From: Ben Hutchings <ben@decadent.org.uk>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Jan Kara <jack@suse.cz>, Brian Foster <bfoster@redhat.com>,
xfs@oss.sgi.com, Dave Chinner <dchinner@redhat.com>,
akpm@linux-foundation.org
Subject: [PATCH 3.16 097/114] xfs: mmap lock needs to be inside freeze protection
Date: Mon, 13 Jun 2016 19:36:37 +0100 [thread overview]
Message-ID: <lsq.1465842997.733859592@decadent.org.uk> (raw)
In-Reply-To: <lsq.1465842997.838358341@decadent.org.uk>
3.16.36-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Dave Chinner <dchinner@redhat.com>
commit ec56b1f1fdc69599963574ce94cc5693d535dd64 upstream.
Lock ordering for the new mmap lock needs to be:
mmap_sem
sb_start_pagefault
i_mmap_lock
page lock
<fault processsing>
Right now xfs_vm_page_mkwrite gets this the wrong way around,
While technically it cannot deadlock due to the current freeze
ordering, it's still a landmine that might explode if we change
anything in future. Hence we need to nest the locks correctly.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Jan Kara <jack@suse.cz>
Cc: xfs@oss.sgi.com
---
fs/xfs/xfs_file.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1441,15 +1441,20 @@ xfs_filemap_page_mkwrite(
struct vm_fault *vmf)
{
struct xfs_inode *ip = XFS_I(vma->vm_file->f_mapping->host);
- int error;
+ int ret;
trace_xfs_filemap_page_mkwrite(ip);
+ sb_start_pagefault(VFS_I(ip)->i_sb);
+ file_update_time(vma->vm_file);
xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
- error = block_page_mkwrite(vma, vmf, xfs_get_blocks);
+
+ ret = __block_page_mkwrite(vma, vmf, xfs_get_blocks);
+
xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
+ sb_end_pagefault(VFS_I(ip)->i_sb);
- return error;
+ return block_page_mkwrite_return(ret);
}
const struct file_operations xfs_file_operations = {
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next prev parent reply other threads:[~2016-06-13 18:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <lsq.1465842997.838358341@decadent.org.uk>
2016-06-13 18:36 ` [PATCH 3.16 093/114] xfs: use i_mmaplock on write faults Ben Hutchings
2016-06-13 18:36 ` Ben Hutchings [this message]
2016-06-13 18:36 ` [PATCH 3.16 094/114] xfs: take i_mmap_lock on extent manipulation operations Ben Hutchings
2016-06-13 18:36 ` [PATCH 3.16 092/114] xfs: use i_mmaplock on read faults Ben Hutchings
2016-06-13 18:36 ` [PATCH 3.16 091/114] xfs: introduce mmap/truncate lock Ben Hutchings
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