X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=fs%2Fmpage.c;h=692a3e578fc8f1102823548dbc5d49a1a1850953;hb=7bd473fcc217adec000f213e8864bf9a161d57e1;hp=f1d2d02bd4c81ebeb0ccde0c2d66d6c4a980d3d3;hpb=b9abaa3fb7328851bdeaad19e694048f0ff71d9a;p=pandora-kernel.git

diff --git a/fs/mpage.c b/fs/mpage.c
index f1d2d02bd4c8..692a3e578fc8 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -163,9 +163,19 @@ map_buffer_to_page(struct page *page, struct buffer_head *bh, int page_block)
 	} while (page_bh != head);
 }
 
+/*
+ * This is the worker routine which does all the work of mapping the disk
+ * blocks and constructs largest possible bios, submits them for IO if the
+ * blocks are not contiguous on the disk.
+ *
+ * We pass a buffer_head back and forth and use its buffer_mapped() flag to
+ * represent the validity of its disk mapping and to decide when to do the next
+ * get_block() call.
+ */
 static struct bio *
 do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
-			sector_t *last_block_in_bio, get_block_t get_block)
+		sector_t *last_block_in_bio, struct buffer_head *map_bh,
+		unsigned long *first_logical_block, get_block_t get_block)
 {
 	struct inode *inode = page->mapping->host;
 	const unsigned blkbits = inode->i_blkbits;
@@ -173,33 +183,72 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
 	const unsigned blocksize = 1 << blkbits;
 	sector_t block_in_file;
 	sector_t last_block;
+	sector_t last_block_in_file;
 	sector_t blocks[MAX_BUF_PER_PAGE];
 	unsigned page_block;
 	unsigned first_hole = blocks_per_page;
 	struct block_device *bdev = NULL;
-	struct buffer_head bh;
 	int length;
 	int fully_mapped = 1;
+	unsigned nblocks;
+	unsigned relative_block;
 
 	if (page_has_buffers(page))
 		goto confused;
 
-	block_in_file = page->index << (PAGE_CACHE_SHIFT - blkbits);
-	last_block = (i_size_read(inode) + blocksize - 1) >> blkbits;
+	block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
+	last_block = block_in_file + nr_pages * blocks_per_page;
+	last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits;
+	if (last_block > last_block_in_file)
+		last_block = last_block_in_file;
+	page_block = 0;
+
+	/*
+	 * Map blocks using the result from the previous get_blocks call first.
+	 */
+	nblocks = map_bh->b_size >> blkbits;
+	if (buffer_mapped(map_bh) && block_in_file > *first_logical_block &&
+			block_in_file < (*first_logical_block + nblocks)) {
+		unsigned map_offset = block_in_file - *first_logical_block;
+		unsigned last = nblocks - map_offset;
+
+		for (relative_block = 0; ; relative_block++) {
+			if (relative_block == last) {
+				clear_buffer_mapped(map_bh);
+				break;
+			}
+			if (page_block == blocks_per_page)
+				break;
+			blocks[page_block] = map_bh->b_blocknr + map_offset +
+						relative_block;
+			page_block++;
+			block_in_file++;
+		}
+		bdev = map_bh->b_bdev;
+	}
+
+	/*
+	 * Then do more get_blocks calls until we are done with this page.
+	 */
+	map_bh->b_page = page;
+	while (page_block < blocks_per_page) {
+		map_bh->b_state = 0;
+		map_bh->b_size = 0;
 
-	bh.b_page = page;
-	for (page_block = 0; page_block < blocks_per_page;
-				page_block++, block_in_file++) {
-		bh.b_state = 0;
 		if (block_in_file < last_block) {
-			if (get_block(inode, block_in_file, &bh, 0))
+			map_bh->b_size = (last_block-block_in_file) << blkbits;
+			if (get_block(inode, block_in_file, map_bh, 0))
 				goto confused;
+			*first_logical_block = block_in_file;
 		}
 
-		if (!buffer_mapped(&bh)) {
+		if (!buffer_mapped(map_bh)) {
 			fully_mapped = 0;
 			if (first_hole == blocks_per_page)
 				first_hole = page_block;
+			page_block++;
+			block_in_file++;
+			clear_buffer_mapped(map_bh);
 			continue;
 		}
 
@@ -209,8 +258,8 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
 		 * we just collected from get_block into the page's buffers
 		 * so readpage doesn't have to repeat the get_block call
 		 */
-		if (buffer_uptodate(&bh)) {
-			map_buffer_to_page(page, &bh, page_block);
+		if (buffer_uptodate(map_bh)) {
+			map_buffer_to_page(page, map_bh, page_block);
 			goto confused;
 		}
 	
@@ -218,10 +267,20 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
 			goto confused;		/* hole -> non-hole */
 
 		/* Contiguous blocks? */
-		if (page_block && blocks[page_block-1] != bh.b_blocknr-1)
+		if (page_block && blocks[page_block-1] != map_bh->b_blocknr-1)
 			goto confused;
-		blocks[page_block] = bh.b_blocknr;
-		bdev = bh.b_bdev;
+		nblocks = map_bh->b_size >> blkbits;
+		for (relative_block = 0; ; relative_block++) {
+			if (relative_block == nblocks) {
+				clear_buffer_mapped(map_bh);
+				break;
+			} else if (page_block == blocks_per_page)
+				break;
+			blocks[page_block] = map_bh->b_blocknr+relative_block;
+			page_block++;
+			block_in_file++;
+		}
+		bdev = map_bh->b_bdev;
 	}
 
 	if (first_hole != blocks_per_page) {
@@ -260,7 +319,7 @@ alloc_new:
 		goto alloc_new;
 	}
 
