3.16.36-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Dave Chinner <dchinner@xxxxxxxxxx>
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@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
Signed-off-by: Dave Chinner <david@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: xfs@xxxxxxxxxxx
---
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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