[PATCH v2 4/5] xfs: Remove mrlock wrapper

Matthew Wilcox (Oracle)
2023-10-07T20:36:05Z

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 812d6f255d84..a6d9a834d869 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)
- BUG_ON(!ip->i_lock.mr_writer);
+ __rwsem_assert_held_write(&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 b70f3e8e4525..1c2484b6afff 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 2492b746912e..fcceb2b4e40d 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -1279,9 +1279,9 @@ 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 e9d317a3dafe..15fdaef578fe 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 819a3568b28f..19435fa4c6b3 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -717,9 +717,7 @@ 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);
}

/*
--
2.40.1