-	if (buffer_boundary(&bh) || (first_hole != blocks_per_page))
+	if (buffer_boundary(map_bh) || (first_hole != blocks_per_page))
 		bio = mpage_bio_submit(READ, bio);
 	else
 		*last_block_in_bio = blocks[blocks_per_page - 1];
@@ -331,7 +390,10 @@ mpage_readpages(struct address_space *mapping, struct list_head *pages,
 	unsigned page_idx;
 	sector_t last_block_in_bio = 0;
 	struct pagevec lru_pvec;
+	struct buffer_head map_bh;
+	unsigned long first_logical_block = 0;
 
+	clear_buffer_mapped(&map_bh);
 	pagevec_init(&lru_pvec, 0);
 	for (page_idx = 0; page_idx < nr_pages; page_idx++) {
 		struct page *page = list_entry(pages->prev, struct page, lru);
@@ -342,7 +404,9 @@ mpage_readpages(struct address_space *mapping, struct list_head *pages,
 					page->index, GFP_KERNEL)) {
 			bio = do_mpage_readpage(bio, page,
 					nr_pages - page_idx,
-					&last_block_in_bio, get_block);
+					&last_block_in_bio, &map_bh,
+					&first_logical_block,
+					get_block);
 			if (!pagevec_add(&lru_pvec, page))
 				__pagevec_lru_add(&lru_pvec);
 		} else {
@@ -364,9 +428,12 @@ int mpage_readpage(struct page *page, get_block_t get_block)
 {
 	struct bio *bio = NULL;
 	sector_t last_block_in_bio = 0;
+	struct buffer_head map_bh;
+	unsigned long first_logical_block = 0;
 
-	bio = do_mpage_readpage(bio, page, 1,
-			&last_block_in_bio, get_block);
+	clear_buffer_mapped(&map_bh);
+	bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio,
+			&map_bh, &first_logical_block, get_block);
 	if (bio)
 		mpage_bio_submit(READ, bio);
 	return 0;
@@ -466,12 +533,13 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
 	 * The page has no buffers: map it to disk
 	 */
 	BUG_ON(!PageUptodate(page));
-	block_in_file = page->index << (PAGE_CACHE_SHIFT - blkbits);
+	block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
 	last_block = (i_size - 1) >> blkbits;
 	map_bh.b_page = page;
 	for (page_block = 0; page_block < blocks_per_page; ) {
 
 		map_bh.b_state = 0;
+		map_bh.b_size = 1 << blkbits;
 		if (get_block(inode, block_in_file, &map_bh, 1))
 			goto confused;
 		if (buffer_new(&map_bh))
@@ -625,6 +693,8 @@ out:
  * the call was made get new I/O started against them.  If wbc->sync_mode is
  * WB_SYNC_ALL then we were called for data integrity and we must wait for
  * existing IO to complete.
+ *
+ * If you fix this you should check generic_writepages() also!
  */
 int
 mpage_writepages(struct address_space *mapping,
@@ -639,9 +709,9 @@ mpage_writepages(struct address_space *mapping,
 	struct pagevec pvec;
 	int nr_pages;
 	pgoff_t index;
-	pgoff_t end = -1;		/* Inclusive */
+	pgoff_t end;		/* Inclusive */
 	int scanned = 0;
-	int is_range = 0;
+	int range_whole = 0;
 
 	if (wbc->nonblocking && bdi_write_congested(bdi)) {
 		wbc->encountered_congestion = 1;
@@ -653,16 +723,14 @@ mpage_writepages(struct address_space *mapping,
 		writepage = mapping->a_ops->writepage;
 
 	pagevec_init(&pvec, 0);
-	if (wbc->sync_mode == WB_SYNC_NONE) {
+	if (wbc->range_cyclic) {
 		index = mapping->writeback_index; /* Start from prev offset */
+		end = -1;
 	} else {
-		index = 0;			  /* whole-file sweep */
-		scanned = 1;
-	}
-	if (wbc->start || wbc->end) {
-		index = wbc->start >> PAGE_CACHE_SHIFT;
-		end = wbc->end >> PAGE_CACHE_SHIFT;
-		is_range = 1;
+		index = wbc->range_start >> PAGE_CACHE_SHIFT;
+		end = wbc->range_end >> PAGE_CACHE_SHIFT;
+		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
+			range_whole = 1;
 		scanned = 1;
 	}
 retry:
@@ -691,7 +759,7 @@ retry:
 				continue;
 			}
 
-			if (unlikely(is_range) && page->index > end) {
+			if (!wbc->range_cyclic && page->index > end) {
 				done = 1;
 				unlock_page(page);
 				continue;
@@ -742,7 +810,7 @@ retry:
 		index = 0;
 		goto retry;
 	}
-	if (!is_range)
+	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 		mapping->writeback_index = index;
 	if (bio)
 		mpage_bio_submit(WRITE, bio);