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From: Nikolay Borisov <nborisov@suse.com>
To: linux-xfs@vger.kernel.org
Cc: david@fromorbit.com, Nikolay Borisov <nborisov@suse.com>
Subject: [RFC PATCH 2/3] xfs: Convert i_lock/i_mmaplock to  rw_semaphore
Date: Wed, 13 Jan 2021 13:17:05 +0200	[thread overview]
Message-ID: <20210113111707.756662-3-nborisov@suse.com> (raw)
In-Reply-To: <20210113111707.756662-1-nborisov@suse.com>

Having the mrlock_t doesn't provide any benefit since rwsem is perfectly
equipped to answer the question whether a rwsem is held for write or
not. Exploit this fact to convert the i_lock/i_mmaplock to direct
semaphores, thus making mrlock unused. This removes a level of
indirection internal to xfs but also paves the way to lifting i_mmaplock
to VFS in the future.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/xfs/xfs_inode.c | 41 +++++++++++++++++++++--------------------
 fs/xfs/xfs_inode.h |  6 +++---
 fs/xfs/xfs_super.c |  7 ++-----
 3 files changed, 26 insertions(+), 28 deletions(-)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 499e63da935c..dcf216eb7505 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -4,6 +4,7 @@
  * All Rights Reserved.
  */
 #include <linux/iversion.h>
+#include <linux/rwsem.h>
 
 #include "xfs.h"
 #include "xfs_fs.h"
@@ -191,14 +192,14 @@ xfs_ilock(
 	}
 
 	if (lock_flags & XFS_MMAPLOCK_EXCL)
-		mrupdate_nested(&ip->i_mmaplock, XFS_MMAPLOCK_DEP(lock_flags));
+		down_write_nested(&ip->i_mmaplock, XFS_MMAPLOCK_DEP(lock_flags));
 	else if (lock_flags & XFS_MMAPLOCK_SHARED)
-		mraccess_nested(&ip->i_mmaplock, XFS_MMAPLOCK_DEP(lock_flags));
+		down_read_nested(&ip->i_mmaplock, XFS_MMAPLOCK_DEP(lock_flags));
 
 	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));
 }
 
 /*
@@ -242,27 +243,27 @@ xfs_ilock_nowait(
 	}
 
 	if (lock_flags & XFS_MMAPLOCK_EXCL) {
-		if (!mrtryupdate(&ip->i_mmaplock))
+		if (!down_write_trylock(&ip->i_mmaplock))
 			goto out_undo_iolock;
 	} else if (lock_flags & XFS_MMAPLOCK_SHARED) {
-		if (!mrtryaccess(&ip->i_mmaplock))
+		if (!down_read_trylock(&ip->i_mmaplock))
 			goto out_undo_iolock;
 	}
 
 	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;
 
 out_undo_mmaplock:
 	if (lock_flags & XFS_MMAPLOCK_EXCL)
-		mrunlock_excl(&ip->i_mmaplock);
+		up_write(&ip->i_mmaplock);
 	else if (lock_flags & XFS_MMAPLOCK_SHARED)
-		mrunlock_shared(&ip->i_mmaplock);
+		up_read(&ip->i_mmaplock);
 out_undo_iolock:
 	if (lock_flags & XFS_IOLOCK_EXCL)
 		up_write(&VFS_I(ip)->i_rwsem);
@@ -309,14 +310,14 @@ xfs_iunlock(
 		up_read(&VFS_I(ip)->i_rwsem);
 
 	if (lock_flags & XFS_MMAPLOCK_EXCL)
-		mrunlock_excl(&ip->i_mmaplock);
+		up_write(&ip->i_mmaplock);
 	else if (lock_flags & XFS_MMAPLOCK_SHARED)
-		mrunlock_shared(&ip->i_mmaplock);
+		up_read(&ip->i_mmaplock);
 
 	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_);
 }
@@ -335,9 +336,9 @@ 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)
-		mrdemote(&ip->i_mmaplock);
+		downgrade_write(&ip->i_mmaplock);
 	if (lock_flags & XFS_IOLOCK_EXCL)
 		downgrade_write(&VFS_I(ip)->i_rwsem);
 
@@ -359,14 +360,14 @@ xfs_isilocked(
 {
 	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);
+			return is_rwsem_write_locked(&ip->i_lock);
+		return rwsem_is_locked(&ip->i_lock);
 	}
 
 	if (lock_flags & (XFS_MMAPLOCK_EXCL|XFS_MMAPLOCK_SHARED)) {
 		if (!(lock_flags & XFS_MMAPLOCK_SHARED))
-			return !!ip->i_mmaplock.mr_writer;
-		return rwsem_is_locked(&ip->i_mmaplock.mr_lock);
+			return is_rwsem_write_locked(&ip->i_mmaplock);
+		return rwsem_is_locked(&ip->i_mmaplock);
 	}
 
 	if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) {
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index eca333f5f715..dd1d81afc4ce 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -39,8 +39,8 @@ typedef struct xfs_inode {
 
 	/* Transaction and locking information. */
 	struct xfs_inode_log_item *i_itemp;	/* logging information */
-	mrlock_t		i_lock;		/* inode lock */
-	mrlock_t		i_mmaplock;	/* inode mmap IO lock */
+	struct rw_semaphore	i_lock;		/* inode lock */
+	struct rw_semaphore	i_mmaplock;	/* inode mmap IO lock */
 	atomic_t		i_pincount;	/* inode pin count */
 
 	/*
@@ -310,7 +310,7 @@ static inline bool xfs_inode_has_bigtime(struct xfs_inode *ip)
  * 5		PARENT subclass (not nestable)
  * 6		RTBITMAP subclass (not nestable)
  * 7		RTSUM subclass (not nestable)
- * 
+ *
  */
 #define XFS_IOLOCK_SHIFT		16
 #define XFS_IOLOCK_MAX_SUBCLASS		3
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 813be879a5e5..7646001324c3 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -709,11 +709,8 @@ xfs_fs_inode_init_once(
 	/* xfs inode */
 	atomic_set(&ip->i_pincount, 0);
 	spin_lock_init(&ip->i_flags_lock);
-
-	mrlock_init(&ip->i_mmaplock, MRLOCK_ALLOW_EQUAL_PRI|MRLOCK_BARRIER,
-		     "xfsino", ip->i_ino);
-	mrlock_init(&ip->i_lock, MRLOCK_ALLOW_EQUAL_PRI|MRLOCK_BARRIER,
-		     "xfsino", ip->i_ino);
+	init_rwsem(&ip->i_mmaplock);
+	init_rwsem(&ip->i_lock);
 }
 
 /*
-- 
2.25.1


  parent reply	other threads:[~2021-01-13 11:18 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-13 11:17 [RFC PATCH 0/3] Remove mrlock Nikolay Borisov
2021-01-13 11:17 ` [RFC PATCH 1/3] xfs: Add is_rwsem_write_locked function Nikolay Borisov
2021-01-13 11:17 ` Nikolay Borisov [this message]
2021-01-13 11:17 ` [RFC PATCH 3/3] xfs: Remove mrlock Nikolay Borisov
2021-01-13 11:17 ` Nikolay Borisov
2021-01-13 11:27 ` [RFC PATCH 0/3] " Christoph Hellwig
2021-01-13 11:41   ` Nikolay Borisov
2021-01-13 12:09     ` Christoph Hellwig
2021-01-13 12:17       ` Nikolay Borisov
2021-01-20 20:14         ` Darrick J. Wong

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