ext4: add first unit test for ext4_mb_new_blocks_simple in mballoc

Here are prepared work:
1. Include mballoc-test.c to mballoc.c to be able test static function
in mballoc.c.
2. Implement static stub to avoid read IO to disk.
3. Construct fake super_block. Only partial members are set, more members
will be set when more functions are tested.
Then unit test for ext4_mb_new_blocks_simple is added.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230928160407.142069-12-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/mballoc-test.c b/fs/ext4/mballoc-test.c
new file mode 100644 (file)
index 0000000..120c494
--- /dev/null
+++ b/fs/ext4/mballoc-test.c
@@ -0,0 +1,325 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit test of ext4 multiblocks allocation.
+ */
+
+#include <kunit/test.h>
+#include <kunit/static_stub.h>
+
+#include "ext4.h"
+
+struct mbt_grp_ctx {
+       struct buffer_head bitmap_bh;
+       /* desc and gd_bh are just the place holders for now */
+       struct ext4_group_desc desc;
+       struct buffer_head gd_bh;
+};
+
+struct mbt_ctx {
+       struct mbt_grp_ctx *grp_ctx;
+};
+
+struct mbt_ext4_super_block {
+       struct super_block sb;
+       struct mbt_ctx mbt_ctx;
+};
+
+#define MBT_CTX(_sb) (&(container_of((_sb), struct mbt_ext4_super_block, sb)->mbt_ctx))
+#define MBT_GRP_CTX(_sb, _group) (&MBT_CTX(_sb)->grp_ctx[_group])
+
+static struct super_block *mbt_ext4_alloc_super_block(void)
+{
+       struct ext4_super_block *es = kzalloc(sizeof(*es), GFP_KERNEL);
+       struct ext4_sb_info *sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
+       struct mbt_ext4_super_block *fsb = kzalloc(sizeof(*fsb), GFP_KERNEL);
+
+       if (fsb == NULL || sbi == NULL || es == NULL)
+               goto out;
+
+       sbi->s_es = es;
+       fsb->sb.s_fs_info = sbi;
+       return &fsb->sb;
+
+out:
+       kfree(fsb);
+       kfree(sbi);
+       kfree(es);
+       return NULL;
+}
+
+static void mbt_ext4_free_super_block(struct super_block *sb)
+{
+       struct mbt_ext4_super_block *fsb =
+               container_of(sb, struct mbt_ext4_super_block, sb);
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+       kfree(sbi->s_es);
+       kfree(sbi);
+       kfree(fsb);
+}
+
+struct mbt_ext4_block_layout {
+       unsigned char blocksize_bits;
+       unsigned int cluster_bits;
+       uint32_t blocks_per_group;
+       ext4_group_t group_count;
+       uint16_t desc_size;
+};
+
+static void mbt_init_sb_layout(struct super_block *sb,
+                              struct mbt_ext4_block_layout *layout)
+{
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+       struct ext4_super_block *es = sbi->s_es;
+
+       sb->s_blocksize = 1UL << layout->blocksize_bits;
+       sb->s_blocksize_bits = layout->blocksize_bits;
+
+       sbi->s_groups_count = layout->group_count;
+       sbi->s_blocks_per_group = layout->blocks_per_group;
+       sbi->s_cluster_bits = layout->cluster_bits;
+       sbi->s_cluster_ratio = 1U << layout->cluster_bits;
+       sbi->s_clusters_per_group = layout->blocks_per_group >>
+                                   layout->cluster_bits;
+       sbi->s_desc_size = layout->desc_size;
+
+       es->s_first_data_block = cpu_to_le32(0);
+       es->s_blocks_count_lo = cpu_to_le32(layout->blocks_per_group *
+                                           layout->group_count);
+}
+
+static int mbt_grp_ctx_init(struct super_block *sb,
+                           struct mbt_grp_ctx *grp_ctx)
+{
+       grp_ctx->bitmap_bh.b_data = kzalloc(EXT4_BLOCK_SIZE(sb), GFP_KERNEL);
+       if (grp_ctx->bitmap_bh.b_data == NULL)
+               return -ENOMEM;
+
+       return 0;
+}
+
+static void mbt_grp_ctx_release(struct mbt_grp_ctx *grp_ctx)
+{
+       kfree(grp_ctx->bitmap_bh.b_data);
+       grp_ctx->bitmap_bh.b_data = NULL;
+}
+
+static void mbt_ctx_mark_used(struct super_block *sb, ext4_group_t group,
+                             unsigned int start, unsigned int len)
+{
+       struct mbt_grp_ctx *grp_ctx = MBT_GRP_CTX(sb, group);
+
+       mb_set_bits(grp_ctx->bitmap_bh.b_data, start, len);
+}
+
+/* called after mbt_init_sb_layout */
+static int mbt_ctx_init(struct super_block *sb)
+{
+       struct mbt_ctx *ctx = MBT_CTX(sb);
+       ext4_group_t i, ngroups = ext4_get_groups_count(sb);
+
+       ctx->grp_ctx = kcalloc(ngroups, sizeof(struct mbt_grp_ctx),
+                              GFP_KERNEL);
+       if (ctx->grp_ctx == NULL)
+               return -ENOMEM;
+
+       for (i = 0; i < ngroups; i++)
+               if (mbt_grp_ctx_init(sb, &ctx->grp_ctx[i]))
+                       goto out;
+
+       /*
+        * first data block(first cluster in first group) is used by
+        * metadata, mark it used to avoid to alloc data block at first
+        * block which will fail ext4_sb_block_valid check.
