9p: saner ->write_end() on failing copy into non-uptodate page (77469c3f) · Commits · 戴 / test

If we had a short copy into an uptodate page, there's no reason whatsoever to zero anything; OTOH, if that page had _not_ been uptodate, we must have been trying to overwrite it completely and got a short copy. In that case, overwriting the end with zeroes, marking uptodate and sending to server is just plain wrong. Just unlock, keep it non-uptodate and return 0. Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk>

fs/9p/vfs_addr.c

+4 −11

Original line number	Diff line number	Diff line
		@@ -309,18 +309,10 @@ static int v9fs_write_end(struct file filp, struct address_space mapping,

		p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);

		if (unlikely(copied < len)) {
		/*
		* zero out the rest of the area
		*/
		unsigned from = pos & (PAGE_SIZE - 1);

		zero_user(page, from + copied, len - copied);
		flush_dcache_page(page);
		if (unlikely(copied < len && !PageUptodate(page))) {
		copied = 0;
		goto out;
		}

		if (!PageUptodate(page))
		SetPageUptodate(page);
		/*
		* No need to use i_size_read() here, the i_size
		* cannot change under us because we hold the i_mutex.
		@@ -330,6 +322,7 @@ static int v9fs_write_end(struct file filp, struct address_space mapping,
		i_size_write(inode, last_pos);
		}
		set_page_dirty(page);
		out:
		unlock_page(page);
		put_page(page);

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