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: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/20240822023545.1994557-24-libaokun@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index dbadf2aa43768f857001763bf18b44e8f1d08874..e671ad642cfb7ba066ea2349be042293f1288420 100644 (file)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -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:
-               ext4_free_ext_path(path1);
-               ext4_free_ext_path(path2);
-               path1 = path2 = NULL;
        }
+
+errout:
+       ext4_free_ext_path(path1);
+       ext4_free_ext_path(path2);
        return replaced_count;
 }