On Wed 04-03-15 18:48:06, Boaz Harrosh wrote:
> From: Yigal Korman <yigal@xxxxxxxxxxxxx>
>
> 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)
>
> Signed-off-by: Yigal Korman <yigal@xxxxxxxxxxxxx>
> Signed-off-by: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
> ---
> fs/dax.c | 13 +++++++++++++
> fs/ext2/file.c | 1 +
> fs/ext4/file.c | 1 +
> include/linux/fs.h | 1 +
> 4 files changed, 16 insertions(+)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index ed1619e..cd63adc 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -464,6 +464,19 @@ 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)
> +{
> + file_update_time(vma->vm_file);
> + return VM_FAULT_NOPAGE;
> +}
> +EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
Hum, you likely want a freeze protection in there as well
(sb_start_pagefault() and sb_end_pagefault()). Don't you? Otherwise user
could start writing to the page while filesystem is frozen. That's another
bug you could mention in your description.
Honza
> +
> +/**
> * 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 33a09da..b43a7a6 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 b4d71b5..24af817 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2597,6 +2597,7 @@ 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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