Btrfs: devid subset filter

Select chunks which have at least one byte of at least one stripe
located on a device with devid X in a given [pstart,pend) physical
address range.

This filter only works when devid filter is turned on.

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

1 files changed, 46 insertions, 0 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 9ff5cd09a256..c60071a448a5 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2167,6 +2167,46 @@ static int chunk_devid_filter(struct extent_buffer *leaf,
         return 1;
 }
 
+/* [pstart, pend) */
+static int chunk_drange_filter(struct extent_buffer *leaf,
+                               struct btrfs_chunk *chunk,
+                               u64 chunk_offset,
+                               struct btrfs_balance_args *bargs)
+{
+        struct btrfs_stripe *stripe;
+        int num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
+        u64 stripe_offset;
+        u64 stripe_length;
+        int factor;
+        int i;
+
+        if (!(bargs->flags & BTRFS_BALANCE_ARGS_DEVID))
+                return 0;
+
+        if (btrfs_chunk_type(leaf, chunk) & (BTRFS_BLOCK_GROUP_DUP |
+             BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID10))
+                factor = 2;
+        else
+                factor = 1;
+        factor = num_stripes / factor;
+
+        for (i = 0; i < num_stripes; i++) {
+                stripe = btrfs_stripe_nr(chunk, i);
+                if (btrfs_stripe_devid(leaf, stripe) != bargs->devid)
+                        continue;
+
+                stripe_offset = btrfs_stripe_offset(leaf, stripe);
+                stripe_length = btrfs_chunk_length(leaf, chunk);
+                do_div(stripe_length, factor);
+
+                if (stripe_offset < bargs->pend &&
+                    stripe_offset + stripe_length > bargs->pstart)
+                        return 0;
+        }
+
+        return 1;
+}
+
 static int should_balance_chunk(struct btrfs_root *root,
                                 struct extent_buffer *leaf,
                                 struct btrfs_chunk *chunk, u64 chunk_offset)
@@ -2206,6 +2246,12 @@ static int should_balance_chunk(struct btrfs_root *root,
                 return 0;
         }
 
+        /* drange filter, makes sense only with devid filter */
+        if ((bargs->flags & BTRFS_BALANCE_ARGS_DRANGE) &&
+            chunk_drange_filter(leaf, chunk, chunk_offset, bargs)) {
+                return 0;
+        }
+
         return 1;
 }