[PATCH 0/2] Balance filters: stripes, enhanced limit

[PATCH 0/2] Balance filters: stripes, enhanced limit

[David Sterba]

Update to balance filters, intended fro 4.4:

* new 'stripes=<range>' - process only stripes that cross given number of
  devices, specified by a range

* updated 'limit=<range>' - previously a single number was accepted, it's a
  range so now we can specify a minimum number of chunks to process

There will be more documentation about the use in the btrfs-progs patches, the
kernel side just applies the ranges. The update to 'limit' is backward
compatible, reuses the previous struct member.

Can be pulled from

  git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git dev/balance-filters

I'm finalizing the progs patches and haven't tested that them extensively.


David Sterba (1):
  btrfs: extend balance filter limit to take minimum and maximum

Gabríel Arthúr Pétursson (1):
  btrfs: add balance filter for stripes

 fs/btrfs/ctree.h           | 23 ++++++++++++++++++++---
 fs/btrfs/volumes.c         | 33 +++++++++++++++++++++++++++++++++
 fs/btrfs/volumes.h         |  2 ++
 include/uapi/linux/btrfs.h | 23 +++++++++++++++++++++--
 4 files changed, 76 insertions(+), 5 deletions(-)

-- 
2.6.1

[PATCH 1/2] btrfs: extend balance filter limit to take minimum and maximum

[David Sterba]

The 'limit' filter is underdesigned, it should have been a range for
[min,max], with some relaxed semantics when one of the bounds is
missing. Besides that, using a full u64 for a single value is a waste of
bytes.

Let's fix both by extending the use of the u64 bytes for the [min,max]
range. This can be done in a backward compatible way, the range will be
interpreted only if the appropriate flag is set
(BTRFS_BALANCE_ARGS_LIMITS).

Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/ctree.h           | 14 ++++++++++++--
 fs/btrfs/volumes.c         | 14 ++++++++++++++
 fs/btrfs/volumes.h         |  1 +
 include/uapi/linux/btrfs.h | 13 ++++++++++++-
 4 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 938efe33be80..7d2e1b6d0ac1 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -846,8 +846,18 @@ struct btrfs_disk_balance_args {
 	/* BTRFS_BALANCE_ARGS_* */
 	__le64 flags;
 
-	/* BTRFS_BALANCE_ARGS_LIMIT value */
-	__le64 limit;
+	/*
+	 * BTRFS_BALANCE_ARGS_LIMIT with value 'limit'
+	 * BTRFS_BALANCE_ARGS_LIMITS - the extend version can use minimum and
+	 * maximum
+	 */
+	union {
+		__le64 limit;
+		struct {
+			__le32 limit_min;
+			__le32 limit_max;
+		};
+	};
 
 	__le64 unused[7];
 } __attribute__ ((__packed__));
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6fc735869c18..0693e974f1c0 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3250,6 +3250,15 @@ static int should_balance_chunk(struct btrfs_root *root,
 			return 0;
 		else
 			bargs->limit--;
+	} else if ((bargs->flags & BTRFS_BALANCE_ARGS_LIMITS)) {
+		if (bargs->limit_min < bargs->limit_max) {
+			bargs->limit_max--;
+		} else if (bargs->limit_min == bargs->limit_max) {
+			bargs->limit_min = UINT_MAX;
+			bargs->limit_max = 0;
+		} else {
+			return 0;
+		}
 	}
 
 	return 1;
@@ -3274,6 +3283,7 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
 	int ret;
 	int enospc_errors = 0;
 	bool counting = true;
+	/* The single value limit and min/max limits use the same bytes in the */
 	u64 limit_data = bctl->data.limit;
 	u64 limit_meta = bctl->meta.limit;
 	u64 limit_sys = bctl->sys.limit;
@@ -3317,6 +3327,10 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
 	spin_unlock(&fs_info->balance_lock);
 again:
 	if (!counting) {
+		/*
+		 * The single value limit and min/max limits use the same bytes
+		 * in the
+		 */
 		bctl->data.limit = limit_data;
 		bctl->meta.limit = limit_meta;
 		bctl->sys.limit = limit_sys;
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 2ca784a14e84..1c9d8edd7d57 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -375,6 +375,7 @@ struct map_lookup {
 #define BTRFS_BALANCE_ARGS_DRANGE	(1ULL << 3)
 #define BTRFS_BALANCE_ARGS_VRANGE	(1ULL << 4)
 #define BTRFS_BALANCE_ARGS_LIMIT	(1ULL << 5)
+#define BTRFS_BALANCE_ARGS_LIMITS	(1ULL << 6)
 
