linux-kernel - Re: [f2fs-dev] [PATCH v4 2/2] f2fs: don't allow unaligned truncation to smaller/equal size on pinned file

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Message-ID: <4a227a94-6e8e-4ab3-a6f4-fdebc6419764@kernel.org>
Date: Mon, 30 Jun 2025 10:04:56 +0800
From: Chao Yu <chao@...nel.org>
To: wangzijie <wangzijie1@...or.com>, jaegeuk@...nel.org
Cc: chao@...nel.org, linux-f2fs-devel@...ts.sourceforge.net,
 linux-kernel@...r.kernel.org, bintian.wang@...or.com, feng.han@...or.com,
 niuzhiguo84@...il.com
Subject: Re: [f2fs-dev] [PATCH v4 2/2] f2fs: don't allow unaligned truncation
 to smaller/equal size on pinned file

On 6/24/25 11:59, wangzijie wrote:
> To prevent scattered pin block generation, don't allow non-section aligned truncation
> to smaller or equal size on pinned file. But for truncation to larger size, after
> commit 3fdd89b452c2("f2fs: prevent writing without fallocate() for pinned files"),
> we only support overwrite IO to pinned file, so we don't need to consider
> attr->ia_size > i_size case.

Zijie, can you take a look generic/494? suspect that it is caused by this change.

generic/494 3s ... - output mismatch (see /share/git/fstests/results//generic/494.out.bad)
    --- tests/generic/494.out   2025-01-12 21:57:40.279440664 +0800
    +++ /share/git/fstests/results//generic/494.out.bad 2025-06-30 10:01:37.000000000 +0800
    @@ -2,7 +2,7 @@
     Format and mount
     Initialize file
     Try to truncate
    -ftruncate: Text file busy
    +ftruncate: Invalid argument
     Try to punch hole
     fallocate: Text file busy
    ...
    (Run 'diff -u /share/git/fstests/tests/generic/494.out /share/git/fstests/results//generic/494.out.bad'  to see the entire diff)
Ran: generic/494
Failures: generic/494
Failed 1 of 1 tests

Thanks,

> 
> Signed-off-by: wangzijie <wangzijie1@...or.com>
> ---
> v4:
> - convert sbi first and apply change
> ---
>  fs/f2fs/file.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 209f43653..4809f0fd6 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -1048,6 +1048,17 @@ 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;
> +		/*
> +		 * To prevent scattered pin block generation, we don't allow
> +		 * smaller/equal size unaligned truncation for pinned file.
> +		 * We only support overwrite IO to pinned file, so don't
> +		 * care about larger size truncation.
> +		 */
> +		if (f2fs_is_pinned_file(inode) &&
> +			attr->ia_size <= i_size_read(inode) &&
> +			!IS_ALIGNED(attr->ia_size,
> +			F2FS_BLK_TO_BYTES(CAP_BLKS_PER_SEC(sbi))))
> +			return -EINVAL;
>  	}
>  
>  	err = setattr_prepare(idmap, dentry, attr);