linux-kernel - Re: [f2fs-dev] [PATCH v2] f2fs: show the list of donation files

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Message-ID: <c7b8c81e-c0fe-4edf-8ad0-e10df5d80bd5@kernel.org>
Date: Thu, 14 Aug 2025 10:22:41 +0800
From: Chao Yu <chao@...nel.org>
To: Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org,
 linux-f2fs-devel@...ts.sourceforge.net
Cc: chao@...nel.org
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: show the list of donation files

On 8/14/25 00:24, Jaegeuk Kim via Linux-f2fs-devel wrote:
> This patch introduces a proc entry to show the currently enrolled donation
> files.
> 
> - "File path" indicates a file.
> - "Status"
>  a. "Donated" means the file is registed in the donation list by
>     fadvise(offset, length, POSIX_FADV_NOREUSE)
>  b. "Evicted" means the donated pages were reclaimed.
> - "Offset (kb)" and "Length (kb) show the registered donation range.
> - "Cached pages (kb)" shows the amount of cached pages in the inode page cache.
> 
> For example,
> 
> Donation List
>  # of files  : 2
>  File path                                              Status     Offset (kb)     Length (kb)    Cached pages (kb)
> ---
>  /local/tmp/test2                                      Donated               0         1048576              2097152
>  /local/tmp/test                                       Evicted               0         1048576              1048576
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> ---
>  v2: use inode_lock|unlock_shared
>  
>  fs/f2fs/sysfs.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 64 insertions(+)
> 
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 1ffaf9e74ce9..9f90d1878ec6 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -1769,6 +1769,68 @@ static int __maybe_unused disk_map_seq_show(struct seq_file *seq,
>  	return 0;
>  }
>  
> +static int __maybe_unused donation_list_seq_show(struct seq_file *seq,
> +						void *offset)
> +{
> +	struct super_block *sb = seq->private;
> +	struct f2fs_sb_info *sbi = F2FS_SB(sb);
> +	struct inode *inode;
> +	struct f2fs_inode_info *fi;
> +	struct dentry *dentry;
> +	char *buf, *path;
> +	int i;
> +
> +	buf = f2fs_getname(sbi);
> +	if (!buf)
> +		return 0;
> +
> +	seq_printf(seq, "Donation List\n");
> +	seq_printf(seq, " # of files  : %u\n", sbi->donate_files);
> +	seq_printf(seq, " %-50s %10s %15s %15s %20s\n",
> +			"File path", "Status", "Offset (kb)",
> +			"Length (kb)", "Cached pages (kb)");
> +	seq_printf(seq, "---\n");
> +
> +	for (i = 0; i < sbi->donate_files; i++) {
> +		spin_lock(&sbi->inode_lock[DONATE_INODE]);
> +		if (list_empty(&sbi->inode_list[DONATE_INODE])) {
> +			spin_unlock(&sbi->inode_lock[DONATE_INODE]);
> +			break;
> +		}
> +		fi = list_first_entry(&sbi->inode_list[DONATE_INODE],
> +					struct f2fs_inode_info, gdonate_list);
> +		list_move_tail(&fi->gdonate_list, &sbi->inode_list[DONATE_INODE]);
> +		inode = igrab(&fi->vfs_inode);
> +		spin_unlock(&sbi->inode_lock[DONATE_INODE]);
> +
> +		if (!inode)
> +			continue;
> +
> +		inode_lock_shared(inode);
> +
> +		dentry = d_find_alias(inode);
> +		if (!dentry) {
> +			path = NULL;
> +		} else {
> +			path = dentry_path_raw(dentry, buf, PATH_MAX);
> +			if (IS_ERR(path))
> +				goto next;
> +		}
> +		seq_printf(seq, " %-50s %10s %15lu %15lu %20lu\n",
> +				path ? path : "<unlinked>",
> +				is_inode_flag_set(inode, FI_DONATE_FINISHED) ?
> +				"Evicted" : "Donated",
> +				fi->donate_start << (PAGE_SHIFT - 10),

It needs to avoid overflow while left shift?

(loff_t)fi->donate_start << (PAGE_SHIFT - 10)
(loff_t)(fi->donate_end + 1) << (PAGE_SHIFT - 10)
(loff_t)inode->i_mapping->nrpages << (PAGE_SHIFT - 10))

Thanks,

> +				(fi->donate_end + 1) << (PAGE_SHIFT - 10),
> +				inode->i_mapping->nrpages << (PAGE_SHIFT - 10));
> +next:
> +		inode_unlock_shared(inode);
> +		iput(inode);
> +	}
> +	f2fs_putname(buf);
> +	return 0;
> +}
> +
>  #ifdef CONFIG_F2FS_FAULT_INJECTION
>  static int __maybe_unused inject_stats_seq_show(struct seq_file *seq,
>  						void *offset)
> @@ -1878,6 +1940,8 @@ int f2fs_register_sysfs(struct f2fs_sb_info *sbi)
>  				discard_plist_seq_show, sb);
>  	proc_create_single_data("disk_map", 0444, sbi->s_proc,
>  				disk_map_seq_show, sb);
> +	proc_create_single_data("donation_list", 0444, sbi->s_proc,
> +				donation_list_seq_show, sb);
>  #ifdef CONFIG_F2FS_FAULT_INJECTION
>  	proc_create_single_data("inject_stats", 0444, sbi->s_proc,
>  				inject_stats_seq_show, sb);