Re: [f2fs-dev] [PATCH] f2fs: Create COW inode from parent dentry for atomic write

[Daeho Jeong <daeho43@gmail.com>]

On Tue, Aug 13, 2024 at 12:34 AM Yeongjin Gil <youngjin.gil@samsung.com> wrote:
>
> The i_pino in f2fs_inode_info has the previous parent's i_ino when inode
> was renamed, which may cause f2fs_ioc_start_atomic_write to fail.
> If file_wrong_pino is true and i_nlink is 1, then to find a valid pino,
> we should refer to the dentry from inode.
>
> To resolve this issue, let's get parent inode using parent dentry
> directly.
>
> Fixes: 3db1de0e582c ("f2fs: change the current atomic write way")
> Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
> Reviewed-by: Sunmin Jeong <s_min.jeong@samsung.com>
> Signed-off-by: Yeongjin Gil <youngjin.gil@samsung.com>
> ---
>  fs/f2fs/file.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index fba8b5f216f9..1eae123f0315 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -2127,7 +2127,6 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
>         struct mnt_idmap *idmap = file_mnt_idmap(filp);
>         struct f2fs_inode_info *fi = F2FS_I(inode);
>         struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> -       struct inode *pinode;
>         loff_t isize;
>         int ret;
>
> @@ -2178,15 +2177,10 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
>         /* Check if the inode already has a COW inode */
>         if (fi->cow_inode == NULL) {
>                 /* Create a COW inode for atomic write */
> -               pinode = f2fs_iget(inode->i_sb, fi->i_pino);
> -               if (IS_ERR(pinode)) {
> -                       f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
> -                       ret = PTR_ERR(pinode);
> -                       goto out;
> -               }
> +               struct dentry *dentry = file_dentry(filp);
> +               struct inode *dir = d_inode(dentry->d_parent);
>
> -               ret = f2fs_get_tmpfile(idmap, pinode, &fi->cow_inode);
> -               iput(pinode);
> +               ret = f2fs_get_tmpfile(idmap, dir, &fi->cow_inode);
>                 if (ret) {
>                         f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
>                         goto out;
> --
> 2.40.1
>

Reviewed-by: Daeho Jeong <daehojeong@google.com>

Thanks,

>
>
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