btrfs: balance filter: add limit of processed chunks
This started as debugging helper, to watch the effects of converting
between raid levels on multiple devices, but could be useful standalone.
In my case the usage filter was not finegrained enough and led to
converting too many chunks at once. Another example use is in connection
with drange+devid or vrange filters that allow to work with a specific
chunk or even with a chunk on a given device.
The limit filter applies last, the value of 0 means no limiting.
CC: Ilya Dryomov <idryomov@gmail.com>
CC: Hugo Mills <hugo@carfax.org.uk>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index ba6b885..e6f899d 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -840,7 +840,10 @@
/* BTRFS_BALANCE_ARGS_* */
__le64 flags;
- __le64 unused[8];
+ /* BTRFS_BALANCE_ARGS_LIMIT value */
+ __le64 limit;
+
+ __le64 unused[7];
} __attribute__ ((__packed__));
/*
@@ -2897,6 +2900,7 @@
cpu->vend = le64_to_cpu(disk->vend);
cpu->target = le64_to_cpu(disk->target);
cpu->flags = le64_to_cpu(disk->flags);
+ cpu->limit = le64_to_cpu(disk->limit);
}
static inline void
@@ -2914,6 +2918,7 @@
disk->vend = cpu_to_le64(cpu->vend);
disk->target = cpu_to_le64(cpu->target);
disk->flags = cpu_to_le64(cpu->flags);
+ disk->limit = cpu_to_le64(cpu->limit);
}
/* struct btrfs_super_block */
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 49d7fab..3b761a4 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2922,6 +2922,16 @@
return 0;
}
+ /*
+ * limited by count, must be the last filter
+ */
+ if ((bargs->flags & BTRFS_BALANCE_ARGS_LIMIT)) {
+ if (bargs->limit == 0)
+ return 0;
+ else
+ bargs->limit--;
+ }
+
return 1;
}
@@ -2944,6 +2954,9 @@
int ret;
int enospc_errors = 0;
bool counting = true;
+ u64 limit_data = bctl->data.limit;
+ u64 limit_meta = bctl->meta.limit;
+ u64 limit_sys = bctl->sys.limit;
/* step one make some room on all the devices */
devices = &fs_info->fs_devices->devices;
@@ -2982,6 +2995,11 @@
memset(&bctl->stat, 0, sizeof(bctl->stat));
spin_unlock(&fs_info->balance_lock);
again:
+ if (!counting) {
+ bctl->data.limit = limit_data;
+ bctl->meta.limit = limit_meta;
+ bctl->sys.limit = limit_sys;
+ }
key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
key.offset = (u64)-1;
key.type = BTRFS_CHUNK_ITEM_KEY;
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 80754f9..1a15bbe 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -255,6 +255,7 @@
#define BTRFS_BALANCE_ARGS_DEVID (1ULL << 2)
#define BTRFS_BALANCE_ARGS_DRANGE (1ULL << 3)
#define BTRFS_BALANCE_ARGS_VRANGE (1ULL << 4)
+#define BTRFS_BALANCE_ARGS_LIMIT (1ULL << 5)
/*
* 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 b4d6909..901a3c5 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -211,7 +211,8 @@
__u64 flags;
- __u64 unused[8];
+ __u64 limit; /* limit number of processed chunks */
+ __u64 unused[7];
} __attribute__ ((__packed__));
/* report balance progress to userspace */