 /*
  * Profile changing flags.  When SOFT is set we won't relocate chunk if
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index b6dec05c7196..264ecea5ecfc 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -217,7 +217,18 @@ struct btrfs_balance_args {
 
 	__u64 flags;
 
-	__u64 limit;		/* limit number of processed chunks */
+	/*
+	 * BTRFS_BALANCE_ARGS_LIMIT with value 'limit'
+	 * BTRFS_BALANCE_ARGS_LIMITS - the extend version can use minimum and
+	 * maximum
+	 */
+	union {
+		__u64 limit;		/* limit number of processed chunks */
+		struct {
+			__u32 limit_min;
+			__u32 limit_max;
+		};
+	};
 	__u64 unused[7];
 } __attribute__ ((__packed__));
 
-- 
2.6.1

[PATCH 2/2] btrfs: add balance filter for stripes

[David Sterba]

From: Gabríel Arthúr Pétursson <gabriel@system.is>

Balance block groups which have the given number of stripes, defined by
a range min..max. This is useful to selectively rebalance only chunks
that do not span enough devices, applies to RAID0/10/5/6.

Signed-off-by: Gabríel Arthúr Pétursson <gabriel@system.is>
[ renamed bargs members, added to the UAPI, wrote the changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/ctree.h           |  9 ++++++++-
 fs/btrfs/volumes.c         | 19 +++++++++++++++++++
 fs/btrfs/volumes.h         |  1 +
 include/uapi/linux/btrfs.h | 10 +++++++++-
 4 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 7d2e1b6d0ac1..e2eefa222999 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -859,7 +859,14 @@ struct btrfs_disk_balance_args {
 		};
 	};
 
-	__le64 unused[7];
+	/*
+	 * Process chunks that cross stripes_min..stripes_max devices,
+	 * BTRFS_BALANCE_ARGS_STRIPES
+	 */
+	__le32 stripes_min;
+	__le32 stripes_max;
+
+	__le64 unused[6];
 } __attribute__ ((__packed__));
 
 /*
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 0693e974f1c0..51c0e5b219a3 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3170,6 +3170,19 @@ static int chunk_vrange_filter(struct extent_buffer *leaf,
 	return 1;
 }
 
+static int chunk_stripes_filter(struct extent_buffer *leaf,
+			       struct btrfs_chunk *chunk,
+			       struct btrfs_balance_args *bargs)
+{
+	int num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
+
+	if (bargs->stripes_min <= num_stripes
+			&& num_stripes <= bargs->stripes_max)
+		return 0;
+
+	return 1;
+}
+
 static int chunk_soft_convert_filter(u64 chunk_type,
 				     struct btrfs_balance_args *bargs)
 {
@@ -3236,6 +3249,12 @@ static int should_balance_chunk(struct btrfs_root *root,
 		return 0;
 	}
 
+	/* stripes filter */
+	if ((bargs->flags & BTRFS_BALANCE_ARGS_STRIPES) &&
+	    chunk_stripes_filter(leaf, chunk, bargs)) {
+		return 0;
+	}
+
 	/* soft profile changing mode */
 	if ((bargs->flags & BTRFS_BALANCE_ARGS_SOFT) &&
 	    chunk_soft_convert_filter(chunk_type, bargs)) {
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 1c9d8edd7d57..a87d96d75d07 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -376,6 +376,7 @@ struct map_lookup {
 #define BTRFS_BALANCE_ARGS_VRANGE	(1ULL << 4)
 #define BTRFS_BALANCE_ARGS_LIMIT	(1ULL << 5)
 #define BTRFS_BALANCE_ARGS_LIMITS	(1ULL << 6)
+#define BTRFS_BALANCE_ARGS_STRIPES	(1ULL << 7)
 
 /*
  * Profile changing flags.  When SOFT is set we won't relocate chunk if
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 264ecea5ecfc..ab720200d0f7 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -229,7 +229,15 @@ struct btrfs_balance_args {
 			__u32 limit_max;
 		};
 	};
-	__u64 unused[7];
+
+	/*
+	 * Process chunks that cross stripes_min..stripes_max devices,
+	 * BTRFS_BALANCE_ARGS_STRIPES
+	 */
+	__le32 stripes_min;
+	__le32 stripes_max;
+
+	__u64 unused[6];
 } __attribute__ ((__packed__));
 
 /* report balance progress to userspace */
-- 
2.6.1