v4.19.13 snapshot.
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
new file mode 100644
index 0000000..6648d55
--- /dev/null
+++ b/fs/btrfs/extent_map.c
@@ -0,0 +1,593 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include "ctree.h"
+#include "extent_map.h"
+#include "compression.h"
+
+
+static struct kmem_cache *extent_map_cache;
+
+int __init extent_map_init(void)
+{
+ extent_map_cache = kmem_cache_create("btrfs_extent_map",
+ sizeof(struct extent_map), 0,
+ SLAB_MEM_SPREAD, NULL);
+ if (!extent_map_cache)
+ return -ENOMEM;
+ return 0;
+}
+
+void __cold extent_map_exit(void)
+{
+ kmem_cache_destroy(extent_map_cache);
+}
+
+/**
+ * extent_map_tree_init - initialize extent map tree
+ * @tree: tree to initialize
+ *
+ * Initialize the extent tree @tree. Should be called for each new inode
+ * or other user of the extent_map interface.
+ */
+void extent_map_tree_init(struct extent_map_tree *tree)
+{
+ tree->map = RB_ROOT;
+ INIT_LIST_HEAD(&tree->modified_extents);
+ rwlock_init(&tree->lock);
+}
+
+/**
+ * alloc_extent_map - allocate new extent map structure
+ *
+ * Allocate a new extent_map structure. The new structure is
+ * returned with a reference count of one and needs to be
+ * freed using free_extent_map()
+ */
+struct extent_map *alloc_extent_map(void)
+{
+ struct extent_map *em;
+ em = kmem_cache_zalloc(extent_map_cache, GFP_NOFS);
+ if (!em)
+ return NULL;
+ RB_CLEAR_NODE(&em->rb_node);
+ em->flags = 0;
+ em->compress_type = BTRFS_COMPRESS_NONE;
+ em->generation = 0;
+ refcount_set(&em->refs, 1);
+ INIT_LIST_HEAD(&em->list);
+ return em;
+}
+
+/**
+ * free_extent_map - drop reference count of an extent_map
+ * @em: extent map being released
+ *
+ * Drops the reference out on @em by one and free the structure
+ * if the reference count hits zero.
+ */
+void free_extent_map(struct extent_map *em)
+{
+ if (!em)
+ return;
+ WARN_ON(refcount_read(&em->refs) == 0);
+ if (refcount_dec_and_test(&em->refs)) {
+ WARN_ON(extent_map_in_tree(em));
+ WARN_ON(!list_empty(&em->list));
+ if (test_bit(EXTENT_FLAG_FS_MAPPING, &em->flags))
+ kfree(em->map_lookup);
+ kmem_cache_free(extent_map_cache, em);
+ }
+}
+
+/* simple helper to do math around the end of an extent, handling wrap */
+static u64 range_end(u64 start, u64 len)
+{
+ if (start + len < start)
+ return (u64)-1;
+ return start + len;
+}
+
+static int tree_insert(struct rb_root *root, struct extent_map *em)
+{
+ struct rb_node **p = &root->rb_node;
+ struct rb_node *parent = NULL;
+ struct extent_map *entry = NULL;
+ struct rb_node *orig_parent = NULL;
+ u64 end = range_end(em->start, em->len);
+
+ while (*p) {
+ parent = *p;
+ entry = rb_entry(parent, struct extent_map, rb_node);
+
+ if (em->start < entry->start)
+ p = &(*p)->rb_left;
+ else if (em->start >= extent_map_end(entry))
+ p = &(*p)->rb_right;
+ else
+ return -EEXIST;
+ }
+
+ orig_parent = parent;
+ while (parent && em->start >= extent_map_end(entry)) {
+ parent = rb_next(parent);
+ entry = rb_entry(parent, struct extent_map, rb_node);
+ }
+ if (parent)
+ if (end > entry->start && em->start < extent_map_end(entry))
+ return -EEXIST;
+
+ parent = orig_parent;
+ entry = rb_entry(parent, struct extent_map, rb_node);
+ while (parent && em->start < entry->start) {
+ parent = rb_prev(parent);
+ entry = rb_entry(parent, struct extent_map, rb_node);
+ }
+ if (parent)
+ if (end > entry->start && em->start < extent_map_end(entry))
+ return -EEXIST;
+
+ rb_link_node(&em->rb_node, orig_parent, p);
+ rb_insert_color(&em->rb_node, root);
+ return 0;
+}
+
+/*
+ * search through the tree for an extent_map with a given offset. If
+ * it can't be found, try to find some neighboring extents
+ */
+static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
+ struct rb_node **prev_ret,
