Btrfs: when forced to cow for file_write, get the page uptodate first (2932f3ec) · Commits · e / devices / android_kernel_oneplus_sm7250

fs/btrfs/super.c

+14 −1

Original line number	Diff line number	Diff line
		@@ -1268,6 +1268,8 @@ static int prepare_pages(struct btrfs_trans_handle *trans,
		struct page **pages,
		size_t num_pages,
		loff_t pos,
		unsigned long first_index,
		unsigned long last_index,
		size_t write_bytes)
		{
		int i;
		@@ -1289,6 +1291,13 @@ static int prepare_pages(struct btrfs_trans_handle *trans,
		}
		offset = pos & (PAGE_CACHE_SIZE -1);
		this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
		if (!PageUptodate(pages[i]) &&
		(pages[i]->index == first_index \|\|
		pages[i]->index == last_index) && pos < isize) {
		ret = mpage_readpage(pages[i], btrfs_get_block);
		BUG_ON(ret);
		lock_page(pages[i]);
		}
		ret = nobh_prepare_write(pages[i], offset,
		offset + this_write,
		btrfs_get_block);
		@@ -1323,6 +1332,8 @@ static ssize_t btrfs_file_write(struct file file, const char __user buf,
		struct inode *inode = file->f_path.dentry->d_inode;
		struct btrfs_root *root = BTRFS_I(inode)->root;
		struct page *pages[1];
		unsigned long first_index;
		unsigned long last_index;

		if (file->f_flags & O_DIRECT)
		return -EINVAL;
		@@ -1340,13 +1351,15 @@ static ssize_t btrfs_file_write(struct file file, const char __user buf,
		goto out;
		file_update_time(file);
		mutex_lock(&inode->i_mutex);
		first_index = pos >> PAGE_CACHE_SHIFT;
		last_index = (pos + count) >> PAGE_CACHE_SHIFT;
		while(count > 0) {
		size_t offset = pos & (PAGE_CACHE_SIZE - 1);
		size_t write_bytes = min(count, PAGE_CACHE_SIZE - offset);
		size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
		PAGE_CACHE_SHIFT;
		ret = prepare_pages(NULL, root, file, pages, num_pages,
		pos, write_bytes);
		pos, first_index, last_index, write_bytes);
		BUG_ON(ret);
		ret = btrfs_copy_from_user(pos, num_pages,
		write_bytes, pages, buf);