v4.19.13 snapshot.
diff --git a/fs/btrfs/tests/extent-map-tests.c b/fs/btrfs/tests/extent-map-tests.c
new file mode 100644
index 0000000..385a531
--- /dev/null
+++ b/fs/btrfs/tests/extent-map-tests.c
@@ -0,0 +1,373 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017 Oracle. All rights reserved.
+ */
+
+#include <linux/types.h>
+#include "btrfs-tests.h"
+#include "../ctree.h"
+
+static void free_extent_map_tree(struct extent_map_tree *em_tree)
+{
+ struct extent_map *em;
+ struct rb_node *node;
+
+ while (!RB_EMPTY_ROOT(&em_tree->map)) {
+ node = rb_first(&em_tree->map);
+ em = rb_entry(node, struct extent_map, rb_node);
+ remove_extent_mapping(em_tree, em);
+
+#ifdef CONFIG_BTRFS_DEBUG
+ if (refcount_read(&em->refs) != 1) {
+ test_err(
+"em leak: em (start 0x%llx len 0x%llx block_start 0x%llx block_len 0x%llx) refs %d",
+ em->start, em->len, em->block_start,
+ em->block_len, refcount_read(&em->refs));
+
+ refcount_set(&em->refs, 1);
+ }
+#endif
+ free_extent_map(em);
+ }
+}
+
+/*
+ * Test scenario:
+ *
+ * Suppose that no extent map has been loaded into memory yet, there is a file
+ * extent [0, 16K), followed by another file extent [16K, 20K), two dio reads
+ * are entering btrfs_get_extent() concurrently, t1 is reading [8K, 16K), t2 is
+ * reading [0, 8K)
+ *
+ * t1 t2
+ * btrfs_get_extent() btrfs_get_extent()
+ * -> lookup_extent_mapping() ->lookup_extent_mapping()
+ * -> add_extent_mapping(0, 16K)
+ * -> return em
+ * ->add_extent_mapping(0, 16K)
+ * -> #handle -EEXIST
+ */
+static void test_case_1(struct btrfs_fs_info *fs_info,
+ struct extent_map_tree *em_tree)
+{
+ struct extent_map *em;
+ u64 start = 0;
+ u64 len = SZ_8K;
+ int ret;
+
+ em = alloc_extent_map();
+ if (!em)
+ /* Skip the test on error. */
+ return;
+
+ /* Add [0, 16K) */
+ em->start = 0;
+ em->len = SZ_16K;
+ em->block_start = 0;
+ em->block_len = SZ_16K;
+ ret = add_extent_mapping(em_tree, em, 0);
+ ASSERT(ret == 0);
+ free_extent_map(em);
+
+ /* Add [16K, 20K) following [0, 16K) */
+ em = alloc_extent_map();
+ if (!em)
+ goto out;
+
+ em->start = SZ_16K;
+ em->len = SZ_4K;
+ em->block_start = SZ_32K; /* avoid merging */
+ em->block_len = SZ_4K;
+ ret = add_extent_mapping(em_tree, em, 0);
+ ASSERT(ret == 0);
+ free_extent_map(em);
+
+ em = alloc_extent_map();
+ if (!em)
+ goto out;
+
+ /* Add [0, 8K), should return [0, 16K) instead. */
+ em->start = start;
+ em->len = len;
+ em->block_start = start;
+ em->block_len = len;
+ ret = btrfs_add_extent_mapping(fs_info, em_tree, &em, em->start, em->len);
+ if (ret)
+ test_err("case1 [%llu %llu]: ret %d", start, start + len, ret);
+ if (em &&
+ (em->start != 0 || extent_map_end(em) != SZ_16K ||
+ em->block_start != 0 || em->block_len != SZ_16K))
+ test_err(
+"case1 [%llu %llu]: ret %d return a wrong em (start %llu len %llu block_start %llu block_len %llu",
+ start, start + len, ret, em->start, em->len,
+ em->block_start, em->block_len);
+ free_extent_map(em);
+out:
+ /* free memory */
+ free_extent_map_tree(em_tree);
+}
+
+/*
+ * Test scenario:
+ *
+ * Reading the inline ending up with EEXIST, ie. read an inline
+ * extent and discard page cache and read it again.
