On 2015/1/8 20:41, Seunghun Lee wrote:
> When file system is mounted read-only workdir is not needed.
>
> Signed-off-by: Seunghun Lee <waydi1@xxxxxxxxx>
> ---
> fs/overlayfs/super.c | 35 +++++++++++++++++++++++------------
> 1 file changed, 23 insertions(+), 12 deletions(-)
>
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index 84f3144..4e50617 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -30,6 +30,7 @@ struct ovl_config {
> char *lowerdir;
> char *upperdir;
> char *workdir;
> + bool is_rw;
> };
>
> /* private information held for overlayfs's superblock */
> @@ -515,10 +516,11 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
> struct ovl_fs *ufs = sb->s_fs_info;
>
> seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir);
> - if (ufs->config.upperdir) {
> + if (ufs->config.upperdir)
> seq_printf(m, ",upperdir=%s", ufs->config.upperdir);
> + if (ufs->config.is_rw)
> seq_printf(m, ",workdir=%s", ufs->config.workdir);
> - }
> +
> return 0;
> }
>
> @@ -822,16 +824,27 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
>
> sb->s_stack_depth = 0;
> if (ufs->config.upperdir) {
> - /* FIXME: workdir is not needed for a R/O mount */
> + err = ovl_mount_dir(ufs->config.upperdir, &upperpath);
> + if (err)
> + goto out_free_config;
> +
> + sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth;
> + }
> +
> + /* If the upper fs is r/o or nonexistent, we mark overlayfs r/o too */
> + if (!upperpath.mnt || (upperpath.mnt->mnt_sb->s_flags & MS_RDONLY)) {
> + ufs->config.is_rw = false;
> + sb->s_flags |= MS_RDONLY;
> + } else {
> + ufs->config.is_rw = true;
> + }
Hi Seunghun,
A partition can be mounted with ro flag. I think workdir is not
needed in this way either.
> +
> + if (ufs->config.is_rw) {
> if (!ufs->config.workdir) {
> pr_err("overlayfs: missing 'workdir'\n");
> goto out_free_config;
> }
>
> - err = ovl_mount_dir(ufs->config.upperdir, &upperpath);
> - if (err)
> - goto out_free_config;
> -
> err = ovl_mount_dir(ufs->config.workdir, &workpath);
> if (err)
> goto out_put_upperpath;
> @@ -844,8 +857,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
> pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
> goto out_put_workpath;
> }
> - sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth;
> }
> +
> err = -ENOMEM;
> lowertmp = kstrdup(ufs->config.lowerdir, GFP_KERNEL);
> if (!lowertmp)
> @@ -884,7 +897,9 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
> pr_err("overlayfs: failed to clone upperpath\n");
> goto out_put_lowerpath;
> }
> + }
>
> + if (ufs->config.is_rw) {
> ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry);
> err = PTR_ERR(ufs->workdir);
> if (IS_ERR(ufs->workdir)) {
> @@ -914,10 +929,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
> ufs->numlower++;
> }
>
> - /* If the upper fs is r/o or nonexistent, we mark overlayfs r/o too */
> - if (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY))
> - sb->s_flags |= MS_RDONLY;
> -
> sb->s_d_op = &ovl_dentry_operations;
>
> err = -ENOMEM;
>
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