9 files changed, 315 insertions, 86 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 8992e0096163..947f04789389 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3291,7 +3291,7 @@ void btrfs_exclop_balance(struct btrfs_fs_info *fs_info,
 int __init btrfs_auto_defrag_init(void);
 void __cold btrfs_auto_defrag_exit(void);
 int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
-			   struct btrfs_inode *inode);
+			   struct btrfs_inode *inode, u32 extent_thresh);
 int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info);
 void btrfs_cleanup_defrag_inodes(struct btrfs_fs_info *fs_info);
 int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync);
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 5a36add21305..c28ceddefae4 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -261,6 +261,7 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
 			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);
+			set_bit(EXTENT_FLAG_MERGED, &em->flags);
 
 			rb_erase_cached(&merge->rb_node, &tree->map);
 			RB_CLEAR_NODE(&merge->rb_node);
@@ -278,6 +279,7 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
 		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);
+		set_bit(EXTENT_FLAG_MERGED, &em->flags);
 		free_extent_map(merge);
 	}
 }
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 8e217337dff9..d2fa32ffe304 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -25,6 +25,8 @@ enum {
 	EXTENT_FLAG_FILLING,
 	/* filesystem extent mapping type */
 	EXTENT_FLAG_FS_MAPPING,
+	/* This em is merged from two or more physically adjacent ems */
+	EXTENT_FLAG_MERGED,
 };
 
 struct extent_map {
@@ -40,6 +42,12 @@ struct extent_map {
 	u64 ram_bytes;
 	u64 block_start;
 	u64 block_len;
+
+	/*
+	 * Generation of the extent map, for merged em it's the highest
+	 * generation of all merged ems.
+	 * For non-merged extents, it's from btrfs_file_extent_item::generation.
+	 */
 	u64 generation;
 	unsigned long flags;
 	/* Used for chunk mappings, flag EXTENT_FLAG_FS_MAPPING must be set */
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 11204dbbe053..a0179cc62913 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -50,11 +50,14 @@ struct inode_defrag {
 	/* root objectid */
 	u64 root;
 
-	/* last offset we were able to defrag */
-	u64 last_offset;
-
-	/* if we've wrapped around back to zero once already */
-	int cycled;
+	/*
+	 * The extent size threshold for autodefrag.
+	 *
+	 * This value is different for compressed/non-compressed extents,
+	 * thus needs to be passed from higher layer.
+	 * (aka, inode_should_defrag())
+	 */
+	u32 extent_thresh;
 };
 
 static int __compare_inode_defrag(struct inode_defrag *defrag1,
@@ -107,8 +110,8 @@ static int __btrfs_add_inode_defrag(struct btrfs_inode *inode,
 			 */
 			if (defrag->transid < entry->transid)
 				entry->transid = defrag->transid;
-			if (defrag->last_offset > entry->last_offset)
-				entry->last_offset = defrag->last_offset;
+			entry->extent_thresh = min(defrag->extent_thresh,
+						   entry->extent_thresh);
 			return -EEXIST;
 		}
 	}
@@ -134,7 +137,7 @@ static inline int __need_auto_defrag(struct btrfs_fs_info *fs_info)
  * enabled
  */
 int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
-			   struct btrfs_inode *inode)
+			   struct btrfs_inode *inode, u32 extent_thresh)
 {
 	struct btrfs_root *root = inode->root;
 	struct btrfs_fs_info *fs_info = root->fs_info;
@@ -160,6 +163,7 @@ int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
 	defrag->ino = btrfs_ino(inode);
 	defrag->transid = transid;
 	defrag->root = root->root_key.objectid;
+	defrag->extent_thresh = extent_thresh;
 
 	spin_lock(&fs_info->defrag_inodes_lock);
 	if (!test_bit(BTRFS_INODE_IN_DEFRAG, &inode->runtime_flags)) {
@@ -179,34 +183,6 @@ int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
 }
 
