Re: [PATCH v2 03/12] fs: only specify I_DIRTY_TIME when needed in generic_update_time()

Jan Kara
2021-01-11T14:51:12Z

On Fri 08-01-21 23:58:54, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> generic_update_time() always passes I_DIRTY_TIME to
> __mark_inode_dirty(), which doesn't really make sense because (a)
> generic_update_time() might be asked to do only an i_version update, not
> also a timestamps update; and (b) I_DIRTY_TIME is only supposed to be
> set in i_state if the filesystem has lazytime enabled, so using it
> unconditionally in generic_update_time() is inconsistent.
>
> As a result there is a weird edge case where if only an i_version update
> was requested (not also a timestamps update) but it is no longer needed
> (i.e. inode_maybe_inc_iversion() returns false), then I_DIRTY_TIME will
> be set in i_state even if the filesystem isn't mounted with lazytime.
>
> Fix this by only passing I_DIRTY_TIME to __mark_inode_dirty() if the
> timestamps were updated and the filesystem has lazytime enabled.
>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> ---
> fs/inode.c | 38 ++++++++++++++++++++------------------
> 1 file changed, 20 insertions(+), 18 deletions(-)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index 6442d97d9a4ab..d0fa43d8e9d5c 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -1743,24 +1743,26 @@ static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
>
> int generic_update_time(struct inode *inode, struct timespec64 *time, int flags)
> {
> - int iflags = I_DIRTY_TIME;
> - bool dirty = false;
> -
> - if (flags & S_ATIME)
> - inode->i_atime = *time;
> - if (flags & S_VERSION)
> - dirty = inode_maybe_inc_iversion(inode, false);
> - if (flags & S_CTIME)
> - inode->i_ctime = *time;
> - if (flags & S_MTIME)
> - inode->i_mtime = *time;
> - if ((flags & (S_ATIME | S_CTIME | S_MTIME)) &&
> - !(inode->i_sb->s_flags & SB_LAZYTIME))
> - dirty = true;
> -
> - if (dirty)
> - iflags |= I_DIRTY_SYNC;
> - __mark_inode_dirty(inode, iflags);
> + int dirty_flags = 0;
> +
> + if (flags & (S_ATIME | S_CTIME | S_MTIME)) {
> + if (flags & S_ATIME)
> + inode->i_atime = *time;
> + if (flags & S_CTIME)
> + inode->i_ctime = *time;
> + if (flags & S_MTIME)
> + inode->i_mtime = *time;
> +
> + if (inode->i_sb->s_flags & SB_LAZYTIME)
> + dirty_flags |= I_DIRTY_TIME;
> + else
> + dirty_flags |= I_DIRTY_SYNC;
> + }
> +
> + if ((flags & S_VERSION) && inode_maybe_inc_iversion(inode, false))
> + dirty_flags |= I_DIRTY_SYNC;
> +
> + __mark_inode_dirty(inode, dirty_flags);
> return 0;
> }
> EXPORT_SYMBOL(generic_update_time);
> --
> 2.30.0
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR