[PATCH v3 0/4] Remove the XFS mrlock

[PATCH v3 0/4] Remove the XFS mrlock

[Matthew Wilcox (Oracle)]

XFS has an mrlock wrapper around the rwsem which adds only the
functionality of knowing whether the rwsem is currently held in read
or write mode.  Both regular rwsems and rt-rwsems know this, they just
don't expose it as an API.  By adding that, we can remove the XFS mrlock
as well as improving the debug assertions for the mmap_lock when lockdep
is disabled.

v3:
 - Rename __rwsem_assert_held() and __rwsem_assert_held_write() to
   rwsem_assert_held*_nolockdep()
 - Use IS_ENABLED(CONFIG_LOCKDEP) to only dump the information once
 - Use ASSERT instead of BUG_ON in xfs
 - Fix typo in subject line of patch 4
 - Drop patch 5 (inode_assert_locked)
 - Rebase on top of xfs-6.7-merge-2 which had a merge conflict

v2: Add rwsem_assert_held() and rwsem_assert_held_write() instead of
augmenting the existing rwsem_is_locked() with rwsem_is_write_locked().
There's also an __rwsem_assert_held() and __rwsem_assert_held_write()
for the benefit of XFS when it's in a context where lockdep doesn't
know what's going on.  It's still an improvement, so I hope those who
are looking for perfection can accept a mere improvement.

We can do more to replace uses of rwsem_is_locked(), and I have a few of
those in my tree, but let's focus on these two use cases for now and
we can trickle in other improvements through other maintainers after 6.8.

Matthew Wilcox (Oracle) (4):
  locking: Add rwsem_assert_held() and rwsem_assert_held_write()
  mm: Use rwsem assertion macros for mmap_lock
  xfs: Replace xfs_isilocked with xfs_assert_ilocked
  xfs: Remove mrlock wrapper

 fs/xfs/libxfs/xfs_attr.c        |  2 +-
 fs/xfs/libxfs/xfs_attr_remote.c |  2 +-
 fs/xfs/libxfs/xfs_bmap.c        | 19 ++++----
 fs/xfs/libxfs/xfs_defer.c       |  2 +-
 fs/xfs/libxfs/xfs_inode_fork.c  |  2 +-
 fs/xfs/libxfs/xfs_rtbitmap.c    |  2 +-
 fs/xfs/libxfs/xfs_trans_inode.c |  6 +--
 fs/xfs/mrlock.h                 | 78 ------------------------------
 fs/xfs/scrub/readdir.c          |  4 +-
 fs/xfs/xfs_attr_list.c          |  2 +-
 fs/xfs/xfs_bmap_util.c          | 10 ++--
 fs/xfs/xfs_dir2_readdir.c       |  2 +-
 fs/xfs/xfs_dquot.c              |  4 +-
 fs/xfs/xfs_file.c               |  4 +-
 fs/xfs/xfs_inode.c              | 86 ++++++++++++---------------------
 fs/xfs/xfs_inode.h              |  4 +-
 fs/xfs/xfs_inode_item.c         |  4 +-
 fs/xfs/xfs_iops.c               |  7 ++-
 fs/xfs/xfs_linux.h              |  2 +-
 fs/xfs/xfs_qm.c                 | 10 ++--
 fs/xfs/xfs_reflink.c            |  2 +-
 fs/xfs/xfs_rtalloc.c            |  4 +-
 fs/xfs/xfs_super.c              |  4 +-
 fs/xfs/xfs_symlink.c            |  2 +-
 fs/xfs/xfs_trans_dquot.c        |  2 +-
 include/linux/mmap_lock.h       | 10 ++--
 include/linux/rwbase_rt.h       |  9 +++-
 include/linux/rwsem.h           | 46 ++++++++++++++++--
 28 files changed, 132 insertions(+), 199 deletions(-)
 delete mode 100644 fs/xfs/mrlock.h

-- 
2.42.0

[PATCH v3 1/4] locking: Add rwsem_assert_held() and rwsem_assert_held_write()

[Matthew Wilcox (Oracle)]

Modelled after lockdep_assert_held() and lockdep_assert_held_write(),
but are always active, even when lockdep is disabled.  Of course, they
don't test that _this_ thread is the owner, but it's sufficient to catch
many bugs and doesn't incur the same performance penalty as lockdep.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/rwbase_rt.h |  9 ++++++--
 include/linux/rwsem.h     | 46 ++++++++++++++++++++++++++++++++++-----
 2 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/include/linux/rwbase_rt.h b/include/linux/rwbase_rt.h
index 1d264dd08625..a04acd85705b 100644
--- a/include/linux/rwbase_rt.h
+++ b/include/linux/rwbase_rt.h
@@ -26,12 +26,17 @@ struct rwbase_rt {
 	} while (0)
 
 
-static __always_inline bool rw_base_is_locked(struct rwbase_rt *rwb)
+static __always_inline bool rw_base_is_locked(const struct rwbase_rt *rwb)
 {
 	return atomic_read(&rwb->readers) != READER_BIAS;
 }
 
-static __always_inline bool rw_base_is_contended(struct rwbase_rt *rwb)
+static inline void rw_base_assert_held_write(const struct rwbase_rt *rwb)
+{
+	BUG_ON(atomic_read(&rwb->readers) != WRITER_BIAS);
+}
+
+static __always_inline bool rw_base_is_contended(const struct rwbase_rt *rwb)
 {
 	return atomic_read(&rwb->readers) > 0;
 }
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 1dd530ce8b45..b5b34cca86f3 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -66,14 +66,24 @@ struct rw_semaphore {
 #endif
 };
 
-/* In all implementations count != 0 means locked */
+#define RWSEM_UNLOCKED_VALUE		0UL
+#define RWSEM_WRITER_LOCKED		(1UL << 0)
+#define __RWSEM_COUNT_INIT(name)	.count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE)
+
 static inline int rwsem_is_locked(struct rw_semaphore *sem)
 {
-	return atomic_long_read(&sem->count) != 0;
+	return atomic_long_read(&sem->count) != RWSEM_UNLOCKED_VALUE;
 }
 
-#define RWSEM_UNLOCKED_VALUE		0L
-#define __RWSEM_COUNT_INIT(name)	.count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE)
+static inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem)
+{
+	WARN_ON(atomic_long_read(&sem->count) == RWSEM_UNLOCKED_VALUE);
+}
+
+static inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem)
+{
+	WARN_ON(!(atomic_long_read(&sem->count) & RWSEM_WRITER_LOCKED));
+}
 
 /* Common initializer macros and functions */
 
@@ -152,11 +162,21 @@ do {								\
 	__init_rwsem((sem), #sem, &__key);			\
 } while (0)
 
