On Thu, Nov 9, 2017 at 10:50 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> If an inode has been copied up metadata only, then we need to query the
> number of blocks from lower and fill up the stat->st_blocks.
>
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
> ---
> fs/overlayfs/inode.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
> index 405a8c34471b..7ba19a97a8da 100644
> --- a/fs/overlayfs/inode.c
> +++ b/fs/overlayfs/inode.c
> @@ -76,6 +76,10 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
> bool is_dir = S_ISDIR(dentry->d_inode->i_mode);
> bool samefs = ovl_same_sb(dentry->d_sb);
> int err;
> + bool metacopy = false;
> +
> + if (ovl_dentry_upper(dentry) && !ovl_has_upperdata(dentry))
> + metacopy = true;
>
> type = ovl_path_real(dentry, &realpath);
> old_cred = ovl_override_creds(dentry->d_sb);
> @@ -93,7 +97,8 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
> if (!is_dir || samefs) {
> if (OVL_TYPE_ORIGIN(type)) {
> struct kstat lowerstat;
> - u32 lowermask = STATX_INO | (!is_dir ? STATX_NLINK : 0);
> + u32 lowermask = STATX_INO | STATX_BLOCKS |
> + (!is_dir ? STATX_NLINK : 0);
>
> ovl_path_lower(dentry, &realpath);
> err = vfs_getattr(&realpath, &lowerstat,
> @@ -117,6 +122,9 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
> WARN_ON_ONCE(stat->dev != lowerstat.dev);
> else
> stat->dev = ovl_get_pseudo_dev(dentry);
> +
> + if (metacopy)
> + stat->blocks = lowerstat.blocks;
OVL_TYPE_ORIGIN(type) implies ovl_dentry_upper(dentry), so you don't
need the boolean
var, you can test !ovl_has_upperdata(dentry) here instead.
To be honest, I am not fond of the patches adding memory barriers
being separate from
that patches that introduce the races, even though technically races
cannot happen
until last patch enables metacopy.
Amir.
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