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Date: Thu, 16 Oct 2014 12:28:26 +0200
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Matthew Wilcox <matthew.r.wilcox@...el.com>
Cc: linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v11 10/21] dax,ext2: Replace xip_truncate_page with
dax_truncate_page
On 25-Sep-2014 04:33:27 PM, Matthew Wilcox wrote:
> It takes a get_block parameter just like nobh_truncate_page() and
> block_truncate_page()
>
> Signed-off-by: Matthew Wilcox <matthew.r.wilcox@...el.com>
> ---
> fs/dax.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
> fs/ext2/inode.c | 2 +-
> include/linux/fs.h | 4 ++--
> mm/filemap_xip.c | 40 ----------------------------------------
> 4 files changed, 47 insertions(+), 43 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index ac5d3a6..6801be7 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -460,3 +460,47 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
> return result;
> }
> EXPORT_SYMBOL_GPL(dax_fault);
> +
> +/**
> + * dax_truncate_page - handle a partial page being truncated in a DAX file
> + * @inode: The file being truncated
> + * @from: The file offset that is being truncated to
> + * @get_block: The filesystem method used to translate file offsets to blocks
> + *
> + * Similar to block_truncate_page(), this function can be called by a
> + * filesystem when it is truncating an DAX file to handle the partial page.
> + *
> + * We work in terms of PAGE_CACHE_SIZE here for commonality with
> + * block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem
> + * took care of disposing of the unnecessary blocks. Even if the filesystem
> + * block size is smaller than PAGE_SIZE, we have to zero the rest of the page
> + * since the file might be mmaped.
> + */
> +int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block)
> +{
> + struct buffer_head bh;
> + pgoff_t index = from >> PAGE_CACHE_SHIFT;
> + unsigned offset = from & (PAGE_CACHE_SIZE-1);
> + unsigned length = PAGE_CACHE_ALIGN(from) - from;
nits: unsigned -> unsigned int (I'm starting to think that FS code
perhaps has different coding style than kernel/ core code)
> + int err;
> +
> + /* Block boundary? Nothing to do */
> + if (!length)
> + return 0;
> +
> + memset(&bh, 0, sizeof(bh));
> + bh.b_size = PAGE_CACHE_SIZE;
> + err = get_block(inode, index, &bh, 0);
> + if (err < 0)
> + return err;
> + if (buffer_written(&bh)) {
> + void *addr;
missing newline.
Other than that:
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Thanks,
Mathieu
> + err = dax_get_addr(&bh, &addr, inode->i_blkbits);
> + if (err < 0)
> + return err;
> + memset(addr + offset, 0, length);
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(dax_truncate_page);
> diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
> index 52978b8..5ac0a34 100644
> --- a/fs/ext2/inode.c
> +++ b/fs/ext2/inode.c
> @@ -1210,7 +1210,7 @@ static int ext2_setsize(struct inode *inode, loff_t newsize)
> inode_dio_wait(inode);
>
> if (IS_DAX(inode))
> - error = xip_truncate_page(inode->i_mapping, newsize);
> + error = dax_truncate_page(inode, newsize, ext2_get_block);
> else if (test_opt(inode->i_sb, NOBH))
> error = nobh_truncate_page(inode->i_mapping,
> newsize, ext2_get_block);
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 338f04b..eee848d 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2492,7 +2492,7 @@ extern int nonseekable_open(struct inode * inode, struct file * filp);
>
> #ifdef CONFIG_FS_XIP
> int dax_clear_blocks(struct inode *, sector_t block, long size);
> -extern int xip_truncate_page(struct address_space *mapping, loff_t from);
> +int dax_truncate_page(struct inode *, loff_t from, get_block_t);
> ssize_t dax_do_io(int rw, struct kiocb *, struct inode *, struct iov_iter *,
> loff_t, get_block_t, dio_iodone_t, int flags);
> int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t);
> @@ -2503,7 +2503,7 @@ static inline int dax_clear_blocks(struct inode *i, sector_t blk, long sz)
> return 0;
> }
>
> -static inline int xip_truncate_page(struct address_space *mapping, loff_t from)
> +static inline int dax_truncate_page(struct inode *i, loff_t frm, get_block_t gb)
> {
> return 0;
> }
> diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
> index 9dd45f3..6316578 100644
> --- a/mm/filemap_xip.c
> +++ b/mm/filemap_xip.c
> @@ -21,43 +21,3 @@
> #include <asm/tlbflush.h>
> #include <asm/io.h>
>
> -/*
> - * truncate a page used for execute in place
> - * functionality is analog to block_truncate_page but does use get_xip_mem
> - * to get the page instead of page cache
> - */
> -int
> -xip_truncate_page(struct address_space *mapping, loff_t from)
> -{
> - pgoff_t index = from >> PAGE_CACHE_SHIFT;
> - unsigned offset = from & (PAGE_CACHE_SIZE-1);
> - unsigned blocksize;
> - unsigned length;
> - void *xip_mem;
> - unsigned long xip_pfn;
> - int err;
> -
> - BUG_ON(!mapping->a_ops->get_xip_mem);
> -
> - blocksize = 1 << mapping->host->i_blkbits;
> - length = offset & (blocksize - 1);
> -
> - /* Block boundary? Nothing to do */
> - if (!length)
> - return 0;
> -
> - length = blocksize - length;
> -
> - err = mapping->a_ops->get_xip_mem(mapping, index, 0,
> - &xip_mem, &xip_pfn);
> - if (unlikely(err)) {
> - if (err == -ENODATA)
> - /* Hole? No need to truncate */
> - return 0;
> - else
> - return err;
> - }
> - memset(xip_mem + offset, 0, length);
> - return 0;
> -}
> -EXPORT_SYMBOL_GPL(xip_truncate_page);
> --
> 2.1.0
>
> --
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>
>
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
Key fingerprint: 2A0B 4ED9 15F2 D3FA 45F5 B162 1728 0A97 8118 6ACF
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