Btrfs: virtual address space subset filter

Select chunks which have at least one byte located inside a given
[vstart, vend) virtual address space range.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

2 files changed, 21 insertions, 0 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c60071a448a5..e86c9e4fe51e 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2207,6 +2207,20 @@ static int chunk_drange_filter(struct extent_buffer *leaf,
         return 1;
 }
 
+/* [vstart, vend) */
+static int chunk_vrange_filter(struct extent_buffer *leaf,
+                               struct btrfs_chunk *chunk,
+                               u64 chunk_offset,
+                               struct btrfs_balance_args *bargs)
+{
+        if (chunk_offset < bargs->vend &&
+            chunk_offset + btrfs_chunk_length(leaf, chunk) > bargs->vstart)
+                /* at least part of the chunk is inside this vrange */
+                return 0;
+
+        return 1;
+}
+
 static int should_balance_chunk(struct btrfs_root *root,
                                 struct extent_buffer *leaf,
                                 struct btrfs_chunk *chunk, u64 chunk_offset)
@@ -2252,6 +2266,12 @@ static int should_balance_chunk(struct btrfs_root *root,
                 return 0;
         }
 
+        /* vrange filter */
+        if ((bargs->flags & BTRFS_BALANCE_ARGS_VRANGE) &&
+            chunk_vrange_filter(leaf, chunk, chunk_offset, bargs)) {
+                return 0;
+        }
+
         return 1;
 }
 
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 844b08e388f2..eac26c359312 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -203,6 +203,7 @@ struct map_lookup {
 #define BTRFS_BALANCE_ARGS_USAGE        (1ULL << 1)
 #define BTRFS_BALANCE_ARGS_DEVID        (1ULL << 2)
 #define BTRFS_BALANCE_ARGS_DRANGE       (1ULL << 3)
+#define BTRFS_BALANCE_ARGS_VRANGE       (1ULL << 4)
 
 struct btrfs_balance_args;
 struct btrfs_balance_control {