dax,ext2: replace xip_truncate_page with dax_truncate_page

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>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Cc: Boaz Harrosh <boaz@plexistor.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 46 insertions, 50 deletions

diff --git a/fs/dax.c b/fs/dax.c
index 553e55b93495..ebf9b2231b0f 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -462,3 +462,47 @@ 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;
+        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(&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 52978b853226..5ac0a3461b3c 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 6bad6d4c579b..2c8f9055af38 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2591,18 +2591,10 @@ extern int nonseekable_open(struct inode * inode, struct file * filp);
 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_clear_blocks(struct inode *, sector_t block, long size);
+int dax_truncate_page(struct inode *, loff_t from, get_block_t);
 int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t);
 #define dax_mkwrite(vma, vmf, gb)       dax_fault(vma, vmf, gb)
 
-#ifdef CONFIG_FS_XIP
-extern int xip_truncate_page(struct address_space *mapping, loff_t from);
-#else
-static inline int xip_truncate_page(struct address_space *mapping, loff_t from)
-{
-        return 0;
-}
-#endif
-
 #ifdef CONFIG_BLOCK
 typedef void (dio_submit_t)(int rw, struct bio *bio, struct inode *inode,
                             loff_t file_offset);
diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index 59fb387b2238..8e3f99b61959 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -22,43 +22,3 @@
 #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);