From: Dave Chinner <dchin...@redhat.com> ->pfn_mkwrite support is needed so that when a page with allocated backing store takes a write fault we can check that the fault has not raced with a truncate and is pointing to a region beyond the current end of file.
This also allows us to update the timestamp on the inode, too, which fixes a generic/080 failure. Signed-off-by: Dave Chinner <dchin...@redhat.com> --- fs/xfs/xfs_file.c | 35 +++++++++++++++++++++++++++++++++++ fs/xfs/xfs_trace.h | 1 + 2 files changed, 36 insertions(+) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 9c8eef7..f429662 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -1572,11 +1572,46 @@ xfs_filemap_pmd_fault( return ret; } +/* + * pfn_mkwrite was originally inteneded to ensure we capture time stamp + * updates on write faults. In reality, it's need to serialise against + * truncate similar to page_mkwrite. Hence we open-code dax_pfn_mkwrite() + * here and cycle the XFS_MMAPLOCK_SHARED to ensure we serialise the fault + * barrier in place. + */ +static int +xfs_filemap_pfn_mkwrite( + struct vm_area_struct *vma, + struct vm_fault *vmf) +{ + + struct inode *inode = file_inode(vma->vm_file); + struct xfs_inode *ip = XFS_I(inode); + int ret = VM_FAULT_NOPAGE; + loff_t size; + + trace_xfs_filemap_pfn_mkwrite(ip); + + sb_start_pagefault(inode->i_sb); + file_update_time(vma->vm_file); + + /* check if the faulting page hasn't raced with truncate */ + xfs_ilock(ip, XFS_MMAPLOCK_SHARED); + size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; + if (vmf->pgoff >= size) + ret = VM_FAULT_SIGBUS; + xfs_iunlock(ip, XFS_MMAPLOCK_SHARED); + sb_end_pagefault(inode->i_sb); + return ret; + +} + static const struct vm_operations_struct xfs_file_vm_ops = { .fault = xfs_filemap_fault, .pmd_fault = xfs_filemap_pmd_fault, .map_pages = filemap_map_pages, .page_mkwrite = xfs_filemap_page_mkwrite, + .pfn_mkwrite = xfs_filemap_pfn_mkwrite, }; STATIC int diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h index 5ed36b1..c53beda 100644 --- a/fs/xfs/xfs_trace.h +++ b/fs/xfs/xfs_trace.h @@ -689,6 +689,7 @@ DEFINE_INODE_EVENT(xfs_inode_free_eofblocks_invalid); DEFINE_INODE_EVENT(xfs_filemap_fault); DEFINE_INODE_EVENT(xfs_filemap_pmd_fault); DEFINE_INODE_EVENT(xfs_filemap_page_mkwrite); +DEFINE_INODE_EVENT(xfs_filemap_pfn_mkwrite); DECLARE_EVENT_CLASS(xfs_iref_class, TP_PROTO(struct xfs_inode *ip, unsigned long caller_ip), -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/