Update dax_pfn_mkwrite() so that it validates i_size before returning.
This is necessary to ensure that the page fault has not raced with truncate
and is now pointing to a region beyond the end of the current file.
This change is based on a similar outstanding patch for XFS from Dave
Chinner entitled "xfs: add ->pfn_mkwrite support for DAX".
Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
---
fs/dax.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 131fd35a..82be6e4 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -693,12 +693,21 @@ EXPORT_SYMBOL_GPL(dax_pmd_fault);
*/
int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
- struct super_block *sb = file_inode(vma->vm_file)->i_sb;
+ struct inode *inode = file_inode(vma->vm_file);
+ struct super_block *sb = inode->i_sb;
+ int ret = VM_FAULT_NOPAGE;
+ loff_t size;
sb_start_pagefault(sb);
file_update_time(vma->vm_file);
+
+ /* check that the faulting page hasn't raced with truncate */
+ size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ if (vmf->pgoff >= size)
+ ret = VM_FAULT_SIGBUS;
+
sb_end_pagefault(sb);
- return VM_FAULT_NOPAGE;
+ return ret;
}
EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
--
2.1.0
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