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| author | Nikolay Borisov <nborisov@suse.com> | 2019-08-21 10:42:57 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2019-09-09 14:59:13 +0200 |
| commit | a6bd9cd1559b8e78d1d03fe64445ae6dc419ea16 (patch) | |
| tree | 0a3735e4c27a50ad4456bfa2e3ce193e1287b9e0 /fs/btrfs/extent-tree.c | |
| parent | 3e024846d241b992ded27fdfdb78ea819abaa0cb (diff) | |
btrfs: improve comments around nocow path
run_delalloc_nocow contains numerous, somewhat subtle, checks when
figuring out whether a particular extent should be CoW'ed or not. This
patch explicitly states the assumptions those checks verify. As a
result also document 2 of the more subtle checks in check_committed_ref
as well.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/extent-tree.c')
| -rw-r--r-- | fs/btrfs/extent-tree.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 5e8c6a0bac4b..af7631472073 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -2357,16 +2357,19 @@ static noinline int check_committed_ref(struct btrfs_root *root, item_size = btrfs_item_size_nr(leaf, path->slots[0]); ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item); + /* If extent item has more than 1 inline ref then it's shared */ if (item_size != sizeof(*ei) + btrfs_extent_inline_ref_size(BTRFS_EXTENT_DATA_REF_KEY)) goto out; + /* If extent created before last snapshot => it's definitely shared */ if (btrfs_extent_generation(leaf, ei) <= btrfs_root_last_snapshot(&root->root_item)) goto out; iref = (struct btrfs_extent_inline_ref *)(ei + 1); + /* If this extent has SHARED_DATA_REF then it's shared */ type = btrfs_get_extent_inline_ref_type(leaf, iref, BTRFS_REF_TYPE_DATA); if (type != BTRFS_EXTENT_DATA_REF_KEY) goto out; |