 /*
- * Requeue the defrag object. If there is a defrag object that points to
- * the same inode in the tree, we will merge them together (by
- * __btrfs_add_inode_defrag()) and free the one that we want to requeue.
- */
-static void btrfs_requeue_inode_defrag(struct btrfs_inode *inode,
-				       struct inode_defrag *defrag)
-{
-	struct btrfs_fs_info *fs_info = inode->root->fs_info;
-	int ret;
-
-	if (!__need_auto_defrag(fs_info))
-		goto out;
-
-	/*
-	 * Here we don't check the IN_DEFRAG flag, because we need merge
-	 * them together.
-	 */
-	spin_lock(&fs_info->defrag_inodes_lock);
-	ret = __btrfs_add_inode_defrag(inode, defrag);
-	spin_unlock(&fs_info->defrag_inodes_lock);
-	if (ret)
-		goto out;
-	return;
-out:
-	kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
-}
-
-/*
  * pick the defragable inode that we want, if it doesn't exist, we will get
  * the next one.
  */
@@ -278,8 +254,14 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
 	struct btrfs_root *inode_root;
 	struct inode *inode;
 	struct btrfs_ioctl_defrag_range_args range;
-	int num_defrag;
-	int ret;
+	int ret = 0;
+	u64 cur = 0;
+
+again:
+	if (test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state))
+		goto cleanup;
+	if (!__need_auto_defrag(fs_info))
+		goto cleanup;
 
 	/* get the inode */
 	inode_root = btrfs_get_fs_root(fs_info, defrag->root, true);
@@ -295,39 +277,30 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
 		goto cleanup;
 	}
 
+	if (cur >= i_size_read(inode)) {
+		iput(inode);
+		goto cleanup;
+	}
+
 	/* do a chunk of defrag */
 	clear_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
 	memset(&range, 0, sizeof(range));
 	range.len = (u64)-1;
-	range.start = defrag->last_offset;
+	range.start = cur;
+	range.extent_thresh = defrag->extent_thresh;
 
 	sb_start_write(fs_info->sb);
-	num_defrag = btrfs_defrag_file(inode, NULL, &range, defrag->transid,
+	ret = btrfs_defrag_file(inode, NULL, &range, defrag->transid,
 				       BTRFS_DEFRAG_BATCH);
 	sb_end_write(fs_info->sb);
-	/*
-	 * if we filled the whole defrag batch, there
-	 * must be more work to do.  Queue this defrag
-	 * again
-	 */
-	if (num_defrag == BTRFS_DEFRAG_BATCH) {
-		defrag->last_offset = range.start;
-		btrfs_requeue_inode_defrag(BTRFS_I(inode), defrag);
-	} else if (defrag->last_offset && !defrag->cycled) {
-		/*
-		 * we didn't fill our defrag batch, but
-		 * we didn't start at zero.  Make sure we loop
-		 * around to the start of the file.
-		 */
-		defrag->last_offset = 0;
-		defrag->cycled = 1;
-		btrfs_requeue_inode_defrag(BTRFS_I(inode), defrag);
-	} else {
-		kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
-	}
-
 	iput(inode);
-	return 0;
+
+	if (ret < 0)
+		goto cleanup;
+
+	cur = max(cur + fs_info->sectorsize, range.start);
+	goto again;
+
 cleanup:
 	kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 	return ret;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 3b2403b6127f..76e530f76e3c 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -560,12 +560,12 @@ static inline int inode_need_compress(struct btrfs_inode *inode, u64 start,
 }
 
 static inline void inode_should_defrag(struct btrfs_inode *inode,
-		u64 start, u64 end, u64 num_bytes, u64 small_write)
+		u64 start, u64 end, u64 num_bytes, u32 small_write)
 {
 	/* If this is a small write inside eof, kick off a defrag */
 	if (num_bytes < small_write &&
 	    (start > 0 || end + 1 < inode->disk_i_size))
-		btrfs_add_inode_defrag(NULL, inode);
+		btrfs_add_inode_defrag(NULL, inode, small_write);
 }
 
 /*
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 33eda39df685..8d47ec5fc4f4 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1012,8 +1012,155 @@ out:
 	return ret;
 }
 
