From: Jan Kara <jack@suse.cz> To: Dave Chinner <david@fromorbit.com> Cc: Jan Kara <jack@suse.cz>, linux-fsdevel@vger.kernel.org, Christoph Hellwig <hch@infradead.org>, ceph-devel@vger.kernel.org, Chao Yu <yuchao0@huawei.com>, Damien Le Moal <damien.lemoal@wdc.com>, "Darrick J. Wong" <darrick.wong@oracle.com>, Jaegeuk Kim <jaegeuk@kernel.org>, Jeff Layton <jlayton@kernel.org>, Johannes Thumshirn <jth@kernel.org>, linux-cifs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mm@kvack.org, linux-xfs@vger.kernel.org, Miklos Szeredi <miklos@szeredi.hu>, Steve French <sfrench@samba.org>, Ted Tso <tytso@mit.edu>, Matthew Wilcox <willy@infradead.org>, Christoph Hellwig <hch@lst.de> Subject: Re: [PATCH 07/13] xfs: Convert to use invalidate_lock Date: Wed, 26 May 2021 12:20:59 +0200 [thread overview] Message-ID: <20210526102059.GD30369@quack2.suse.cz> (raw) In-Reply-To: <20210525214041.GJ664593@dread.disaster.area> On Wed 26-05-21 07:40:41, Dave Chinner wrote: > On Tue, May 25, 2021 at 03:50:44PM +0200, Jan Kara wrote: > > 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 396ef36dcd0a..dc9cb5c20549 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/XFS_MMAPLOCK - 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); > > This seems kinda messy. filemap_fault() basically takes the > invalidate lock around the entire operation, it runs, so maybe it > would be cleaner to implement it as: > > filemap_fault_locked(vmf) > { > /* does the filemap fault work */ > } > > filemap_fault(vmf) > { > filemap_invalidate_down_read(...) > ret = filemap_fault_locked(vmf) > filemap_invalidate_up_read(...) > return ret; > } > > And that means XFS could just call filemap_fault_locked() and not > have to do all this messy locking just to avoid holding the lock > that filemap_fault has now internalised. Sure, I can do that. > > @@ -355,8 +358,11 @@ 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); > > } > > <sigh> > > And so here we are again, losing more of our read vs write debug > checks on debug kernels when lockdep is not enabled.... > > Can we please add rwsem_is_locked_read() and rwsem_is_locked_write() > wrappers that just look at the rwsem counter value to determine how > the lock is held? Then the mrlock_t can go away entirely.... Apparently someone already did that for XFS as Darrick pointed out. So we just have to sort out how to merge it. Honza -- Jan Kara <jack@suse.com> SUSE Labs, CR
WARNING: multiple messages have this Message-ID (diff)
From: Jan Kara <jack@suse.cz> To: Dave Chinner <david@fromorbit.com> Cc: linux-cifs@vger.kernel.org, Damien Le Moal <damien.lemoal@wdc.com>, linux-ext4@vger.kernel.org, Jan Kara <jack@suse.cz>, "Darrick J. Wong" <darrick.wong@oracle.com>, Steve French <sfrench@samba.org>, Jeff Layton <jlayton@kernel.org>, Matthew Wilcox <willy@infradead.org>, linux-f2fs-devel@lists.sourceforge.net, Christoph Hellwig <hch@infradead.org>, linux-mm@kvack.org, Miklos Szeredi <miklos@szeredi.hu>, Ted Tso <tytso@mit.edu>, linux-fsdevel@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>, ceph-devel@vger.kernel.org, Johannes Thumshirn <jth@kernel.org>, Christoph Hellwig <hch@lst.de>, linux-xfs@vger.kernel.org Subject: Re: [f2fs-dev] [PATCH 07/13] xfs: Convert to use invalidate_lock Date: Wed, 26 May 2021 12:20:59 +0200 [thread overview] Message-ID: <20210526102059.GD30369@quack2.suse.cz> (raw) In-Reply-To: <20210525214041.GJ664593@dread.disaster.area> On Wed 26-05-21 07:40:41, Dave Chinner wrote: > On Tue, May 25, 2021 at 03:50:44PM +0200, Jan Kara wrote: > > 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 396ef36dcd0a..dc9cb5c20549 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/XFS_MMAPLOCK - 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); > > This seems kinda messy. filemap_fault() basically takes the > invalidate lock around the entire operation, it runs, so maybe it > would be cleaner to implement it as: > > filemap_fault_locked(vmf) > { > /* does the filemap fault work */ > } > > filemap_fault(vmf) > { > filemap_invalidate_down_read(...) > ret = filemap_fault_locked(vmf) > filemap_invalidate_up_read(...) > return