Btrfs: fix nodatasum handling in balancing code

Checksums on data can be disabled by mount option, so it's
possible some data extents don't have checksums or have
invalid checksums. This causes trouble for data relocation.
This patch contains following things to make data relocation
work.

1) make nodatasum/nodatacow mount option only affects new
files. Checksums and COW on data are only controlled by the
inode flags.

2) check the existence of checksum in the nodatacow checker.
If checksums exist, force COW the data extent. This ensure that
checksum for a given block is either valid or does not exist.

3) update data relocation code to properly handle the case
of checksum missing.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>

1 files changed, 3 insertions, 6 deletions

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index ad7274137309..2436163d5436 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -124,8 +124,7 @@ static int check_compressed_csum(struct inode *inode,
         u32 csum;
         u32 *cb_sum = &cb->sums;
 
-        if (btrfs_test_opt(root, NODATASUM) ||
-            btrfs_test_flag(inode, NODATASUM))
+        if (btrfs_test_flag(inode, NODATASUM))
                 return 0;
 
         for (i = 0; i < cb->nr_pages; i++) {
@@ -671,8 +670,7 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
                          */
                         atomic_inc(&cb->pending_bios);
 
-                        if (!btrfs_test_opt(root, NODATASUM) &&
-                            !btrfs_test_flag(inode, NODATASUM)) {
+                        if (!btrfs_test_flag(inode, NODATASUM)) {
                                 btrfs_lookup_bio_sums(root, inode, comp_bio,
                                                       sums);
                         }
@@ -699,8 +697,7 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
         ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
         BUG_ON(ret);
 
-        if (!btrfs_test_opt(root, NODATASUM) &&
-            !btrfs_test_flag(inode, NODATASUM)) {
+        if (!btrfs_test_flag(inode, NODATASUM)) {
                 btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
         }