+/*
+ * Defrag specific helper to get an extent map.
+ *
+ * Differences between this and btrfs_get_extent() are:
+ *
+ * - No extent_map will be added to inode->extent_tree
+ *   To reduce memory usage in the long run.
+ *
+ * - Extra optimization to skip file extents older than @newer_than
+ *   By using btrfs_search_forward() we can skip entire file ranges that
+ *   have extents created in past transactions, because btrfs_search_forward()
+ *   will not visit leaves and nodes with a generation smaller than given
+ *   minimal generation threshold (@newer_than).
+ *
+ * Return valid em if we find a file extent matching the requirement.
+ * Return NULL if we can not find a file extent matching the requirement.
+ *
+ * Return ERR_PTR() for error.
+ */
+static struct extent_map *defrag_get_extent(struct btrfs_inode *inode,
+					    u64 start, u64 newer_than)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_file_extent_item *fi;
+	struct btrfs_path path = { 0 };
+	struct extent_map *em;
+	struct btrfs_key key;
+	u64 ino = btrfs_ino(inode);
+	int ret;
+
+	em = alloc_extent_map();
+	if (!em) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	key.objectid = ino;
+	key.type = BTRFS_EXTENT_DATA_KEY;
+	key.offset = start;
+
+	if (newer_than) {
+		ret = btrfs_search_forward(root, &key, &path, newer_than);
+		if (ret < 0)
+			goto err;
+		/* Can't find anything newer */
+		if (ret > 0)
+			goto not_found;
+	} else {
+		ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+		if (ret < 0)
+			goto err;
+	}
+	if (path.slots[0] >= btrfs_header_nritems(path.nodes[0])) {
+		/*
+		 * If btrfs_search_slot() makes path to point beyond nritems,
+		 * we should not have an empty leaf, as this inode must at
+		 * least have its INODE_ITEM.
+		 */
+		ASSERT(btrfs_header_nritems(path.nodes[0]));
+		path.slots[0] = btrfs_header_nritems(path.nodes[0]) - 1;
+	}
+	btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
+	/* Perfect match, no need to go one slot back */
+	if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY &&
+	    key.offset == start)
+		goto iterate;
+
+	/* We didn't find a perfect match, needs to go one slot back */
+	if (path.slots[0] > 0) {
+		btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
+		if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY)
+			path.slots[0]--;
+	}
+
+iterate:
+	/* Iterate through the path to find a file extent covering @start */
+	while (true) {
+		u64 extent_end;
+
+		if (path.slots[0] >= btrfs_header_nritems(path.nodes[0]))
+			goto next;
+
+		btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
+
+		/*
+		 * We may go one slot back to INODE_REF/XATTR item, then
+		 * need to go forward until we reach an EXTENT_DATA.
+		 * But we should still has the correct ino as key.objectid.
+		 */
+		if (WARN_ON(key.objectid < ino) || key.type < BTRFS_EXTENT_DATA_KEY)
+			goto next;
+
+		/* It's beyond our target range, definitely not extent found */
+		if (key.objectid > ino || key.type > BTRFS_EXTENT_DATA_KEY)
+			goto not_found;
+
+		/*
+		 *	|	|<- File extent ->|
+		 *	\- start
+		 *
+		 * This means there is a hole between start and key.offset.
+		 */
+		if (key.offset > start) {
+			em->start = start;
+			em->orig_start = start;
+			em->block_start = EXTENT_MAP_HOLE;
+			em->len = key.offset - start;
+			break;
+		}
+
+		fi = btrfs_item_ptr(path.nodes[0], path.slots[0],
+				    struct btrfs_file_extent_item);
+		extent_end = btrfs_file_extent_end(&path);
+
+		/*
+		 *	|<- file extent ->|	|
+		 *				\- start
+		 *
+		 * We haven't reached start, search next slot.
+		 */
+		if (extent_end <= start)
+			goto next;
+
+		/* Now this extent covers @start, convert it to em */
+		btrfs_extent_item_to_extent_map(inode, &path, fi, false, em);
+		break;
+next:
+		ret = btrfs_next_item(root, &path);
+		if (ret < 0)
+			goto err;
+		if (ret > 0)
+			goto not_found;
+	}
+	btrfs_release_path(&path);
+	return em;
+
+not_found:
+	btrfs_release_path(&path);
+	free_extent_map(em);
+	return NULL;
+
+err:
+	btrfs_release_path(&path);
+	free_extent_map(em);
+	return ERR_PTR(ret);
+}
+
 static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start,
-					       bool locked)
+					       u64 newer_than, bool locked)
 {
 	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
@@ -1028,6 +1175,20 @@ static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start,
 	em = lookup_extent_mapping(em_tree, start, sectorsize);
 	read_unlock(&em_tree->lock);
 
