ext_get_access(handle, inode2, path2 + path2->p_depth);

		if (unlikely(*erp))

			goto finish;

			goto errout;



		/* Both extents are fully inside boundaries. Swap it now */

		tmp_ex = *ex1;
@@ -5794,7 +5790,7 @@ ext4_swap_extents(handle_t *handle, struct inode *inode1, 
		*erp = ext4_ext_dirty(handle, inode2, path2 +

				      path2->p_depth);

		if (unlikely(*erp))

			goto finish;

			goto errout;

		*erp = ext4_ext_dirty(handle, inode1, path1 +

				      path1->p_depth);

		/*
@@ -5804,17 +5800,17 @@ ext4_swap_extents(handle_t *handle, struct inode *inode1, 
		 * aborted anyway.

		 */

		if (unlikely(*erp))

			goto finish;

			goto errout;



		lblk1 += len;

		lblk2 += len;

		replaced_count += len;

		count -= len;

	}



	repeat:

errout:

	ext4_free_ext_path(path1);

	ext4_free_ext_path(path2);

		path1 = path2 = NULL;

	}

	return replaced_count;

}