-static __always_inline int rwsem_is_locked(struct rw_semaphore *sem)
+static __always_inline int rwsem_is_locked(const struct rw_semaphore *sem)
 {
 	return rw_base_is_locked(&sem->rwbase);
 }
 
+static inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem)
+{
+	BUG_ON(!rwsem_is_locked(sem));
+}
+
+static inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem)
+{
+	rw_base_assert_held_write(sem);
+}
+
 static __always_inline int rwsem_is_contended(struct rw_semaphore *sem)
 {
 	return rw_base_is_contended(&sem->rwbase);
@@ -169,6 +189,22 @@ static __always_inline int rwsem_is_contended(struct rw_semaphore *sem)
  * the RT specific variant.
  */
 
+static inline void rwsem_assert_held(const struct rw_semaphore *sem)
+{
+	if (IS_ENABLED(CONFIG_LOCKDEP))
+		lockdep_assert_held(sem);
+	else
+		rwsem_assert_held_nolockdep(sem);
+}
+
+static inline void rwsem_assert_held_write(const struct rw_semaphore *sem)
+{
+	if (IS_ENABLED(CONFIG_LOCKDEP))
+		lockdep_assert_held_write(sem);
+	else
+		rwsem_assert_held_write_nolockdep(sem);
+}
+
 /*
  * lock for reading
  */
-- 
2.42.0

[PATCH v3 2/4] mm: Use rwsem assertion macros for mmap_lock

[Matthew Wilcox (Oracle)]

This slightly strengthens our write assertion when lockdep is disabled.
It also downgrades us from BUG_ON to WARN_ON, but I think that's an
improvement.  I don't think dumping the mm_struct was all that valuable;
the call chain is what's important.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/mmap_lock.h | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
index 8d38dcb6d044..de9dc20b01ba 100644
--- a/include/linux/mmap_lock.h
+++ b/include/linux/mmap_lock.h
@@ -60,16 +60,14 @@ static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
 
 #endif /* CONFIG_TRACING */
 
-static inline void mmap_assert_locked(struct mm_struct *mm)
+static inline void mmap_assert_locked(const struct mm_struct *mm)
 {
-	lockdep_assert_held(&mm->mmap_lock);
-	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
+	rwsem_assert_held(&mm->mmap_lock);
 }
 
-static inline void mmap_assert_write_locked(struct mm_struct *mm)
+static inline void mmap_assert_write_locked(const struct mm_struct *mm)
 {
-	lockdep_assert_held_write(&mm->mmap_lock);
-	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
+	rwsem_assert_held_write(&mm->mmap_lock);
 }
 
 #ifdef CONFIG_PER_VMA_LOCK
-- 
2.42.0

[PATCH v3 3/4] xfs: Replace xfs_isilocked with xfs_assert_ilocked

[Matthew Wilcox (Oracle)]

To use the new rwsem_assert_held()/rwsem_assert_held_write(), we can't
use the existing ASSERT macro.  Add a new xfs_assert_ilocked() and
convert all the callers.

Fix an apparent bug in xfs_isilocked(): If the caller specifies
XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL, xfs_assert_ilocked() will check both
the IOLOCK and the ILOCK are held for write.  xfs_isilocked() only
checked that the ILOCK was held for write.

xfs_assert_ilocked() is always on, even if DEBUG or XFS_WARN aren't
defined.  It's a cheap check, so I don't think it's worth defining
it away.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/xfs/libxfs/xfs_attr.c        |  2 +-
 fs/xfs/libxfs/xfs_attr_remote.c |  2 +-
 fs/xfs/libxfs/xfs_bmap.c        | 19 +++++----
 fs/xfs/libxfs/xfs_defer.c       |  2 +-
 fs/xfs/libxfs/xfs_inode_fork.c  |  2 +-
 fs/xfs/libxfs/xfs_rtbitmap.c    |  2 +-
 fs/xfs/libxfs/xfs_trans_inode.c |  6 +--
 fs/xfs/scrub/readdir.c          |  4 +-
 fs/xfs/xfs_attr_list.c          |  2 +-
 fs/xfs/xfs_bmap_util.c          | 10 ++---
 fs/xfs/xfs_dir2_readdir.c       |  2 +-
 fs/xfs/xfs_dquot.c              |  4 +-
 fs/xfs/xfs_file.c               |  4 +-
 fs/xfs/xfs_inode.c              | 72 +++++++++++----------------------
 fs/xfs/xfs_inode.h              |  2 +-
 fs/xfs/xfs_inode_item.c         |  4 +-
 fs/xfs/xfs_iops.c               |  3 +-
 fs/xfs/xfs_qm.c                 | 10 ++---
 fs/xfs/xfs_reflink.c            |  2 +-
 fs/xfs/xfs_rtalloc.c            |  4 +-
 fs/xfs/xfs_symlink.c            |  2 +-
 fs/xfs/xfs_trans_dquot.c        |  2 +-
 22 files changed, 66 insertions(+), 96 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index e28d93d232de..ebf0722d8963 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -224,7 +224,7 @@ int
 xfs_attr_get_ilocked(
 	struct xfs_da_args	*args)
 {
-	ASSERT(xfs_isilocked(args->dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(args->dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);
 
 	if (!xfs_inode_hasattr(args->dp))
 		return -ENOATTR;
diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
index d440393b40eb..1c007ebf153a 100644
--- a/fs/xfs/libxfs/xfs_attr_remote.c
+++ b/fs/xfs/libxfs/xfs_attr_remote.c
@@ -545,7 +545,7 @@ xfs_attr_rmtval_stale(
 	struct xfs_buf		*bp;
 	int			error;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 
 	if (XFS_IS_CORRUPT(mp, map->br_startblock == DELAYSTARTBLOCK) ||
 	    XFS_IS_CORRUPT(mp, map->br_startblock == HOLESTARTBLOCK))
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index be62acffad6c..eaa1dbe9a6b3 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1189,7 +1189,7 @@ xfs_iread_extents(
 	if (!xfs_need_iread_extents(ifp))
 		return 0;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 
 	ir.loaded = 0;
 	xfs_iext_first(ifp, &ir.icur);
@@ -3883,7 +3883,7 @@ xfs_bmapi_read(
 
 	ASSERT(*nmap >= 1);
 	ASSERT(!(flags & ~(XFS_BMAPI_ATTRFORK | XFS_BMAPI_ENTIRE)));
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_SHARED|XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_SHARED|XFS_ILOCK_EXCL);
 
 	if (WARN_ON_ONCE(!ifp))
 		return -EFSCORRUPTED;
@@ -4354,7 +4354,7 @@ xfs_bmapi_write(
 	ASSERT(tp != NULL);
 	ASSERT(len > 0);
 	ASSERT(ifp->if_format != XFS_DINODE_FMT_LOCAL);
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	ASSERT(!(flags & XFS_BMAPI_REMAP));
 
