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Btrfs: save balance parameters to disk
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Introduce a new btree objectid for storing balance item.  The reason is
to be able to resume restriper after a crash with the same parameters.
Balance item has a very high objectid and goes into tree of tree roots.

The key for the new item is as follows:

	[ BTRFS_BALANCE_OBJECTID ; BTRFS_BALANCE_ITEM_KEY ; 0 ]

Older kernels simply ignore it so it's safe to mount with an older
kernel and then go back to the newer one.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
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Ilya Dryomov committed Jan 16, 2012
1 parent cfa4c96 commit 0940ebf
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Showing 2 changed files with 231 additions and 1 deletion.
133 changes: 132 additions & 1 deletion fs/btrfs/ctree.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,9 @@ struct btrfs_ordered_sum;
/* holds checksums of all the data extents */
#define BTRFS_CSUM_TREE_OBJECTID 7ULL

/* for storing balance parameters in the root tree */
#define BTRFS_BALANCE_OBJECTID -4ULL

/* orhpan objectid for tracking unlinked/truncated files */
#define BTRFS_ORPHAN_OBJECTID -5ULL

Expand Down Expand Up @@ -692,6 +695,54 @@ struct btrfs_root_ref {
__le16 name_len;
} __attribute__ ((__packed__));

struct btrfs_disk_balance_args {
/*
* profiles to operate on, single is denoted by
* BTRFS_AVAIL_ALLOC_BIT_SINGLE
*/
__le64 profiles;

/* usage filter */
__le64 usage;

/* devid filter */
__le64 devid;

/* devid subset filter [pstart..pend) */
__le64 pstart;
__le64 pend;

/* btrfs virtual address space subset filter [vstart..vend) */
__le64 vstart;
__le64 vend;

/*
* profile to convert to, single is denoted by
* BTRFS_AVAIL_ALLOC_BIT_SINGLE
*/
__le64 target;

/* BTRFS_BALANCE_ARGS_* */
__le64 flags;

__le64 unused[8];
} __attribute__ ((__packed__));

/*
* store balance parameters to disk so that balance can be properly
* resumed after crash or unmount
*/
struct btrfs_balance_item {
/* BTRFS_BALANCE_* */
__le64 flags;

struct btrfs_disk_balance_args data;
struct btrfs_disk_balance_args meta;
struct btrfs_disk_balance_args sys;

__le64 unused[4];
} __attribute__ ((__packed__));

#define BTRFS_FILE_EXTENT_INLINE 0
#define BTRFS_FILE_EXTENT_REG 1
#define BTRFS_FILE_EXTENT_PREALLOC 2
Expand Down Expand Up @@ -1409,6 +1460,8 @@ struct btrfs_ioctl_defrag_range_args {
#define BTRFS_DEV_ITEM_KEY 216
#define BTRFS_CHUNK_ITEM_KEY 228

#define BTRFS_BALANCE_ITEM_KEY 248

/*
* string items are for debugging. They just store a short string of
* data in the FS
Expand Down Expand Up @@ -2103,8 +2156,86 @@ BTRFS_SETGET_STACK_FUNCS(backup_bytes_used, struct btrfs_root_backup,
BTRFS_SETGET_STACK_FUNCS(backup_num_devices, struct btrfs_root_backup,
num_devices, 64);

/* struct btrfs_super_block */
/* struct btrfs_balance_item */
BTRFS_SETGET_FUNCS(balance_flags, struct btrfs_balance_item, flags, 64);

static inline void btrfs_balance_data(struct extent_buffer *eb,
struct btrfs_balance_item *bi,
struct btrfs_disk_balance_args *ba)
{
read_eb_member(eb, bi, struct btrfs_balance_item, data, ba);
}

static inline void btrfs_set_balance_data(struct extent_buffer *eb,
struct btrfs_balance_item *bi,
struct btrfs_disk_balance_args *ba)
{
write_eb_member(eb, bi, struct btrfs_balance_item, data, ba);
}

static inline void btrfs_balance_meta(struct extent_buffer *eb,
struct btrfs_balance_item *bi,
struct btrfs_disk_balance_args *ba)
{
read_eb_member(eb, bi, struct btrfs_balance_item, meta, ba);
}

static inline void btrfs_set_balance_meta(struct extent_buffer *eb,
struct btrfs_balance_item *bi,
struct btrfs_disk_balance_args *ba)
{
write_eb_member(eb, bi, struct btrfs_balance_item, meta, ba);
}

static inline void btrfs_balance_sys(struct extent_buffer *eb,
struct btrfs_balance_item *bi,
struct btrfs_disk_balance_args *ba)
{
read_eb_member(eb, bi, struct btrfs_balance_item, sys, ba);
}

static inline void btrfs_set_balance_sys(struct extent_buffer *eb,
struct btrfs_balance_item *bi,
struct btrfs_disk_balance_args *ba)
{
write_eb_member(eb, bi, struct btrfs_balance_item, sys, ba);
}

static inline void
btrfs_disk_balance_args_to_cpu(struct btrfs_balance_args *cpu,
struct btrfs_disk_balance_args *disk)
{
memset(cpu, 0, sizeof(*cpu));

