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Date: Thu, 16 Oct 2014 12:05:25 +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 08/21] dax,ext2: Replace ext2_clear_xip_target with
dax_clear_blocks
On 25-Sep-2014 04:33:25 PM, Matthew Wilcox wrote:
> This is practically generic code; other filesystems will want to call
> it from other places, but there's nothing ext2-specific about it.
>
> Make it a little more generic by allowing it to take a count of the number
> of bytes to zero rather than fixing it to a single page. Thanks to Dave
> Hansen for suggesting that I need to call cond_resched() if zeroing more
> than one page.
>
> Signed-off-by: Matthew Wilcox <matthew.r.wilcox@...el.com>
> ---
> fs/dax.c | 35 +++++++++++++++++++++++++++++++++++
> fs/ext2/inode.c | 8 +++++---
> fs/ext2/xip.c | 14 --------------
> fs/ext2/xip.h | 3 ---
> include/linux/fs.h | 6 ++++++
> 5 files changed, 46 insertions(+), 20 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 108c68e..02e226f 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -20,8 +20,43 @@
> #include <linux/fs.h>
> #include <linux/genhd.h>
> #include <linux/mutex.h>
> +#include <linux/sched.h>
> #include <linux/uio.h>
>
> +int dax_clear_blocks(struct inode *inode, sector_t block, long size)
> +{
> + struct block_device *bdev = inode->i_sb->s_bdev;
> + sector_t sector = block << (inode->i_blkbits - 9);
Is there a define e.g. SECTOR_SHIFT rather than using this hardcoded "9"
value ?
> +
> + might_sleep();
> + do {
> + void *addr;
> + unsigned long pfn;
> + long count;
> +
> + count = bdev_direct_access(bdev, sector, &addr, &pfn, size);
> + if (count < 0)
> + return count;
> + while (count > 0) {
> + unsigned pgsz = PAGE_SIZE - offset_in_page(addr);
unsigned -> unsigned int
add a newline between variable declaration and following code.
> + if (pgsz > count)
> + pgsz = count;
> + if (pgsz < PAGE_SIZE)
> + memset(addr, 0, pgsz);
> + else
> + clear_page(addr);
> + addr += pgsz;
> + size -= pgsz;
> + count -= pgsz;
> + sector += pgsz / 512;
Also wondering about those 512 constants everywhere in the code
(including prior patches). Perhaps it calls for a SECTOR_SIZE define ?
> + cond_resched();
> + }
> + } while (size);
Just to stay on the safe side, can we do while (size > 0) ? Just in case
an unforeseen issue makes size negative, and gets us in a very long loop.
Thanks,
Mathieu
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(dax_clear_blocks);
> +
> static long dax_get_addr(struct buffer_head *bh, void **addr, unsigned blkbits)
> {
> unsigned long pfn;
> diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
> index 3ccd5fd..52978b8 100644
> --- a/fs/ext2/inode.c
> +++ b/fs/ext2/inode.c
> @@ -733,10 +733,12 @@ static int ext2_get_blocks(struct inode *inode,
>
> if (IS_DAX(inode)) {
> /*
> - * we need to clear the block
> + * block must be initialised before we put it in the tree
> + * so that it's not found by another thread before it's
> + * initialised
> */
> - err = ext2_clear_xip_target (inode,
> - le32_to_cpu(chain[depth-1].key));
> + err = dax_clear_blocks(inode, le32_to_cpu(chain[depth-1].key),
> + 1 << inode->i_blkbits);
> if (err) {
> mutex_unlock(&ei->truncate_mutex);
> goto cleanup;
> diff --git a/fs/ext2/xip.c b/fs/ext2/xip.c
> index bbc5fec..8cfca3a 100644
> --- a/fs/ext2/xip.c
> +++ b/fs/ext2/xip.c
> @@ -42,20 +42,6 @@ __ext2_get_block(struct inode *inode, pgoff_t pgoff, int create,
> return rc;
> }
>
> -int
> -ext2_clear_xip_target(struct inode *inode, sector_t block)
> -{
> - void *kaddr;
> - unsigned long pfn;
> - long size;
> -
> - size = __inode_direct_access(inode, block, &kaddr, &pfn, PAGE_SIZE);
> - if (size < 0)
> - return size;
> - clear_page(kaddr);
> - return 0;
> -}
> -
> void ext2_xip_verify_sb(struct super_block *sb)
> {
> struct ext2_sb_info *sbi = EXT2_SB(sb);
> diff --git a/fs/ext2/xip.h b/fs/ext2/xip.h
> index 29be737..b2592f2 100644
> --- a/fs/ext2/xip.h
> +++ b/fs/ext2/xip.h
> @@ -7,8 +7,6 @@
>
> #ifdef CONFIG_EXT2_FS_XIP
> extern void ext2_xip_verify_sb (struct super_block *);
> -extern int ext2_clear_xip_target (struct inode *, sector_t);
> -
> static inline int ext2_use_xip (struct super_block *sb)
> {
> struct ext2_sb_info *sbi = EXT2_SB(sb);
> @@ -19,6 +17,5 @@ int ext2_get_xip_mem(struct address_space *, pgoff_t, int,
> #else
> #define ext2_xip_verify_sb(sb) do { } while (0)
> #define ext2_use_xip(sb) 0
> -#define ext2_clear_xip_target(inode, chain) 0
> #define ext2_get_xip_mem NULL
> #endif
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 45839e8..c04d371 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2490,11 +2490,17 @@ extern int generic_file_open(struct inode * inode, struct file * filp);
> 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_file_mmap(struct file * file, struct vm_area_struct * vma);
> extern int xip_truncate_page(struct address_space *mapping, loff_t from);
> ssize_t dax_do_io(int rw, struct kiocb *, struct inode *, struct iov_iter *,
> loff_t, get_block_t, dio_iodone_t, int flags);
> #else
> +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)
> {
> return 0;
> --
> 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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