linux-kernel - Re: [f2fs-dev] [PATCH 1/2] f2fs: avoid non-section-aligned size pinned file generation

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Message-ID: <20250617073643.2361088-1-wangzijie1@honor.com>
Date: Tue, 17 Jun 2025 15:36:43 +0800
From: wangzijie <wangzijie1@...or.com>
To: <linux-f2fs-devel@...ts.sourceforge.net>
CC: <chao@...nel.org>, <feng.han@...or.com>, <jaegeuk@...nel.org>,
	<linux-kernel@...r.kernel.org>, <wangzijie1@...or.com>
Subject: Re: [f2fs-dev] [PATCH 1/2] f2fs: avoid non-section-aligned size pinned file generation

> On 6/17/25 11:57, wangzijie wrote:
> > To prevent non-section-aligned size pinned file generated from truncation,
> > add check condition in setattr.
> > 
> > Signed-off-by: wangzijie <wangzijie1@...or.com>
> > ---
> >  fs/f2fs/file.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 6bd3de64f..72f7d1b4a 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -1026,6 +1026,7 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
> >  {
> >  	struct inode *inode = d_inode(dentry);
> >  	struct f2fs_inode_info *fi = F2FS_I(inode);
> > +	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> >  	int err;
> >  
> >  	if (unlikely(f2fs_cp_error(F2FS_I_SB(inode))))
> > @@ -1047,6 +1048,11 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
> >  			!IS_ALIGNED(attr->ia_size,
> >  			F2FS_BLK_TO_BYTES(fi->i_cluster_size)))
> >  			return -EINVAL;
> > +		if (f2fs_is_pinned_file(inode) &&
> > +			attr->ia_size < i_size_read(inode) &&
> 
> Do we need to consider attr->ia_size > i_size case?
> 
> Thanks,

Hi, Chao
After commit 3fdd89b452c2("f2fs: prevent writing without fallocate() for pinned
files"), when we want to write data to pinned file, we need to use pin+fallocate, 
and we did CAP_BLKS_PER_SEC roundup align when fallocate pinned file:

block_t sec_len = roundup(map.m_len, sec_blks);

Even if we truncate the file to a larger size(maybe larger than sec_len, section
align or not), and write data to offset beyond sec_len, the write will fail(commit
3fdd89b452c2 prevent it). The scattered pin block cannot be generated by this way,
so I did not consider attr->ia_size > i_size case.
Do you have some suggestions?

> > +			!IS_ALIGNED(attr->ia_size,
> > +			F2FS_BLK_TO_BYTES(CAP_BLKS_PER_SEC(sbi))))
> > +			return -EINVAL;
> >  	}
> >  
> >  	err = setattr_prepare(idmap, dentry, attr);