Message ID | 6dfcb89b254ee5016edfa9816fce3487a23b446c.1559233731.git.dsterba@suse.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | Extent buffer lock cleanups | expand |
On 30.05.19 г. 19:31 ч., David Sterba wrote: > The spinning_writers is either 0 or 1 and always updated under the lock, > so we don't need the atomic_t semantics. > > Signed-off-by: David Sterba <dsterba@suse.com> > --- > fs/btrfs/extent_io.c | 2 +- > fs/btrfs/extent_io.h | 2 +- > fs/btrfs/locking.c | 10 +++++----- > fs/btrfs/print-tree.c | 2 +- > 4 files changed, 8 insertions(+), 8 deletions(-) > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index 57b6de9df7c4..71ee9e976307 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -4842,7 +4842,7 @@ __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start, > BUG_ON(len > MAX_INLINE_EXTENT_BUFFER_SIZE); > > #ifdef CONFIG_BTRFS_DEBUG > - atomic_set(&eb->spinning_writers, 0); > + eb->spinning_writers = 0; > atomic_set(&eb->spinning_readers, 0); > atomic_set(&eb->read_locks, 0); > atomic_set(&eb->write_locks, 0); > diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h > index 201da61dfc21..5616b96c365d 100644 > --- a/fs/btrfs/extent_io.h > +++ b/fs/btrfs/extent_io.h > @@ -187,7 +187,7 @@ struct extent_buffer { > wait_queue_head_t read_lock_wq; > struct page *pages[INLINE_EXTENT_BUFFER_PAGES]; > #ifdef CONFIG_BTRFS_DEBUG > - atomic_t spinning_writers; > + int spinning_writers; > atomic_t spinning_readers; > atomic_t read_locks; > atomic_t write_locks; > diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c > index 5feb01147e19..270667627977 100644 > --- a/fs/btrfs/locking.c > +++ b/fs/btrfs/locking.c > @@ -15,19 +15,19 @@ > #ifdef CONFIG_BTRFS_DEBUG > static void btrfs_assert_spinning_writers_get(struct extent_buffer *eb) > { > - WARN_ON(atomic_read(&eb->spinning_writers)); > - atomic_inc(&eb->spinning_writers); > + WARN_ON(eb->spinning_writers); > + eb->spinning_writers++; > } > > static void btrfs_assert_spinning_writers_put(struct extent_buffer *eb) > { > - WARN_ON(atomic_read(&eb->spinning_writers) != 1); > - atomic_dec(&eb->spinning_writers); > + WARN_ON(eb->spinning_writers != 1); > + eb->spinning_writers--; > } > > static void btrfs_assert_no_spinning_writers(struct extent_buffer *eb) > { > - WARN_ON(atomic_read(&eb->spinning_writers)); > + WARN_ON(eb->spinning_writers); > } IMO longterm it will be good if those debug functions contained lockdep_assert_held_exclusive/read macros for posterity. > > static void btrfs_assert_spinning_readers_get(struct extent_buffer *eb) > diff --git a/fs/btrfs/print-tree.c b/fs/btrfs/print-tree.c > index 7cb4f1fbe043..c5cc435ed39a 100644 > --- a/fs/btrfs/print-tree.c > +++ b/fs/btrfs/print-tree.c > @@ -157,7 +157,7 @@ static void print_eb_refs_lock(struct extent_buffer *eb) > atomic_read(&eb->read_locks), > eb->blocking_writers, > atomic_read(&eb->blocking_readers), > - atomic_read(&eb->spinning_writers), > + eb->spinning_writers, > atomic_read(&eb->spinning_readers), > eb->lock_owner, current->pid); > #endif >
On Fri, May 31, 2019 at 12:19:15PM +0300, Nikolay Borisov wrote: > > { > > - WARN_ON(atomic_read(&eb->spinning_writers)); > > - atomic_inc(&eb->spinning_writers); > > + WARN_ON(eb->spinning_writers); > > + eb->spinning_writers++; > > } > > > > static void btrfs_assert_spinning_writers_put(struct extent_buffer *eb) > > { > > - WARN_ON(atomic_read(&eb->spinning_writers) != 1); > > - atomic_dec(&eb->spinning_writers); > > + WARN_ON(eb->spinning_writers != 1); > > + eb->spinning_writers--; > > } > > > > static void btrfs_assert_no_spinning_writers(struct extent_buffer *eb) > > { > > - WARN_ON(atomic_read(&eb->spinning_writers)); > > + WARN_ON(eb->spinning_writers); > > } > > IMO longterm it will be good if those debug functions contained > lockdep_assert_held_exclusive/read macros for posterity. The functions are not public and used only inside implementation of locks, so the chances of wrong use are low so I don't see much value adding it.
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 57b6de9df7c4..71ee9e976307 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -4842,7 +4842,7 @@ __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start, BUG_ON(len > MAX_INLINE_EXTENT_BUFFER_SIZE); #ifdef CONFIG_BTRFS_DEBUG - atomic_set(&eb->spinning_writers, 0); + eb->spinning_writers = 0; atomic_set(&eb->spinning_readers, 0); atomic_set(&eb->read_locks, 0); atomic_set(&eb->write_locks, 0); diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index 201da61dfc21..5616b96c365d 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -187,7 +187,7 @@ struct extent_buffer { wait_queue_head_t read_lock_wq; struct page *pages[INLINE_EXTENT_BUFFER_PAGES]; #ifdef CONFIG_BTRFS_DEBUG - atomic_t spinning_writers; + int spinning_writers; atomic_t spinning_readers; atomic_t read_locks; atomic_t write_locks; diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 5feb01147e19..270667627977 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -15,19 +15,19 @@ #ifdef CONFIG_BTRFS_DEBUG static void btrfs_assert_spinning_writers_get(struct extent_buffer *eb) { - WARN_ON(atomic_read(&eb->spinning_writers)); - atomic_inc(&eb->spinning_writers); + WARN_ON(eb->spinning_writers); + eb->spinning_writers++; } static void btrfs_assert_spinning_writers_put(struct extent_buffer *eb) { - WARN_ON(atomic_read(&eb->spinning_writers) != 1); - atomic_dec(&eb->spinning_writers); + WARN_ON(eb->spinning_writers != 1); + eb->spinning_writers--; } static void btrfs_assert_no_spinning_writers(struct extent_buffer *eb) { - WARN_ON(atomic_read(&eb->spinning_writers)); + WARN_ON(eb->spinning_writers); } static void btrfs_assert_spinning_readers_get(struct extent_buffer *eb) diff --git a/fs/btrfs/print-tree.c b/fs/btrfs/print-tree.c index 7cb4f1fbe043..c5cc435ed39a 100644 --- a/fs/btrfs/print-tree.c +++ b/fs/btrfs/print-tree.c @@ -157,7 +157,7 @@ static void print_eb_refs_lock(struct extent_buffer *eb) atomic_read(&eb->read_locks), eb->blocking_writers, atomic_read(&eb->blocking_readers), - atomic_read(&eb->spinning_writers), + eb->spinning_writers, atomic_read(&eb->spinning_readers), eb->lock_owner, current->pid); #endif
The spinning_writers is either 0 or 1 and always updated under the lock, so we don't need the atomic_t semantics. Signed-off-by: David Sterba <dsterba@suse.com> --- fs/btrfs/extent_io.c | 2 +- fs/btrfs/extent_io.h | 2 +- fs/btrfs/locking.c | 10 +++++----- fs/btrfs/print-tree.c | 2 +- 4 files changed, 8 insertions(+), 8 deletions(-)