 	/* zeroing is for currently only for data extents, not metadata */
@@ -4651,7 +4651,7 @@ xfs_bmapi_remap(
 	ifp = xfs_ifork_ptr(ip, whichfork);
 	ASSERT(len > 0);
 	ASSERT(len <= (xfs_filblks_t)XFS_MAX_BMBT_EXTLEN);
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	ASSERT(!(flags & ~(XFS_BMAPI_ATTRFORK | XFS_BMAPI_PREALLOC |
 			   XFS_BMAPI_NORMAP)));
 	ASSERT((flags & (XFS_BMAPI_ATTRFORK | XFS_BMAPI_PREALLOC)) !=
@@ -5287,7 +5287,7 @@ __xfs_bunmapi(
 	if (xfs_is_shutdown(mp))
 		return -EIO;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	ASSERT(len > 0);
 	ASSERT(nexts >= 0);
 
@@ -5631,8 +5631,7 @@ xfs_bmse_merge(
 
 	blockcount = left->br_blockcount + got->br_blockcount;
 
-	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
 	ASSERT(xfs_bmse_can_merge(left, got, shift));
 
 	new = *left;
@@ -5760,7 +5759,7 @@ xfs_bmap_collapse_extents(
 	if (xfs_is_shutdown(mp))
 		return -EIO;
 
-	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
 
 	error = xfs_iread_extents(tp, ip, whichfork);
 	if (error)
@@ -5833,7 +5832,7 @@ xfs_bmap_can_insert_extents(
 	int			is_empty;
 	int			error = 0;
 
-	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL);
 
 	if (xfs_is_shutdown(ip->i_mount))
 		return -EIO;
@@ -5875,7 +5874,7 @@ xfs_bmap_insert_extents(
 	if (xfs_is_shutdown(mp))
 		return -EIO;
 
-	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
 
 	error = xfs_iread_extents(tp, ip, whichfork);
 	if (error)
diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
index bcfb6a4203cd..7927a721dc86 100644
--- a/fs/xfs/libxfs/xfs_defer.c
+++ b/fs/xfs/libxfs/xfs_defer.c
@@ -744,7 +744,7 @@ xfs_defer_ops_capture(
 	 * transaction.
 	 */
 	for (i = 0; i < dfc->dfc_held.dr_inos; i++) {
-		ASSERT(xfs_isilocked(dfc->dfc_held.dr_ip[i], XFS_ILOCK_EXCL));
+		xfs_assert_ilocked(dfc->dfc_held.dr_ip[i], XFS_ILOCK_EXCL);
 		ihold(VFS_I(dfc->dfc_held.dr_ip[i]));
 	}
 
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 5a2e7ddfa76d..14193e044f3d 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -563,7 +563,7 @@ xfs_iextents_copy(
 	struct xfs_bmbt_irec	rec;
 	int64_t			copied = 0;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED);
 	ASSERT(ifp->if_bytes > 0);
 
 	for_each_xfs_iext(ifp, &icur, &rec) {
diff --git a/fs/xfs/libxfs/xfs_rtbitmap.c b/fs/xfs/libxfs/xfs_rtbitmap.c
index c269d704314d..0b094a44c6e2 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.c
+++ b/fs/xfs/libxfs/xfs_rtbitmap.c
@@ -946,7 +946,7 @@ xfs_rtfree_extent(
 	struct timespec64	atime;
 
 	ASSERT(mp->m_rbmip->i_itemp != NULL);
-	ASSERT(xfs_isilocked(mp->m_rbmip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(mp->m_rbmip, XFS_ILOCK_EXCL);
 
 	error = xfs_rtcheck_alloc_range(&args, start, len);
 	if (error)
diff --git a/fs/xfs/libxfs/xfs_trans_inode.c b/fs/xfs/libxfs/xfs_trans_inode.c
index 70e97ea6eee7..69fc5b981352 100644
--- a/fs/xfs/libxfs/xfs_trans_inode.c
+++ b/fs/xfs/libxfs/xfs_trans_inode.c
@@ -31,7 +31,7 @@ xfs_trans_ijoin(
 {
 	struct xfs_inode_log_item *iip;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	if (ip->i_itemp == NULL)
 		xfs_inode_item_init(ip, ip->i_mount);
 	iip = ip->i_itemp;
@@ -60,7 +60,7 @@ xfs_trans_ichgtime(
 	struct timespec64	tv;
 
 	ASSERT(tp);
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 
 	tv = current_time(inode);
 
@@ -90,7 +90,7 @@ xfs_trans_log_inode(
 	struct inode		*inode = VFS_I(ip);
 
 	ASSERT(iip);
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	ASSERT(!xfs_iflags_test(ip, XFS_ISTALE));
 
 	tp->t_flags |= XFS_TRANS_DIRTY;
diff --git a/fs/xfs/scrub/readdir.c b/fs/xfs/scrub/readdir.c
index e51c1544be63..0b200bab04c8 100644
--- a/fs/xfs/scrub/readdir.c
+++ b/fs/xfs/scrub/readdir.c
@@ -283,7 +283,7 @@ xchk_dir_walk(
 		return -EIO;
 
 	ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
-	ASSERT(xfs_isilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);
 
 	if (dp->i_df.if_format == XFS_DINODE_FMT_LOCAL)
 		return xchk_dir_walk_sf(sc, dp, dirent_fn, priv);
@@ -334,7 +334,7 @@ xchk_dir_lookup(
 		return -EIO;
 
 	ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
-	ASSERT(xfs_isilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);
 
 	if (dp->i_df.if_format == XFS_DINODE_FMT_LOCAL) {
 		error = xfs_dir2_sf_lookup(&args);
diff --git a/fs/xfs/xfs_attr_list.c b/fs/xfs/xfs_attr_list.c
index 99bbbe1a0e44..235dd125c92f 100644
--- a/fs/xfs/xfs_attr_list.c
+++ b/fs/xfs/xfs_attr_list.c
@@ -505,7 +505,7 @@ xfs_attr_list_ilocked(
 {
 	struct xfs_inode		*dp = context->dp;
 
-	ASSERT(xfs_isilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);
 
 	/*
 	 * Decide on what work routines to call based on the inode size.
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 731260a5af6d..0887fb37d84f 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -649,8 +649,8 @@ xfs_can_free_eofblocks(
 	 * Caller must either hold the exclusive io lock; or be inactivating
 	 * the inode, which guarantees there are no other users of the inode.
 	 */
-	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL) ||
-	       (VFS_I(ip)->i_state & I_FREEING));
+	if (!(VFS_I(ip)->i_state & I_FREEING))
+		xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL);
 
