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xfs: xfs_filemap_pmd_fault treats read faults as write faults

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The code initially committed didn't have the same checks for write
faults as the dax_pmd_fault code and hence treats all faults as
write faults. We can get read faults through this path because they
is no pmd_mkwrite path for write faults similar to the normal page
fault path. Hence we need to ensure that we only do c/mtime updates
on write faults, and freeze protection is unnecessary for read
faults.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Dave Chinner 2015-11-03 12:37:02 +11:00 committed by Dave Chinner
parent 3af4928585
commit 13ad4fe3e0
1 changed files with 16 additions and 4 deletions
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20
fs/xfs/xfs_file.c
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@ -1477,7 +1477,7 @@ xfs_file_llseek(
*
* mmap_sem (MM)
* sb_start_pagefault(vfs, freeze)
* i_mmap_lock (XFS - truncate serialisation)
* i_mmaplock (XFS - truncate serialisation)
* page_lock (MM)
* i_lock (XFS - extent map serialisation)
*/
@ -1545,6 +1545,13 @@ xfs_filemap_fault(
return ret;
}
/*
* Similar to xfs_filemap_fault(), the DAX fault path can call into here on
* both read and write faults. Hence we need to handle both cases. There is no
* ->pmd_mkwrite callout for huge pages, so we have a single function here to
* handle both cases here. @flags carries the information on the type of fault
* occuring.
*/
STATIC int
xfs_filemap_pmd_fault(
struct vm_area_struct *vma,
@ -1561,13 +1568,18 @@ xfs_filemap_pmd_fault(
trace_xfs_filemap_pmd_fault(ip);
sb_start_pagefault(inode->i_sb);
file_update_time(vma->vm_file);
if (flags & FAULT_FLAG_WRITE) {
sb_start_pagefault(inode->i_sb);
file_update_time(vma->vm_file);
}
xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
ret = __dax_pmd_fault(vma, addr, pmd, flags, xfs_get_blocks_dax_fault,
NULL);
xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
sb_end_pagefault(inode->i_sb);
if (flags & FAULT_FLAG_WRITE)
sb_end_pagefault(inode->i_sb);
return ret;
}