On 10/12/20 6:03 PM, Brian Foster wrote:
> 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;
>> + }
...
>
> 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?
>
Hi Brian, is following change what you had in mind? Thanks!
>> @@ -349,14 +349,16 @@ xfs_ilock_demote(
static inline bool
__xfs_rwsem_islocked(
struct rw_semaphore *rwsem,
- int lock_flags)
+ int lock_flags,
+ int shift)
{
int arg;
+ const int shifted_lock_flags = lock_flags >> shift;
if (!debug_locks)
return rwsem_is_locked(rwsem);
- if (lock_flags & (1 << XFS_SHARED_LOCK_SHIFT)) {
+ if (shifted_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
@@ -387,20 +389,20 @@ xfs_isilocked(
{
if (lock_flags & (XFS_ILOCK_EXCL | XFS_ILOCK_SHARED)) {
ASSERT(!(lock_flags & ~(XFS_ILOCK_EXCL | XFS_ILOCK_SHARED)));
- return __xfs_rwsem_islocked(&ip->i_lock,
- (lock_flags >> XFS_ILOCK_FLAG_SHIFT));
+ return __xfs_rwsem_islocked(&ip->i_lock, lock_flags,
+ XFS_ILOCK_FLAG_SHIFT);
}
if (lock_flags & (XFS_MMAPLOCK_EXCL | XFS_MMAPLOCK_SHARED)) {
ASSERT(!(lock_flags &
~(XFS_MMAPLOCK_EXCL | XFS_MMAPLOCK_SHARED)));
- return __xfs_rwsem_islocked(&ip->i_mmaplock,
- (lock_flags >> XFS_MMAPLOCK_FLAG_SHIFT));
+ return __xfs_rwsem_islocked(&ip->i_mmaplock, lock_flags,
+ XFS_MMAPLOCK_FLAG_SHIFT);
}
if (lock_flags & (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED)) {
- return __xfs_rwsem_islocked(&VFS_I(ip)->i_rwsem,
- (lock_flags >> XFS_IOLOCK_FLAG_SHIFT));
+ return __xfs_rwsem_islocked(&VFS_I(ip)->i_rwsem, lock_flags,
+ XFS_IOLOCK_FLAG_SHIFT);
}
ASSERT(0);
