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Date: Fri, 18 Aug 2017 23:16:33 +0800
From: Yunlong Song <yunlong.song@...wei.com>
To: Chao Yu <yuchao0@...wei.com>, <jaegeuk@...nel.org>,
<chao@...nel.org>, <yunlong.song@...oud.com>
CC: <miaoxie@...wei.com>, <bintian.wang@...wei.com>,
<linux-fsdevel@...r.kernel.org>,
<linux-f2fs-devel@...ts.sourceforge.net>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] f2fs: introduce cur_reserved_blocks in sysfs
I send a v3 patch, please review, and the main difference is shown below.
On 2017/8/18 18:20, Chao Yu wrote:
> Hi Yunlong,
>
> IMO, we don't need additional sysfs entry, how about changing a bit as below?
>
> >From 3fc8206871fe457859f1537c9dc8918b45f14601 Mon Sep 17 00:00:00 2001
> From: Yunlong Song <yunlong.song@...wei.com>
> Date: Wed, 16 Aug 2017 23:01:56 +0800
> Subject: [PATCH] f2fs: support soft block reservation
>
> It supports to extend reserved_blocks sysfs interface to be soft
> threshold, which allows user configure it exceeding current available
> user space.
>
> Signed-off-by: Yunlong Song <yunlong.song@...wei.com>
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
> Documentation/ABI/testing/sysfs-fs-f2fs | 3 ++-
> fs/f2fs/f2fs.h | 12 ++++++++++--
> fs/f2fs/super.c | 3 ++-
> fs/f2fs/sysfs.c | 16 ++++++++++++++--
> 4 files changed, 28 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index 11b7f4ebea7c..45c3d92f77c8 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -138,7 +138,8 @@ What: /sys/fs/f2fs/<disk>/reserved_blocks
> Date: June 2017
> Contact: "Chao Yu" <yuchao0@...wei.com>
> Description:
> - Controls current reserved blocks in system.
> + Controls current reserved blocks in system, the threshold
> + is soft, it could exceed current avaible user space.
>
> What: /sys/fs/f2fs/<disk>/gc_urgent
> Date: August 2017
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 336021b9b93e..a7b2d257e8ee 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1046,6 +1046,7 @@ struct f2fs_sb_info {
> block_t discard_blks; /* discard command candidats */
> block_t last_valid_block_count; /* for recovery */
> block_t reserved_blocks; /* configurable reserved blocks */
> + block_t current_reserved_blocks; /* current reserved blocks */
>
> u32 s_next_generation; /* for NFS support */
>
> @@ -1520,7 +1521,8 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
>
> spin_lock(&sbi->stat_lock);
> sbi->total_valid_block_count += (block_t)(*count);
> - avail_user_block_count = sbi->user_block_count - sbi->reserved_blocks;
> + avail_user_block_count = sbi->user_block_count -
> + sbi->current_reserved_blocks;
> if (unlikely(sbi->total_valid_block_count > avail_user_block_count)) {
> diff = sbi->total_valid_block_count - avail_user_block_count;
> *count -= diff;
> @@ -1554,6 +1556,9 @@ static inline void dec_valid_block_count(struct f2fs_sb_info *sbi,
> f2fs_bug_on(sbi, sbi->total_valid_block_count < (block_t) count);
> f2fs_bug_on(sbi, inode->i_blocks < sectors);
> sbi->total_valid_block_count -= (block_t)count;
> + if (sbi->reserved_blocks)
Add sbi->reserved_blocks != sbi->cur_reserved_blocks check
> + sbi->current_reserved_blocks = min(sbi->reserved_blocks,
> + sbi->current_reserved_blocks + count);
> spin_unlock(&sbi->stat_lock);
> f2fs_i_blocks_write(inode, count, false, true);
> }
> @@ -1700,7 +1705,7 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
> spin_lock(&sbi->stat_lock);
>
> valid_block_count = sbi->total_valid_block_count + 1;
> - if (unlikely(valid_block_count + sbi->reserved_blocks >
> + if (unlikely(valid_block_count + sbi->current_reserved_blocks >
> sbi->user_block_count)) {
> spin_unlock(&sbi->stat_lock);
> goto enospc;
> @@ -1743,6 +1748,9 @@ static inline void dec_valid_node_count(struct f2fs_sb_info *sbi,
>
> sbi->total_valid_node_count--;
> sbi->total_valid_block_count--;
> + if (sbi->reserved_blocks)
> + sbi->current_reserved_blocks = min(sbi->reserved_blocks,
> + sbi->current_reserved_blocks + 1);
change to sbi->cur_reserved_blocks++;
>
> spin_unlock(&sbi->stat_lock);
>
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 4c1bdcb94133..036f083bbf56 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -957,7 +957,7 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
> buf->f_blocks = total_count - start_count;
> buf->f_bfree = user_block_count - valid_user_blocks(sbi) + ovp_count;
> buf->f_bavail = user_block_count - valid_user_blocks(sbi) -
> - sbi->reserved_blocks;
> + sbi->current_reserved_blocks;
>
> avail_node_count = sbi->total_node_count - F2FS_RESERVED_NODE_NUM;
>
> @@ -2411,6 +2411,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
> le64_to_cpu(sbi->ckpt->valid_block_count);
> sbi->last_valid_block_count = sbi->total_valid_block_count;
> sbi->reserved_blocks = 0;
> + sbi->current_reserved_blocks = 0;
>
> for (i = 0; i < NR_INODE_TYPE; i++) {
> INIT_LIST_HEAD(&sbi->inode_list[i]);
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 4bcaa9059026..3173a272fe7c 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -104,12 +104,23 @@ static ssize_t features_show(struct f2fs_attr *a,
> return len;
> }
>
> +static ssize_t f2fs_reserved_blocks_show(struct f2fs_attr *a,
> + struct f2fs_sb_info *sbi, char *buf)
> +{
> + return snprintf(buf, PAGE_SIZE,
> + "expected: %u\ncurrent: %u\n",
> + sbi->reserved_blocks, sbi->current_reserved_blocks);
> +}
> +
> static ssize_t f2fs_sbi_show(struct f2fs_attr *a,
> struct f2fs_sb_info *sbi, char *buf)
> {
> unsigned char *ptr = NULL;
> unsigned int *ui;
>
> + if (a->struct_type == RESERVED_BLOCKS)
> + return f2fs_reserved_blocks_show(a, sbi, buf);
> +
> ptr = __struct_ptr(sbi, a->struct_type);
> if (!ptr)
> return -EINVAL;
> @@ -143,12 +154,13 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a,
> #endif
> if (a->struct_type == RESERVED_BLOCKS) {
> spin_lock(&sbi->stat_lock);
> - if ((unsigned long)sbi->total_valid_block_count + t >
> - (unsigned long)sbi->user_block_count) {
> + if (t > (unsigned long)sbi->user_block_count) {
> spin_unlock(&sbi->stat_lock);
> return -EINVAL;
> }
> *ui = t;
> + sbi->current_reserved_blocks = min(sbi->reserved_blocks,
> + sbi->user_block_count - valid_user_blocks(sbi));
This is not safe for support system's activation, since the user
available space can be suddenly zero!
So I change this to only admit t < sbi->cur_reserved_blocks then change
its value.
> spin_unlock(&sbi->stat_lock);
> return count;
> }
--
Thanks,
Yunlong Song
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