iomap: Add a page_prepare callback

Move the page_done callback into a separate iomap_page_ops structure and add a page_prepare calback to be called before the next page is written to. In gfs2, we'll want to start a transaction in page_prepare and end it in page_done. Other filesystems that implement data journaling will require the same kind of mechanism.

Andreas Gruenbacher committed 7 years ago

Commit df0db3e1 parent 7a77dad3 files · +53 −20Browse files

Showing the changes to include/linux (1 of 3 files). Show all

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include/linux/iomap.h+17−5

@@ -53,6 +53,8 @@ struct vm_fault; · 52 unmodified lines
53	53	*/
54	54	#define IOMAP_NULL_ADDR -1ULL /* addr is not valid */
55	55
	56	+struct iomap_page_ops;
	57	+
56	58	struct iomap {
57	59	u64 addr; /* disk offset of mapping, bytes */
58	60	loff_t offset; /* file offset of mapping, bytes */
@@ -63,12 +65,22 @@ struct iomap { · 4 unmodified lines
63	65	struct dax_device dax_dev; / dax_dev for dax operations */
64	66	void *inline_data;
65	67	void private; / filesystem private */
	68	+ const struct iomap_page_ops *page_ops;
	69	+};
66	70
67		− /*
68		− * Called when finished processing a page in the mapping returned in
69		− * this iomap. At least for now this is only supported in the buffered
70		− * write path.
71		− */
	71	+/*
	72	+ * When a filesystem sets page_ops in an iomap mapping it returns, page_prepare
	73	+ * and page_done will be called for each page written to. This only applies to
	74	+ * buffered writes as unbuffered writes will not typically have pages
	75	+ * associated with them.
	76	+ *
	77	+ * When page_prepare succeeds, page_done will always be called to do any
	78	+ * cleanup work necessary. In that page_done call, @page will be NULL if the
	79	+ * associated page could not be obtained.
	80	+ */
	81	+struct iomap_page_ops {
	82	+ int (page_prepare)(struct inode inode, loff_t pos, unsigned len,
	83	+ struct iomap *iomap);
72	84	void (page_done)(struct inode inode, loff_t pos, unsigned copied,
73	85	struct page page, struct iomap iomap);
74	86	};

iomap: Add a page_prepare callback

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