+	/*
+	 * We can get a merged extent, in that case, we need to re-search
+	 * tree to get the original em for defrag.
+	 *
+	 * If @newer_than is 0 or em::generation < newer_than, we can trust
+	 * this em, as either we don't care about the generation, or the
+	 * merged extent map will be rejected anyway.
+	 */
+	if (em && test_bit(EXTENT_FLAG_MERGED, &em->flags) &&
+	    newer_than && em->generation >= newer_than) {
+		free_extent_map(em);
+		em = NULL;
+	}
+
 	if (!em) {
 		struct extent_state *cached = NULL;
 		u64 end = start + sectorsize - 1;
@@ -1035,7 +1196,7 @@ static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start,
 		/* get the big lock and read metadata off disk */
 		if (!locked)
 			lock_extent_bits(io_tree, start, end, &cached);
-		em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, sectorsize);
+		em = defrag_get_extent(BTRFS_I(inode), start, newer_than);
 		if (!locked)
 			unlock_extent_cached(io_tree, start, end, &cached);
 
@@ -1046,23 +1207,42 @@ static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start,
 	return em;
 }
 
+static u32 get_extent_max_capacity(const struct extent_map *em)
+{
+	if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
+		return BTRFS_MAX_COMPRESSED;
+	return BTRFS_MAX_EXTENT_SIZE;
+}
+
 static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em,
 				     bool locked)
 {
 	struct extent_map *next;
-	bool ret = true;
+	bool ret = false;
 
 	/* this is the last extent */
 	if (em->start + em->len >= i_size_read(inode))
 		return false;
 
-	next = defrag_lookup_extent(inode, em->start + em->len, locked);
+	/*
+	 * We want to check if the next extent can be merged with the current
+	 * one, which can be an extent created in a past generation, so we pass
+	 * a minimum generation of 0 to defrag_lookup_extent().
+	 */
+	next = defrag_lookup_extent(inode, em->start + em->len, 0, locked);
+	/* No more em or hole */
 	if (!next || next->block_start >= EXTENT_MAP_LAST_BYTE)
-		ret = false;
-	else if ((em->block_start + em->block_len == next->block_start) &&
-		 (em->block_len > SZ_128K && next->block_len > SZ_128K))
-		ret = false;
-
+		goto out;
+	if (test_bit(EXTENT_FLAG_PREALLOC, &next->flags))
+		goto out;
+	/*
+	 * If the next extent is at its max capacity, defragging current extent
+	 * makes no sense, as the total number of extents won't change.
+	 */
+	if (next->len >= get_extent_max_capacity(em))
+		goto out;
+	ret = true;
+out:
 	free_extent_map(next);
 	return ret;
 }
@@ -1186,8 +1366,10 @@ struct defrag_target_range {
 static int defrag_collect_targets(struct btrfs_inode *inode,
 				  u64 start, u64 len, u32 extent_thresh,
 				  u64 newer_than, bool do_compress,
-				  bool locked, struct list_head *target_list)
+				  bool locked, struct list_head *target_list,
+				  u64 *last_scanned_ret)
 {
+	bool last_is_target = false;
 	u64 cur = start;
 	int ret = 0;
 
@@ -1197,7 +1379,9 @@ static int defrag_collect_targets(struct btrfs_inode *inode,
 		bool next_mergeable = true;
 		u64 range_len;
 
-		em = defrag_lookup_extent(&inode->vfs_inode, cur, locked);
+		last_is_target = false;
+		em = defrag_lookup_extent(&inode->vfs_inode, cur,
+					  newer_than, locked);
 		if (!em)
 			break;
 
@@ -1210,6 +1394,10 @@ static int defrag_collect_targets(struct btrfs_inode *inode,
 		if (em->generation < newer_than)
 			goto next;
 
+		/* This em is under writeback, no need to defrag */
+		if (em->generation == (u64)-1)
+			goto next;
+
 		/*
 		 * Our start offset might be in the middle of an existing extent
 		 * map, so take that into account.
@@ -1250,6 +1438,13 @@ static int defrag_collect_targets(struct btrfs_inode *inode,
 		if (range_len >= extent_thresh)
 			goto next;
 
