1 files changed, 57 insertions, 169 deletions

diff --git a/fs/iomap/seek.c b/fs/iomap/seek.c
index 89f61d93c0bc..6cbc587c93da 100644
--- a/fs/iomap/seek.c
+++ b/fs/iomap/seek.c
@@ -1,212 +1,100 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2017 Red Hat, Inc.
- * Copyright (c) 2018 Christoph Hellwig.
+ * Copyright (c) 2018-2021 Christoph Hellwig.
  */
-#include <linux/module.h>
-#include <linux/compiler.h>
-#include <linux/fs.h>
 #include <linux/iomap.h>
 #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)
+static int iomap_seek_hole_iter(struct iomap_iter *iter,
+		loff_t *hole_pos)
 {
-	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;
+	loff_t length = iomap_length(iter);
 
-		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,
-		      void *data, struct iomap *iomap, struct iomap *srcmap)
-{
-	switch (iomap->type) {
+	switch (iter->iomap.type) {
 	case IOMAP_UNWRITTEN:
-		offset = page_cache_seek_hole_data(inode, offset, length,
-						   SEEK_HOLE);
-		if (offset < 0)
-			return length;
-		/* fall through */
+		*hole_pos = mapping_seek_hole_data(iter->inode->i_mapping,
+				iter->pos, iter->pos + length, SEEK_HOLE);
+		if (*hole_pos == iter->pos + length)
+			return iomap_iter_advance(iter, length);
+		return 0;
 	case IOMAP_HOLE:
-		*(loff_t *)data = offset;
+		*hole_pos = iter->pos;
 		return 0;
 	default:
-		return length;
+		return iomap_iter_advance(iter, length);
 	}
 }
 
 loff_t
-iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
+iomap_seek_hole(struct inode *inode, loff_t pos, const struct iomap_ops *ops)
 {
 	loff_t size = i_size_read(inode);
-	loff_t length = size - offset;
-	loff_t ret;
+	struct iomap_iter iter = {
+		.inode	= inode,
+		.pos	= pos,
+		.flags	= IOMAP_REPORT,
+	};
+	int ret;
 
 	/* Nothing to be found before or beyond the end of the file. */
-	if (offset < 0 || offset >= size)
+	if (pos < 0 || pos >= size)
 		return -ENXIO;
 
-	while (length > 0) {
-		ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
-				  &offset, iomap_seek_hole_actor);
-		if (ret < 0)
-			return ret;
-		if (ret == 0)
-			break;
-
-		offset += ret;
-		length -= ret;
-	}
-
-	return offset;
+	iter.len = size - pos;
+	while ((ret = iomap_iter(&iter, ops)) > 0)
+		iter.status = iomap_seek_hole_iter(&iter, &pos);
+	if (ret < 0)
+		return ret;
+	if (iter.len) /* found hole before EOF */
+		return pos;
+	return size;
 }
 EXPORT_SYMBOL_GPL(iomap_seek_hole);
 
-static loff_t
-iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length,
-		      void *data, struct iomap *iomap, struct iomap *srcmap)
+static int iomap_seek_data_iter(struct iomap_iter *iter,
+		loff_t *hole_pos)
 {
-	switch (iomap->type) {
+	loff_t length = iomap_length(iter);
+
+	switch (iter->iomap.type) {
 	case IOMAP_HOLE:
-		return length;
+		return iomap_iter_advance(iter, length);
 	case IOMAP_UNWRITTEN:
-		offset = page_cache_seek_hole_data(inode, offset, length,
-						   SEEK_DATA);
-		if (offset < 0)
-			return length;
-		/*FALLTHRU*/
+		*hole_pos = mapping_seek_hole_data(iter->inode->i_mapping,
+				iter->pos, iter->pos + length, SEEK_DATA);
+		if (*hole_pos < 0)
+			return iomap_iter_advance(iter, length);
+		return 0;
 	default:
-		*(loff_t *)data = offset;
+		*hole_pos = iter->pos;
 		return 0;
 	}
 }
 
 loff_t
-iomap_seek_data(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
+iomap_seek_data(struct inode *inode, loff_t pos, const struct iomap_ops *ops)
 {
 	loff_t size = i_size_read(inode);
-	loff_t length = size - offset;
-	loff_t ret;
+	struct iomap_iter iter = {
+		.inode	= inode,
+		.pos	= pos,
+		.flags	= IOMAP_REPORT,
+	};
+	int ret;
 
 	/* Nothing to be found before or beyond the end of the file. */
-	if (offset < 0 || offset >= size)
+	if (pos < 0 || pos >= size)
 		return -ENXIO;
 
-	while (length > 0) {
-		ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
-				  &offset, iomap_seek_data_actor);
-		if (ret < 0)
-			return ret;
-		if (ret == 0)
-			break;
-
-		offset += ret;
-		length -= ret;
-	}
-
-	if (length <= 0)
-		return -ENXIO;
-	return offset;
+	iter.len = size - pos;
+	while ((ret = iomap_iter(&iter, ops)) > 0)
+		iter.status = iomap_seek_data_iter(&iter, &pos);
+	if (ret < 0)
+		return ret;
+	if (iter.len) /* found data before EOF */
+		return pos;
+	/* We've reached the end of the file without finding data */
+	return -ENXIO;
 }
 EXPORT_SYMBOL_GPL(iomap_seek_data);