btrfs: extend balance filter usage to take minimum and maximum

Similar to the 'limit' filter, we can enhance the 'usage' filter to
accept a range. The change is backward compatible, the range is applied
only in connection with the BTRFS_BALANCE_ARGS_USAGE_RANGE flag.

We don't have a usecase yet, the current syntax has been sufficient. The
enhancement should provide parity with other range-like filters.

Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>

4 files changed, 60 insertions, 4 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 8ccbf4317a4a..4001585ec434 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -823,8 +823,18 @@ struct btrfs_disk_balance_args {
          */
         __le64 profiles;
 
-        /* usage filter */
-        __le64 usage;
+        /*
+         * usage filter
+         * BTRFS_BALANCE_ARGS_USAGE with a single value means '0..N'
+         * BTRFS_BALANCE_ARGS_USAGE_RANGE - range syntax, min..max
+         */
+        union {
+                __le64 usage;
+                struct {
+                        __le32 usage_min;
+                        __le32 usage_max;
+                };
+        };
 
         /* devid filter */
         __le64 devid;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 9f5d16739880..17ed76d18eb6 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3059,16 +3059,19 @@ static void update_balance_args(struct btrfs_balance_control *bctl)
          * (albeit full) chunks.
          */
         if (!(bctl->data.flags & BTRFS_BALANCE_ARGS_USAGE) &&
+            !(bctl->data.flags & BTRFS_BALANCE_ARGS_USAGE_RANGE) &&
             !(bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT)) {
                 bctl->data.flags |= BTRFS_BALANCE_ARGS_USAGE;
                 bctl->data.usage = 90;
         }
         if (!(bctl->sys.flags & BTRFS_BALANCE_ARGS_USAGE) &&
+            !(bctl->sys.flags & BTRFS_BALANCE_ARGS_USAGE_RANGE) &&
             !(bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT)) {
                 bctl->sys.flags |= BTRFS_BALANCE_ARGS_USAGE;
                 bctl->sys.usage = 90;
         }
         if (!(bctl->meta.flags & BTRFS_BALANCE_ARGS_USAGE) &&
+            !(bctl->meta.flags & BTRFS_BALANCE_ARGS_USAGE_RANGE) &&
             !(bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT)) {
                 bctl->meta.flags |= BTRFS_BALANCE_ARGS_USAGE;
                 bctl->meta.usage = 90;
@@ -3124,13 +3127,46 @@ static int chunk_usage_filter(struct btrfs_fs_info *fs_info, u64 chunk_offset,
                               struct btrfs_balance_args *bargs)
 {
         struct btrfs_block_group_cache *cache;
+        u64 chunk_used;
+        u64 user_thresh_min;
+        u64 user_thresh_max;
+        int ret = 1;
+
+        cache = btrfs_lookup_block_group(fs_info, chunk_offset);
+        chunk_used = btrfs_block_group_used(&cache->item);
+
+        if (bargs->usage_min == 0)
+                user_thresh_min = 0;
+        else
+                user_thresh_min = div_factor_fine(cache->key.offset,
+                                        bargs->usage_min);
+
+        if (bargs->usage_max == 0)
+                user_thresh_max = 1;
+        else if (bargs->usage_max > 100)
+                user_thresh_max = cache->key.offset;
+        else
+                user_thresh_max = div_factor_fine(cache->key.offset,
+                                        bargs->usage_max);
+
+        if (user_thresh_min <= chunk_used && chunk_used < user_thresh_max)
+                ret = 0;
+
+        btrfs_put_block_group(cache);
+        return ret;
+}
+
+static int chunk_usage_range_filter(struct btrfs_fs_info *fs_info,
+                u64 chunk_offset, struct btrfs_balance_args *bargs)
+{
+        struct btrfs_block_group_cache *cache;
         u64 chunk_used, user_thresh;
         int ret = 1;
 
         cache = btrfs_lookup_block_group(fs_info, chunk_offset);
         chunk_used = btrfs_block_group_used(&cache->item);
 
-        if (bargs->usage == 0)
+        if (bargs->usage_min == 0)
                 user_thresh = 1;
         else if (bargs->usage > 100)
                 user_thresh = cache->key.offset;
@@ -3279,6 +3315,9 @@ static int should_balance_chunk(struct btrfs_root *root,
         if ((bargs->flags & BTRFS_BALANCE_ARGS_USAGE) &&
             chunk_usage_filter(bctl->fs_info, chunk_offset, bargs)) {
                 return 0;
+        } else if ((bargs->flags & BTRFS_BALANCE_ARGS_USAGE_RANGE) &&
+            chunk_usage_range_filter(bctl->fs_info, chunk_offset, bargs)) {
+                return 0;
         }
 
         /* devid filter */
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index a5bf224d3c65..2a396cbb14a5 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -382,6 +382,7 @@ struct map_lookup {
 #define BTRFS_BALANCE_ARGS_LIMIT        (1ULL << 5)
 #define BTRFS_BALANCE_ARGS_LIMIT_RANGE  (1ULL << 6)
 #define BTRFS_BALANCE_ARGS_STRIPES_RANGE (1ULL << 7)
+#define BTRFS_BALANCE_ARGS_USAGE_RANGE  (1ULL << 8)
 
 #define BTRFS_BALANCE_ARGS_MASK                 \
         (BTRFS_BALANCE_ARGS_PROFILES |          \
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 17a94704b183..dea893199257 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -206,7 +206,13 @@ struct btrfs_ioctl_feature_flags {
  */
 struct btrfs_balance_args {
         __u64 profiles;
-        __u64 usage;
+        union {
+                __le64 usage;
+                struct {
+                        __le32 usage_min;
+                        __le32 usage_max;
+                };
+        };
         __u64 devid;
         __u64 pstart;
         __u64 pend;