Originally-from: Christoph Hellwig <hch@xxxxxx>
This function uses the iomap infrastructure to re-write all pages
in a given range. This is useful for doing a copy-up of COW ranges,
and might be useful for scrubbing in the future.
XXX: might want a bigger name, and possible a better implementation
that doesn't require two lookups in the radix tree.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/iomap.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/iomap.h | 2 +
2 files changed, 84 insertions(+)
diff --git a/fs/iomap.c b/fs/iomap.c
index 0342254..7b295d5 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -252,6 +252,88 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
}
EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
+static struct page *
+__iomap_read_page(struct inode *inode, loff_t offset)
+{
+ struct address_space *mapping = inode->i_mapping;
+ struct page *page;
+
+ page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
+ if (IS_ERR(page))
+ return page;
+ if (!PageUptodate(page)) {
+ put_page(page);
+ return ERR_PTR(-EIO);
+ }
+ return page;
+}
+
+static loff_t
+iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
+ struct iomap *iomap)
+{
+ long status = 0;
+ ssize_t written = 0;
+
+ do {
+ struct page *page, *rpage;
+ unsigned long offset; /* Offset into pagecache page */
+ unsigned long bytes; /* Bytes to write to page */
+
+ offset = (pos & (PAGE_SIZE - 1));
+ bytes = min_t(unsigned long, PAGE_SIZE - offset, length);
+
+ rpage = __iomap_read_page(inode, pos);
+ if (IS_ERR(rpage))
+ return PTR_ERR(rpage);
+
+ status = iomap_write_begin(inode, pos, bytes,
+ AOP_FLAG_NOFS | AOP_FLAG_UNINTERRUPTIBLE,
+ &page, iomap);
+ put_page(rpage);
+ if (unlikely(status))
+ return status;
+
+ WARN_ON_ONCE(!PageUptodate(page));
+
+ status = iomap_write_end(inode, pos, bytes, bytes, page);
+ if (unlikely(status <= 0)) {
+ if (WARN_ON_ONCE(status == 0))
+ return -EIO;
+ return status;
+ }
+
+ cond_resched();
+
+ pos += status;
+ written += status;
+ length -= status;
+
+ balance_dirty_pages_ratelimited(inode->i_mapping);
+ } while (length);
+
+ return written;
+}
+
+int
+iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len,
+ struct iomap_ops *ops)
+{
+ loff_t ret;
+
+ while (len) {
+ ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
+ iomap_dirty_actor);
+ if (ret <= 0)
+ return ret;
+ pos += ret;
+ len -= ret;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(iomap_file_dirty);
+
static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
unsigned bytes, struct iomap *iomap)
{
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 3267df4..b2e30e5 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -58,6 +58,8 @@ struct iomap_ops {
ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from,
struct iomap_ops *ops);
+int iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len,
+ struct iomap_ops *ops);
int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
bool *did_zero, struct iomap_ops *ops);
int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
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