[PATCH 05/12] xfs: Convert to use invalidate_lock

Jan Kara
2021-04-23T17:30:25Z

Use invalidate_lock instead of XFS internal i_mmap_lock. The intended
purpose of invalidate_lock is exactly the same. Note that the locking in
__xfs_filemap_fault() slightly changes as filemap_fault() already takes
invalidate_lock.

Reviewed-by: Christoph Hellwig <hch@lst.de>
CC: <linux-xfs@vger.kernel.org>
CC: "Darrick J. Wong" <darrick.wong@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/xfs/xfs_file.c | 12 ++++++-----
fs/xfs/xfs_inode.c | 52 ++++++++++++++++++++++++++--------------------
fs/xfs/xfs_inode.h | 1 -
fs/xfs/xfs_super.c | 2 --
4 files changed, 36 insertions(+), 31 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index a007ca0711d9..2fc04ce0e9f9 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1282,7 +1282,7 @@ xfs_file_llseek(
*
* mmap_lock (MM)
* sb_start_pagefault(vfs, freeze)
- * i_mmaplock (XFS - truncate serialisation)
+ * invalidate_lock (vfs - truncate serialisation)
* page_lock (MM)
* i_lock (XFS - extent map serialisation)
*/
@@ -1303,24 +1303,26 @@ __xfs_filemap_fault(
file_update_time(vmf->vma->vm_file);
}

- xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
if (IS_DAX(inode)) {
pfn_t pfn;

+ xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
ret = dax_iomap_fault(vmf, pe_size, &pfn, NULL,
(write_fault && !vmf->cow_page) ?
&xfs_direct_write_iomap_ops :
&xfs_read_iomap_ops);
if (ret & VM_FAULT_NEEDDSYNC)
ret = dax_finish_sync_fault(vmf, pe_size, pfn);
+ xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
} else {
- if (write_fault)
+ if (write_fault) {
+ xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
ret = iomap_page_mkwrite(vmf,
&xfs_buffered_write_iomap_ops);
- else
+ xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
+ } else
ret = filemap_fault(vmf);
}
- xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);

if (write_fault)
sb_end_pagefault(inode->i_sb);
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index f93370bd7b1e..ac83409d0bf3 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -134,7 +134,7 @@ xfs_ilock_attr_map_shared(

/*
* In addition to i_rwsem in the VFS inode, the xfs inode contains 2
- * multi-reader locks: i_mmap_lock and the i_lock. This routine allows
+ * multi-reader locks: invalidate_lock and the i_lock. This routine allows
* various combinations of the locks to be obtained.
*
* The 3 locks should always be ordered so that the IO lock is obtained first,
@@ -142,23 +142,23 @@ xfs_ilock_attr_map_shared(
*
* Basic locking order:
*
- * i_rwsem -> i_mmap_lock -> page_lock -> i_ilock
+ * i_rwsem -> invalidate_lock -> page_lock -> i_ilock
*
* mmap_lock locking order:
*
* i_rwsem -> page lock -> mmap_lock
- * mmap_lock -> i_mmap_lock -> page_lock
+ * mmap_lock -> invalidate_lock -> page_lock
*
* The difference in mmap_lock locking order mean that we cannot hold the
- * i_mmap_lock over syscall based read(2)/write(2) based IO. These IO paths can
- * fault in pages during copy in/out (for buffered IO) or require the mmap_lock
- * in get_user_pages() to map the user pages into the kernel address space for
- * direct IO. Similarly the i_rwsem cannot be taken inside a page fault because
- * page faults already hold the mmap_lock.
+ * invalidate_lock over syscall based read(2)/write(2) based IO. These IO paths
+ * can fault in pages during copy in/out (for buffered IO) or require the
+ * mmap_lock in get_user_pages() to map the user pages into the kernel address
+ * space for direct IO. Similarly the i_rwsem cannot be taken inside a page
+ * fault because page faults already hold the mmap_lock.
*
* Hence to serialise fully against both syscall and mmap based IO, we need to
- * take both the i_rwsem and the i_mmap_lock. These locks should *only* be both
- * taken in places where we need to invalidate the page cache in a race
+ * take both the i_rwsem and the invalidate_lock. These locks should *only* be
+ * both taken in places where we need to invalidate the page cache in a race
* free manner (e.g. truncate, hole punch and other extent manipulation
* functions).
*/
@@ -190,10 +190,13 @@ xfs_ilock(
XFS_IOLOCK_DEP(lock_flags));
}

