On Fri, Sep 21, 2012 at 05:07:46PM +0800, Miao Xie wrote:
> div_factor{_fine} has been implemented for two times, and these two functions
> are very similar, so cleanup the reduplicate implement and drop the original
> div_factor(), and then rename div_factor_fine() to div_factor(). So the
> divisor
> of the new div_factor() is 100, not 10.
>
> And I move div_factor into a independent file named math.h because it is a
> common math function, may be used by every composition of btrfs.
>
> Because these functions are mostly used on the hot path, and we are sure
> the parameters are right in the most cases, we don't add complex checks
> for the parameters. But in the other place, we must check and make sure
> the parameters are right. So besides the code cleanup, this patch also
> add a check for the usage of the space balance, it is the only place that
> we need add check to make sure the parameters of div_factor are right till
> now.
>
> Signed-off-by: Miao Xie <mi...@cn.fujitsu.com>
> ---
> Changelog v2 -> v3:
> - drop the original div_factor and rename div_factor_fine to div_factor
> - drop the check of the factor
>
> Changelog v1 -> v2:
> - add missing check
> ---
> fs/btrfs/extent-tree.c | 29 ++++++-----------------------
> fs/btrfs/ioctl.c | 18 ++++++++++++++++++
> fs/btrfs/math.h | 33 +++++++++++++++++++++++++++++++++
> fs/btrfs/relocation.c | 2 +-
> fs/btrfs/transaction.c | 2 +-
> fs/btrfs/volumes.c | 30 +++++-------------------------
> 6 files changed, 64 insertions(+), 50 deletions(-)
> create mode 100644 fs/btrfs/math.h
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index a010234..bcb9ced 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -33,6 +33,7 @@
> #include "volumes.h"
> #include "locking.h"
> #include "free-space-cache.h"
> +#include "math.h"
>
> #undef SCRAMBLE_DELAYED_REFS
>
> @@ -648,24 +649,6 @@ void btrfs_clear_space_info_full(struct btrfs_fs_info
> *info)
> rcu_read_unlock();
> }
>
> -static u64 div_factor(u64 num, int factor)
> -{
> - if (factor == 10)
> - return num;
> - num *= factor;
> - do_div(num, 10);
> - return num;
> -}
> -
> -static u64 div_factor_fine(u64 num, int factor)
> -{
> - if (factor == 100)
> - return num;
> - num *= factor;
> - do_div(num, 100);
> - return num;
> -}
> -
> u64 btrfs_find_block_group(struct btrfs_root *root,
> u64 search_start, u64 search_hint, int owner)
> {
> @@ -674,7 +657,7 @@ u64 btrfs_find_block_group(struct btrfs_root *root,
> u64 last = max(search_hint, search_start);
> u64 group_start = 0;
> int full_search = 0;
> - int factor = 9;
> + int factor = 90;
> int wrapped = 0;
> again:
> while (1) {
> @@ -708,7 +691,7 @@ again:
> if (!full_search && factor < 10) {
> last = search_start;
> full_search = 1;
> - factor = 10;
> + factor = 100;
> goto again;
> }
> found:
> @@ -3513,7 +3496,7 @@ static int should_alloc_chunk(struct btrfs_root *root,
> if (force == CHUNK_ALLOC_LIMITED) {
> thresh = btrfs_super_total_bytes(root->fs_info->super_copy);
> thresh = max_t(u64, 64 * 1024 * 1024,
> - div_factor_fine(thresh, 1));
> + div_factor(thresh, 1));
>
> if (num_bytes - num_allocated < thresh)
> return 1;
> @@ -3521,12 +3504,12 @@ static int should_alloc_chunk(struct btrfs_root *root,
> thresh = btrfs_super_total_bytes(root->fs_info->super_copy);
>
> /* 256MB or 2% of the FS */
> - thresh = max_t(u64, 256 * 1024 * 1024, div_factor_fine(thresh, 2));
> + thresh = max_t(u64, 256 * 1024 * 1024, div_factor(thresh, 2));
> /* system chunks need a much small threshold */
> if (sinfo->flags & BTRFS_BLOCK_GROUP_SYSTEM)
> thresh = 32 * 1024 * 1024;
>
> - if (num_bytes > thresh && sinfo->bytes_used < div_factor(num_bytes, 8))
> + if (num_bytes > thresh && sinfo->bytes_used < div_factor(num_bytes, 80))
> return 0;
> return 1;
> }
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 9384a2a..d8d53f7 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -3335,6 +3335,24 @@ static long btrfs_ioctl_balance(struct file *file,
> void __user *arg)
>
> goto do_balance;
> }
> +
> + if ((bargs->data.flags & BTRFS_BALANCE_ARGS_USAGE) &&
> + (bargs->data.usage < 0 || bargs->data.usage > 100)) {
> + ret = -EINVAL;
> + goto out_bargs;
> + }
> +
> + if ((bargs->meta.flags & BTRFS_BALANCE_ARGS_USAGE) &&
> + (bargs->meta.usage < 0 || bargs->meta.usage > 100)) {
> + ret = -EINVAL;
> + goto out_bargs;
> + }
> +
> + if ((bargs->sys.flags & BTRFS_BALANCE_ARGS_USAGE) &&
> + (bargs->sys.usage < 0 || bargs->sys.usage > 100)) {
> + ret = -EINVAL;
> + goto out_bargs;
> + }
> } else {
> bargs = NULL;
> }
Why not drop this hunk ...