+        */
+       mb_set_bits(ctx->grp_ctx[0].bitmap_bh.b_data, 0, 1);
+
+       return 0;
+out:
+       while (i-- > 0)
+               mbt_grp_ctx_release(&ctx->grp_ctx[i]);
+       kfree(ctx->grp_ctx);
+       return -ENOMEM;
+}
+
+static void mbt_ctx_release(struct super_block *sb)
+{
+       struct mbt_ctx *ctx = MBT_CTX(sb);
+       ext4_group_t i, ngroups = ext4_get_groups_count(sb);
+
+       for (i = 0; i < ngroups; i++)
+               mbt_grp_ctx_release(&ctx->grp_ctx[i]);
+       kfree(ctx->grp_ctx);
+}
+
+static struct buffer_head *
+ext4_read_block_bitmap_nowait_stub(struct super_block *sb, ext4_group_t block_group,
+                                  bool ignore_locked)
+{
+       struct mbt_grp_ctx *grp_ctx = MBT_GRP_CTX(sb, block_group);
+
+       /* paired with brelse from caller of ext4_read_block_bitmap_nowait */
+       get_bh(&grp_ctx->bitmap_bh);
+       return &grp_ctx->bitmap_bh;
+}
+
+static int ext4_wait_block_bitmap_stub(struct super_block *sb,
+                                      ext4_group_t block_group,
+                                      struct buffer_head *bh)
+{
+       return 0;
+}
+
+static struct ext4_group_desc *
+ext4_get_group_desc_stub(struct super_block *sb, ext4_group_t block_group,
+                        struct buffer_head **bh)
+{
+       struct mbt_grp_ctx *grp_ctx = MBT_GRP_CTX(sb, block_group);
+
+       if (bh != NULL)
+               *bh = &grp_ctx->gd_bh;
+
+       return &grp_ctx->desc;
+}
+
+static int
+ext4_mb_mark_context_stub(handle_t *handle, struct super_block *sb, bool state,
+                         ext4_group_t group, ext4_grpblk_t blkoff,
+                         ext4_grpblk_t len, int flags,
+                         ext4_grpblk_t *ret_changed)
+{
+       struct mbt_grp_ctx *grp_ctx = MBT_GRP_CTX(sb, group);
+       struct buffer_head *bitmap_bh = &grp_ctx->bitmap_bh;
+
+       if (state)
+               mb_set_bits(bitmap_bh->b_data, blkoff, len);
+       else
+               mb_clear_bits(bitmap_bh->b_data, blkoff, len);
+
+       return 0;
+}
+
+#define TEST_BLOCKSIZE_BITS 10
+#define TEST_CLUSTER_BITS 3
+#define TEST_BLOCKS_PER_GROUP 8192
+#define TEST_GROUP_COUNT 4
+#define TEST_DESC_SIZE 64
+#define TEST_GOAL_GROUP 1
+static int mbt_kunit_init(struct kunit *test)
+{
+       struct mbt_ext4_block_layout layout = {
+               .blocksize_bits = TEST_BLOCKSIZE_BITS,
+               .cluster_bits = TEST_CLUSTER_BITS,
+               .blocks_per_group = TEST_BLOCKS_PER_GROUP,
+               .group_count = TEST_GROUP_COUNT,
+               .desc_size = TEST_DESC_SIZE,
+       };
+       struct super_block *sb;
+       int ret;
+
+       sb = mbt_ext4_alloc_super_block();
+       if (sb == NULL)
+               return -ENOMEM;
+
+       mbt_init_sb_layout(sb, &layout);
+
+       ret = mbt_ctx_init(sb);
+       if (ret != 0) {
+               mbt_ext4_free_super_block(sb);
+               return ret;
+       }
+
+       test->priv = sb;
+       kunit_activate_static_stub(test,
+                                  ext4_read_block_bitmap_nowait,
+                                  ext4_read_block_bitmap_nowait_stub);
+       kunit_activate_static_stub(test,
+                                  ext4_wait_block_bitmap,
+                                  ext4_wait_block_bitmap_stub);
+       kunit_activate_static_stub(test,
+                                  ext4_get_group_desc,
+                                  ext4_get_group_desc_stub);
+       kunit_activate_static_stub(test,
+                                  ext4_mb_mark_context,
