Modelled after the loop in iomap_write_iter(), copy larger chunks from
userspace if the filesystem has created large folios.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
This patch dependss on patches currently in the iomap tree. Sending it
out now for feedback, but I'll resend it after rc1.
mm/filemap.c | 34 ++++++++++++++++++++--------------
1 file changed, 20 insertions(+), 14 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index bf6219d9aaac..fd28767c760a 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3908,6 +3908,7 @@ EXPORT_SYMBOL(generic_file_direct_write);
ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i)
{
struct file *file = iocb->ki_filp;
+ size_t chunk = PAGE_SIZE << MAX_PAGECACHE_ORDER;
loff_t pos = iocb->ki_pos;
struct address_space *mapping = file->f_mapping;
const struct address_space_operations *a_ops = mapping->a_ops;
@@ -3916,16 +3917,16 @@ ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i)
do {
struct page *page;
- unsigned long offset; /* Offset into pagecache page */
- unsigned long bytes; /* Bytes to write to page */
+ struct folio *folio;
+ size_t offset; /* Offset into folio */
+ size_t bytes; /* Bytes to write to folio */
size_t copied; /* Bytes copied from user */
void *fsdata = NULL;
- offset = (pos & (PAGE_SIZE - 1));
- bytes = min_t(unsigned long, PAGE_SIZE - offset,
- iov_iter_count(i));
+ offset = pos & (chunk - 1);
+ bytes = min(chunk - offset, iov_iter_count(i));
+ balance_dirty_pages_ratelimited(mapping);
-again:
/*
* Bring in the user page that we will copy from _first_.
* Otherwise there's a nasty deadlock on copying from the
@@ -3947,11 +3948,16 @@ ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i)
if (unlikely(status < 0))
break;
+ folio = page_folio(page);
+ offset = offset_in_folio(folio, pos);
+ if (bytes > folio_size(folio) - offset)
+ bytes = folio_size(folio) - offset;
+
if (mapping_writably_mapped(mapping))
- flush_dcache_page(page);
+ flush_dcache_folio(folio);
- copied = copy_page_from_iter_atomic(page, offset, bytes, i);
- flush_dcache_page(page);
+ copied = copy_folio_from_iter_atomic(folio, offset, bytes, i);
+ flush_dcache_folio(folio);
status = a_ops->write_end(file, mapping, pos, bytes, copied,
page, fsdata);
@@ -3971,12 +3977,12 @@ ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i)
*/
if (copied)
bytes = copied;
- goto again;
+ if (chunk > PAGE_SIZE)
+ chunk /= 2;
+ } else {
+ pos += status;
+ written += status;
}
- pos += status;
- written += status;
-
- balance_dirty_pages_ratelimited(mapping);
} while (iov_iter_count(i));
if (!written)
--
2.40.1
