On Fri, Oct 09, 2020 at 09:55:12PM +0200, Pavel Reichl wrote:
> Refactor xfs_isilocked() to use newly introduced __xfs_rwsem_islocked().
> __xfs_rwsem_islocked() is a helper function which encapsulates checking
> state of rw_semaphores hold by inode.
>
> Signed-off-by: Pavel Reichl <preichl@xxxxxxxxxx>
> Suggested-by: Dave Chinner <dchinner@xxxxxxxxxx>
> Suggested-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> Suggested-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/xfs/xfs_inode.c | 48 ++++++++++++++++++++++++++++++++++++++--------
> fs/xfs/xfs_inode.h | 21 +++++++++++++-------
> 2 files changed, 54 insertions(+), 15 deletions(-)
>
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index c06129cffba9..7c1ceb4df4ec 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -345,9 +345,43 @@ xfs_ilock_demote(
> }
>
> #if defined(DEBUG) || defined(XFS_WARN)
> -int
> +static inline bool
> +__xfs_rwsem_islocked(
> + struct rw_semaphore *rwsem,
> + int lock_flags)
> +{
> + int arg;
> +
> + if (!debug_locks)
> + return rwsem_is_locked(rwsem);
> +
> + if (lock_flags & (1 << XFS_SHARED_LOCK_SHIFT)) {
> + /*
> + * The caller could be asking if we have (shared | excl)
> + * access to the lock. Ask lockdep if the rwsem is
> + * locked either for read or write access.
> + *
> + * The caller could also be asking if we have only
> + * shared access to the lock. Holding a rwsem
> + * write-locked implies read access as well, so the
> + * request to lockdep is the same for this case.
> + */
> + arg = -1;
> + } else {
> + /*
> + * The caller is asking if we have only exclusive access
> + * to the lock. Ask lockdep if the rwsem is locked for
> + * write access.
> + */
> + arg = 0;
> + }
Are these arg values documented somewhere? A quick look at the function
below didn't show anything..
Also, I find the pattern of shifting in the caller slightly confusing,
particularly with the 'lock_flags' name being passed down through the
caller. Any reason we couldn't pass the shift value as a parameter and
do the shift at the top of the function so the logic is clear and in one
place?
> +
> + return lockdep_is_held_type(rwsem, arg);
> +}
> +
> +bool
> xfs_isilocked(
> - xfs_inode_t *ip,
> + struct xfs_inode *ip,
> uint lock_flags)
> {
> if (lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) {
...
> diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> index e9a8bb184d1f..77776af75c77 100644
> --- a/fs/xfs/xfs_inode.h
> +++ b/fs/xfs/xfs_inode.h
> @@ -268,12 +268,19 @@ static inline void xfs_ifunlock(struct xfs_inode *ip)
> * Bit ranges: 1<<1 - 1<<16-1 -- iolock/ilock modes (bitfield)
> * 1<<16 - 1<<32-1 -- lockdep annotation (integers)
> */
> -#define XFS_IOLOCK_EXCL (1<<0)
> -#define XFS_IOLOCK_SHARED (1<<1)
> -#define XFS_ILOCK_EXCL (1<<2)
> -#define XFS_ILOCK_SHARED (1<<3)
> -#define XFS_MMAPLOCK_EXCL (1<<4)
> -#define XFS_MMAPLOCK_SHARED (1<<5)
> +
> +#define XFS_IOLOCK_FLAG_SHIFT 0
> +#define XFS_ILOCK_FLAG_SHIFT 2
> +#define XFS_MMAPLOCK_FLAG_SHIFT 4
> +
> +#define XFS_SHARED_LOCK_SHIFT 1
> +
> +#define XFS_IOLOCK_EXCL (1 << (XFS_IOLOCK_FLAG_SHIFT))
> +#define XFS_IOLOCK_SHARED (XFS_IOLOCK_EXCL << (XFS_SHARED_LOCK_SHIFT))
> +#define XFS_ILOCK_EXCL (1 << (XFS_ILOCK_FLAG_SHIFT))
> +#define XFS_ILOCK_SHARED (XFS_ILOCK_EXCL << (XFS_SHARED_LOCK_SHIFT))
> +#define XFS_MMAPLOCK_EXCL (1 << (XFS_MMAPLOCK_FLAG_SHIFT))
> +#define XFS_MMAPLOCK_SHARED (XFS_MMAPLOCK_EXCL << (XFS_SHARED_LOCK_SHIFT))
>
Any reason for the extra params around the shift values?
Brian
> #define XFS_LOCK_MASK (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED \
> | XFS_ILOCK_EXCL | XFS_ILOCK_SHARED \
> @@ -412,7 +419,7 @@ void xfs_ilock(xfs_inode_t *, uint);
> int xfs_ilock_nowait(xfs_inode_t *, uint);
> void xfs_iunlock(xfs_inode_t *, uint);
> void xfs_ilock_demote(xfs_inode_t *, uint);
> -int xfs_isilocked(xfs_inode_t *, uint);
> +bool xfs_isilocked(struct xfs_inode *, uint);
> uint xfs_ilock_data_map_shared(struct xfs_inode *);
> uint xfs_ilock_attr_map_shared(struct xfs_inode *);
>
> --
> 2.26.2
>