 	/* prealloc/delalloc exists only on regular files */
 	if (!S_ISREG(VFS_I(ip)->i_mode))
@@ -1106,8 +1106,7 @@ xfs_collapse_file_space(
 	xfs_fileoff_t		shift_fsb = XFS_B_TO_FSB(mp, len);
 	bool			done = false;
 
-	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
-	ASSERT(xfs_isilocked(ip, XFS_MMAPLOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL);
 
 	trace_xfs_collapse_file_space(ip);
 
@@ -1176,8 +1175,7 @@ xfs_insert_file_space(
 	xfs_fileoff_t		shift_fsb = XFS_B_TO_FSB(mp, len);
 	bool			done = false;
 
-	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
-	ASSERT(xfs_isilocked(ip, XFS_MMAPLOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL);
 
 	trace_xfs_insert_file_space(ip);
 
diff --git a/fs/xfs/xfs_dir2_readdir.c b/fs/xfs/xfs_dir2_readdir.c
index 9f3ceb461515..95cd8b9cf3dc 100644
--- a/fs/xfs/xfs_dir2_readdir.c
+++ b/fs/xfs/xfs_dir2_readdir.c
@@ -521,7 +521,7 @@ xfs_readdir(
 		return -EIO;
 
 	ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
-	ASSERT(xfs_isilocked(dp, XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
+	xfs_assert_ilocked(dp, XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL);
 	XFS_STATS_INC(dp->i_mount, xs_dir_getdents);
 
 	args.dp = dp;
diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index ac6ba646624d..4b2f1b82badc 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -949,7 +949,7 @@ xfs_qm_dqget_inode(
 	if (error)
 		return error;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	ASSERT(xfs_inode_dquot(ip, type) == NULL);
 
 	id = xfs_qm_id_for_quotatype(ip, type);
@@ -1006,7 +1006,7 @@ xfs_qm_dqget_inode(
 	}
 
 dqret:
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	trace_xfs_dqget_miss(dqp);
 	*O_dqpp = dqp;
 	return 0;
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index e33e5e13b95f..632653e00906 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -879,7 +879,7 @@ xfs_break_dax_layouts(
 {
 	struct page		*page;
 
-	ASSERT(xfs_isilocked(XFS_I(inode), XFS_MMAPLOCK_EXCL));
+	xfs_assert_ilocked(XFS_I(inode), XFS_MMAPLOCK_EXCL);
 
 	page = dax_layout_busy_page(inode->i_mapping);
 	if (!page)
@@ -900,7 +900,7 @@ xfs_break_layouts(
 	bool			retry;
 	int			error;
 
-	ASSERT(xfs_isilocked(XFS_I(inode), XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL));
+	xfs_assert_ilocked(XFS_I(inode), XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL);
 
 	do {
 		retry = false;
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index c0f1c89786c2..1ed6bed19bec 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -333,52 +333,26 @@ xfs_ilock_demote(
 	trace_xfs_ilock_demote(ip, lock_flags, _RET_IP_);
 }
 
-#if defined(DEBUG) || defined(XFS_WARN)
-static inline bool
-__xfs_rwsem_islocked(
-	struct rw_semaphore	*rwsem,
-	bool			shared)
-{
-	if (!debug_locks)
-		return rwsem_is_locked(rwsem);
-
-	if (!shared)
-		return lockdep_is_held_type(rwsem, 0);
-
-	/*
-	 * We are checking that the lock is held at least in shared
-	 * mode but don't care that it might be held exclusively
-	 * (i.e. shared | excl). Hence we check if the lock is held
-	 * in any mode rather than an explicit shared mode.
-	 */
-	return lockdep_is_held_type(rwsem, -1);
-}
-
-bool
-xfs_isilocked(
+void
+xfs_assert_ilocked(
 	struct xfs_inode	*ip,
 	uint			lock_flags)
 {
-	if (lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) {
-		if (!(lock_flags & XFS_ILOCK_SHARED))
-			return !!ip->i_lock.mr_writer;
-		return rwsem_is_locked(&ip->i_lock.mr_lock);
-	}
-
-	if (lock_flags & (XFS_MMAPLOCK_EXCL|XFS_MMAPLOCK_SHARED)) {
-		return __xfs_rwsem_islocked(&VFS_I(ip)->i_mapping->invalidate_lock,
-				(lock_flags & XFS_MMAPLOCK_SHARED));
-	}
-
-	if (lock_flags & (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED)) {
-		return __xfs_rwsem_islocked(&VFS_I(ip)->i_rwsem,
-				(lock_flags & XFS_IOLOCK_SHARED));
-	}
-
-	ASSERT(0);
-	return false;
+	if (lock_flags & XFS_ILOCK_SHARED)
+		rwsem_assert_held(&ip->i_lock.mr_lock);
+	else if (lock_flags & XFS_ILOCK_EXCL)
+		ASSERT(ip->i_lock.mr_writer);
+
+	if (lock_flags & XFS_MMAPLOCK_SHARED)
+		rwsem_assert_held(&VFS_I(ip)->i_mapping->invalidate_lock);
+	else if (lock_flags & XFS_MMAPLOCK_EXCL)
+		rwsem_assert_held_write(&VFS_I(ip)->i_mapping->invalidate_lock);
+
+	if (lock_flags & XFS_IOLOCK_SHARED)
+		rwsem_assert_held(&VFS_I(ip)->i_rwsem);
+	else if (lock_flags & XFS_IOLOCK_EXCL)
+		rwsem_assert_held_write(&VFS_I(ip)->i_rwsem);
 }
-#endif
 
 /*
  * xfs_lockdep_subclass_ok() is only used in an ASSERT, so is only called when
@@ -1342,9 +1316,9 @@ xfs_itruncate_extents_flags(
 	xfs_filblks_t		unmap_len;
 	int			error = 0;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
-	ASSERT(!atomic_read(&VFS_I(ip)->i_count) ||
-	       xfs_isilocked(ip, XFS_IOLOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
+	if (atomic_read(&VFS_I(ip)->i_count))
+		xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL);
 	ASSERT(new_size <= XFS_ISIZE(ip));
 	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
 	ASSERT(ip->i_itemp != NULL);
@@ -1605,7 +1579,7 @@ xfs_inactive_ifree(
 	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 
 	error = xfs_ifree(tp, ip);
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	if (error) {
 		/*
 		 * If we fail to free the inode, shut down.  The cancel
@@ -2359,7 +2333,7 @@ xfs_ifree(
 	struct xfs_inode_log_item *iip = ip->i_itemp;
 	int			error;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	ASSERT(VFS_I(ip)->i_nlink == 0);
 	ASSERT(ip->i_df.if_nextents == 0);
 	ASSERT(ip->i_disk_size == 0 || !S_ISREG(VFS_I(ip)->i_mode));
@@ -2428,7 +2402,7 @@ static void
 xfs_iunpin(
 	struct xfs_inode	*ip)
 {
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED);
 
 	trace_xfs_inode_unpin_nowait(ip, _RET_IP_);
 
