Btrfs: Handle write errors on raid1 and raid10

When duplicate copies exist, writes are allowed to fail to one of those
copies.  This changeset includes a few changes that allow the FS to
continue even when some IOs fail.

It also adds verification of the parent generation number for btree blocks.
This generation is stored in the pointer to a block, and it ensures
that missed writes to are detected.

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

1 files changed, 4 insertions, 3 deletions

diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c
index 5085e9e693b9..c02e2bf2f028 100644
--- a/fs/btrfs/tree-defrag.c
+++ b/fs/btrfs/tree-defrag.c
@@ -51,6 +51,7 @@ static int defrag_walk_down(struct btrfs_trans_handle *trans,
         struct extent_buffer *next;
         struct extent_buffer *cur;
         u64 bytenr;
+        u64 ptr_gen;
         int ret = 0;
         int is_extent = 0;
 
@@ -93,11 +94,12 @@ static int defrag_walk_down(struct btrfs_trans_handle *trans,
                         break;
                 }
                 bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
+                ptr_gen = btrfs_node_ptr_generation(cur, path->slots[*level]);
 
                 if (cache_only) {
                         next = btrfs_find_tree_block(root, bytenr,
                                            btrfs_level_size(root, *level - 1));
-                        if (!next || !btrfs_buffer_uptodate(next) ||
+                        if (!next || !btrfs_buffer_uptodate(next, ptr_gen) ||
                             !btrfs_buffer_defrag(next)) {
                                 free_extent_buffer(next);
                                 path->slots[*level]++;
@@ -106,8 +108,7 @@ static int defrag_walk_down(struct btrfs_trans_handle *trans,
                 } else {
                         next = read_tree_block(root, bytenr,
                                        btrfs_level_size(root, *level - 1),
-                                       btrfs_node_ptr_generation(cur,
-                                                         path->slots[*level]));
+                                       ptr_gen);
                 }
                 ret = btrfs_cow_block(trans, root, next, path->nodes[*level],
                                       path->slots[*level], &next);