iomap: use mapping_seek_hole_data

Enhance mapping_seek_hole_data() to handle partially uptodate pages and
convert the iomap seek code to call it.

Link: https://lkml.kernel.org/r/20201112212641.27837-9-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 114 deletions

diff --git a/fs/iomap/seek.c b/fs/iomap/seek.c
index 107ee80c3568..dab1b02eba5b 100644
--- a/fs/iomap/seek.c
+++ b/fs/iomap/seek.c
@@ -10,122 +10,17 @@
 #include <linux/pagemap.h>
 #include <linux/pagevec.h>
 
-/*
- * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff.
- * Returns true if found and updates @lastoff to the offset in file.
- */
-static bool
-page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff,
-		int whence)
-{
-	const struct address_space_operations *ops = inode->i_mapping->a_ops;
-	unsigned int bsize = i_blocksize(inode), off;
-	bool seek_data = whence == SEEK_DATA;
-	loff_t poff = page_offset(page);
-
-	if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE))
-		return false;
-
-	if (*lastoff < poff) {
-		/*
-		 * Last offset smaller than the start of the page means we found
-		 * a hole:
-		 */
-		if (whence == SEEK_HOLE)
-			return true;
-		*lastoff = poff;
-	}
-
-	/*
-	 * Just check the page unless we can and should check block ranges:
-	 */
-	if (bsize == PAGE_SIZE || !ops->is_partially_uptodate)
-		return PageUptodate(page) == seek_data;
-
-	lock_page(page);
-	if (unlikely(page->mapping != inode->i_mapping))
-		goto out_unlock_not_found;
-
-	for (off = 0; off < PAGE_SIZE; off += bsize) {
-		if (offset_in_page(*lastoff) >= off + bsize)
-			continue;
-		if (ops->is_partially_uptodate(page, off, bsize) == seek_data) {
-			unlock_page(page);
-			return true;
-		}
-		*lastoff = poff + off + bsize;
-	}
-
-out_unlock_not_found:
-	unlock_page(page);
-	return false;
-}
-
-/*
- * Seek for SEEK_DATA / SEEK_HOLE in the page cache.
- *
- * Within unwritten extents, the page cache determines which parts are holes
- * and which are data: uptodate buffer heads count as data; everything else
- * counts as a hole.
- *
- * Returns the resulting offset on successs, and -ENOENT otherwise.
- */
 static loff_t
-page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length,
-		int whence)
-{
-	pgoff_t index = offset >> PAGE_SHIFT;
-	pgoff_t end = DIV_ROUND_UP(offset + length, PAGE_SIZE);
-	loff_t lastoff = offset;
-	struct pagevec pvec;
-
-	if (length <= 0)
-		return -ENOENT;
-
-	pagevec_init(&pvec);
-
-	do {
-		unsigned nr_pages, i;
-
-		nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping, &index,
-						end - 1);
-		if (nr_pages == 0)
-			break;
-
-		for (i = 0; i < nr_pages; i++) {
-			struct page *page = pvec.pages[i];
-
-			if (page_seek_hole_data(inode, page, &lastoff, whence))
-				goto check_range;
-			lastoff = page_offset(page) + PAGE_SIZE;
-		}
-		pagevec_release(&pvec);
-	} while (index < end);
-
-	/* When no page at lastoff and we are not done, we found a hole. */
-	if (whence != SEEK_HOLE)
-		goto not_found;
-
-check_range:
-	if (lastoff < offset + length)
-		goto out;
-not_found:
-	lastoff = -ENOENT;
-out:
-	pagevec_release(&pvec);
-	return lastoff;
-}
-
-
-static loff_t
-iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length,
+iomap_seek_hole_actor(struct inode *inode, loff_t start, loff_t length,
 		      void *data, struct iomap *iomap, struct iomap *srcmap)
 {
+	loff_t offset = start;
+
 	switch (iomap->type) {
 	case IOMAP_UNWRITTEN:
-		offset = page_cache_seek_hole_data(inode, offset, length,
-						   SEEK_HOLE);
-		if (offset < 0)
+		offset = mapping_seek_hole_data(inode->i_mapping, start,
+				start + length, SEEK_HOLE);
+		if (offset == start + length)
 			return length;
 		fallthrough;
 	case IOMAP_HOLE:
@@ -164,15 +59,17 @@ iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
 EXPORT_SYMBOL_GPL(iomap_seek_hole);
 
 static loff_t
-iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length,
+iomap_seek_data_actor(struct inode *inode, loff_t start, loff_t length,
 		      void *data, struct iomap *iomap, struct iomap *srcmap)
 {
+	loff_t offset = start;
+
 	switch (iomap->type) {
 	case IOMAP_HOLE:
 		return length;
 	case IOMAP_UNWRITTEN:
-		offset = page_cache_seek_hole_data(inode, offset, length,
-						   SEEK_DATA);
+		offset = mapping_seek_hole_data(inode->i_mapping, start,
+				start + length, SEEK_DATA);
 		if (offset < 0)
 			return length;
 		fallthrough;