btrfs: simplify update of last_dir_index_offset when logging a directory

When logging a directory, we always set the inode's last_dir_index_offset
to the offset of the last dir index item we found. This is using an extra
field in the log context structure, and it makes more sense to update it
only after we insert dir index items, and we could directly update the
inode's last_dir_index_offset field instead.

So make this simpler by updating the inode's last_dir_index_offset only
when we actually insert dir index keys in the log tree, and getting rid
of the last_dir_item_offset field in the log context structure.

Reported-by: David Arendt <admin@prnet.org>
Link: https://lore.kernel.org/linux-btrfs/ae169fc6-f504-28f0-a098-6fa6a4dfb612@leemhuis.info/
Reported-by: Maxim Mikityanskiy <maxtram95@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/Y8voyTXdnPDz8xwY@mail.gmail.com/
Reported-by: Hunter Wardlaw <wardlawhunter@gmail.com>
Link: https://bugzilla.suse.com/show_bug.cgi?id=1207231
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=216851
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/tree-log.c

@@ -3576,17 +3576,19 @@ static noinline int insert_dir_log_key(struct btrfs_trans_handle *trans,
 }
 
 static int flush_dir_items_batch(struct btrfs_trans_handle *trans,
-				 struct btrfs_root *log,
+				 struct btrfs_inode *inode,
 				 struct extent_buffer *src,
 				 struct btrfs_path *dst_path,
 				 int start_slot,
 				 int count)
 {
+	struct btrfs_root *log = inode->root->log_root;
 	char *ins_data = NULL;
 	struct btrfs_item_batch batch;
 	struct extent_buffer *dst;
 	unsigned long src_offset;
 	unsigned long dst_offset;
+	u64 last_index;
 	struct btrfs_key key;
 	u32 item_size;
 	int ret;
@@ -3644,6 +3646,19 @@ static int flush_dir_items_batch(struct btrfs_trans_handle *trans,
 	src_offset = btrfs_item_ptr_offset(src, start_slot + count - 1);
 	copy_extent_buffer(dst, src, dst_offset, src_offset, batch.total_data_size);
 	btrfs_release_path(dst_path);
+
+	last_index = batch.keys[count - 1].offset;
+	ASSERT(last_index > inode->last_dir_index_offset);
+
+	/*
+	 * If for some unexpected reason the last item's index is not greater
+	 * than the last index we logged, warn and return an error to fallback
+	 * to a transaction commit.
+	 */
+	if (WARN_ON(last_index <= inode->last_dir_index_offset))
+		ret = -EUCLEAN;
+	else
+		inode->last_dir_index_offset = last_index;
 out:
 	kfree(ins_data);
 
@@ -3693,7 +3708,6 @@ static int process_dir_items_leaf(struct btrfs_trans_handle *trans,
 		}
 
 		di = btrfs_item_ptr(src, i, struct btrfs_dir_item);
-		ctx->last_dir_item_offset = key.offset;
 
 		/*
 		 * Skip ranges of items that consist only of dir item keys created
@@ -3756,7 +3770,7 @@ static int process_dir_items_leaf(struct btrfs_trans_handle *trans,
 	if (batch_size > 0) {
 		int ret;
 
-		ret = flush_dir_items_batch(trans, log, src, dst_path,
+		ret = flush_dir_items_batch(trans, inode, src, dst_path,
 					    batch_start, batch_size);
 		if (ret < 0)
 			return ret;
@@ -4044,7 +4058,6 @@ static noinline int log_directory_changes(struct btrfs_trans_handle *trans,
 
 	min_key = BTRFS_DIR_START_INDEX;
 	max_key = 0;
-	ctx->last_dir_item_offset = inode->last_dir_index_offset;
 
 	while (1) {
 		ret = log_dir_items(trans, inode, path, dst_path,
@@ -4056,8 +4069,6 @@ static noinline int log_directory_changes(struct btrfs_trans_handle *trans,
 		min_key = max_key + 1;
 	}
 
-	inode->last_dir_index_offset = ctx->last_dir_item_offset;
-
 	return 0;
 }
 

fs/btrfs/tree-log.h

@@ -24,8 +24,6 @@ struct btrfs_log_ctx {
 	bool logging_new_delayed_dentries;
 	/* Indicate if the inode being logged was logged before. */
 	bool logged_before;
-	/* Tracks the last logged dir item/index key offset. */
-	u64 last_dir_item_offset;
 	struct inode *inode;
 	struct list_head list;
 	/* Only used for fast fsyncs. */