| Message ID | 20200221004134.30599-3-ira.weiny@intel.com (mailing list archive) |
|---|---|
| State | Deferred, archived |
| Headers | show |
| Series | Enable per-file/per-directory DAX operations V4 | expand |
On Thu, Feb 20, 2020 at 04:41:23PM -0800, ira.weiny@intel.com wrote: > From: Ira Weiny <ira.weiny@intel.com> > > xfs_isilocked() can't work fully without CONFIG_LOCKDEP. However, > making xfs_isilocked() dependant on CONFIG_LOCKDEP is not feasible > because it is used for more than the i_rwsem. Therefore a short-circuit > was provided via debug_locks. However, this caused confusion while > working through the xfs locking. > > Rather than use debug_locks as a flag specify this clearly using > IS_ENABLED(CONFIG_LOCKDEP). > > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > > --- > Changes from V3: > Reordered to be a "pre-cleanup" patch > > Changes from V2: > This patch is new for V3 > --- > fs/xfs/xfs_inode.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c > index c5077e6326c7..35df324875db 100644 > --- a/fs/xfs/xfs_inode.c > +++ b/fs/xfs/xfs_inode.c > @@ -364,7 +364,7 @@ xfs_isilocked( > > if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) { > if (!(lock_flags & XFS_IOLOCK_SHARED)) > - return !debug_locks || > + return !IS_ENABLED(CONFIG_LOCKDEP) || > lockdep_is_held_type(&VFS_I(ip)->i_rwsem, 0); This breaks expected lockdep behaviour. We need to use debug_locks here because lockdep turns off lock checking via debug_locks when lockdep encounters a locking inconsistency. We only want to know about the first locking problem, not spew cascading lock problems over and over once we already know there is a locking problem. IOWs, checking debug_locks is required here for the same reason it is used in lockdep_assert_held_{read/write}(). essentially we are open coding lockdep_assert_held_write() here because this function is only called from within ASSERT() statements and we don't want multiple WARN/BUGs being issued when this triggers.... Cheers, Dave.
On Fri, Feb 21, 2020 at 12:34:51PM +1100, Dave Chinner wrote: > On Thu, Feb 20, 2020 at 04:41:23PM -0800, ira.weiny@intel.com wrote: > > From: Ira Weiny <ira.weiny@intel.com> > > > > xfs_isilocked() can't work fully without CONFIG_LOCKDEP. However, > > making xfs_isilocked() dependant on CONFIG_LOCKDEP is not feasible > > because it is used for more than the i_rwsem. Therefore a short-circuit > > was provided via debug_locks. However, this caused confusion while > > working through the xfs locking. > > > > Rather than use debug_locks as a flag specify this clearly using > > IS_ENABLED(CONFIG_LOCKDEP). > > > > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > > > > --- > > Changes from V3: > > Reordered to be a "pre-cleanup" patch > > > > Changes from V2: > > This patch is new for V3 > > --- > > fs/xfs/xfs_inode.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c > > index c5077e6326c7..35df324875db 100644 > > --- a/fs/xfs/xfs_inode.c > > +++ b/fs/xfs/xfs_inode.c > > @@ -364,7 +364,7 @@ xfs_isilocked( > > > > if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) { > > if (!(lock_flags & XFS_IOLOCK_SHARED)) > > - return !debug_locks || > > + return !IS_ENABLED(CONFIG_LOCKDEP) || > > lockdep_is_held_type(&VFS_I(ip)->i_rwsem, 0); > > This breaks expected lockdep behaviour. > > We need to use debug_locks here because lockdep turns off lock > checking via debug_locks when lockdep encounters a locking > inconsistency. We only want to know about the first locking > problem, not spew cascading lock problems over and over once we > already know there is a locking problem. Ah... ok... Seems like that should be part of the lockdep interface... I'll drop the patch for now, Ira > > IOWs, checking debug_locks is required here for the same reason it > is used in lockdep_assert_held_{read/write}(). essentially we are > open coding lockdep_assert_held_write() here because this function > is only called from within ASSERT() statements and we don't want > multiple WARN/BUGs being issued when this triggers.... > > Cheers, > > Dave. > -- > Dave Chinner > david@fromorbit.com
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c index c5077e6326c7..35df324875db 100644 --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -364,7 +364,7 @@ xfs_isilocked( if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) { if (!(lock_flags & XFS_IOLOCK_SHARED)) - return !debug_locks || + return !IS_ENABLED(CONFIG_LOCKDEP) || lockdep_is_held_type(&VFS_I(ip)->i_rwsem, 0); return rwsem_is_locked(&VFS_I(ip)->i_rwsem); }