Re: [PATCH v2 1/8] introduce __sb_{acquire,release}_write() helpers

Jan Kara
2015-08-13T09:56:25Z

On Thu 13-08-15 11:45:52, Jan Kara wrote:
> On Tue 11-08-15 19:03:58, Oleg Nesterov wrote:
> > Preparation to hide the sb->s_writers internals from xfs and btrfs.
> > Add 2 trivial define's they can use rather than play with ->s_writers
> > directly. No changes in btrfs/transaction.o and xfs/xfs_aops.o.
> >
> > Signed-off-by: Oleg Nesterov <oleg@redhat.com>
>
> Looks good. You can add:
>
> Reviewed-by: Jan Kara <jack@suse.com>

One comment when looking at other patches - I'd prefer somewhat better name
than __sb_acquire_write(). It doesn't tell that it's only a trylock
acquisition. Maybe something like

__sb_writers_acquire_nowait()

and then

__sb_writers_release()?

Honza
> > ---
> > fs/btrfs/transaction.c | 8 ++------
> > fs/xfs/xfs_aops.c | 6 ++----
> > include/linux/fs.h | 5 +++++
> > 3 files changed, 9 insertions(+), 10 deletions(-)
> >
> > diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> > index 5628e25..6dca4e9 100644
> > --- a/fs/btrfs/transaction.c
> > +++ b/fs/btrfs/transaction.c
> > @@ -1620,9 +1620,7 @@ static void do_async_commit(struct work_struct *work)
> > * Tell lockdep about it.
> > */
> > if (ac->newtrans->type & __TRANS_FREEZABLE)
> > - rwsem_acquire_read(
> > - &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
> > - 0, 1, _THIS_IP_);
> > + __sb_acquire_write(ac->root->fs_info->sb, SB_FREEZE_FS);
> >
> > current->journal_info = ac->newtrans;
> >
> > @@ -1661,9 +1659,7 @@ int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
> > * async commit thread will be the one to unlock it.
> > */
> > if (ac->newtrans->type & __TRANS_FREEZABLE)
> > - rwsem_release(
> > - &root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
> > - 1, _THIS_IP_);
> > + __sb_release_write(root->fs_info->sb, SB_FREEZE_FS);
> >
> > schedule_work(&ac->work);
> >
> > diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> > index a56960d..8034c78 100644
> > --- a/fs/xfs/xfs_aops.c
> > +++ b/fs/xfs/xfs_aops.c
> > @@ -119,8 +119,7 @@ xfs_setfilesize_trans_alloc(
> > * We may pass freeze protection with a transaction. So tell lockdep
> > * we released it.
> > */
> > - rwsem_release(&ioend->io_inode->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
> > - 1, _THIS_IP_);
> > + __sb_release_write(ioend->io_inode->i_sb, SB_FREEZE_FS);
> > /*
> > * We hand off the transaction to the completion thread now, so
> > * clear the flag here.
> > @@ -171,8 +170,7 @@ xfs_setfilesize_ioend(
> > * Similarly for freeze protection.
> > */
> > current_set_flags_nested(&tp->t_pflags, PF_FSTRANS);
> > - rwsem_acquire_read(&VFS_I(ip)->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
> > - 0, 1, _THIS_IP_);
> > + __sb_acquire_write(VFS_I(ip)->i_sb, SB_FREEZE_FS);
> >
> > return xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size);
> > }
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index 35ec87e..78ac768 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -1362,6 +1362,11 @@ extern struct timespec current_fs_time(struct super_block *sb);
> > void __sb_end_write(struct super_block *sb, int level);
> > int __sb_start_write(struct super_block *sb, int level, bool wait);
> >
> > +#define __sb_acquire_write(sb, lev) \
> > + rwsem_acquire_read(&(sb)->s_writers.lock_map[(lev)-1], 0, 1, _THIS_IP_)
> > +#define __sb_release_write(sb, lev) \
> > + rwsem_release(&(sb)->s_writers.lock_map[(lev)-1], 1, _THIS_IP_)
> > +
> > /**
> > * sb_end_write - drop write access to a superblock
> > * @sb: the super we wrote to
> > --
> > 1.5.5.1
> >
> --
> Jan Kara <jack@suse.com>
> SUSE Labs, CR
--
Jan Kara <jack@suse.com>
SUSE Labs, CR