@@ -3189,7 +3163,7 @@ xfs_iflush(
 	struct xfs_mount	*mp = ip->i_mount;
 	int			error;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED);
 	ASSERT(xfs_iflags_test(ip, XFS_IFLUSHING));
 	ASSERT(ip->i_df.if_format != XFS_DINODE_FMT_BTREE ||
 	       ip->i_df.if_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 3dc47937da5d..dd8b8339ba1b 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -523,7 +523,7 @@ 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);
-bool		xfs_isilocked(struct xfs_inode *, uint);
+void		xfs_assert_ilocked(struct xfs_inode *, uint);
 uint		xfs_ilock_data_map_shared(struct xfs_inode *);
 uint		xfs_ilock_attr_map_shared(struct xfs_inode *);
 
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index cd7803fda8b1..3e125be356c1 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -649,7 +649,7 @@ xfs_inode_item_pin(
 {
 	struct xfs_inode	*ip = INODE_ITEM(lip)->ili_inode;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	ASSERT(lip->li_buf);
 
 	trace_xfs_inode_pin(ip, _RET_IP_);
@@ -755,7 +755,7 @@ xfs_inode_item_release(
 	unsigned short		lock_flags;
 
 	ASSERT(ip->i_itemp != NULL);
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 
 	lock_flags = iip->ili_lock_flags;
 	iip->ili_lock_flags = 0;
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index fdfda4fba12b..e711668d601b 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -796,8 +796,7 @@ xfs_setattr_size(
 	uint			lock_flags = 0;
 	bool			did_zeroing = false;
 
-	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
-	ASSERT(xfs_isilocked(ip, XFS_MMAPLOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL);
 	ASSERT(S_ISREG(inode->i_mode));
 	ASSERT((iattr->ia_valid & (ATTR_UID|ATTR_GID|ATTR_ATIME|ATTR_ATIME_SET|
 		ATTR_MTIME_SET|ATTR_TIMES_SET)) == 0);
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index 94a7932ac570..45cf9a557eb9 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -254,7 +254,7 @@ xfs_qm_dqattach_one(
 	struct xfs_dquot	*dqp;
 	int			error;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	error = 0;
 
 	/*
@@ -322,7 +322,7 @@ xfs_qm_dqattach_locked(
 	if (!xfs_qm_need_dqattach(ip))
 		return 0;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 
 	if (XFS_IS_UQUOTA_ON(mp) && !ip->i_udquot) {
 		error = xfs_qm_dqattach_one(ip, XFS_DQTYPE_USER,
@@ -353,7 +353,7 @@ xfs_qm_dqattach_locked(
 	 * Don't worry about the dquots that we may have attached before any
 	 * error - they'll get detached later if it has not already been done.
 	 */
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	return error;
 }
 
@@ -1809,7 +1809,7 @@ xfs_qm_vop_chown(
 				 XFS_TRANS_DQ_RTBCOUNT : XFS_TRANS_DQ_BCOUNT;
 
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	ASSERT(XFS_IS_QUOTA_ON(ip->i_mount));
 
 	/* old dquot */
@@ -1897,7 +1897,7 @@ xfs_qm_vop_create_dqattach(
 	if (!XFS_IS_QUOTA_ON(mp))
 		return;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 
 	if (udqp && XFS_IS_UQUOTA_ON(mp)) {
 		ASSERT(ip->i_udquot == NULL);
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 658edee8381d..d10eba9548dc 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -527,7 +527,7 @@ xfs_reflink_allocate_cow(
 	int			error;
 	bool			found;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	if (!ip->i_cowfp) {
 		ASSERT(!xfs_is_reflink_inode(ip));
 		xfs_ifork_init_cow(ip);
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 88c48de5c9c8..5e5eedff71c9 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -1182,7 +1182,7 @@ xfs_rtallocate_extent(
 	int			error;	/* error value */
 	xfs_rtxnum_t		r;	/* result allocated rtext */
 
-	ASSERT(xfs_isilocked(args.mp->m_rbmip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(args.mp->m_rbmip, XFS_ILOCK_EXCL);
 	ASSERT(minlen > 0 && minlen <= maxlen);
 
 	/*
@@ -1425,7 +1425,7 @@ xfs_rtpick_extent(
 	uint64_t		seq;		/* sequence number of file creation */
 	struct timespec64	ts;		/* timespec in inode */
 
-	ASSERT(xfs_isilocked(mp->m_rbmip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(mp->m_rbmip, XFS_ILOCK_EXCL);
 
 	ts = inode_get_atime(VFS_I(mp->m_rbmip));
 	if (!(mp->m_rbmip->i_diflags & XFS_DIFLAG_NEWRTBM)) {
diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c
index 85e433df6a3f..2ca157de4a73 100644
--- a/fs/xfs/xfs_symlink.c
+++ b/fs/xfs/xfs_symlink.c
@@ -43,7 +43,7 @@ xfs_readlink_bmap_ilocked(
 	int			fsblocks = 0;
 	int			offset;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);
 
 	fsblocks = xfs_symlink_blocks(mp, pathlen);
 	error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
diff --git a/fs/xfs/xfs_trans_dquot.c b/fs/xfs/xfs_trans_dquot.c
index aa00cf67ad72..9c159d016ecf 100644
--- a/fs/xfs/xfs_trans_dquot.c
+++ b/fs/xfs/xfs_trans_dquot.c
@@ -796,7 +796,7 @@ xfs_trans_reserve_quota_nblks(
 		return 0;
 
 	ASSERT(!xfs_is_quota_inode(&mp->m_sb, ip->i_ino));
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 
 	if (force)
 		qflags |= XFS_QMOPT_FORCE_RES;
-- 
2.42.0

[PATCH v3 4/4] xfs: Remove mrlock wrapper

[Matthew Wilcox (Oracle)]

mrlock was an rwsem wrapper that also recorded whether the lock was
held for read or write.  Now that we can ask the generic code whether
the lock is held for read or write, we can remove this wrapper and use
an rwsem directly.

