X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=fs%2Fmpage.c;h=c1698f2291aa2ee953b54f71a092b4908b4fb343;hb=03b9ae4b80dd5b20d7bf7e15902592d50c66780d;hp=7903b740cc111f6250bd75ebc83b4652118a0474;hpb=b0cf2321c6599138f860517745503691556d8453;p=safe%2Fjmp%2Flinux-2.6

diff --git a/fs/mpage.c b/fs/mpage.c
index 7903b74..c1698f2 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;
@@ -173,34 +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 = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
-	last_block = (i_size_read(inode) + blocksize - 1) >> 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) {
-			bh.b_size = blocksize;
-			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;
 		}
 
@@ -210,8 +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;
 		}
 	
@@ -219,18 +267,26 @@ 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) {
-		char *kaddr = kmap_atomic(page, KM_USER0);
-		memset(kaddr + (first_hole << blkbits), 0,
-				PAGE_CACHE_SIZE - (first_hole << blkbits));
-		flush_dcache_page(page);
-		kunmap_atomic(kaddr, KM_USER0);
+		zero_user_page(page, first_hole << blkbits,
+				PAGE_CACHE_SIZE - (first_hole << blkbits),
+				KM_USER0);
 		if (first_hole == 0) {
 			SetPageUptodate(page);
 			unlock_page(page);
@@ -261,7 +317,7 @@ 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];
@@ -332,7 +388,10 @@ 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);
@@ -343,7 +402,9 @@ 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 {
@@ -365,9 +426,12 @@ 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;
@@ -390,11 +454,18 @@ EXPORT_SYMBOL(mpage_readpage);
  * written, so it can intelligently allocate a suitably-sized BIO.  For now,
  * just allocate full-size (16-page) BIOs.
  */
-static struct bio *
-__mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
-	sector_t *last_block_in_bio, int *ret, struct writeback_control *wbc,
-	writepage_t writepage_fn)
+struct mpage_data {
+	struct bio *bio;
+	sector_t last_block_in_bio;
+	get_block_t *get_block;
+	unsigned use_writepage;
+};
+
+static int __mpage_writepage(struct page *page, struct writeback_control *wbc,
+			     void *data)
 {
+	struct mpage_data *mpd = data;
+	struct bio *bio = mpd->bio;
 	struct address_space *mapping = page->mapping;
 	struct inode *inode = page->mapping->host;
 	const unsigned blkbits = inode->i_blkbits;
@@ -412,6 +483,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
 	int length;
 	struct buffer_head map_bh;
 	loff_t i_size = i_size_read(inode);
+	int ret = 0;
 
 	if (page_has_buffers(page)) {
 		struct buffer_head *head = page_buffers(page);
@@ -474,7 +546,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
 
 		map_bh.b_state = 0;
 		map_bh.b_size = 1 << blkbits;
-		if (get_block(inode, block_in_file, &map_bh, 1))
+		if (mpd->get_block(inode, block_in_file, &map_bh, 1))
 			goto confused;
 		if (buffer_new(&map_bh))
 			unmap_underlying_metadata(map_bh.b_bdev,
@@ -510,20 +582,17 @@ page_is_mapped:
 		 * written out to the file."
 		 */
 		unsigned offset = i_size & (PAGE_CACHE_SIZE - 1);
-		char *kaddr;
 
 		if (page->index > end_index || !offset)
 			goto confused;
-		kaddr = kmap_atomic(page, KM_USER0);
-		memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
-		flush_dcache_page(page);
-		kunmap_atomic(kaddr, KM_USER0);
+		zero_user_page(page, offset, PAGE_CACHE_SIZE - offset,
+				KM_USER0);
 	}
 
 	/*
 	 * This page will go to BIO.  Do we need to send this BIO off first?
 	 */
-	if (bio && *last_block_in_bio != blocks[0] - 1)
+	if (bio && mpd->last_block_in_bio != blocks[0] - 1)
 		bio = mpage_bio_submit(WRITE, bio);
 
 alloc_new:
@@ -580,7 +649,7 @@ alloc_new:
 					boundary_block, 1 << blkbits);
 		}
 	} else {
-		*last_block_in_bio = blocks[blocks_per_page - 1];
+		mpd->last_block_in_bio = blocks[blocks_per_page - 1];
 	}
 	goto out;
 
@@ -588,23 +657,19 @@ confused:
 	if (bio)
 		bio = mpage_bio_submit(WRITE, bio);
 
-	if (writepage_fn) {
-		*ret = (*writepage_fn)(page, wbc);
+	if (mpd->use_writepage) {
+		ret = mapping->a_ops->writepage(page, wbc);
 	} else {
-		*ret = -EAGAIN;
+		ret = -EAGAIN;
 		goto out;
 	}
 	/*
 	 * The caller has a ref on the inode, so *mapping is stable
 	 */
-	if (*ret) {
-		if (*ret == -ENOSPC)
-			set_bit(AS_ENOSPC, &mapping->flags);
-		else
-			set_bit(AS_EIO, &mapping->flags);
-	}
+	mapping_set_error(mapping, ret);
 out:
-	return bio;
+	mpd->bio = bio;
+	return ret;
 }
 
