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xfs: mmap lock needs to be inside freeze protection

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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>
This commit is contained in:
Dave Chinner 2015-06-04 09:18:18 +10:00 committed by Dave Chinner
parent 5ebe6afaf0
commit ec56b1f1fd
1 changed files with 9 additions and 4 deletions
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13
fs/xfs/xfs_file.c
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@ -1487,15 +1487,20 @@ 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);
xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
return error;
ret = __block_page_mkwrite(vma, vmf, xfs_get_blocks);
xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
sb_end_pagefault(VFS_I(ip)->i_sb);
return block_page_mkwrite_return(ret);
}
const struct file_operations xfs_file_operations = {