On Tue 07-04-15 11:43:50, Boaz Harrosh wrote:
> From: Yigal Korman <yigal@xxxxxxxxxxxxx>
>
> [v1]
> Without this patch, c/mtime is not updated correctly when mmap'ed page is
> first read from and then written to.
>
> A new xfstest is submitted for testing this (generic/080)
>
> [v2]
> Jan Kara has pointed out that if we add the
> sb_start/end_pagefault pair in the new pfn_mkwrite we
> are then fixing another bug where: A user could start
> writing to the page while filesystem is frozen.
The patch looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> CC: Jan Kara <jack@xxxxxxx>
> CC: Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx>
> CC: Dave Chinner <david@xxxxxxxxxxxxx>
> CC: Stable Tree <stable@xxxxxxxxxxxxxxx>
>
> Signed-off-by: Yigal Korman <yigal@xxxxxxxxxxxxx>
> Signed-off-by: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
> ---
> fs/dax.c | 17 +++++++++++++++++
> fs/ext2/file.c | 1 +
> fs/ext4/file.c | 1 +
> include/linux/fs.h | 1 +
> 4 files changed, 20 insertions(+)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index ed1619e..d0bd1f4 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -464,6 +464,23 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
> EXPORT_SYMBOL_GPL(dax_fault);
>
> /**
> + * dax_pfn_mkwrite - handle first write to DAX page
> + * @vma: The virtual memory area where the fault occurred
> + * @vmf: The description of the 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;
> +
> + sb_start_pagefault(sb);
> + file_update_time(vma->vm_file);
> + sb_end_pagefault(sb);
> + return VM_FAULT_NOPAGE;
> +}
> +EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
> +
> +/**
> * dax_zero_page_range - zero a range within a page of a DAX file
> * @inode: The file being truncated
> * @from: The file offset that is being truncated to
> diff --git a/fs/ext2/file.c b/fs/ext2/file.c
> index e317017..866a3ce 100644
> --- a/fs/ext2/file.c
> +++ b/fs/ext2/file.c
> @@ -39,6 +39,7 @@ static int ext2_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
> static const struct vm_operations_struct ext2_dax_vm_ops = {
> .fault = ext2_dax_fault,
> .page_mkwrite = ext2_dax_mkwrite,
> + .pfn_mkwrite = dax_pfn_mkwrite,
> };
>
> static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 598abbb..aa78c70 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -206,6 +206,7 @@ static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
> static const struct vm_operations_struct ext4_dax_vm_ops = {
> .fault = ext4_dax_fault,
> .page_mkwrite = ext4_dax_mkwrite,
> + .pfn_mkwrite = dax_pfn_mkwrite,
> };
> #else
> #define ext4_dax_vm_ops ext4_file_vm_ops
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 368e349..394035f 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2628,6 +2628,7 @@ int dax_clear_blocks(struct inode *, sector_t block, long size);
> int dax_zero_page_range(struct inode *, loff_t from, unsigned len, get_block_t);
> int dax_truncate_page(struct inode *, loff_t from, get_block_t);
> int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t);
> +int dax_pfn_mkwrite(struct vm_area_struct *, struct vm_fault *);
> #define dax_mkwrite(vma, vmf, gb) dax_fault(vma, vmf, gb)
>
> #ifdef CONFIG_BLOCK
> --
> 1.9.3
>
>
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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