 /**
@@ -632,122 +697,22 @@ int
 mpage_writepages(struct address_space *mapping,
 		struct writeback_control *wbc, get_block_t get_block)
 {
-	struct backing_dev_info *bdi = mapping->backing_dev_info;
-	struct bio *bio = NULL;
-	sector_t last_block_in_bio = 0;
-	int ret = 0;
-	int done = 0;
-	int (*writepage)(struct page *page, struct writeback_control *wbc);
-	struct pagevec pvec;
-	int nr_pages;
-	pgoff_t index;
-	pgoff_t end = -1;		/* Inclusive */
-	int scanned = 0;
-	int is_range = 0;
-
-	if (wbc->nonblocking && bdi_write_congested(bdi)) {
-		wbc->encountered_congestion = 1;
-		return 0;
+	int ret;
+
+	if (!get_block)
+		ret = generic_writepages(mapping, wbc);
+	else {
+		struct mpage_data mpd = {
+			.bio = NULL,
+			.last_block_in_bio = 0,
+			.get_block = get_block,
+			.use_writepage = 1,
+		};
+
+		ret = write_cache_pages(mapping, wbc, __mpage_writepage, &mpd);
+		if (mpd.bio)
+			mpage_bio_submit(WRITE, mpd.bio);
 	}
-
-	writepage = NULL;
-	if (get_block == NULL)
-		writepage = mapping->a_ops->writepage;
-
-	pagevec_init(&pvec, 0);
-	if (wbc->sync_mode == WB_SYNC_NONE) {
-		index = mapping->writeback_index; /* Start from prev offset */
-	} 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;
-		scanned = 1;
-	}
-retry:
-	while (!done && (index <= end) &&
-			(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
-			PAGECACHE_TAG_DIRTY,
-			min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
-		unsigned i;
-
-		scanned = 1;
-		for (i = 0; i < nr_pages; i++) {
-			struct page *page = pvec.pages[i];
-
-			/*
-			 * At this point we hold neither mapping->tree_lock nor
-			 * lock on the page itself: the page may be truncated or
-			 * invalidated (changing page->mapping to NULL), or even
-			 * swizzled back from swapper_space to tmpfs file
-			 * mapping
-			 */
-
-			lock_page(page);
-
-			if (unlikely(page->mapping != mapping)) {
-				unlock_page(page);
-				continue;
-			}
-
-			if (unlikely(is_range) && page->index > end) {
-				done = 1;
-				unlock_page(page);
-				continue;
-			}
-
-			if (wbc->sync_mode != WB_SYNC_NONE)
-				wait_on_page_writeback(page);
-
-			if (PageWriteback(page) ||
-					!clear_page_dirty_for_io(page)) {
-				unlock_page(page);
-				continue;
-			}
-
-			if (writepage) {
-				ret = (*writepage)(page, wbc);
-				if (ret) {
-					if (ret == -ENOSPC)
-						set_bit(AS_ENOSPC,
-							&mapping->flags);
-					else
-						set_bit(AS_EIO,
-							&mapping->flags);
-				}
-			} else {
-				bio = __mpage_writepage(bio, page, get_block,
-						&last_block_in_bio, &ret, wbc,
-						page->mapping->a_ops->writepage);
-			}
-			if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
-				unlock_page(page);
-			if (ret || (--(wbc->nr_to_write) <= 0))
-				done = 1;
-			if (wbc->nonblocking && bdi_write_congested(bdi)) {
-				wbc->encountered_congestion = 1;
-				done = 1;
-			}
-		}
-		pagevec_release(&pvec);
-		cond_resched();
-	}
-	if (!scanned && !done) {
-		/*
-		 * We hit the last page and there is more work to be done: wrap
-		 * back to the start of the file
-		 */
-		scanned = 1;
-		index = 0;
-		goto retry;
-	}
-	if (!is_range)
-		mapping->writeback_index = index;
-	if (bio)
-		mpage_bio_submit(WRITE, bio);
 	return ret;
 }
 EXPORT_SYMBOL(mpage_writepages);
@@ -755,15 +720,15 @@ EXPORT_SYMBOL(mpage_writepages);
 int mpage_writepage(struct page *page, get_block_t get_block,
 	struct writeback_control *wbc)
 {
-	int ret = 0;
-	struct bio *bio;
-	sector_t last_block_in_bio = 0;
-
-	bio = __mpage_writepage(NULL, page, get_block,
-			&last_block_in_bio, &ret, wbc, NULL);
-	if (bio)
-		mpage_bio_submit(WRITE, bio);
-
+	struct mpage_data mpd = {
+		.bio = NULL,
+		.last_block_in_bio = 0,
+		.get_block = get_block,
+		.use_writepage = 0,
+	};
+	int ret = __mpage_writepage(page, wbc, &mpd);
+	if (mpd.bio)
+		mpage_bio_submit(WRITE, mpd.bio);
 	return ret;
 }
 EXPORT_SYMBOL(mpage_writepage);