Commit 7d824b6f authored by David Sterba's avatar David Sterba Committed by Chris Mason
Browse files

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: default avatarDavid Sterba <dsterba@suse.cz>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent fc19c5e7

fs/btrfs/ctree.h

+6 −1
Original line number Diff line number Diff line
@@ -840,7 +840,10 @@ struct btrfs_disk_balance_args { 
	/* BTRFS_BALANCE_ARGS_* */

	__le64 flags;



	__le64 unused[8];

	/* BTRFS_BALANCE_ARGS_LIMIT value */

	__le64 limit;



	__le64 unused[7];

} __attribute__ ((__packed__));



/*
@@ -2897,6 +2900,7 @@ btrfs_disk_balance_args_to_cpu(struct btrfs_balance_args *cpu, 
	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 @@ btrfs_cpu_balance_args_to_disk(struct btrfs_disk_balance_args *disk, 
	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 */

fs/btrfs/volumes.c

+18 −0
Original line number Diff line number Diff line
@@ -2922,6 +2922,16 @@ static int should_balance_chunk(struct btrfs_root *root, 
		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 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info) 
	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 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info) 
	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;

fs/btrfs/volumes.h

+1 −0
Original line number Diff line number Diff line
@@ -255,6 +255,7 @@ struct map_lookup { 
#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

include/uapi/linux/btrfs.h

+2 −1
Original line number Diff line number Diff line
@@ -211,7 +211,8 @@ struct btrfs_balance_args { 


	__u64 flags;



	__u64 unused[8];

	__u64 limit;		/* limit number of processed chunks */

	__u64 unused[7];

} __attribute__ ((__packed__));



/* report balance progress to userspace */

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