[PATCH v10 08/21] Replace ext2_clear_xip_target with dax_clear_blocks

Matthew Wilcox
2014-08-27T04:36:58Z

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 | 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);
+
+ 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);
+ 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;
+ cond_resched();
+ }
+ } while (size);
+
+ 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;
--
2.0.0