On Tue, Aug 16, 2022 at 09:15:22AM -0400, Jeff Layton wrote:
> ext4 currently updates the i_version counter when the atime is updated
> during a read. This is less than ideal as it can cause unnecessary cache
> invalidations with NFSv4. The increment in ext4_mark_iloc_dirty is also
> problematic since it can also corrupt the i_version counter for
> ea_inodes.
>
> We aren't bumping the file times in ext4_mark_iloc_dirty, so changing
> the i_version there seems wrong, and is the cause of both problems.
> Remove that callsite and add increments to the setattr and setxattr
> codepaths (at the same time that we update the ctime). The i_version
> bump that already happens during timestamp updates should take care of
> the rest.
>
> Cc: Lukas Czerner <lczerner@xxxxxxxxxx>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: Christian Brauner <brauner@xxxxxxxxxx>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
Seems good to me. But it seems that the xfs patch you sent does have
inode_inc_version() right after setattr_copy() as well. So I wonder if
we couldn't just try and move inode_inc_version() into setattr_copy()
itself.
> fs/ext4/inode.c | 10 +++++-----
> fs/ext4/xattr.c | 2 ++
> 2 files changed, 7 insertions(+), 5 deletions(-)
>
> I think this patch should probably supersede Lukas' patch entitled:
>
> ext4: don't increase iversion counter for ea_inodes
>
> This will also mean that we'll need to respin the patch to turn on the
> i_version counter unconditionally in ext4 (though that should be
> trivial).
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 601214453c3a..a70921df89a5 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -5342,6 +5342,7 @@ int ext4_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
> int error, rc = 0;
> int orphan = 0;
> const unsigned int ia_valid = attr->ia_valid;
> + bool inc_ivers = IS_IVERSION(inode);
>
> if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
> return -EIO;
> @@ -5425,8 +5426,8 @@ int ext4_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
> return -EINVAL;
> }
>
> - if (IS_I_VERSION(inode) && attr->ia_size != inode->i_size)
> - inode_inc_iversion(inode);
> + if (attr->ia_size == inode->i_size)
> + inc_ivers = false;
>
> if (shrink) {
> if (ext4_should_order_data(inode)) {
> @@ -5528,6 +5529,8 @@ int ext4_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
> }
>
> if (!error) {
> + if (inc_ivers)
> + inode_inc_iversion(inode);
> setattr_copy(mnt_userns, inode, attr);
> mark_inode_dirty(inode);
> }
> @@ -5731,9 +5734,6 @@ int ext4_mark_iloc_dirty(handle_t *handle,
> }
> ext4_fc_track_inode(handle, inode);
>
> - if (IS_I_VERSION(inode))
> - inode_inc_iversion(inode);
> -
> /* the do_update_inode consumes one bh->b_count */
> get_bh(iloc->bh);
>
> diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
> index 533216e80fa2..4d84919d1c9c 100644
> --- a/fs/ext4/xattr.c
> +++ b/fs/ext4/xattr.c
> @@ -2412,6 +2412,8 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
> if (!error) {
> ext4_xattr_update_super_block(handle, inode->i_sb);
> inode->i_ctime = current_time(inode);
> + if (IS_IVERSION(inode))
> + inode_inc_iversion(inode);
> if (!value)
> no_expand = 0;
> error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
> --
> 2.37.2
>
