Am 21.07.2015 um 10:37 schrieb Dongsheng Yang:
> There is a long-term pain in ubifs, we have to introduce a
> ui_mutex in ubifs_inode to solve two problems below:
>
> 1: make some process atomic, such as ubifs_rename.
> 2: make sure we budget space for inode before dirting it.
>
> About 1, it's true and we have to do it.
>
> About 2, we can do it better.
> There is a ubifs_assert(mutex_is_locked(&ui->mutex)) in
> ubifs_dirty_inode(). But there is probably some processes
> are very long, and we can not make all of it into a pair of
> lock/unlock ui->mutex.
>
> E.g: dquot_disable().
> It would mark the quota files as dirty and write the
> inode back. We can do a budget before this function, but we
> can not make the whole dquot_disable() into mutex_lock/mutex_unlock.
> Because we need to lock the ui_mutex in dquot_disable().
>
> So, this commit introduce a ui->budgeted to allow us to make
> budgeting and dirting in two different lock windows.
>
> Result:
> ubifs_budget_space()
> mutex_lock();
> ui->budgeted = 1;
> mutex_unlock();
> ...
> dquot_disable();
I'm confused by this changelog.
Why do you need ui->budgeted? You set it but never read it
except in an ubifs_assert().
> Signed-off-by: Dongsheng Yang <yangds.fnst@xxxxxxxxxxxxxx>
> ---
> fs/ubifs/file.c | 7 +++++++
> fs/ubifs/ioctl.c | 1 +
> fs/ubifs/super.c | 14 +++++++++++++-
> fs/ubifs/ubifs.h | 1 +
> 4 files changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
> index dc8bf0b..113c3a6 100644
> --- a/fs/ubifs/file.c
> +++ b/fs/ubifs/file.c
> @@ -307,6 +307,7 @@ static int write_begin_slow(struct address_space *mapping,
> * budget we allocated.
> */
> ubifs_release_dirty_inode_budget(c, ui);
> + ui->budgeted = 1;
> }
>
> *pagep = page;
> @@ -357,6 +358,7 @@ static int allocate_budget(struct ubifs_info *c, struct page *page,
> * we need to budget the inode change.
> */
> req.dirtied_ino = 1;
> + ui->budgeted = 1;
> } else {
> if (PageChecked(page))
> /*
> @@ -384,6 +386,7 @@ static int allocate_budget(struct ubifs_info *c, struct page *page,
> * needs a budget.
> */
> req.dirtied_ino = 1;
> + ui->budgeted = 1;
> }
> }
>
> @@ -1237,6 +1240,7 @@ static int do_setattr(struct ubifs_info *c, struct inode *inode,
> do_attr_changes(inode, attr);
>
> release = ui->dirty;
> + ui->budgeted = 1;
> if (attr->ia_valid & ATTR_SIZE)
> /*
> * Inode length changed, so we have to make sure
> @@ -1397,6 +1401,7 @@ static int ubifs_update_time(struct inode *inode, struct timespec *time,
> iflags |= I_DIRTY_SYNC;
>
> release = ui->dirty;
> + ui->budgeted = 1;
> __mark_inode_dirty(inode, iflags);
> mutex_unlock(&ui->ui_mutex);
> if (release)
> @@ -1430,6 +1435,7 @@ static int update_mctime(struct inode *inode)
> mutex_lock(&ui->ui_mutex);
> inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
> release = ui->dirty;
> + ui->budgeted = 1;
> mark_inode_dirty_sync(inode);
> mutex_unlock(&ui->ui_mutex);
> if (release)
> @@ -1556,6 +1562,7 @@ static int ubifs_vm_page_mkwrite(struct vm_area_struct *vma,
> mutex_lock(&ui->ui_mutex);
> inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
> release = ui->dirty;
> + ui->budgeted = 1;
> mark_inode_dirty_sync(inode);
> mutex_unlock(&ui->ui_mutex);
> if (release)
> diff --git a/fs/ubifs/ioctl.c b/fs/ubifs/ioctl.c
> index 3c7b29d..f015b81 100644
> --- a/fs/ubifs/ioctl.c
> +++ b/fs/ubifs/ioctl.c
> @@ -128,6 +128,7 @@ static int setflags(struct inode *inode, int flags)
> ubifs_set_inode_flags(inode);
> inode->i_ctime = ubifs_current_time(inode);
> release = ui->dirty;
> + ui->budgeted = 1;
> mark_inode_dirty_sync(inode);
> mutex_unlock(&ui->ui_mutex);
>
> diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
> index 2491fff..5fa21d6 100644
> --- a/fs/ubifs/super.c
> +++ b/fs/ubifs/super.c
> @@ -331,6 +331,7 @@ static int ubifs_write_inode(struct inode *inode, struct writeback_control *wbc)
> }
>
> ui->dirty = 0;
> + ui->budgeted = 0;
> mutex_unlock(&ui->ui_mutex);
> ubifs_release_dirty_inode_budget(c, ui);
> return err;
> @@ -386,12 +387,23 @@ done:
> static void ubifs_dirty_inode(struct inode *inode, int flags)
> {
> struct ubifs_inode *ui = ubifs_inode(inode);
> + int need_unlock = 0;
>
> - ubifs_assert(mutex_is_locked(&ui->ui_mutex));
> + if (unlikely(!mutex_is_locked(&ui->ui_mutex))) {
> + /* We need to lock ui_mutex to access ui->budgeted */
> + mutex_lock(&ui->ui_mutex);
> + need_unlock = 1;
> + }
> +
> + /* Check the budget for this inode */
> + ubifs_assert(ui->budgeted);
> if (!ui->dirty) {
> ui->dirty = 1;
> dbg_gen("inode %lu", inode->i_ino);
> }
> +
> + if (need_unlock)
> + mutex_unlock(&ui->ui_mutex);
> }
>
> static int ubifs_statfs(struct dentry *dentry, struct kstatfs *buf)
> diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
> index 9754bb6..28392a6 100644
> --- a/fs/ubifs/ubifs.h
> +++ b/fs/ubifs/ubifs.h
> @@ -410,6 +410,7 @@ struct ubifs_inode {
> unsigned int xattr_cnt;
> unsigned int xattr_names;
> unsigned int dirty:1;
> + unsigned int budgeted:1;
Please document that new flag too.
Thanks,
//richard
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