As the comment says, we can't use lockdep to assert that the ILOCK is
held for write, because we might be in a workqueue, and we aren't able
to tell lockdep that we do in fact own the lock.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/xfs/mrlock.h    | 78 ----------------------------------------------
 fs/xfs/xfs_inode.c | 22 +++++++------
 fs/xfs/xfs_inode.h |  2 +-
 fs/xfs/xfs_iops.c  |  4 +--
 fs/xfs/xfs_linux.h |  2 +-
 fs/xfs/xfs_super.c |  4 +--
 6 files changed, 18 insertions(+), 94 deletions(-)
 delete mode 100644 fs/xfs/mrlock.h

diff --git a/fs/xfs/mrlock.h b/fs/xfs/mrlock.h
deleted file mode 100644
index 79155eec341b..000000000000
--- a/fs/xfs/mrlock.h
+++ /dev/null
@@ -1,78 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Copyright (c) 2000-2006 Silicon Graphics, Inc.
- * All Rights Reserved.
- */
-#ifndef __XFS_SUPPORT_MRLOCK_H__
-#define __XFS_SUPPORT_MRLOCK_H__
-
-#include <linux/rwsem.h>
-
-typedef struct {
-	struct rw_semaphore	mr_lock;
-#if defined(DEBUG) || defined(XFS_WARN)
-	int			mr_writer;
-#endif
-} mrlock_t;
-
-#if defined(DEBUG) || defined(XFS_WARN)
-#define mrinit(mrp, name)	\
-	do { (mrp)->mr_writer = 0; init_rwsem(&(mrp)->mr_lock); } while (0)
-#else
-#define mrinit(mrp, name)	\
-	do { init_rwsem(&(mrp)->mr_lock); } while (0)
-#endif
-
-#define mrlock_init(mrp, t,n,s)	mrinit(mrp, n)
-#define mrfree(mrp)		do { } while (0)
-
-static inline void mraccess_nested(mrlock_t *mrp, int subclass)
-{
-	down_read_nested(&mrp->mr_lock, subclass);
-}
-
-static inline void mrupdate_nested(mrlock_t *mrp, int subclass)
-{
-	down_write_nested(&mrp->mr_lock, subclass);
-#if defined(DEBUG) || defined(XFS_WARN)
-	mrp->mr_writer = 1;
-#endif
-}
-
-static inline int mrtryaccess(mrlock_t *mrp)
-{
-	return down_read_trylock(&mrp->mr_lock);
-}
-
-static inline int mrtryupdate(mrlock_t *mrp)
-{
-	if (!down_write_trylock(&mrp->mr_lock))
-		return 0;
-#if defined(DEBUG) || defined(XFS_WARN)
-	mrp->mr_writer = 1;
-#endif
-	return 1;
-}
-
-static inline void mrunlock_excl(mrlock_t *mrp)
-{
-#if defined(DEBUG) || defined(XFS_WARN)
-	mrp->mr_writer = 0;
-#endif
-	up_write(&mrp->mr_lock);
-}
-
-static inline void mrunlock_shared(mrlock_t *mrp)
-{
-	up_read(&mrp->mr_lock);
-}
-
-static inline void mrdemote(mrlock_t *mrp)
-{
-#if defined(DEBUG) || defined(XFS_WARN)
-	mrp->mr_writer = 0;
-#endif
-	downgrade_write(&mrp->mr_lock);
-}
-
-#endif /* __XFS_SUPPORT_MRLOCK_H__ */
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 1ed6bed19bec..7661084ca568 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -208,9 +208,9 @@ xfs_ilock(
 	}
 
 	if (lock_flags & XFS_ILOCK_EXCL)
-		mrupdate_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
+		down_write_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
 	else if (lock_flags & XFS_ILOCK_SHARED)
-		mraccess_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
+		down_read_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
 }
 
 /*
@@ -251,10 +251,10 @@ xfs_ilock_nowait(
 	}
 
 	if (lock_flags & XFS_ILOCK_EXCL) {
-		if (!mrtryupdate(&ip->i_lock))
+		if (!down_write_trylock(&ip->i_lock))
 			goto out_undo_mmaplock;
 	} else if (lock_flags & XFS_ILOCK_SHARED) {
-		if (!mrtryaccess(&ip->i_lock))
+		if (!down_read_trylock(&ip->i_lock))
 			goto out_undo_mmaplock;
 	}
 	return 1;
@@ -303,9 +303,9 @@ xfs_iunlock(
 		up_read(&VFS_I(ip)->i_mapping->invalidate_lock);
 
 	if (lock_flags & XFS_ILOCK_EXCL)
-		mrunlock_excl(&ip->i_lock);
+		up_write(&ip->i_lock);
 	else if (lock_flags & XFS_ILOCK_SHARED)
-		mrunlock_shared(&ip->i_lock);
+		up_read(&ip->i_lock);
 
 	trace_xfs_iunlock(ip, lock_flags, _RET_IP_);
 }
@@ -324,7 +324,7 @@ xfs_ilock_demote(
 		~(XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL|XFS_ILOCK_EXCL)) == 0);
 
 	if (lock_flags & XFS_ILOCK_EXCL)
-		mrdemote(&ip->i_lock);
+		downgrade_write(&ip->i_lock);
 	if (lock_flags & XFS_MMAPLOCK_EXCL)
 		downgrade_write(&VFS_I(ip)->i_mapping->invalidate_lock);
 	if (lock_flags & XFS_IOLOCK_EXCL)
@@ -338,10 +338,14 @@ xfs_assert_ilocked(
 	struct xfs_inode	*ip,
 	uint			lock_flags)
 {
+	/*
+	 * Sometimes we assert the ILOCK is held exclusively, but we're in
+	 * a workqueue, so lockdep doesn't know we're the owner.
+	 */
 	if (lock_flags & XFS_ILOCK_SHARED)
-		rwsem_assert_held(&ip->i_lock.mr_lock);
+		rwsem_assert_held(&ip->i_lock);
 	else if (lock_flags & XFS_ILOCK_EXCL)
-		ASSERT(ip->i_lock.mr_writer);
+		rwsem_assert_held_write_nolockdep(&ip->i_lock);
 
 	if (lock_flags & XFS_MMAPLOCK_SHARED)
 		rwsem_assert_held(&VFS_I(ip)->i_mapping->invalidate_lock);
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index dd8b8339ba1b..3cade5903fda 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -39,7 +39,7 @@ typedef struct xfs_inode {
 
 	/* Transaction and locking information. */
 	struct xfs_inode_log_item *i_itemp;	/* logging information */
-	mrlock_t		i_lock;		/* inode lock */
+	struct rw_semaphore	i_lock;		/* inode lock */
 	atomic_t		i_pincount;	/* inode pin count */
 	struct llist_node	i_gclist;	/* deferred inactivation list */
 