+		/*
+		 * Skip extents already at its max capacity, this is mostly for
+		 * compressed extents, which max cap is only 128K.
+		 */
+		if (em->len >= get_extent_max_capacity(em))
+			goto next;
+
 		next_mergeable = defrag_check_next_extent(&inode->vfs_inode, em,
 							  locked);
 		if (!next_mergeable) {
@@ -1268,6 +1463,7 @@ static int defrag_collect_targets(struct btrfs_inode *inode,
 		}
 
 add:
+		last_is_target = true;
 		range_len = min(extent_map_end(em), start + len) - cur;
 		/*
 		 * This one is a good target, check if it can be merged into
@@ -1311,6 +1507,17 @@ next:
 			kfree(entry);
 		}
 	}
+	if (!ret && last_scanned_ret) {
+		/*
+		 * If the last extent is not a target, the caller can skip to
+		 * the end of that extent.
+		 * Otherwise, we can only go the end of the specified range.
+		 */
+		if (!last_is_target)
+			*last_scanned_ret = max(cur, *last_scanned_ret);
+		else
+			*last_scanned_ret = max(start + len, *last_scanned_ret);
+	}
 	return ret;
 }
 
@@ -1369,7 +1576,8 @@ static int defrag_one_locked_target(struct btrfs_inode *inode,
 }
 
 static int defrag_one_range(struct btrfs_inode *inode, u64 start, u32 len,
-			    u32 extent_thresh, u64 newer_than, bool do_compress)
+			    u32 extent_thresh, u64 newer_than, bool do_compress,
+			    u64 *last_scanned_ret)
 {
 	struct extent_state *cached_state = NULL;
 	struct defrag_target_range *entry;
@@ -1415,7 +1623,7 @@ static int defrag_one_range(struct btrfs_inode *inode, u64 start, u32 len,
 	 */
 	ret = defrag_collect_targets(inode, start, len, extent_thresh,
 				     newer_than, do_compress, true,
-				     &target_list);
+				     &target_list, last_scanned_ret);
 	if (ret < 0)
 		goto unlock_extent;
 
@@ -1450,7 +1658,8 @@ static int defrag_one_cluster(struct btrfs_inode *inode,
 			      u64 start, u32 len, u32 extent_thresh,
 			      u64 newer_than, bool do_compress,
 			      unsigned long *sectors_defragged,
-			      unsigned long max_sectors)
+			      unsigned long max_sectors,
+			      u64 *last_scanned_ret)
 {
 	const u32 sectorsize = inode->root->fs_info->sectorsize;
 	struct defrag_target_range *entry;
@@ -1461,7 +1670,7 @@ static int defrag_one_cluster(struct btrfs_inode *inode,
 	BUILD_BUG_ON(!IS_ALIGNED(CLUSTER_SIZE, PAGE_SIZE));
 	ret = defrag_collect_targets(inode, start, len, extent_thresh,
 				     newer_than, do_compress, false,
-				     &target_list);
+				     &target_list, NULL);
 	if (ret < 0)
 		goto out;
 
@@ -1478,6 +1687,15 @@ static int defrag_one_cluster(struct btrfs_inode *inode,
 			range_len = min_t(u32, range_len,
 				(max_sectors - *sectors_defragged) * sectorsize);
 
+		/*
+		 * If defrag_one_range() has updated last_scanned_ret,
+		 * our range may already be invalid (e.g. hole punched).
+		 * Skip if our range is before last_scanned_ret, as there is
+		 * no need to defrag the range anymore.
+		 */
+		if (entry->start + range_len <= *last_scanned_ret)
+			continue;
+
 		if (ra)
 			page_cache_sync_readahead(inode->vfs_inode.i_mapping,
 				ra, NULL, entry->start >> PAGE_SHIFT,
@@ -1490,7 +1708,8 @@ static int defrag_one_cluster(struct btrfs_inode *inode,
 		 * accounting.
 		 */
 		ret = defrag_one_range(inode, entry->start, range_len,
-				       extent_thresh, newer_than, do_compress);
+				       extent_thresh, newer_than, do_compress,
+				       last_scanned_ret);
 		if (ret < 0)
 			break;
 		*sectors_defragged += range_len >>
@@ -1501,6 +1720,8 @@ out:
 		list_del_init(&entry->list);
 		kfree(entry);
 	}
+	if (ret >= 0)
+		*last_scanned_ret = max(*last_scanned_ret, start + len);
 	return ret;
 }
 
