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>
diff --git a/fs/dax.c b/fs/dax.c
index 553e55b..ebf9b22 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -462,3 +462,47 @@
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);