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index e711668d601b..79010d60ee21 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -1284,9 +1284,9 @@ xfs_setup_inode(
 		 */
 		lockdep_set_class(&inode->i_rwsem,
 				  &inode->i_sb->s_type->i_mutex_dir_key);
-		lockdep_set_class(&ip->i_lock.mr_lock, &xfs_dir_ilock_class);
+		lockdep_set_class(&ip->i_lock, &xfs_dir_ilock_class);
 	} else {
-		lockdep_set_class(&ip->i_lock.mr_lock, &xfs_nondir_ilock_class);
+		lockdep_set_class(&ip->i_lock, &xfs_nondir_ilock_class);
 	}
 
 	/*
diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h
index d7873e0360f0..ec3c6c138a63 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -22,7 +22,6 @@ typedef __u32			xfs_nlink_t;
 #include "xfs_types.h"
 
 #include "kmem.h"
-#include "mrlock.h"
 
 #include <linux/semaphore.h>
 #include <linux/mm.h>
@@ -51,6 +50,7 @@ typedef __u32			xfs_nlink_t;
 #include <linux/notifier.h>
 #include <linux/delay.h>
 #include <linux/log2.h>
+#include <linux/rwsem.h>
 #include <linux/spinlock.h>
 #include <linux/random.h>
 #include <linux/ctype.h>
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 764304595e8b..cd0200ed51f0 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -724,9 +724,7 @@ xfs_fs_inode_init_once(
 	/* xfs inode */
 	atomic_set(&ip->i_pincount, 0);
 	spin_lock_init(&ip->i_flags_lock);
-
-	mrlock_init(&ip->i_lock, MRLOCK_ALLOW_EQUAL_PRI|MRLOCK_BARRIER,
-		     "xfsino", ip->i_ino);
+	init_rwsem(&ip->i_lock);
 }
 
 /*
-- 
2.42.0

Re: [PATCH v3 1/4] locking: Add rwsem_assert_held() and rwsem_assert_held_write()

[Waiman Long]

On 11/10/23 15:41, Matthew Wilcox (Oracle) wrote:
> Modelled after lockdep_assert_held() and lockdep_assert_held_write(),
> but are always active, even when lockdep is disabled.  Of course, they
> don't test that _this_ thread is the owner, but it's sufficient to catch
> many bugs and doesn't incur the same performance penalty as lockdep.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>   include/linux/rwbase_rt.h |  9 ++++++--
>   include/linux/rwsem.h     | 46 ++++++++++++++++++++++++++++++++++-----
>   2 files changed, 48 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/rwbase_rt.h b/include/linux/rwbase_rt.h
> index 1d264dd08625..a04acd85705b 100644
> --- a/include/linux/rwbase_rt.h
> +++ b/include/linux/rwbase_rt.h
> @@ -26,12 +26,17 @@ struct rwbase_rt {
>   	} while (0)
>   
>   
> -static __always_inline bool rw_base_is_locked(struct rwbase_rt *rwb)
> +static __always_inline bool rw_base_is_locked(const struct rwbase_rt *rwb)
>   {
>   	return atomic_read(&rwb->readers) != READER_BIAS;
>   }
>   
> -static __always_inline bool rw_base_is_contended(struct rwbase_rt *rwb)
> +static inline void rw_base_assert_held_write(const struct rwbase_rt *rwb)
> +{
> +	BUG_ON(atomic_read(&rwb->readers) != WRITER_BIAS);
> +}
> +
> +static __always_inline bool rw_base_is_contended(const struct rwbase_rt *rwb)
>   {
>   	return atomic_read(&rwb->readers) > 0;
>   }
> diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
> index 1dd530ce8b45..b5b34cca86f3 100644
> --- a/include/linux/rwsem.h
> +++ b/include/linux/rwsem.h
> @@ -66,14 +66,24 @@ struct rw_semaphore {
>   #endif
>   };
>   
> -/* In all implementations count != 0 means locked */
> +#define RWSEM_UNLOCKED_VALUE		0UL
> +#define RWSEM_WRITER_LOCKED		(1UL << 0)
> +#define __RWSEM_COUNT_INIT(name)	.count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE)
> +
>   static inline int rwsem_is_locked(struct rw_semaphore *sem)
>   {
> -	return atomic_long_read(&sem->count) != 0;
> +	return atomic_long_read(&sem->count) != RWSEM_UNLOCKED_VALUE;
>   }
>   
> -#define RWSEM_UNLOCKED_VALUE		0L
> -#define __RWSEM_COUNT_INIT(name)	.count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE)
> +static inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem)
> +{
> +	WARN_ON(atomic_long_read(&sem->count) == RWSEM_UNLOCKED_VALUE);
> +}
That is not correct. You mean "!= RWSEM_UNLOCKED_VALUE". Right?
> +
> +static inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem)
> +{
> +	WARN_ON(!(atomic_long_read(&sem->count) & RWSEM_WRITER_LOCKED));
> +}
>   
>   /* Common initializer macros and functions */
>   
> @@ -152,11 +162,21 @@ do {								\
>   	__init_rwsem((sem), #sem, &__key);			\
>   } while (0)
>   
> -static __always_inline int rwsem_is_locked(struct rw_semaphore *sem)
> +static __always_inline int rwsem_is_locked(const struct rw_semaphore *sem)
>   {
>   	return rw_base_is_locked(&sem->rwbase);
>   }
>   
> +static inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem)
> +{
> +	BUG_ON(!rwsem_is_locked(sem));
> +}
> +

There are some inconsistency in the use of WARN_ON() and BUG_ON() in the 
assertions. For PREEMPT_RT, held_write is a BUG_ON. For non-PREEMPT_RT, 
held is a BUG_ON. It is not clear why one is BUG_ON and other one is 
WARN_ON. Is there a rationale for that?

BTW, we can actually check if the current process is the write-lock 
owner of a rwsem, but not for a reader-owned rwsem.

Cheers,
Longman

Re: [PATCH v3 1/4] locking: Add rwsem_assert_held() and rwsem_assert_held_write()

[Peter Zijlstra]

On Fri, Nov 10, 2023 at 08:41:16PM +0000, Matthew Wilcox (Oracle) wrote:

> +static inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem)
> +{
> +	WARN_ON(atomic_long_read(&sem->count) == RWSEM_UNLOCKED_VALUE);
> +}
> +
> +static inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem)
> +{
> +	WARN_ON(!(atomic_long_read(&sem->count) & RWSEM_WRITER_LOCKED));
> +}

> +static inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem)
> +{
> +	BUG_ON(!rwsem_is_locked(sem));
> +}

What's with the WARN_ON() vs BUG_ON() thing?

