Commit f0b65f39 authored by Al Viro's avatar Al Viro
Browse files

iov_iter: replace iov_iter_copy_from_user_atomic() with iterator-advancing variant 



Replacement is called copy_page_from_iter_atomic(); unlike the old primitive the
callers do *not* need to do iov_iter_advance() after it.  In case when they end
up consuming less than they'd been given they need to do iov_iter_revert() on
everything they had not consumed.  That, however, needs to be done only on slow
paths.

All in-tree callers converted.  And that kills the last user of iterate_all_kinds()

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent e4f8df86

Documentation/filesystems/porting.rst

+9 −0
Original line number Diff line number Diff line
@@ -890,3 +890,12 @@ been called or returned with non -EIOCBQUEUED code. 


mnt_want_write_file() can now only be paired with mnt_drop_write_file(),

whereas previously it could be paired with mnt_drop_write() as well.



---



**mandatory**



iov_iter_copy_from_user_atomic() is gone; use copy_page_from_iter_atomic().

The difference is copy_page_from_iter_atomic() advances the iterator and

you don't need iov_iter_advance() after it.  However, if you decide to use

only a part of obtained data, you should do iov_iter_revert().

fs/btrfs/file.c

+11 −12
Original line number Diff line number Diff line
@@ -398,7 +398,7 @@ static noinline int btrfs_copy_from_user(loff_t pos, size_t write_bytes, 
		/*

		 * Copy data from userspace to the current page

		 */

		copied = iov_iter_copy_from_user_atomic(page, i, offset, count);

		copied = copy_page_from_iter_atomic(page, offset, count, i);



		/* Flush processor's dcache for this page */

		flush_dcache_page(page);
@@ -412,20 +412,19 @@ static noinline int btrfs_copy_from_user(loff_t pos, size_t write_bytes, 
		 * The rest of the btrfs_file_write code will fall

		 * back to page at a time copies after we return 0.

		 */

		if (!PageUptodate(page) && copied < count)

		if (unlikely(copied < count)) {

			if (!PageUptodate(page)) {

				iov_iter_revert(i, copied);

				copied = 0;

			}

			if (!copied)

				break;

		}



		iov_iter_advance(i, copied);

		write_bytes -= copied;

		total_copied += copied;



		/* Return to btrfs_file_write_iter to fault page */

		if (unlikely(copied == 0))

			break;



		if (copied < PAGE_SIZE - offset) {

		offset += copied;

		} else {

		if (offset == PAGE_SIZE) {

			pg++;

			offset = 0;

		}

fs/fuse/file.c

+1 −2
Original line number Diff line number Diff line
@@ -1171,10 +1171,9 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia, 
		if (mapping_writably_mapped(mapping))

			flush_dcache_page(page);



		tmp = iov_iter_copy_from_user_atomic(page, ii, offset, bytes);

		tmp = copy_page_from_iter_atomic(page, offset, bytes, ii);

		flush_dcache_page(page);



		iov_iter_advance(ii, tmp);

		if (!tmp) {

			unlock_page(page);

			put_page(page);

fs/iomap/buffered-io.c

+7 −7
Original line number Diff line number Diff line
@@ -785,13 +785,15 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data, 
		if (mapping_writably_mapped(inode->i_mapping))

			flush_dcache_page(page);



		copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);

		copied = copy_page_from_iter_atomic(page, offset, bytes, i);



		status = iomap_write_end(inode, pos, bytes, copied, page, iomap,

				srcmap);



		cond_resched();

		if (unlikely(copied != status))

			iov_iter_revert(i, copied - status);



		cond_resched();

		if (unlikely(status == 0)) {

			/*

			 * A short copy made iomap_write_end() reject the
@@ -803,11 +805,9 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data, 
				bytes = copied;

			goto again;

		}

		copied = status;

		iov_iter_advance(i, copied);

		pos += copied;

		written += copied;

		length -= copied;

		pos += status;

		written += status;

		length -= status;



		balance_dirty_pages_ratelimited(inode->i_mapping);

	} while (iov_iter_count(i) && length);

fs/ntfs/file.c

+1 −3
Original line number Diff line number Diff line
@@ -1690,9 +1690,7 @@ static size_t ntfs_copy_from_user_iter(struct page **pages, unsigned nr_pages, 
		len = PAGE_SIZE - ofs;

		if (len > bytes)

			len = bytes;

		copied = iov_iter_copy_from_user_atomic(*pages, i, ofs,

				len);

		iov_iter_advance(i, copied);

		copied = copy_page_from_iter_atomic(*pages, ofs, len, i);

		total += copied;

		bytes -= copied;

		if (!bytes)