- if (lock_flags & XFS_MMAPLOCK_EXCL)
- mrupdate_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));
+ if (lock_flags & XFS_MMAPLOCK_EXCL) {
+ down_write_nested(&VFS_I(ip)->i_mapping->invalidate_lock,
+ XFS_MMAPLOCK_DEP(lock_flags));
+ } else if (lock_flags & XFS_MMAPLOCK_SHARED) {
+ down_read_nested(&VFS_I(ip)->i_mapping->invalidate_lock,
+ XFS_MMAPLOCK_DEP(lock_flags));
+ }

if (lock_flags & XFS_ILOCK_EXCL)
mrupdate_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
@@ -242,10 +245,10 @@ xfs_ilock_nowait(
}

if (lock_flags & XFS_MMAPLOCK_EXCL) {
- if (!mrtryupdate(&ip->i_mmaplock))
+ if (!down_write_trylock(&VFS_I(ip)->i_mapping->invalidate_lock))
goto out_undo_iolock;
} else if (lock_flags & XFS_MMAPLOCK_SHARED) {
- if (!mrtryaccess(&ip->i_mmaplock))
+ if (!down_read_trylock(&VFS_I(ip)->i_mapping->invalidate_lock))
goto out_undo_iolock;
}

@@ -260,9 +263,9 @@ xfs_ilock_nowait(

out_undo_mmaplock:
if (lock_flags & XFS_MMAPLOCK_EXCL)
- mrunlock_excl(&ip->i_mmaplock);
+ up_write(&VFS_I(ip)->i_mapping->invalidate_lock);
else if (lock_flags & XFS_MMAPLOCK_SHARED)
- mrunlock_shared(&ip->i_mmaplock);
+ up_read(&VFS_I(ip)->i_mapping->invalidate_lock);
out_undo_iolock:
if (lock_flags & XFS_IOLOCK_EXCL)
up_write(&VFS_I(ip)->i_rwsem);
@@ -309,9 +312,9 @@ xfs_iunlock(
up_read(&VFS_I(ip)->i_rwsem);

if (lock_flags & XFS_MMAPLOCK_EXCL)
- mrunlock_excl(&ip->i_mmaplock);
+ up_write(&VFS_I(ip)->i_mapping->invalidate_lock);
else if (lock_flags & XFS_MMAPLOCK_SHARED)
- mrunlock_shared(&ip->i_mmaplock);
+ up_read(&VFS_I(ip)->i_mapping->invalidate_lock);

if (lock_flags & XFS_ILOCK_EXCL)
mrunlock_excl(&ip->i_lock);
@@ -337,7 +340,7 @@ xfs_ilock_demote(
if (lock_flags & XFS_ILOCK_EXCL)
mrdemote(&ip->i_lock);
if (lock_flags & XFS_MMAPLOCK_EXCL)
- mrdemote(&ip->i_mmaplock);
+ downgrade_write(&VFS_I(ip)->i_mapping->invalidate_lock);
if (lock_flags & XFS_IOLOCK_EXCL)
downgrade_write(&VFS_I(ip)->i_rwsem);

@@ -358,8 +361,11 @@ xfs_isilocked(

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 !debug_locks ||
+ lockdep_is_held_type(
+ &VFS_I(ip)->i_mapping->invalidate_lock,
+ 0);
+ return rwsem_is_locked(&VFS_I(ip)->i_mapping->invalidate_lock);
}

if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) {
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 88ee4c3930ae..147537be751c 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -40,7 +40,6 @@ 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 */
atomic_t i_pincount; /* inode pin count */

/*
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index e5e0713bebcd..a1536a02aaa5 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -715,8 +715,6 @@ xfs_fs_inode_init_once(
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);
}
--
2.26.2