On Tue, Aug 29, 2017 at 06:26:13PM +0200, Christoph Hellwig wrote:
> Add a new __xfs_filemap_fault helper that implements all four page fault
> callouts, and make these methods themselves small stubs that set the
> correct write_fault flag, and exit early for the non-DAX case for the
> hugepage related ones.
>
> Also remove the extra size checking in the pfn_fault path, which is now
> handled in the core DAX code.
>
> Life would be so much simpler if we only had one method for all this.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> Reviewed-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Looks ok, will test (again),
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/xfs/xfs_file.c | 96 +++++++++++++++++++-----------------------------------
> fs/xfs/xfs_trace.h | 29 +++++++++++++++--
> 2 files changed, 60 insertions(+), 65 deletions(-)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 8b0181c6d2a6..0debbc7e3f03 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -1011,95 +1011,67 @@ xfs_file_llseek(
> * page_lock (MM)
> * i_lock (XFS - extent map serialisation)
> */
> -
> -/*
> - * mmap()d file has taken write protection fault and is being made writable. We
> - * can set the page state up correctly for a writable page, which means we can
> - * do correct delalloc accounting (ENOSPC checking!) and unwritten extent
> - * mapping.
> - */
> -STATIC int
> -xfs_filemap_page_mkwrite(
> - struct vm_fault *vmf)
> +static int
> +__xfs_filemap_fault(
> + struct vm_fault *vmf,
> + enum page_entry_size pe_size,
> + bool write_fault)
> {
> struct inode *inode = file_inode(vmf->vma->vm_file);
> + struct xfs_inode *ip = XFS_I(inode);
> int ret;
>
> - trace_xfs_filemap_page_mkwrite(XFS_I(inode));
> + trace_xfs_filemap_fault(ip, pe_size, write_fault);
>
> - sb_start_pagefault(inode->i_sb);
> - file_update_time(vmf->vma->vm_file);
> - xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
> + if (write_fault) {
> + sb_start_pagefault(inode->i_sb);
> + file_update_time(vmf->vma->vm_file);
> + }
>
> + xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
> if (IS_DAX(inode)) {
> - ret = dax_iomap_fault(vmf, PE_SIZE_PTE, &xfs_iomap_ops);
> + ret = dax_iomap_fault(vmf, pe_size, &xfs_iomap_ops);
> } else {
> - ret = iomap_page_mkwrite(vmf, &xfs_iomap_ops);
> + if (write_fault)
> + ret = iomap_page_mkwrite(vmf, &xfs_iomap_ops);
> + else
> + ret = filemap_fault(vmf);
> }
> -
> xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
> - sb_end_pagefault(inode->i_sb);
>
> + if (write_fault)
> + sb_end_pagefault(inode->i_sb);
> return ret;
> }
>
> -STATIC int
> +static int
> xfs_filemap_fault(
> struct vm_fault *vmf)
> {
> - struct inode *inode = file_inode(vmf->vma->vm_file);
> - int ret;
> -
> - trace_xfs_filemap_fault(XFS_I(inode));
> -
> /* DAX can shortcut the normal fault path on write faults! */
> - if ((vmf->flags & FAULT_FLAG_WRITE) && IS_DAX(inode))
> - return xfs_filemap_page_mkwrite(vmf);
> -
> - xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
> - if (IS_DAX(inode))
> - ret = dax_iomap_fault(vmf, PE_SIZE_PTE, &xfs_iomap_ops);
> - else
> - ret = filemap_fault(vmf);
> - xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
> -
> - return ret;
> + return __xfs_filemap_fault(vmf, PE_SIZE_PTE,
> + IS_DAX(file_inode(vmf->vma->vm_file)) &&
> + (vmf->flags & FAULT_FLAG_WRITE));
> }
>
> -/*
> - * 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
> - * ->huge_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
> +static int
> xfs_filemap_huge_fault(
> struct vm_fault *vmf,
> enum page_entry_size pe_size)
> {
> - struct inode *inode = file_inode(vmf->vma->vm_file);
> - struct xfs_inode *ip = XFS_I(inode);
> - int ret;
> -
> - if (!IS_DAX(inode))
> + if (!IS_DAX(file_inode(vmf->vma->vm_file)))
> return VM_FAULT_FALLBACK;
>
> - trace_xfs_filemap_huge_fault(ip);
> -
> - if (vmf->flags & FAULT_FLAG_WRITE) {
> - sb_start_pagefault(inode->i_sb);
> - file_update_time(vmf->vma->vm_file);
> - }
> -
> - xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
> - ret = dax_iomap_fault(vmf, pe_size, &xfs_iomap_ops);
> - xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
> -
> - if (vmf->flags & FAULT_FLAG_WRITE)
> - sb_end_pagefault(inode->i_sb);
> + /* DAX can shortcut the normal fault path on write faults! */
> + return __xfs_filemap_fault(vmf, pe_size,
> + (vmf->flags & FAULT_FLAG_WRITE));
> +}
>
> - return ret;
> +static int
> +xfs_filemap_page_mkwrite(
> + struct vm_fault *vmf)
> +{
> + return __xfs_filemap_fault(vmf, PE_SIZE_PTE, true);
> }
>
> /*
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index bcc3cdf8e1c5..bae243ad7f3b 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -689,11 +689,34 @@ DEFINE_INODE_EVENT(xfs_inode_set_cowblocks_tag);
> DEFINE_INODE_EVENT(xfs_inode_clear_cowblocks_tag);
> DEFINE_INODE_EVENT(xfs_inode_free_cowblocks_invalid);
>
> -DEFINE_INODE_EVENT(xfs_filemap_fault);
> -DEFINE_INODE_EVENT(xfs_filemap_huge_fault);
> -DEFINE_INODE_EVENT(xfs_filemap_page_mkwrite);
> DEFINE_INODE_EVENT(xfs_filemap_pfn_mkwrite);
>
> +TRACE_EVENT(xfs_filemap_fault,
> + TP_PROTO(struct xfs_inode *ip, enum page_entry_size pe_size,
> + bool write_fault),
> + TP_ARGS(ip, pe_size, write_fault),
> + TP_STRUCT__entry(
> + __field(dev_t, dev)
> + __field(xfs_ino_t, ino)
> + __field(enum page_entry_size, pe_size)
> + __field(bool, write_fault)
> + ),
> + TP_fast_assign(
> + __entry->dev = VFS_I(ip)->i_sb->s_dev;
> + __entry->ino = ip->i_ino;
> + __entry->pe_size = pe_size;
> + __entry->write_fault = write_fault;
> + ),
> + TP_printk("dev %d:%d ino 0x%llx %s write_fault %d",
> + MAJOR(__entry->dev), MINOR(__entry->dev),
> + __entry->ino,
> + __print_symbolic(__entry->pe_size,
> + { PE_SIZE_PTE, "PTE" },
> + { PE_SIZE_PMD, "PMD" },
> + { PE_SIZE_PUD, "PUD" }),
> + __entry->write_fault)
> +)
> +
> DECLARE_EVENT_CLASS(xfs_iref_class,
> TP_PROTO(struct xfs_inode *ip, unsigned long caller_ip),
> TP_ARGS(ip, caller_ip),
> --
> 2.11.0
>
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