@@ -1586,6 +1807,7 @@ int btrfs_defrag_file(struct inode *inode, struct file_ra_state *ra,
 
 	while (cur < last_byte) {
 		const unsigned long prev_sectors_defragged = sectors_defragged;
+		u64 last_scanned = cur;
 		u64 cluster_end;
 
 		/* The cluster size 256K should always be page aligned */
@@ -1615,8 +1837,8 @@ int btrfs_defrag_file(struct inode *inode, struct file_ra_state *ra,
 			BTRFS_I(inode)->defrag_compress = compress_type;
 		ret = defrag_one_cluster(BTRFS_I(inode), ra, cur,
 				cluster_end + 1 - cur, extent_thresh,
-				newer_than, do_compress,
-				&sectors_defragged, max_to_defrag);
+				newer_than, do_compress, &sectors_defragged,
+				max_to_defrag, &last_scanned);
 
 		if (sectors_defragged > prev_sectors_defragged)
 			balance_dirty_pages_ratelimited(inode->i_mapping);
@@ -1624,11 +1846,12 @@ int btrfs_defrag_file(struct inode *inode, struct file_ra_state *ra,
 		btrfs_inode_unlock(inode, 0);
 		if (ret < 0)
 			break;
-		cur = cluster_end + 1;
+		cur = max(cluster_end + 1, last_scanned);
 		if (ret > 0) {
 			ret = 0;
 			break;
 		}
+		cond_resched();
 	}
 
 	if (ra_allocated)
diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c
index 0fb90cbe7669..e6e28a9c7987 100644
--- a/fs/btrfs/lzo.c
+++ b/fs/btrfs/lzo.c
@@ -380,6 +380,17 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 		kunmap(cur_page);
 		cur_in += LZO_LEN;
 
+		if (seg_len > lzo1x_worst_compress(PAGE_SIZE)) {
+			/*
+			 * seg_len shouldn't be larger than we have allocated
+			 * for workspace->cbuf
+			 */
+			btrfs_err(fs_info, "unexpectedly large lzo segment len %u",
+					seg_len);
+			ret = -EIO;
+			goto out;
+		}
+
 		/* Copy the compressed segment payload into workspace */
 		copy_compressed_segment(cb, workspace->cbuf, seg_len, &cur_in);
 
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index d8ccb62aa7d2..201eb2628aea 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -4999,6 +4999,10 @@ static int put_file_data(struct send_ctx *sctx, u64 offset, u32 len)
 			lock_page(page);
 			if (!PageUptodate(page)) {
 				unlock_page(page);
+				btrfs_err(fs_info,
+			"send: IO error at offset %llu for inode %llu root %llu",
+					page_offset(page), sctx->cur_ino,
+					sctx->send_root->root_key.objectid);
 				put_page(page);
 				ret = -EIO;
 				break;
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index c43bbc7f623e..c3cfdfd8de9b 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1981,16 +1981,24 @@ static void btrfs_cleanup_pending_block_groups(struct btrfs_trans_handle *trans)
 static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
 {
 	/*
-	 * We use writeback_inodes_sb here because if we used
+	 * We use try_to_writeback_inodes_sb() here because if we used
 	 * btrfs_start_delalloc_roots we would deadlock with fs freeze.
 	 * Currently are holding the fs freeze lock, if we do an async flush
 	 * we'll do btrfs_join_transaction() and deadlock because we need to
 	 * wait for the fs freeze lock.  Using the direct flushing we benefit
 	 * from already being in a transaction and our join_transaction doesn't
 	 * have to re-take the fs freeze lock.
+	 *
+	 * Note that try_to_writeback_inodes_sb() will only trigger writeback
+	 * if it can read lock sb->s_umount. It will always be able to lock it,
+	 * except when the filesystem is being unmounted or being frozen, but in
+	 * those cases sync_filesystem() is called, which results in calling
+	 * writeback_inodes_sb() while holding a write lock on sb->s_umount.
+	 * Note that we don't call writeback_inodes_sb() directly, because it
+	 * will emit a warning if sb->s_umount is not locked.
 	 */
 	if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
-		writeback_inodes_sb(fs_info->sb, WB_REASON_SYNC);
+		try_to_writeback_inodes_sb(fs_info->sb, WB_REASON_SYNC);
 	return 0;
 }