From: Darrick J. Wong <djwong@xxxxxxxxxx>
In anticipation of enabling reflink on the realtime volume where the
allocation unit is larger than a page, create an iomap function to dirty
arbitrary parts of a file's page cache so that when we dirty part of a
file that could undergo a COW extent, we can dirty an entire allocation
unit's worth of pages.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
fs/iomap/buffered-io.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/iomap.h | 2 ++
2 files changed, 57 insertions(+)
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 356193e44cf0..da5a5d28e2ee 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1141,6 +1141,61 @@ iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
}
EXPORT_SYMBOL_GPL(iomap_file_unshare);
+static loff_t iomap_dirty_iter(struct iomap_iter *iter)
+{
+ loff_t pos = iter->pos;
+ loff_t length = iomap_length(iter);
+ long status = 0;
+ loff_t written = 0;
+
+ do {
+ unsigned long offset = offset_in_page(pos);
+ unsigned long bytes = min_t(loff_t, PAGE_SIZE - offset, length);
+ struct folio *folio;
+
+ status = iomap_write_begin(iter, pos, bytes, &folio);
+ if (unlikely(status))
+ return status;
+
+ folio_mark_accessed(folio);
+
+ status = iomap_write_end(iter, pos, bytes, bytes, folio);
+ if (WARN_ON_ONCE(status == 0))
+ return -EIO;
+
+ cond_resched();
+
+ pos += status;
+ written += status;
+ length -= status;
+
+ balance_dirty_pages_ratelimited(iter->inode->i_mapping);
+ } while (length);
+
+ return written;
+}
+
+int
+iomap_dirty_range(struct inode *inode, loff_t pos, u64 len,
+ const struct iomap_ops *ops)
+{
+ struct iomap_iter iter = {
+ .inode = inode,
+ .pos = pos,
+ .len = len,
+ .flags = IOMAP_WRITE,
+ };
+ int ret;
+
+ if (IS_DAX(inode))
+ return -EINVAL;
+
+ while ((ret = iomap_iter(&iter, ops)) > 0)
+ iter.processed = iomap_dirty_iter(&iter);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(iomap_dirty_range);
+
static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
{
const struct iomap *srcmap = iomap_iter_srcmap(iter);
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 0983dfc9a203..4d911d780165 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -264,6 +264,8 @@ bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags);
void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len);
int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
const struct iomap_ops *ops);
+int iomap_dirty_range(struct inode *inode, loff_t pos, u64 len,
+ const struct iomap_ops *ops);
int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
bool *did_zero, const struct iomap_ops *ops);
int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