> diff --git a/fs/btrfs/math.h b/fs/btrfs/math.h
> new file mode 100644
> index 0000000..a157665
> --- /dev/null
> +++ b/fs/btrfs/math.h
> @@ -0,0 +1,33 @@
> +
> +/*
> + * Copyright (C) 2012 Fujitsu. All rights reserved.
> + * Written by Miao Xie <mi...@cn.fujitsu.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public
> + * License v2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public
> + * License along with this program; if not, write to the
> + * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
> + * Boston, MA 021110-1307, USA.
> + */
> +
> +#ifndef __BTRFS_MATH_H
> +#define __BTRFS_MATH_H
> +
> +#include <asm/div64.h>
> +
> +static inline u64 div_factor(u64 num, int factor)
> +{
> + num *= factor;
> + do_div(num, 100);
> + return num;
> +}
> +
> +#endif
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index f193096..2254478 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -3813,7 +3813,7 @@ restart:
> }
> }
>
> - ret = btrfs_block_rsv_check(rc->extent_root, rc->block_rsv, 5);
> + ret = btrfs_block_rsv_check(rc->extent_root, rc->block_rsv, 50);
> if (ret < 0) {
> if (ret != -ENOSPC) {
> err = ret;
> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> index cf98dbc..115f054 100644
> --- a/fs/btrfs/transaction.c
> +++ b/fs/btrfs/transaction.c
> @@ -489,7 +489,7 @@ static int should_end_transaction(struct
> btrfs_trans_handle *trans,
> {
> int ret;
>
> - ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
> + ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 50);
> return ret ? 1 : 0;
> }
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 3f4e70e..1fd43a4 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -25,7 +25,6 @@
> #include <linux/capability.h>
> #include <linux/ratelimit.h>
> #include <linux/kthread.h>
> -#include <asm/div64.h>
> #include "compat.h"
> #include "ctree.h"
> #include "extent_map.h"
> @@ -36,6 +35,7 @@
> #include "async-thread.h"
> #include "check-integrity.h"
> #include "rcu-string.h"
> +#include "math.h"
>
> static int init_first_rw_device(struct btrfs_trans_handle *trans,
> struct btrfs_root *root,
> @@ -2325,18 +2325,6 @@ static int chunk_profiles_filter(u64 chunk_type,
> return 1;
> }
>
> -static u64 div_factor_fine(u64 num, int factor)
> -{
> - if (factor <= 0)
> - return 0;
> - if (factor >= 100)
> - return num;
> -
> - num *= factor;
> - do_div(num, 100);
> - return num;
> -}
> -
> static int chunk_usage_filter(struct btrfs_fs_info *fs_info, u64
> chunk_offset,
> struct btrfs_balance_args *bargs)
> {
> @@ -2347,7 +2335,8 @@ static int chunk_usage_filter(struct btrfs_fs_info
> *fs_info, u64 chunk_offset,
> cache = btrfs_lookup_block_group(fs_info, chunk_offset);
> chunk_used = btrfs_block_group_used(&cache->item);
>
> - user_thresh = div_factor_fine(cache->key.offset, bargs->usage);
> + BUG_ON(bargs->usage < 0 || bargs->usage > 100);
> + user_thresh = div_factor(cache->key.offset, bargs->usage);
> if (chunk_used < user_thresh)
> ret = 0;
... and leave the check where it was before?
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6019fb2..ff86f91 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2334,8 +2334,13 @@ static int chunk_usage_filter(struct btrfs_fs_info
*fs_info, u64 chunk_offset,
cache = btrfs_lookup_block_group(fs_info, chunk_offset);
chunk_used = btrfs_block_group_used(&cache->item);
- BUG_ON(bargs->usage < 0 || bargs->usage > 100);
- user_thresh = div_factor(cache->key.offset, bargs->usage);
+ if (bargs->usage == 0)
+ user_thresh = 0;
+ else if (bargs->usage >= 100)
+ user_thresh = cache->key.offset;
+ else
+ user_thresh = div_factor(cache->key.offset, bargs->usage);
+
if (chunk_used < user_thresh)
ret = 0;
(diff is on top of the patch in question)
This is the most straightforward transformation I can think of. It
doesn't result in an unnecessary BUG_ON, keeps churn to a minimum and
doesn't change the "style" of the balance ioctl. (If I were to check
every filter argument that way, btrfs_balance_ioctl() would be very long
and complicated.)
Thanks,
Ilya
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