Btrfs: make fsync work after cloning into a file

When cloning into a file, we were correctly replacing the extent
items in the target range and removing the extent maps. However
we weren't replacing the extent maps with new ones that point to
the new extents - as a consequence, an incremental fsync (when the
inode doesn't have the full sync flag) was a NOOP, since it relies
on the existence of extent maps in the modified list of the inode's
extent map tree, which was empty. Therefore add new extent maps to
reflect the target clone range.

A test case for xfstests follows.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 4 insertions, 38 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 477e64a1146f..372b2cb2b297 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6129,7 +6129,6 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 {
 	int ret;
 	int err = 0;
-	u64 bytenr;
 	u64 extent_start = 0;
 	u64 extent_end = 0;
 	u64 objectid = btrfs_ino(inode);
@@ -6143,7 +6142,7 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct btrfs_trans_handle *trans = NULL;
-	int compress_type;
+	const bool new_inline = !page || create;
 
 again:
 	read_lock(&em_tree->lock);
@@ -6217,7 +6216,6 @@ again:
 
 	found_type = btrfs_file_extent_type(leaf, item);
 	extent_start = found_key.offset;
-	compress_type = btrfs_file_extent_compression(leaf, item);
 	if (found_type == BTRFS_FILE_EXTENT_REG ||
 	    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
 		extent_end = extent_start +
@@ -6252,32 +6250,10 @@ next:
 		goto not_found_em;
 	}
 
-	em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, item);
+	btrfs_extent_item_to_extent_map(inode, path, item, new_inline, em);
+
 	if (found_type == BTRFS_FILE_EXTENT_REG ||
 	    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
-		em->start = extent_start;
-		em->len = extent_end - extent_start;
-		em->orig_start = extent_start -
-				 btrfs_file_extent_offset(leaf, item);
-		em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf,
-								      item);
-		bytenr = btrfs_file_extent_disk_bytenr(leaf, item);
-		if (bytenr == 0) {
-			em->block_start = EXTENT_MAP_HOLE;
-			goto insert;
-		}
-		if (compress_type != BTRFS_COMPRESS_NONE) {
-			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
-			em->compress_type = compress_type;
-			em->block_start = bytenr;
-			em->block_len = em->orig_block_len;
-		} else {
-			bytenr += btrfs_file_extent_offset(leaf, item);
-			em->block_start = bytenr;
-			em->block_len = em->len;
-			if (found_type == BTRFS_FILE_EXTENT_PREALLOC)
-				set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
-		}
 		goto insert;
 	} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 		unsigned long ptr;
@@ -6286,12 +6262,8 @@ next:
 		size_t extent_offset;
 		size_t copy_size;
 
-		em->block_start = EXTENT_MAP_INLINE;
-		if (!page || create) {
-			em->start = extent_start;
-			em->len = extent_end - extent_start;
+		if (new_inline)
 			goto out;
-		}
 
 		size = btrfs_file_extent_inline_len(leaf, path->slots[0], item);
 		extent_offset = page_offset(page) + pg_offset - extent_start;
@@ -6301,10 +6273,6 @@ next:
 		em->len = ALIGN(copy_size, root->sectorsize);
 		em->orig_block_len = em->len;
 		em->orig_start = em->start;
-		if (compress_type) {
-			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
-			em->compress_type = compress_type;
-		}
 		ptr = btrfs_file_extent_inline_start(item) + extent_offset;
 		if (create == 0 && !PageUptodate(page)) {
 			if (btrfs_file_extent_compression(leaf, item) !=
@@ -6351,8 +6319,6 @@ next:
 		set_extent_uptodate(io_tree, em->start,
 				    extent_map_end(em) - 1, NULL, GFP_NOFS);
 		goto insert;
-	} else {
-		WARN(1, KERN_ERR "btrfs unknown found_type %d\n", found_type);
 	}
 not_found:
 	em->start = start;