Btrfs: fix btrfs send for inline items and compression

The btrfs send code was assuming the offset of the file item into the
extent translated to bytes on disk.  If we're compressed, this isn't
true, and so it was off into extents owned by other files.

It was also improperly handling inline extents.  This solves a crash
where we may have gone past the end of the file extent item by not
testing early enough for an inline extent.  It also solves problems
where we have a whole between the end of the inline item and the start
of the full extent.

Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/ctree.c

@@ -5073,6 +5073,7 @@ static void tree_move_down(struct btrfs_root *root,
 			   struct btrfs_path *path,
 			   int *level, int root_level)
 {
+	BUG_ON(*level == 0);
 	path->nodes[*level - 1] = read_node_slot(root, path->nodes[*level],
 					path->slots[*level]);
 	path->slots[*level - 1] = 0;
@@ -5089,7 +5090,7 @@ static int tree_move_next_or_upnext(struct btrfs_root *root,
 
 	path->slots[*level]++;
 
-	while (path->slots[*level] == nritems) {
+	while (path->slots[*level] >= nritems) {
 		if (*level == root_level)
 			return -1;
 
@@ -5433,9 +5434,11 @@ int btrfs_compare_trees(struct btrfs_root *left_root,
 					goto out;
 				advance_right = ADVANCE;
 			} else {
+				WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
 				ret = tree_compare_item(left_root, left_path,
 						right_path, tmp_buf);
 				if (ret) {
+					WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
 					ret = changed_cb(left_root, right_root,
 						left_path, right_path,
 						&left_key,

fs/btrfs/extent_io.c

@@ -4332,7 +4332,6 @@ static int release_extent_buffer(struct extent_buffer *eb, gfp_t mask)
 
 		/* Should be safe to release our pages at this point */
 		btrfs_release_extent_buffer_page(eb, 0);
-
 		call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
 		return 1;
 	}

fs/btrfs/send.c

@@ -1149,6 +1149,7 @@ static int find_extent_clone(struct send_ctx *sctx,
 	int ret;
 	int extent_type;
 	u64 logical;
+	u64 disk_byte;
 	u64 num_bytes;
 	u64 extent_item_pos;
 	struct btrfs_file_extent_item *fi;
@@ -1157,6 +1158,7 @@ static int find_extent_clone(struct send_ctx *sctx,
 	struct clone_root *cur_clone_root;
 	struct btrfs_key found_key;
 	struct btrfs_path *tmp_path;
+	int compressed;
 	u32 i;
 
 	tmp_path = alloc_path_for_send();
@@ -1186,17 +1188,18 @@ static int find_extent_clone(struct send_ctx *sctx,
 		ret = -ENOENT;
 		goto out;
 	}
+	compressed = btrfs_file_extent_compression(eb, fi);
 
 	num_bytes = btrfs_file_extent_num_bytes(eb, fi);
-	logical = btrfs_file_extent_disk_bytenr(eb, fi);
-	if (logical == 0) {
+	disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
+	if (disk_byte == 0) {
 		ret = -ENOENT;
 		goto out;
 	}
-	logical += btrfs_file_extent_offset(eb, fi);
+	logical = disk_byte + btrfs_file_extent_offset(eb, fi);
 
 	ret = extent_from_logical(sctx->send_root->fs_info,
-			logical, tmp_path, &found_key);
+			disk_byte, tmp_path, &found_key);
 	btrfs_release_path(tmp_path);
 
 	if (ret < 0)
@@ -1234,10 +1237,16 @@ static int find_extent_clone(struct send_ctx *sctx,
 	/*
 	 * Now collect all backrefs.
 	 */
+	if (compressed == BTRFS_COMPRESS_NONE)
+		extent_item_pos = logical - found_key.objectid;
+	else
+		extent_item_pos = 0;
+
 	extent_item_pos = logical - found_key.objectid;
 	ret = iterate_extent_inodes(sctx->send_root->fs_info,
 					found_key.objectid, extent_item_pos, 1,
 					__iterate_backrefs, backref_ctx);
+
 	if (ret < 0)
 		goto out;
 
@@ -1246,8 +1255,8 @@ static int find_extent_clone(struct send_ctx *sctx,
 		ret = -EIO;
 		printk(KERN_ERR "btrfs: ERROR did not find backref in "
 				"send_root. inode=%llu, offset=%llu, "
-				"logical=%llu\n",
-				ino, data_offset, logical);
+				"disk_byte=%llu found extent=%llu\n",
+				ino, data_offset, disk_byte, found_key.objectid);
 		goto out;
 	}
 
@@ -3678,10 +3687,17 @@ static int send_write_or_clone(struct send_ctx *sctx,
 	ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
 			struct btrfs_file_extent_item);
 	type = btrfs_file_extent_type(path->nodes[0], ei);
-	if (type == BTRFS_FILE_EXTENT_INLINE)
+	if (type == BTRFS_FILE_EXTENT_INLINE) {
 		len = btrfs_file_extent_inline_len(path->nodes[0], ei);
-	else
+		/*
+		 * it is possible the inline item won't cover the whole page,
+		 * but there may be items after this page.  Make
+		 * sure to send the whole thing
+		 */
+		len = PAGE_CACHE_ALIGN(len);
+	} else {
 		len = btrfs_file_extent_num_bytes(path->nodes[0], ei);
+	}
 
 	if (offset + len > sctx->cur_inode_size)
 		len = sctx->cur_inode_size - offset;
@@ -3729,6 +3745,8 @@ static int is_extent_unchanged(struct send_ctx *sctx,
 	u64 left_offset_fixed;
 	u64 left_len;
 	u64 right_len;
+	u64 left_gen;
+	u64 right_gen;
 	u8 left_type;
 	u8 right_type;
 
@@ -3738,17 +3756,17 @@ static int is_extent_unchanged(struct send_ctx *sctx,
 
 	eb = left_path->nodes[0];
 	slot = left_path->slots[0];
-
 	ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
 	left_type = btrfs_file_extent_type(eb, ei);
-	left_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
-	left_len = btrfs_file_extent_num_bytes(eb, ei);
-	left_offset = btrfs_file_extent_offset(eb, ei);
 
 	if (left_type != BTRFS_FILE_EXTENT_REG) {
 		ret = 0;
 		goto out;
 	}
+	left_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
+	left_len = btrfs_file_extent_num_bytes(eb, ei);
+	left_offset = btrfs_file_extent_offset(eb, ei);
+	left_gen = btrfs_file_extent_generation(eb, ei);
 
 	/*
 	 * Following comments will refer to these graphics. L is the left
@@ -3804,6 +3822,7 @@ static int is_extent_unchanged(struct send_ctx *sctx,
 		right_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
 		right_len = btrfs_file_extent_num_bytes(eb, ei);
 		right_offset = btrfs_file_extent_offset(eb, ei);
+		right_gen = btrfs_file_extent_generation(eb, ei);
 
 		if (right_type != BTRFS_FILE_EXTENT_REG) {
 			ret = 0;
@@ -3832,7 +3851,8 @@ static int is_extent_unchanged(struct send_ctx *sctx,
 		 * Check if we have the same extent.
 		 */
 		if (left_disknr != right_disknr ||
-		    left_offset_fixed != right_offset) {
+		    left_offset_fixed != right_offset ||
+		    left_gen != right_gen) {
 			ret = 0;
 			goto out;
 		}