iomap: use write_begin to read pages to unshare (32a38a49) · Commits · 戴 / test

fs/iomap/buffered-io.c

+16 −33

Original line number	Diff line number	Diff line
		@@ -548,6 +548,10 @@ iomap_migrate_page(struct address_space mapping, struct page newpage,
		EXPORT_SYMBOL_GPL(iomap_migrate_page);
		#endif /* CONFIG_MIGRATION */

		enum {
		IOMAP_WRITE_F_UNSHARE = (1 << 0),
		};

		static void
		iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
		{
		@@ -577,7 +581,7 @@ iomap_read_page_sync(loff_t block_start, struct page *page, unsigned poff,
		}

		static int
		__iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
		__iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
		struct page page, struct iomap iomap)
		{
		struct iomap_page *iop = iomap_page_create(inode, page);
		@@ -596,11 +600,14 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
		if (plen == 0)
		break;

		if ((from <= poff \|\| from >= poff + plen) &&
		if (!(flags & IOMAP_WRITE_F_UNSHARE) &&
		(from <= poff \|\| from >= poff + plen) &&
		(to <= poff \|\| to >= poff + plen))
		continue;

		if (iomap_block_needs_zeroing(inode, iomap, block_start)) {
		if (WARN_ON_ONCE(flags & IOMAP_WRITE_F_UNSHARE))
		return -EIO;
		zero_user_segments(page, poff, from, to, poff + plen);
		iomap_set_range_uptodate(page, poff, plen);
		continue;
		@@ -646,7 +653,8 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
		else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
		status = __block_write_begin_int(page, pos, len, NULL, iomap);
		else
		status = __iomap_write_begin(inode, pos, len, page, iomap);
		status = __iomap_write_begin(inode, pos, len, flags, page,
		iomap);

		if (unlikely(status))
		goto out_unlock;
		@@ -869,22 +877,6 @@ iomap_file_buffered_write(struct kiocb iocb, struct iov_iter iter,
		}
		EXPORT_SYMBOL_GPL(iomap_file_buffered_write);

		static struct page *
		__iomap_read_page(struct inode *inode, loff_t offset)
		{
		struct address_space *mapping = inode->i_mapping;
		struct page *page;

		page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
		if (IS_ERR(page))
		return page;
		if (!PageUptodate(page)) {
		put_page(page);
		return ERR_PTR(-EIO);
		}
		return page;
		}

		static loff_t
		iomap_unshare_actor(struct inode inode, loff_t pos, loff_t length, void data,
		struct iomap *iomap)
		@@ -900,24 +892,15 @@ iomap_unshare_actor(struct inode inode, loff_t pos, loff_t length, void data,
		return length;

		do {
		struct page page, rpage;
		unsigned long offset; /* Offset into pagecache page */
		unsigned long bytes; /* Bytes to write to page */

		offset = offset_in_page(pos);
		bytes = min_t(loff_t, PAGE_SIZE - offset, length);

		rpage = __iomap_read_page(inode, pos);
		if (IS_ERR(rpage))
		return PTR_ERR(rpage);
		unsigned long offset = offset_in_page(pos);
		unsigned long bytes = min_t(loff_t, PAGE_SIZE - offset, length);
		struct page *page;

		status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap);
		put_page(rpage);
		status = iomap_write_begin(inode, pos, bytes,
		IOMAP_WRITE_F_UNSHARE, &page, iomap);
		if (unlikely(status))
		return status;

		WARN_ON_ONCE(!PageUptodate(page));

		status = iomap_write_end(inode, pos, bytes, bytes, page, iomap);
		if (unlikely(status <= 0)) {
		if (WARN_ON_ONCE(status == 0))

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