+ */
+static void test_case_2(struct btrfs_fs_info *fs_info,
+ struct extent_map_tree *em_tree)
+{
+ struct extent_map *em;
+ int ret;
+
+ em = alloc_extent_map();
+ if (!em)
+ /* Skip the test on error. */
+ return;
+
+ /* Add [0, 1K) */
+ em->start = 0;
+ em->len = SZ_1K;
+ em->block_start = EXTENT_MAP_INLINE;
+ em->block_len = (u64)-1;
+ ret = add_extent_mapping(em_tree, em, 0);
+ ASSERT(ret == 0);
+ free_extent_map(em);
+
+ /* Add [4K, 4K) following [0, 1K) */
+ em = alloc_extent_map();
+ if (!em)
+ goto out;
+
+ em->start = SZ_4K;
+ em->len = SZ_4K;
+ em->block_start = SZ_4K;
+ em->block_len = SZ_4K;
+ ret = add_extent_mapping(em_tree, em, 0);
+ ASSERT(ret == 0);
+ free_extent_map(em);
+
+ em = alloc_extent_map();
+ if (!em)
+ goto out;
+
+ /* Add [0, 1K) */
+ em->start = 0;
+ em->len = SZ_1K;
+ em->block_start = EXTENT_MAP_INLINE;
+ em->block_len = (u64)-1;
+ ret = btrfs_add_extent_mapping(fs_info, em_tree, &em, em->start, em->len);
+ if (ret)
+ test_err("case2 [0 1K]: ret %d", ret);
+ if (em &&
+ (em->start != 0 || extent_map_end(em) != SZ_1K ||
+ em->block_start != EXTENT_MAP_INLINE || em->block_len != (u64)-1))
+ test_err(
+"case2 [0 1K]: ret %d return a wrong em (start %llu len %llu block_start %llu block_len %llu",
+ ret, em->start, em->len, em->block_start,
+ em->block_len);
+ free_extent_map(em);
+out:
+ /* free memory */
+ free_extent_map_tree(em_tree);
+}
+
+static void __test_case_3(struct btrfs_fs_info *fs_info,
+ struct extent_map_tree *em_tree, u64 start)
+{
+ struct extent_map *em;
+ u64 len = SZ_4K;
+ int ret;
+
+ em = alloc_extent_map();
+ if (!em)
+ /* Skip this test on error. */
+ return;
+
+ /* Add [4K, 8K) */
+ em->start = SZ_4K;
+ em->len = SZ_4K;
+ em->block_start = SZ_4K;
+ em->block_len = SZ_4K;
+ ret = add_extent_mapping(em_tree, em, 0);
+ ASSERT(ret == 0);
+ free_extent_map(em);
+
+ em = alloc_extent_map();
+ if (!em)
+ goto out;
+
+ /* Add [0, 16K) */
+ em->start = 0;
+ em->len = SZ_16K;
+ em->block_start = 0;
+ em->block_len = SZ_16K;
+ ret = btrfs_add_extent_mapping(fs_info, em_tree, &em, start, len);
+ if (ret)
+ test_err("case3 [0x%llx 0x%llx): ret %d",
+ start, start + len, ret);
+ /*
+ * Since bytes within em are contiguous, em->block_start is identical to
+ * em->start.
+ */
+ if (em &&
+ (start < em->start || start + len > extent_map_end(em) ||
+ em->start != em->block_start || em->len != em->block_len))
+ test_err(
+"case3 [0x%llx 0x%llx): ret %d em (start 0x%llx len 0x%llx block_start 0x%llx block_len 0x%llx)",
+ start, start + len, ret, em->start, em->len,
+ em->block_start, em->block_len);
+ free_extent_map(em);
+out:
+ /* free memory */
+ free_extent_map_tree(em_tree);
+}
+
+/*
+ * Test scenario:
+ *
+ * Suppose that no extent map has been loaded into memory yet.
+ * There is a file extent [0, 16K), two jobs are running concurrently
+ * against it, t1 is buffered writing to [4K, 8K) and t2 is doing dio
+ * read from [0, 4K) or [8K, 12K) or [12K, 16K).
+ *
+ * t1 goes ahead of t2 and adds em [4K, 8K) into tree.