Re: [PATCH v3 1/4] locking: Add rwsem_assert_held() and rwsem_assert_held_write()

[Matthew Wilcox]

On Fri, Nov 10, 2023 at 05:21:22PM -0500, Waiman Long wrote:
> On 11/10/23 15:41, Matthew Wilcox (Oracle) wrote:
> >   static inline int rwsem_is_locked(struct rw_semaphore *sem)
> >   {
> > -	return atomic_long_read(&sem->count) != 0;
> > +	return atomic_long_read(&sem->count) != RWSEM_UNLOCKED_VALUE;
> >   }
> > -#define RWSEM_UNLOCKED_VALUE		0L
> > -#define __RWSEM_COUNT_INIT(name)	.count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE)
> > +static inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem)
> > +{
> > +	WARN_ON(atomic_long_read(&sem->count) == RWSEM_UNLOCKED_VALUE);
> > +}
> That is not correct. You mean "!= RWSEM_UNLOCKED_VALUE". Right?

Uhhh ... I always get confused between assert and BUG_ON being opposite
polarity, but I think it's correct.

We are asserting that the rwsem is locked (either for read or write).
That is, it is a bug if the rwsem is unlocked.
So WARN_ON(sem->count == UNLOCKED_VALUE) is correct.  No?

> There are some inconsistency in the use of WARN_ON() and BUG_ON() in the
> assertions. For PREEMPT_RT, held_write is a BUG_ON. For non-PREEMPT_RT, held
> is a BUG_ON. It is not clear why one is BUG_ON and other one is WARN_ON. Is
> there a rationale for that?

I'll fix that up.

> BTW, we can actually check if the current process is the write-lock owner of
> a rwsem, but not for a reader-owned rwsem.

We actually don't want to do that.  See patches 3/4 where I explain how
XFS takes the XFS_ILOCK for write, then passes control to a workqueue
which asserts that the XFS_ILOCK is held for write.  The thread which
took the rwsem for write waits for the workqueue and unlocks the rwsem.

Re: [PATCH v3 1/4] locking: Add rwsem_assert_held() and rwsem_assert_held_write()

[Waiman Long]

On 11/14/23 16:26, Matthew Wilcox wrote:
> On Fri, Nov 10, 2023 at 05:21:22PM -0500, Waiman Long wrote:
>> On 11/10/23 15:41, Matthew Wilcox (Oracle) wrote:
>>>    static inline int rwsem_is_locked(struct rw_semaphore *sem)
>>>    {
>>> -	return atomic_long_read(&sem->count) != 0;
>>> +	return atomic_long_read(&sem->count) != RWSEM_UNLOCKED_VALUE;
>>>    }
>>> -#define RWSEM_UNLOCKED_VALUE		0L
>>> -#define __RWSEM_COUNT_INIT(name)	.count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE)
>>> +static inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem)
>>> +{
>>> +	WARN_ON(atomic_long_read(&sem->count) == RWSEM_UNLOCKED_VALUE);
>>> +}
>> That is not correct. You mean "!= RWSEM_UNLOCKED_VALUE". Right?
> Uhhh ... I always get confused between assert and BUG_ON being opposite
> polarity, but I think it's correct.
>
> We are asserting that the rwsem is locked (either for read or write).
> That is, it is a bug if the rwsem is unlocked.
> So WARN_ON(sem->count == UNLOCKED_VALUE) is correct.  No?
You are right. I got confused too.
>
>> There are some inconsistency in the use of WARN_ON() and BUG_ON() in the
>> assertions. For PREEMPT_RT, held_write is a BUG_ON. For non-PREEMPT_RT, held
>> is a BUG_ON. It is not clear why one is BUG_ON and other one is WARN_ON. Is
>> there a rationale for that?
> I'll fix that up.
The check for write lock ownership is accurate. OTOH, the locked check 
can have false positive and so is less reliable.
>
>> BTW, we can actually check if the current process is the write-lock owner of
>> a rwsem, but not for a reader-owned rwsem.
> We actually don't want to do that.  See patches 3/4 where I explain how
> XFS takes the XFS_ILOCK for write, then passes control to a workqueue
> which asserts that the XFS_ILOCK is held for write.  The thread which
> took the rwsem for write waits for the workqueue and unlocks the rwsem.
>
I see. Thanks for the explanation.

Cheers,
Longman

Re: [PATCH v3 1/4] locking: Add rwsem_assert_held() and rwsem_assert_held_write()

[Matthew Wilcox]

On Tue, Nov 14, 2023 at 08:17:32PM -0500, Waiman Long wrote:
> > > There are some inconsistency in the use of WARN_ON() and BUG_ON() in the
> > > assertions. For PREEMPT_RT, held_write is a BUG_ON. For non-PREEMPT_RT, held
> > > is a BUG_ON. It is not clear why one is BUG_ON and other one is WARN_ON. Is
> > > there a rationale for that?
> > I'll fix that up.
> The check for write lock ownership is accurate. OTOH, the locked check can
> have false positive and so is less reliable.

When you say 'false positive', do you mean it might report the lock as
being held, when it actually isn't, or report the lock as not being held
when it actually is?  The differing polarities of assert and BUG_ON
make this confusing as usual.

Obviously, for an assert, we're OK with it reporting that the lock is
held when actually it's not.  The caller is expected to hold the lock,
so failing to trip the assert when the caller doesn't hold the lock
isn't great, but we can live with it.  OTOH, if the assert fires when
the caller does hold the lock, that is not tolerable.

Re: [PATCH v3 1/4] locking: Add rwsem_assert_held() and rwsem_assert_held_write()

[Waiman Long]

On 11/16/23 11:12, Matthew Wilcox wrote:
> On Tue, Nov 14, 2023 at 08:17:32PM -0500, Waiman Long wrote:
>>>> There are some inconsistency in the use of WARN_ON() and BUG_ON() in the
>>>> assertions. For PREEMPT_RT, held_write is a BUG_ON. For non-PREEMPT_RT, held
>>>> is a BUG_ON. It is not clear why one is BUG_ON and other one is WARN_ON. Is
>>>> there a rationale for that?
>>> I'll fix that up.
>> The check for write lock ownership is accurate. OTOH, the locked check can
>> have false positive and so is less reliable.
> When you say 'false positive', do you mean it might report the lock as
> being held, when it actually isn't, or report the lock as not being held
> when it actually is?  The differing polarities of assert and BUG_ON
> make this confusing as usual.
It means there may be no active lock owner even though the count isn't 
zero. If there is one or more owners, the count will always be non-zero.
>
> Obviously, for an assert, we're OK with it reporting that the lock is
> held when actually it's not.  The caller is expected to hold the lock,
> so failing to trip the assert when the caller doesn't hold the lock
> isn't great, but we can live with it.  OTOH, if the assert fires when
> the caller does hold the lock, that is not tolerable.

The second case shouldn't happen. So the assert should be OK.

Cheers,
Longman