+ struct rb_node **next_ret)
+{
+ struct rb_node *n = root->rb_node;
+ struct rb_node *prev = NULL;
+ struct rb_node *orig_prev = NULL;
+ struct extent_map *entry;
+ struct extent_map *prev_entry = NULL;
+
+ while (n) {
+ entry = rb_entry(n, struct extent_map, rb_node);
+ prev = n;
+ prev_entry = entry;
+
+ if (offset < entry->start)
+ n = n->rb_left;
+ else if (offset >= extent_map_end(entry))
+ n = n->rb_right;
+ else
+ return n;
+ }
+
+ if (prev_ret) {
+ orig_prev = prev;
+ while (prev && offset >= extent_map_end(prev_entry)) {
+ prev = rb_next(prev);
+ prev_entry = rb_entry(prev, struct extent_map, rb_node);
+ }
+ *prev_ret = prev;
+ prev = orig_prev;
+ }
+
+ if (next_ret) {
+ prev_entry = rb_entry(prev, struct extent_map, rb_node);
+ while (prev && offset < prev_entry->start) {
+ prev = rb_prev(prev);
+ prev_entry = rb_entry(prev, struct extent_map, rb_node);
+ }
+ *next_ret = prev;
+ }
+ return NULL;
+}
+
+/* check to see if two extent_map structs are adjacent and safe to merge */
+static int mergable_maps(struct extent_map *prev, struct extent_map *next)
+{
+ if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
+ return 0;
+
+ /*
+ * don't merge compressed extents, we need to know their
+ * actual size
+ */
+ if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
+ return 0;
+
+ if (test_bit(EXTENT_FLAG_LOGGING, &prev->flags) ||
+ test_bit(EXTENT_FLAG_LOGGING, &next->flags))
+ return 0;
+
+ /*
+ * We don't want to merge stuff that hasn't been written to the log yet
+ * since it may not reflect exactly what is on disk, and that would be
+ * bad.
+ */
+ if (!list_empty(&prev->list) || !list_empty(&next->list))
+ return 0;
+
+ if (extent_map_end(prev) == next->start &&
+ prev->flags == next->flags &&
+ prev->bdev == next->bdev &&
+ ((next->block_start == EXTENT_MAP_HOLE &&
+ prev->block_start == EXTENT_MAP_HOLE) ||
+ (next->block_start == EXTENT_MAP_INLINE &&
+ prev->block_start == EXTENT_MAP_INLINE) ||
+ (next->block_start == EXTENT_MAP_DELALLOC &&
+ prev->block_start == EXTENT_MAP_DELALLOC) ||
+ (next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
+ next->block_start == extent_map_block_end(prev)))) {
+ return 1;
+ }
+ return 0;
+}
+
+static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
+{
+ struct extent_map *merge = NULL;
+ struct rb_node *rb;
+
+ if (em->start != 0) {
+ rb = rb_prev(&em->rb_node);
+ if (rb)
+ merge = rb_entry(rb, struct extent_map, rb_node);
+ if (rb && mergable_maps(merge, em)) {
+ em->start = merge->start;
+ em->orig_start = merge->orig_start;
+ em->len += merge->len;
+ em->block_len += merge->block_len;
+ em->block_start = merge->block_start;
+ em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;
+ em->mod_start = merge->mod_start;
+ em->generation = max(em->generation, merge->generation);
+
+ rb_erase(&merge->rb_node, &tree->map);
+ RB_CLEAR_NODE(&merge->rb_node);
+ free_extent_map(merge);
+ }
+ }
+
+ rb = rb_next(&em->rb_node);
+ if (rb)
+ merge = rb_entry(rb, struct extent_map, rb_node);
+ if (rb && mergable_maps(em, merge)) {
+ em->len += merge->len;
+ em->block_len += merge->block_len;
+ rb_erase(&merge->rb_node, &tree->map);
+ RB_CLEAR_NODE(&merge->rb_node);
+ em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
+ em->generation = max(em->generation, merge->generation);
+ free_extent_map(merge);
+ }
+}
+
+/**
+ * unpin_extent_cache - unpin an extent from the cache
+ * @tree: tree to unpin the extent in
+ * @start: logical offset in the file
+ * @len: length of the extent
+ * @gen: generation that this extent has been modified in
+ *
+ * Called after an extent has been written to disk properly. Set the generation
+ * to the generation that actually added the file item to the inode so we know
+ * we need to sync this extent when we call fsync().