ret; > } > > And that means XFS could just call filemap_fault_locked() and not > have to do all this messy locking just to avoid holding the lock > that filemap_fault has now internalised. Sure, I can do that. > > @@ -355,8 +358,11 @@ 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); > > } > > <sigh> > > And so here we are again, losing more of our read vs write debug > checks on debug kernels when lockdep is not enabled.... > > Can we please add rwsem_is_locked_read() and rwsem_is_locked_write() > wrappers that just look at the rwsem counter value to determine how > the lock is held? Then the mrlock_t can go away entirely.... Apparently someone already did that for XFS as Darrick pointed out. So we just have to sort out how to merge it. Honza -- Jan Kara <jack@suse.com> SUSE Labs, CR _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
next prev parent reply other threads:[~2021-05-26 10:21 UTC|newest] Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-25 13:50 [PATCH 0/13 v6] fs: Hole punch vs page cache filling races Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-25 13:50 ` [PATCH 01/13] mm: Fix comments mentioning i_mutex Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-25 13:50 ` [PATCH 02/13] documentation: Sync file_operations members with reality Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-25 20:43 ` Darrick J. Wong 2021-05-25 20:43 ` [f2fs-dev] " Darrick J. Wong 2021-05-25 13:50 ` [PATCH 03/13] mm: Protect operations adding pages to page cache with invalidate_lock Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-25 21:01 ` Darrick J. Wong 2021-05-25 21:01 ` [f2fs-dev] " Darrick J. Wong 2021-05-26 10:00 ` Jan Kara 2021-05-26 10:00 ` [f2fs-dev] " Jan Kara 2021-05-25 13:50 ` [PATCH 04/13] mm: Add functions to lock invalidate_lock for two mappings Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-25 20:48 ` Darrick J. Wong 2021-05-25 20:48 ` [f2fs-dev] " Darrick J. Wong 2021-05-26 10:07 ` Jan Kara 2021-05-26 10:07 ` [f2fs-dev] " Jan Kara 2021-05-26 12:11 ` Damien Le Moal 2021-05-26 12:11 ` [f2fs-dev] " Damien Le Moal 2021-05-26 12:11 ` Damien Le Moal 2021-05-26 13:45 ` Jan Kara 2021-05-26 13:45 ` [f2fs-dev] " Jan Kara 2021-05-26 13:45 ` Jan Kara 2021-05-26 15:25 ` Darrick J. Wong 2021-05-26 15:25 ` [f2fs-dev] " Darrick J. Wong 2021-05-26 15:25 ` Darrick J. Wong 2021-05-25 13:50 ` [PATCH 05/13] ext4: Convert to use mapping->invalidate_lock Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-25 13:50 ` [PATCH 06/13] ext2: Convert to using invalidate_lock Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-25 13:50 ` [PATCH 07/13] xfs: Convert to use invalidate_lock Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-25 21:37 ` Darrick J. Wong 2021-05-25 21:37 ` [f2fs-dev] " Darrick J. Wong 2021-05-26 10:18 ` Jan Kara 2021-05-26 10:18 ` [f2fs-dev] " Jan Kara 2021-05-26 15:32 ` Darrick J. Wong 2021-05-26 15:32 ` [f2fs-dev] " Darrick J. Wong 2021-05-27 12:01 ` Jan Kara 2021-05-27 12:01 ` [f2fs-dev] " Jan Kara 2021-05-25 21:40 ` Dave Chinner 2021-05-25 21:40 ` [f2fs-dev] " Dave Chinner 2021-05-26 10:20 ` Jan Kara [this message] 2021-05-26 10:20 ` Jan Kara 2021-05-26 13:42 ` Jan Kara 2021-05-26 13:42 ` [f2fs-dev] " Jan Kara 2021-05-25 13:50 ` [PATCH 08/13] xfs: Convert double locking of MMAPLOCK to use VFS helpers Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-25 21:41 ` Darrick J. Wong 2021-05-25 21:41 ` [f2fs-dev] " Darrick J. Wong 2021-05-25 13:50 ` [PATCH 09/13] zonefs: Convert to using invalidate_lock Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-25 13:50 ` [PATCH 10/13] f2fs: " Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-26 9:55 ` Chao Yu 2021-05-26 9:55 ` [f2fs-dev] " Chao Yu 2021-05-25 13:50 ` [PATCH 11/13] fuse: " Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-25 13:50 ` [PATCH 12/13] ceph: Fix race between hole punch and page fault Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara 2021-05-25 13:50 ` [PATCH 13/13] cifs: " Jan Kara 2021-05-25 13:50 ` [f2fs-dev] " Jan Kara
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