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    Subject[PATCH v6 11/22] Replace ext2_clear_xip_target with dax_clear_blocks
    Date
    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@intel.com>
    ---
    fs/dax.c | 34 ++++++++++++++++++++++++++++++++++
    fs/ext2/inode.c | 8 +++++---
    fs/ext2/xip.c | 23 -----------------------
    fs/ext2/xip.h | 3 ---
    include/linux/fs.h | 6 ++++++
    5 files changed, 45 insertions(+), 29 deletions(-)

    diff --git a/fs/dax.c b/fs/dax.c
    index a6a1adc..75328bf 100644
    --- a/fs/dax.c
    +++ b/fs/dax.c
    @@ -22,8 +22,42 @@
    #include <linux/highmem.h>
    #include <linux/mm.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;
    + const struct block_device_operations *ops = bdev->bd_disk->fops;
    + sector_t sector = block << (inode->i_blkbits - 9);
    + unsigned long pfn;
    +
    + might_sleep();
    + do {
    + void *addr;
    + long count = ops->direct_access(bdev, sector, &addr, &pfn,
    + size);
    + if (count < 0)
    + return count;
    + while (count >= PAGE_SIZE) {
    + clear_page(addr);
    + addr += PAGE_SIZE;
    + size -= PAGE_SIZE;
    + count -= PAGE_SIZE;
    + sector += PAGE_SIZE / 512;
    + cond_resched();
    + }
    + if (count > 0) {
    + memset(addr, 0, count);
    + sector += count / 512;
    + size -= count;
    + }
    + } while (size);
    +
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(dax_clear_blocks);
    +
    static long dax_get_addr(struct inode *inode, struct buffer_head *bh,
    void **addr)
    {
    diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
    index b156fe8..a9346a9 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),
    + count << 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 ca745ff..132d4da 100644
    --- a/fs/ext2/xip.c
    +++ b/fs/ext2/xip.c
    @@ -13,29 +13,6 @@
    #include "ext2.h"
    #include "xip.h"

    -static inline long __inode_direct_access(struct inode *inode, sector_t block,
    - void **kaddr, unsigned long *pfn, long size)
    -{
    - struct block_device *bdev = inode->i_sb->s_bdev;
    - const struct block_device_operations *ops = bdev->bd_disk->fops;
    - sector_t sector = block * (PAGE_SIZE / 512);
    - return ops->direct_access(bdev, sector, kaddr, pfn, size);
    -}
    -
    -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 0fa8b7f..e7b9f0a 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);
    @@ -17,5 +15,4 @@ static inline int ext2_use_xip (struct super_block *sb)
    #else
    #define ext2_xip_verify_sb(sb) do { } while (0)
    #define ext2_use_xip(sb) 0
    -#define ext2_clear_xip_target(inode, chain) 0
    #endif
    diff --git a/include/linux/fs.h b/include/linux/fs.h
    index c7945fd..6f7f445 100644
    --- a/include/linux/fs.h
    +++ b/include/linux/fs.h
    @@ -2516,12 +2516,18 @@ 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);
    int dax_truncate_page(struct inode *, loff_t from, get_block_t);
    ssize_t dax_do_io(int rw, struct kiocb *, struct inode *, const struct iovec *,
    loff_t, unsigned segs, get_block_t, dio_iodone_t, int flags);
    int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t);
    int dax_mkwrite(struct vm_area_struct *, struct vm_fault *, get_block_t);
    #else
    +static inline int dax_clear_blocks(struct inode *i, sector_t blk, long sz)
    +{
    + return 0;
    +}
    +
    static inline int dax_truncate_page(struct inode *i, loff_t frm, get_block_t gb)
    {
    return 0;
    --
    1.8.5.3


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