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@xxxxxxxx>
---
fs/btrfs/ctree.h | 14 ++++++++++++--
fs/btrfs/volumes.c | 42 ++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/volumes.h | 1 +
include/uapi/linux/btrfs.h | 13 ++++++++++++-
4 files changed, 67 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..0fbe6855ea05 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3250,6 +3250,16 @@ static int should_balance_chunk(struct btrfs_root *root,
return 0;
else
bargs->limit--;
+ } else if ((bargs->flags & BTRFS_BALANCE_ARGS_LIMITS)) {
+ /*
+ * Same logic as the 'limit' filter; the minimum cannot be
+ * determined here because we do not have the global informatoin
+ * about the count of all chunks that satisfy the filters.
+ */
+ if (bargs->limit_max == 0)
+ return 0;
+ else
+ bargs->limit_max--;
}
return 1;
@@ -3264,6 +3274,7 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
struct btrfs_device *device;
u64 old_size;
u64 size_to_free;
+ u64 chunk_type;
struct btrfs_chunk *chunk;
struct btrfs_path *path;
struct btrfs_key key;
@@ -3274,9 +3285,13 @@ 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;
+ u32 count_data = 0;
+ u32 count_meta = 0;
+ u32 count_sys = 0;
/* step one make some room on all the devices */
devices = &fs_info->fs_devices->devices;
@@ -3317,6 +3332,10 @@ 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;
@@ -3364,6 +3383,7 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
}
chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
+ chunk_type = btrfs_chunk_type(leaf, chunk);
if (!counting) {
spin_lock(&fs_info->balance_lock);
@@ -3384,6 +3404,28 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
spin_lock(&fs_info->balance_lock);
bctl->stat.expected++;
spin_unlock(&fs_info->balance_lock);
+
+ if (chunk_type & BTRFS_BLOCK_GROUP_DATA)
+ count_data++;
+ else if (chunk_type & BTRFS_BLOCK_GROUP_SYSTEM)
+ count_sys++;
+ else if (chunk_type & BTRFS_BLOCK_GROUP_METADATA)
+ count_meta++;
+
+ goto loop;
+ }
+
+ /*
+ * Apply limit_min filter, no need to check if the LIMITS
+ * filter is used, limit_min is 0 by default
+ */
+ if (((chunk_type & BTRFS_BLOCK_GROUP_DATA) &&
+ count_data < bctl->data.limit_min)
+ || ((chunk_type & BTRFS_BLOCK_GROUP_METADATA) &&
+ count_meta < bctl->meta.limit_min)
+ || ((chunk_type & BTRFS_BLOCK_GROUP_SYSTEM) &&
+ count_sys < bctl->sys.limit_min)) {
+ mutex_unlock(&fs_info->delete_unused_bgs_mutex);
goto loop;
}
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
--
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