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Message-ID: <20171026144404.GC67431@jaegeuk-macbookpro.roam.corp.google.com>
Date: Thu, 26 Oct 2017 16:44:04 +0200
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <yuchao0@...wei.com>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, chao@...nel.org,
Yunlong Song <yunlong.song@...wei.com>
Subject: Re: [PATCH RESEND] f2fs: support soft block reservation
On 10/26, Chao Yu wrote:
> On 2017/10/26 17:07, Jaegeuk Kim wrote:
> > On 10/26, Chao Yu wrote:
> >> From: Yunlong Song <yunlong.song@...wei.com>
> >>
> >> It supports to extend reserved_blocks sysfs interface to be soft
> >> threshold, which allows user configure it exceeding current available
> >> user space.
> >
> > So, how can we change sbi->reserved_blocks?
> > Could you please summarize how reserved_blocks and current_reserved_blocks
> > are different?
>
> Okay, let me explain this:
>
> Previously, we just support hard reservation of blocks, it means if system
> has 200MB free blocks, we only can reserve <= 200MB free blocks through sysfs,
> otherwise, reserving will fail.
>
> In this patch, we begin to support soft one, it can reserve blocks exceeding
> free blocks, which means, if system has 200MB free blocks, we can reserve >
> 200MB free blocks.
> >
> > What does current_reserved_blocks mean? Isn't "reserved_blocks" current?
>
> So, reserved_blocks means the target block number we want to reserve, and
> current_reserved_blocks is current block number we have reserved. Meanwhile
> blocks are freed by user, we will reserve more free blocks until
> current_reserved_blocks touching the target reserved_blocks.
So, what about target_reserved_blocks and current_reserved_blocks? Then, after
user deletes some files, can we update current_reserved_blocks automatically?
We're able to update it in dev_valid_blocks(), as I guess.
Please update the description in the patch, and use two sysfs entries to change
each of values.
Thanks,
>
> > We have to make sysfs entry show just one value without any string.
>
> For better analysis? So we need another sysfs entry for current_reserved_blocks
> if we can support this feature?
>
> Thanks,
>
> >
> > Thanks,
> >
> >>
> >> 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 | 13 +++++++++++--
> >> fs/f2fs/super.c | 3 ++-
> >> fs/f2fs/sysfs.c | 16 ++++++++++++++--
> >> 4 files changed, 29 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> >> index 11b7f4ebea7c..ba282ca5eb15 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 available 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 6d2984abc50f..6680da47fb1a 100644
> >> --- a/fs/f2fs/f2fs.h
> >> +++ b/fs/f2fs/f2fs.h
> >> @@ -1094,6 +1094,7 @@ 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 */
> >>
> >> @@ -1575,7 +1576,8 @@ 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;
> >> @@ -1609,6 +1611,10 @@ 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 &&
> >> + sbi->current_reserved_blocks < sbi->reserved_blocks)
> >> + 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);
> >> }
> >> @@ -1755,7 +1761,7 @@ 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;
> >> @@ -1798,6 +1804,9 @@ 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 < sbi->reserved_blocks)
> >> + sbi->current_reserved_blocks++;
> >>
> >> spin_unlock(&sbi->stat_lock);
> >>
> >> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> >> index 3fd62ee53eb7..3fd846ac7268 100644
> >> --- a/fs/f2fs/super.c
> >> +++ b/fs/f2fs/super.c
> >> @@ -983,7 +983,7 @@ 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;
> >>
> >> @@ -2450,6 +2450,7 @@ 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 751964da2bca..87487ca8f62e 100644
> >> --- a/fs/f2fs/sysfs.c
> >> +++ b/fs/f2fs/sysfs.c
> >> @@ -107,12 +107,23 @@ 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;
> >> @@ -146,12 +157,13 @@ 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));
> >> spin_unlock(&sbi->stat_lock);
> >> return count;
> >> }
> >> --
> >> 2.13.1.388.g69e6b9b4f4a9
> >
> > .
> >
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