On Thu, Mar 29, 2018 at 10:38 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> Soon in ovl_rename() I will introduce a function to take lock both on old
> and new ovl_inode. That means I don't want ovl_nlink_start() to take lock
> and ovl_nlink_end() to drop lock. It will be done by other functions.
>
> So create ovl_nlink_start_locked() and ovl_nlink_end_locked() which assume
> that by the time they are called, lock has already been taken and these
> don't deal with taking/releasing locks.
>
> These will be used in following patches.
>
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/overlayfs.h | 2 ++
> fs/overlayfs/util.c | 50 +++++++++++++++++++++++++++++-------------------
> 2 files changed, 32 insertions(+), 20 deletions(-)
>
> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> index aa5b0c121fc7..429713653b3b 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -273,7 +273,9 @@ void ovl_inuse_unlock(struct dentry *dentry);
> bool ovl_need_index(struct dentry *dentry);
> int ovl_nlink_prep(struct dentry *dentry);
> int ovl_nlink_start(struct dentry *dentry, bool *locked);
> +int ovl_nlink_start_locked(struct dentry *dentry);
> void ovl_nlink_end(struct dentry *dentry, bool locked);
> +void ovl_nlink_end_locked(struct dentry *dentry);
> int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir);
> int ovl_check_metacopy_xattr(struct dentry *dentry);
> bool ovl_is_metacopy_dentry(struct dentry *dentry);
> diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
> index ed93e233894f..927960aa57ee 100644
> --- a/fs/overlayfs/util.c
> +++ b/fs/overlayfs/util.c
> @@ -709,21 +709,13 @@ int ovl_nlink_prep(struct dentry *dentry)
> * Operations that change overlay inode and upper inode nlink need to be
> * synchronized with copy up for persistent nlink accounting.
> */
> -int ovl_nlink_start(struct dentry *dentry, bool *locked)
> +int ovl_nlink_start_locked(struct dentry *dentry)
> {
> - struct ovl_inode *oi = OVL_I(d_inode(dentry));
> const struct cred *old_cred;
> int err;
>
> - if (!d_inode(dentry))
> - return 0;
> -
> - err = mutex_lock_interruptible(&oi->lock);
> - if (err)
> - return err;
> -
> if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, d_inode(dentry)))
> - goto out;
> + return 0;
>
> old_cred = ovl_override_creds(dentry->d_sb);
> /*
> @@ -734,8 +726,22 @@ int ovl_nlink_start(struct dentry *dentry, bool *locked)
> */
> err = ovl_set_nlink_upper(dentry);
> revert_creds(old_cred);
> + return err;
> +}
>
> -out:
> +int ovl_nlink_start(struct dentry *dentry, bool *locked)
> +{
> + struct ovl_inode *oi = OVL_I(d_inode(dentry));
> + int err;
> +
> + if (!d_inode(dentry))
> + return 0;
> +
> + err = mutex_lock_interruptible(&oi->lock);
> + if (err)
> + return err;
> +
> + err = ovl_nlink_start_locked(dentry);
> if (err)
> mutex_unlock(&oi->lock);
> else
> @@ -744,18 +750,22 @@ int ovl_nlink_start(struct dentry *dentry, bool *locked)
> return err;
> }
>
> -void ovl_nlink_end(struct dentry *dentry, bool locked)
> +void ovl_nlink_end_locked(struct dentry *dentry)
> {
> - if (locked) {
> - if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) &&
> - d_inode(dentry)->i_nlink == 0) {
> - const struct cred *old_cred;
> + if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) &&
> + d_inode(dentry)->i_nlink == 0) {
> + const struct cred *old_cred;
>
> - old_cred = ovl_override_creds(dentry->d_sb);
> - ovl_cleanup_index(dentry);
> - revert_creds(old_cred);
> - }
> + old_cred = ovl_override_creds(dentry->d_sb);
> + ovl_cleanup_index(dentry);
> + revert_creds(old_cred);
> + }
> +}
>
> +void ovl_nlink_end(struct dentry *dentry, bool locked)
> +{
> + if (locked) {
> + ovl_nlink_end_locked(dentry);
> mutex_unlock(&OVL_I(d_inode(dentry))->lock);
> }
> }
> --
> 2.13.6
>
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