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Date: Mon, 16 May 2016 22:59:40 -0500
From: Eric Sandeen <sandeen@...hat.com>
To: Wang Shilong <wangshilong1991@...il.com>,
linux-ext4@...r.kernel.org
Cc: adilger@...ger.ca, sihara@....com
Subject: Re: [PATCH] ext4: add lazyinit stats support
On 5/16/16 10:41 PM, Wang Shilong wrote:
> From: Wang Shilong <wshilong@....com>
>
> Somtimes, we need figure out progress of Lazyinit
> in the background, this patch try to add stats support
> for it, output is something like:
>
> $ cat /sys/fs/ext4/vda/lazyinit_stats
> groups_finished: 80
> groups_total: 80
A few thoughts:
If this goes in, it should be documented in
Documentation/fs/ext4.txt, as well.
I suppose it might be nice, but when do you think this
might be needed in real life?
Also: sysfs is technically supposed to be one value per
file, and (I think) just a number, no text. At least,
that's what every other ext4 device sysfs file has today,
so this should follow that precedent.
And as far as I can tell, "groups total" is the total
uninit groups at mount time, not total in the filesystem,
so this would change on a remount? I think that's unexpected,
and not very useful.
Simply printing the remaining uninitialized block group
count might be enough, i.e.:
$ cat /sys/fs/ext4/vda/lazyinit_remaining
42
-Eric
> Signed-off-by: Wang Shilong <wshilong@....com>
> ---
> Sorry if you received twice, first one is blocked by
> mail list.
> ---
> fs/ext4/ext4.h | 4 ++++
> fs/ext4/super.c | 19 ++++++++++++++++---
> fs/ext4/sysfs.c | 20 ++++++++++++++++++++
> 3 files changed, 40 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 349afeb..9aaae81 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1505,6 +1505,10 @@ struct ext4_sb_info {
> struct ratelimit_state s_err_ratelimit_state;
> struct ratelimit_state s_warning_ratelimit_state;
> struct ratelimit_state s_msg_ratelimit_state;
> +
> + /* for lazyinit stats */
> + unsigned long lazyinit_finished_cnt;
> + unsigned long lazyinit_total_cnt;
> };
>
> static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 304c712..b95e622 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -2660,6 +2660,7 @@ static int ext4_run_li_request(struct ext4_li_request *elr)
> }
> elr->lr_next_sched = jiffies + elr->lr_timeout;
> elr->lr_next_group = group + 1;
> + EXT4_SB(sb)->lazyinit_finished_cnt++;
> }
> sb_end_write(sb);
>
> @@ -2864,10 +2865,12 @@ static struct ext4_li_request *ext4_li_request_new(struct super_block *sb,
> {
> struct ext4_sb_info *sbi = EXT4_SB(sb);
> struct ext4_li_request *elr;
> + ext4_group_t group, ngroups;
> + struct ext4_group_desc *gdp = NULL;
>
> elr = kzalloc(sizeof(*elr), GFP_KERNEL);
> if (!elr)
> - return NULL;
> + return ERR_PTR(-ENOMEM);
>
> elr->lr_super = sb;
> elr->lr_sbi = sbi;
> @@ -2880,6 +2883,16 @@ static struct ext4_li_request *ext4_li_request_new(struct super_block *sb,
> */
> elr->lr_next_sched = jiffies + (prandom_u32() %
> (EXT4_DEF_LI_MAX_START_DELAY * HZ));
> + ngroups = EXT4_SB(sb)->s_groups_count;
> + for (group = elr->lr_next_group; group < ngroups; group++) {
^whitespace issue here
> + gdp = ext4_get_group_desc(sb, group, NULL);
> + if (!gdp) {
> + elr = ERR_PTR(-EIO);
> + break;
> + }
> + if (!(gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_ZEROED)))
> + sbi->lazyinit_total_cnt++;
> + }
> return elr;
> }
>
> @@ -2907,8 +2920,8 @@ int ext4_register_li_request(struct super_block *sb,
> goto out;
>
> elr = ext4_li_request_new(sb, first_not_zeroed);
> - if (!elr) {
> - ret = -ENOMEM;
> + if (IS_ERR(elr)) {
> + ret = PTR_ERR(elr);
> goto out;
> }
>
> diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
> index 1420a3c..8d0c199 100644
> --- a/fs/ext4/sysfs.c
> +++ b/fs/ext4/sysfs.c
> @@ -20,6 +20,7 @@ typedef enum {
> attr_delayed_allocation_blocks,
> attr_session_write_kbytes,
> attr_lifetime_write_kbytes,
> + attr_lazyinit_stats,
> attr_reserved_clusters,
> attr_inode_readahead,
> attr_trigger_test_error,
> @@ -72,6 +73,21 @@ static ssize_t lifetime_write_kbytes_show(struct ext4_attr *a,
> EXT4_SB(sb)->s_sectors_written_start) >> 1)));
> }
>
> +static ssize_t lazyinit_stats_show(struct ext4_attr *a,
> + struct ext4_sb_info *sbi, char *buf)
> +{
> + int len = 0;
> + unsigned long total = sbi->lazyinit_total_cnt;
> + unsigned long finish = sbi->lazyinit_finished_cnt;
> +
> + len += snprintf(buf + len, PAGE_SIZE,
> + "groups_finished: %lu\n", finish);
> + len += snprintf(buf + len, PAGE_SIZE,
> + "groups_total: %lu\n", total);
> +
> + return len;
> +}
> +
> static ssize_t inode_readahead_blks_store(struct ext4_attr *a,
> struct ext4_sb_info *sbi,
> const char *buf, size_t count)
> @@ -165,6 +181,7 @@ static struct ext4_attr ext4_attr_##_name = { \
> EXT4_ATTR_FUNC(delayed_allocation_blocks, 0444);
> EXT4_ATTR_FUNC(session_write_kbytes, 0444);
> EXT4_ATTR_FUNC(lifetime_write_kbytes, 0444);
> +EXT4_ATTR_FUNC(lazyinit_stats, 0444);
> EXT4_ATTR_FUNC(reserved_clusters, 0644);
>
> EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, inode_readahead,
> @@ -195,6 +212,7 @@ static struct attribute *ext4_attrs[] = {
> ATTR_LIST(delayed_allocation_blocks),
> ATTR_LIST(session_write_kbytes),
> ATTR_LIST(lifetime_write_kbytes),
> + ATTR_LIST(lazyinit_stats),
> ATTR_LIST(reserved_clusters),
> ATTR_LIST(inode_readahead_blks),
> ATTR_LIST(inode_goal),
> @@ -265,6 +283,8 @@ static ssize_t ext4_attr_show(struct kobject *kobj,
> return session_write_kbytes_show(a, sbi, buf);
> case attr_lifetime_write_kbytes:
> return lifetime_write_kbytes_show(a, sbi, buf);
> + case attr_lazyinit_stats:
> + return lazyinit_stats_show(a, sbi, buf);
> case attr_reserved_clusters:
> return snprintf(buf, PAGE_SIZE, "%llu\n",
> (unsigned long long)
>
--
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