+ *
+ * t1 t2
+ * cow_file_range() btrfs_get_extent()
+ * -> lookup_extent_mapping()
+ * -> add_extent_mapping()
+ * -> add_extent_mapping()
+ */
+static void test_case_3(struct btrfs_fs_info *fs_info,
+ struct extent_map_tree *em_tree)
+{
+ __test_case_3(fs_info, em_tree, 0);
+ __test_case_3(fs_info, em_tree, SZ_8K);
+ __test_case_3(fs_info, em_tree, (12 * 1024ULL));
+}
+
+static void __test_case_4(struct btrfs_fs_info *fs_info,
+ struct extent_map_tree *em_tree, u64 start)
+{
+ struct extent_map *em;
+ u64 len = SZ_4K;
+ int ret;
+
+ em = alloc_extent_map();
+ if (!em)
+ /* Skip this test on error. */
+ return;
+
+ /* Add [0K, 8K) */
+ em->start = 0;
+ em->len = SZ_8K;
+ em->block_start = 0;
+ em->block_len = SZ_8K;
+ ret = add_extent_mapping(em_tree, em, 0);
+ ASSERT(ret == 0);
+ free_extent_map(em);
+
+ em = alloc_extent_map();
+ if (!em)
+ goto out;
+
+ /* Add [8K, 24K) */
+ em->start = SZ_8K;
+ em->len = 24 * 1024ULL;
+ em->block_start = SZ_16K; /* avoid merging */
+ em->block_len = 24 * 1024ULL;
+ ret = add_extent_mapping(em_tree, em, 0);
+ ASSERT(ret == 0);
+ free_extent_map(em);
+
+ em = alloc_extent_map();
+ if (!em)
+ goto out;
+ /* Add [0K, 32K) */
+ em->start = 0;
+ em->len = SZ_32K;
+ em->block_start = 0;
+ em->block_len = SZ_32K;
+ ret = btrfs_add_extent_mapping(fs_info, em_tree, &em, start, len);
+ if (ret)
+ test_err("case4 [0x%llx 0x%llx): ret %d",
+ start, len, ret);
+ if (em &&
+ (start < em->start || start + len > extent_map_end(em)))
+ test_err(
+"case4 [0x%llx 0x%llx): ret %d, added wrong em (start 0x%llx len 0x%llx block_start 0x%llx block_len 0x%llx)",
+ start, len, ret, em->start, em->len, em->block_start,
+ em->block_len);
+ free_extent_map(em);
+out:
+ /* free memory */
+ free_extent_map_tree(em_tree);
+}
+
+/*
+ * Test scenario:
+ *
+ * Suppose that no extent map has been loaded into memory yet.
+ * There is a file extent [0, 32K), two jobs are running concurrently
+ * against it, t1 is doing dio write to [8K, 32K) and t2 is doing dio
+ * read from [0, 4K) or [4K, 8K).
+ *
+ * t1 goes ahead of t2 and splits em [0, 32K) to em [0K, 8K) and [8K 32K).
+ *
+ * t1 t2
+ * btrfs_get_blocks_direct() btrfs_get_blocks_direct()
+ * -> btrfs_get_extent() -> btrfs_get_extent()
+ * -> lookup_extent_mapping()
+ * -> add_extent_mapping() -> lookup_extent_mapping()
+ * # load [0, 32K)
+ * -> btrfs_new_extent_direct()
+ * -> btrfs_drop_extent_cache()
+ * # split [0, 32K)
+ * -> add_extent_mapping()
+ * # add [8K, 32K)
+ * -> add_extent_mapping()
+ * # handle -EEXIST when adding
+ * # [0, 32K)
+ */
+static void test_case_4(struct btrfs_fs_info *fs_info,
+ struct extent_map_tree *em_tree)
+{
+ __test_case_4(fs_info, em_tree, 0);
+ __test_case_4(fs_info, em_tree, SZ_4K);
+}
+
+int btrfs_test_extent_map(void)
+{
+ struct btrfs_fs_info *fs_info = NULL;
+ struct extent_map_tree *em_tree;
+
+ test_msg("running extent_map tests");
+
+ /*
+ * Note: the fs_info is not set up completely, we only need
+ * fs_info::fsid for the tracepoint.
+ */
+ fs_info = btrfs_alloc_dummy_fs_info(PAGE_SIZE, PAGE_SIZE);
+ if (!fs_info) {
+ test_msg("Couldn't allocate dummy fs info");
+ return -ENOMEM;
+ }
+
+ em_tree = kzalloc(sizeof(*em_tree), GFP_KERNEL);
+ if (!em_tree)
+ /* Skip the test on error. */
+ goto out;
+
+ extent_map_tree_init(em_tree);
+
+ test_case_1(fs_info, em_tree);
+ test_case_2(fs_info, em_tree);
+ test_case_3(fs_info, em_tree);
+ test_case_4(fs_info, em_tree);
+
+ kfree(em_tree);
+out:
+ btrfs_free_dummy_fs_info(fs_info);
+
+ return 0;
+}