+ */
+int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len,
+ u64 gen)
+{
+ int ret = 0;
+ struct extent_map *em;
+ bool prealloc = false;
+
+ write_lock(&tree->lock);
+ em = lookup_extent_mapping(tree, start, len);
+
+ WARN_ON(!em || em->start != start);
+
+ if (!em)
+ goto out;
+
+ em->generation = gen;
+ clear_bit(EXTENT_FLAG_PINNED, &em->flags);
+ em->mod_start = em->start;
+ em->mod_len = em->len;
+
+ if (test_bit(EXTENT_FLAG_FILLING, &em->flags)) {
+ prealloc = true;
+ clear_bit(EXTENT_FLAG_FILLING, &em->flags);
+ }
+
+ try_merge_map(tree, em);
+
+ if (prealloc) {
+ em->mod_start = em->start;
+ em->mod_len = em->len;
+ }
+
+ free_extent_map(em);
+out:
+ write_unlock(&tree->lock);
+ return ret;
+
+}
+
+void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
+{
+ clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
+ if (extent_map_in_tree(em))
+ try_merge_map(tree, em);
+}
+
+static inline void setup_extent_mapping(struct extent_map_tree *tree,
+ struct extent_map *em,
+ int modified)
+{
+ refcount_inc(&em->refs);
+ em->mod_start = em->start;
+ em->mod_len = em->len;
+
+ if (modified)
+ list_move(&em->list, &tree->modified_extents);
+ else
+ try_merge_map(tree, em);
+}
+
+/**
+ * add_extent_mapping - add new extent map to the extent tree
+ * @tree: tree to insert new map in
+ * @em: map to insert
+ *
+ * Insert @em into @tree or perform a simple forward/backward merge with
+ * existing mappings. The extent_map struct passed in will be inserted
+ * into the tree directly, with an additional reference taken, or a
+ * reference dropped if the merge attempt was successful.
+ */
+int add_extent_mapping(struct extent_map_tree *tree,
+ struct extent_map *em, int modified)
+{
+ int ret = 0;
+
+ ret = tree_insert(&tree->map, em);
+ if (ret)
+ goto out;
+
+ setup_extent_mapping(tree, em, modified);
+out:
+ return ret;
+}
+
+static struct extent_map *
+__lookup_extent_mapping(struct extent_map_tree *tree,
+ u64 start, u64 len, int strict)
+{
+ struct extent_map *em;
+ struct rb_node *rb_node;
+ struct rb_node *prev = NULL;
+ struct rb_node *next = NULL;
+ u64 end = range_end(start, len);
+
+ rb_node = __tree_search(&tree->map, start, &prev, &next);
+ if (!rb_node) {
+ if (prev)
+ rb_node = prev;
+ else if (next)
+ rb_node = next;
+ else
+ return NULL;
+ }
+
+ em = rb_entry(rb_node, struct extent_map, rb_node);
+
+ if (strict && !(end > em->start && start < extent_map_end(em)))
+ return NULL;
+
+ refcount_inc(&em->refs);
+ return em;
+}
+
+/**
+ * lookup_extent_mapping - lookup extent_map
+ * @tree: tree to lookup in
+ * @start: byte offset to start the search
+ * @len: length of the lookup range
+ *
+ * Find and return the first extent_map struct in @tree that intersects the
+ * [start, len] range. There may be additional objects in the tree that
+ * intersect, so check the object returned carefully to make sure that no
+ * additional lookups are needed.
+ */
+struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
+ u64 start, u64 len)
+{
+ return __lookup_extent_mapping(tree, start, len, 1);
+}
+
+/**
+ * search_extent_mapping - find a nearby extent map
+ * @tree: tree to lookup in
+ * @start: byte offset to start the search
+ * @len: length of the lookup range
+ *
+ * Find and return the first extent_map struct in @tree that intersects the
+ * [start, len] range.
+ *
+ * If one can't be found, any nearby extent may be returned
+ */
+struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
+ u64 start, u64 len)
+{
+ return __lookup_extent_mapping(tree, start, len, 0);
+}
+
+/**
+ * remove_extent_mapping - removes an extent_map from the extent tree
+ * @tree: extent tree to remove from
+ * @em: extent map being removed
+ *
+ * Removes @em from @tree. No reference counts are dropped, and no checks
+ * are done to see if the range is in use
+ */
+int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
+{
+ int ret = 0;
+
+ WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
+ rb_erase(&em->rb_node, &tree->map);
+ if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))
+ list_del_init(&em->list);
+ RB_CLEAR_NODE(&em->rb_node);
+ return ret;
+}
+
+void replace_extent_mapping(struct extent_map_tree *tree,
+ struct extent_map *cur,
+ struct extent_map *new,
+ int modified)
+{
+ WARN_ON(test_bit(EXTENT_FLAG_PINNED, &cur->flags));
+ ASSERT(extent_map_in_tree(cur));
+ if (!test_bit(EXTENT_FLAG_LOGGING, &cur->flags))
+ list_del_init(&cur->list);
+ rb_replace_node(&cur->rb_node, &new->rb_node, &tree->map);
+ RB_CLEAR_NODE(&cur->rb_node);
+
+ setup_extent_mapping(tree, new, modified);
+}
+
+static struct extent_map *next_extent_map(struct extent_map *em)
+{
+ struct rb_node *next;
+
+ next = rb_next(&em->rb_node);
+ if (!next)
+ return NULL;
+ return container_of(next, struct extent_map, rb_node);
+}
+
+static struct extent_map *prev_extent_map(struct extent_map *em)
+{
+ struct rb_node *prev;
+
+ prev = rb_prev(&em->rb_node);
+ if (!prev)
+ return NULL;
+ return container_of(prev, struct extent_map, rb_node);
+}
+
+/* helper for btfs_get_extent. Given an existing extent in the tree,
+ * the existing extent is the nearest extent to map_start,
+ * and an extent that you want to insert, deal with overlap and insert
+ * the best fitted new extent into the tree.