cpu->profiles = le64_to_cpu(disk->profiles);
cpu->usage = le64_to_cpu(disk->usage);
cpu->devid = le64_to_cpu(disk->devid);
cpu->pstart = le64_to_cpu(disk->pstart);
cpu->pend = le64_to_cpu(disk->pend);
cpu->vstart = le64_to_cpu(disk->vstart);
cpu->vend = le64_to_cpu(disk->vend);
cpu->target = le64_to_cpu(disk->target);
cpu->flags = le64_to_cpu(disk->flags);
}

static inline void
btrfs_cpu_balance_args_to_disk(struct btrfs_disk_balance_args *disk,
struct btrfs_balance_args *cpu)
{
memset(disk, 0, sizeof(*disk));

disk->profiles = cpu_to_le64(cpu->profiles);
disk->usage = cpu_to_le64(cpu->usage);
disk->devid = cpu_to_le64(cpu->devid);
disk->pstart = cpu_to_le64(cpu->pstart);
disk->pend = cpu_to_le64(cpu->pend);
disk->vstart = cpu_to_le64(cpu->vstart);
disk->vend = cpu_to_le64(cpu->vend);
disk->target = cpu_to_le64(cpu->target);
disk->flags = cpu_to_le64(cpu->flags);
}

/* struct btrfs_super_block */
BTRFS_SETGET_STACK_FUNCS(super_bytenr, struct btrfs_super_block, bytenr, 64);
BTRFS_SETGET_STACK_FUNCS(super_flags, struct btrfs_super_block, flags, 64);
BTRFS_SETGET_STACK_FUNCS(super_generation, struct btrfs_super_block,
Expand Down
99 changes: 99 additions & 0 deletions fs/btrfs/volumes.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2073,6 +2073,97 @@ static int btrfs_relocate_sys_chunks(struct btrfs_root *root)
return ret;
}

static int insert_balance_item(struct btrfs_root *root,
struct btrfs_balance_control *bctl)
{
struct btrfs_trans_handle *trans;
struct btrfs_balance_item *item;
struct btrfs_disk_balance_args disk_bargs;
struct btrfs_path *path;
struct extent_buffer *leaf;
struct btrfs_key key;
int ret, err;

path = btrfs_alloc_path();
if (!path)
return -ENOMEM;

trans = btrfs_start_transaction(root, 0);
if (IS_ERR(trans)) {
btrfs_free_path(path);
return PTR_ERR(trans);
}

key.objectid = BTRFS_BALANCE_OBJECTID;
key.type = BTRFS_BALANCE_ITEM_KEY;
key.offset = 0;

ret = btrfs_insert_empty_item(trans, root, path, &key,
sizeof(*item));
if (ret)
goto out;

leaf = path->nodes[0];
item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_balance_item);

memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));

btrfs_cpu_balance_args_to_disk(&disk_bargs, &bctl->data);
btrfs_set_balance_data(leaf, item, &disk_bargs);
btrfs_cpu_balance_args_to_disk(&disk_bargs, &bctl->meta);
btrfs_set_balance_meta(leaf, item, &disk_bargs);
btrfs_cpu_balance_args_to_disk(&disk_bargs, &bctl->sys);
btrfs_set_balance_sys(leaf, item, &disk_bargs);

btrfs_set_balance_flags(leaf, item, bctl->flags);

btrfs_mark_buffer_dirty(leaf);
out:
btrfs_free_path(path);
err = btrfs_commit_transaction(trans, root);
if (err && !ret)
ret = err;
return ret;
}

static int del_balance_item(struct btrfs_root *root)
{
struct btrfs_trans_handle *trans;
struct btrfs_path *path;
struct btrfs_key key;
int ret, err;

path = btrfs_alloc_path();
if (!path)
return -ENOMEM;

trans = btrfs_start_transaction(root, 0);
if (IS_ERR(trans)) {
btrfs_free_path(path);
return PTR_ERR(trans);
}

key.objectid = BTRFS_BALANCE_OBJECTID;
key.type = BTRFS_BALANCE_ITEM_KEY;
key.offset = 0;

ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
if (ret < 0)
goto out;
if (ret > 0) {
ret = -ENOENT;
goto out;
}

ret = btrfs_del_item(trans, root, path);
out:
btrfs_free_path(path);
err = btrfs_commit_transaction(trans, root);
if (err && !ret)
ret = err;
return ret;
}

/*
* Should be called with both balance and volume mutexes held to
* serialize other volume operations (add_dev/rm_dev/resize) with
Expand Down Expand Up @@ -2423,7 +2514,11 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)

static void __cancel_balance(struct btrfs_fs_info *fs_info)
{
int ret;

unset_balance_control(fs_info);
ret = del_balance_item(fs_info->tree_root);
BUG_ON(ret);
}

void update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
Expand Down Expand Up @@ -2530,6 +2625,10 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
}

do_balance:
ret = insert_balance_item(fs_info->tree_root, bctl);
if (ret)
goto out;

set_balance_control(bctl);

mutex_unlock(&fs_info->balance_mutex);
Expand Down

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