+                                  ext4_mb_mark_context_stub);
+       return 0;
+}
+
+static void mbt_kunit_exit(struct kunit *test)
+{
+       struct super_block *sb = (struct super_block *)test->priv;
+
+       mbt_ctx_release(sb);
+       mbt_ext4_free_super_block(sb);
+}
+
+static void test_new_blocks_simple(struct kunit *test)
+{
+       struct super_block *sb = (struct super_block *)test->priv;
+       struct inode inode = { .i_sb = sb, };
+       struct ext4_allocation_request ar;
+       ext4_group_t i, goal_group = TEST_GOAL_GROUP;
+       int err = 0;
+       ext4_fsblk_t found;
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+       ar.inode = &inode;
+
+       /* get block at goal */
+       ar.goal = ext4_group_first_block_no(sb, goal_group);
+       found = ext4_mb_new_blocks_simple(&ar, &err);
+       KUNIT_ASSERT_EQ_MSG(test, ar.goal, found,
+               "failed to alloc block at goal, expected %llu found %llu",
+               ar.goal, found);
+
+       /* get block after goal in goal group */
+       ar.goal = ext4_group_first_block_no(sb, goal_group);
+       found = ext4_mb_new_blocks_simple(&ar, &err);
+       KUNIT_ASSERT_EQ_MSG(test, ar.goal + EXT4_C2B(sbi, 1), found,
+               "failed to alloc block after goal in goal group, expected %llu found %llu",
+               ar.goal + 1, found);
+
+       /* get block after goal group */
+       mbt_ctx_mark_used(sb, goal_group, 0, EXT4_CLUSTERS_PER_GROUP(sb));
+       ar.goal = ext4_group_first_block_no(sb, goal_group);
+       found = ext4_mb_new_blocks_simple(&ar, &err);
+       KUNIT_ASSERT_EQ_MSG(test,
+               ext4_group_first_block_no(sb, goal_group + 1), found,
+               "failed to alloc block after goal group, expected %llu found %llu",
+               ext4_group_first_block_no(sb, goal_group + 1), found);
+
+       /* get block before goal group */
+       for (i = goal_group; i < ext4_get_groups_count(sb); i++)
+               mbt_ctx_mark_used(sb, i, 0, EXT4_CLUSTERS_PER_GROUP(sb));
+       ar.goal = ext4_group_first_block_no(sb, goal_group);
+       found = ext4_mb_new_blocks_simple(&ar, &err);
+       KUNIT_ASSERT_EQ_MSG(test,
+               ext4_group_first_block_no(sb, 0) + EXT4_C2B(sbi, 1), found,
+               "failed to alloc block before goal group, expected %llu found %llu",
+               ext4_group_first_block_no(sb, 0 + EXT4_C2B(sbi, 1)), found);
+
+       /* no block available, fail to allocate block */
+       for (i = 0; i < ext4_get_groups_count(sb); i++)
+               mbt_ctx_mark_used(sb, i, 0, EXT4_CLUSTERS_PER_GROUP(sb));
+       ar.goal = ext4_group_first_block_no(sb, goal_group);
+       found = ext4_mb_new_blocks_simple(&ar, &err);
+       KUNIT_ASSERT_NE_MSG(test, err, 0,
+               "unexpectedly get block when no block is available");
+}
+
+
+static struct kunit_case mbt_test_cases[] = {
+       KUNIT_CASE(test_new_blocks_simple),
+       {}
+};
+
+static struct kunit_suite mbt_test_suite = {
+       .name = "ext4_mballoc_test",
+       .init = mbt_kunit_init,
+       .exit = mbt_kunit_exit,
+       .test_cases = mbt_test_cases,
+};
+
+kunit_test_suites(&mbt_test_suite);
+
+MODULE_LICENSE("GPL");

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 401b8329d1e13f97428661b5e9cbc75a8cb9a406..454d5612641ee3c32e71114e4d6148c52b484459 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -6991,3 +6991,7 @@ out_unload:
 
        return error;
 }
+
+#ifdef CONFIG_EXT4_KUNIT_TESTS
+#include "mballoc-test.c"
+#endif