+ */
+static noinline int merge_extent_mapping(struct extent_map_tree *em_tree,
+ struct extent_map *existing,
+ struct extent_map *em,
+ u64 map_start)
+{
+ struct extent_map *prev;
+ struct extent_map *next;
+ u64 start;
+ u64 end;
+ u64 start_diff;
+
+ BUG_ON(map_start < em->start || map_start >= extent_map_end(em));
+
+ if (existing->start > map_start) {
+ next = existing;
+ prev = prev_extent_map(next);
+ } else {
+ prev = existing;
+ next = next_extent_map(prev);
+ }
+
+ start = prev ? extent_map_end(prev) : em->start;
+ start = max_t(u64, start, em->start);
+ end = next ? next->start : extent_map_end(em);
+ end = min_t(u64, end, extent_map_end(em));
+ start_diff = start - em->start;
+ em->start = start;
+ em->len = end - start;
+ if (em->block_start < EXTENT_MAP_LAST_BYTE &&
+ !test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
+ em->block_start += start_diff;
+ em->block_len = em->len;
+ }
+ return add_extent_mapping(em_tree, em, 0);
+}
+
+/**
+ * btrfs_add_extent_mapping - add extent mapping into em_tree
+ * @fs_info - used for tracepoint
+ * @em_tree - the extent tree into which we want to insert the extent mapping
+ * @em_in - extent we are inserting
+ * @start - start of the logical range btrfs_get_extent() is requesting
+ * @len - length of the logical range btrfs_get_extent() is requesting
+ *
+ * Note that @em_in's range may be different from [start, start+len),
+ * but they must be overlapped.
+ *
+ * Insert @em_in into @em_tree. In case there is an overlapping range, handle
+ * the -EEXIST by either:
+ * a) Returning the existing extent in @em_in if @start is within the
+ * existing em.
+ * b) Merge the existing extent with @em_in passed in.
+ *
+ * Return 0 on success, otherwise -EEXIST.
+ *
+ */
+int btrfs_add_extent_mapping(struct btrfs_fs_info *fs_info,
+ struct extent_map_tree *em_tree,
+ struct extent_map **em_in, u64 start, u64 len)
+{
+ int ret;
+ struct extent_map *em = *em_in;
+
+ ret = add_extent_mapping(em_tree, em, 0);
+ /* it is possible that someone inserted the extent into the tree
+ * while we had the lock dropped. It is also possible that
+ * an overlapping map exists in the tree
+ */
+ if (ret == -EEXIST) {
+ struct extent_map *existing;
+
+ ret = 0;
+
+ existing = search_extent_mapping(em_tree, start, len);
+
+ trace_btrfs_handle_em_exist(fs_info, existing, em, start, len);
+
+ /*
+ * existing will always be non-NULL, since there must be
+ * extent causing the -EEXIST.
+ */
+ if (start >= existing->start &&
+ start < extent_map_end(existing)) {
+ free_extent_map(em);
+ *em_in = existing;
+ ret = 0;
+ } else {
+ u64 orig_start = em->start;
+ u64 orig_len = em->len;
+
+ /*
+ * The existing extent map is the one nearest to
+ * the [start, start + len) range which overlaps
+ */
+ ret = merge_extent_mapping(em_tree, existing,
+ em, start);
+ if (ret) {
+ free_extent_map(em);
+ *em_in = NULL;
+ WARN_ONCE(ret,
+"unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n",
+ ret, existing->start, existing->len,
+ orig_start, orig_len);
+ }
+ free_extent_map(existing);
+ }
+ }
+
+ ASSERT(ret == 0 || ret == -EEXIST);
+ return ret;
+}