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Subject[PATCH v7 08/22] Replace xip_truncate_page with dax_truncate_page
Date
It takes a get_block parameter just like nobh_truncate_page() and
block_truncate_page()

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
---
fs/dax.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++----
fs/ext2/inode.c | 2 +-
include/linux/fs.h | 4 ++--
mm/filemap_xip.c | 40 ----------------------------------------
4 files changed, 51 insertions(+), 47 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 863749c..7271be0 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -374,13 +374,13 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
}

/**
- * dax_fault - handle a page fault on an XIP file
+ * dax_fault - handle a page fault on a DAX file
* @vma: The virtual memory area where the fault occurred
* @vmf: The description of the fault
* @get_block: The filesystem method used to translate file offsets to blocks
*
* When a page fault occurs, filesystems may call this helper in their
- * fault handler for XIP files.
+ * fault handler for DAX files.
*/
int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
get_block_t get_block)
@@ -398,12 +398,12 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
EXPORT_SYMBOL_GPL(dax_fault);

/**
- * dax_mkwrite - convert a read-only page to read-write in an XIP file
+ * dax_mkwrite - convert a read-only page to read-write in a DAX file
* @vma: The virtual memory area where the fault occurred
* @vmf: The description of the fault
* @get_block: The filesystem method used to translate file offsets to blocks
*
- * XIP handles reads of holes by adding pages full of zeroes into the
+ * DAX handles reads of holes by adding pages full of zeroes into the
* mapping. If the page is subsequenty written to, we have to allocate
* the page on media and free the page that was in the cache.
*/
@@ -421,3 +421,47 @@ int dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
return result;
}
EXPORT_SYMBOL_GPL(dax_mkwrite);
+
+/**
+ * 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;
+ 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;
+ err = dax_get_addr(inode, &bh, &addr);
+ if (err)
+ 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 f128ebf..252481f 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1207,7 +1207,7 @@ 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 1607812..9752ae5 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2522,13 +2522,13 @@ 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
-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 *, 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 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);
--
1.9.0


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