1 files changed, 542 insertions, 0 deletions

diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c
new file mode 100644
index 0000000..7b18be8
--- /dev/null
+++ b/fs/nilfs2/page.c
@@ -0,0 +1,542 @@
+/*
+ * page.c - buffer/page management specific to NILFS
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>,
+ *            Seiji Kihara <kihara@osrg.net>.
+ */
+
+#include <linux/pagemap.h>
+#include <linux/writeback.h>
+#include <linux/swap.h>
+#include <linux/bitops.h>
+#include <linux/page-flags.h>
+#include <linux/list.h>
+#include <linux/highmem.h>
+#include <linux/pagevec.h>
+#include "nilfs.h"
+#include "page.h"
+#include "mdt.h"
+
+
+#define NILFS_BUFFER_INHERENT_BITS  \
+	((1UL << BH_Uptodate) | (1UL << BH_Mapped) | (1UL << BH_NILFS_Node) | \
+	 (1UL << BH_NILFS_Volatile) | (1UL << BH_NILFS_Allocated))
+
+static struct buffer_head *
+__nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
+		       int blkbits, unsigned long b_state)
+
+{
+	unsigned long first_block;
+	struct buffer_head *bh;
+
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, 1 << blkbits, b_state);
+
+	first_block = (unsigned long)index << (PAGE_CACHE_SHIFT - blkbits);
+	bh = nilfs_page_get_nth_block(page, block - first_block);
+
+	touch_buffer(bh);
+	wait_on_buffer(bh);
+	return bh;
+}
+
+/*
+ * Since the page cache of B-tree node pages or data page cache of pseudo
+ * inodes does not have a valid mapping->host pointer, calling
+ * mark_buffer_dirty() for their buffers causes a NULL pointer dereference;
+ * it calls __mark_inode_dirty(NULL) through __set_page_dirty().
+ * To avoid this problem, the old style mark_buffer_dirty() is used instead.
+ */
+void nilfs_mark_buffer_dirty(struct buffer_head *bh)
+{
+	if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh))
+		__set_page_dirty_nobuffers(bh->b_page);
+}
+
+struct buffer_head *nilfs_grab_buffer(struct inode *inode,
+				      struct address_space *mapping,
+				      unsigned long blkoff,
+				      unsigned long b_state)
+{
+	int blkbits = inode->i_blkbits;
+	pgoff_t index = blkoff >> (PAGE_CACHE_SHIFT - blkbits);
+	struct page *page, *opage;
+	struct buffer_head *bh, *obh;
+
+	page = grab_cache_page(mapping, index);
+	if (unlikely(!page))
+		return NULL;
+
+	bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
+	if (unlikely(!bh)) {
+		unlock_page(page);
+		page_cache_release(page);
+		return NULL;
+	}
+	if (!buffer_uptodate(bh) && mapping->assoc_mapping != NULL) {
+		/*
+		 * Shadow page cache uses assoc_mapping to point its original
+		 * page cache.  The following code tries the original cache
+		 * if the given cache is a shadow and it didn't hit.
+		 */
+		opage = find_lock_page(mapping->assoc_mapping, index);
+		if (!opage)
+			return bh;
+
+		obh = __nilfs_get_page_block(opage, blkoff, index, blkbits,
+					     b_state);
+		if (buffer_uptodate(obh)) {
+			nilfs_copy_buffer(bh, obh);
+			if (buffer_dirty(obh)) {
+				nilfs_mark_buffer_dirty(bh);
+				if (!buffer_nilfs_node(bh) && NILFS_MDT(inode))
+					nilfs_mdt_mark_dirty(inode);
+			}
+		}
+		brelse(obh);
+		unlock_page(opage);
+		page_cache_release(opage);
+	}
+	return bh;
+}
+
+/**
+ * nilfs_forget_buffer - discard dirty state
+ * @inode: owner inode of the buffer
+ * @bh: buffer head of the buffer to be discarded
+ */
+void nilfs_forget_buffer(struct buffer_head *bh)
+{
+	struct page *page = bh->b_page;
+
+	lock_buffer(bh);
+	clear_buffer_nilfs_volatile(bh);
+	if (test_clear_buffer_dirty(bh) && nilfs_page_buffers_clean(page))
+		__nilfs_clear_page_dirty(page);
+
+	clear_buffer_uptodate(bh);
+	clear_buffer_mapped(bh);
+	bh->b_blocknr = -1;
+	ClearPageUptodate(page);
+	ClearPageMappedToDisk(page);
+	unlock_buffer(bh);
+	brelse(bh);
+}
+
+/**
+ * nilfs_copy_buffer -- copy buffer data and flags
+ * @dbh: destination buffer
+ * @sbh: source buffer
+ */
+void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
+{
+	void *kaddr0, *kaddr1;
+	unsigned long bits;
+	struct page *spage = sbh->b_page, *dpage = dbh->b_page;
+	struct buffer_head *bh;
+
+	kaddr0 = kmap_atomic(spage, KM_USER0);
+	kaddr1 = kmap_atomic(dpage, KM_USER1);
+	memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
+	kunmap_atomic(kaddr1, KM_USER1);
+	kunmap_atomic(kaddr0, KM_USER0);
+
+	dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
+	dbh->b_blocknr = sbh->b_blocknr;
+	dbh->b_bdev = sbh->b_bdev;
+
+	bh = dbh;
+	bits = sbh->b_state & ((1UL << BH_Uptodate) | (1UL << BH_Mapped));
+	while ((bh = bh->b_this_page) != dbh) {
+		lock_buffer(bh);
+		bits &= bh->b_state;
+		unlock_buffer(bh);
+	}
+	if (bits & (1UL << BH_Uptodate))
+		SetPageUptodate(dpage);
+	else
+		ClearPageUptodate(dpage);
+	if (bits & (1UL << BH_Mapped))
+		SetPageMappedToDisk(dpage);
+	else
+		ClearPageMappedToDisk(dpage);
+}
+
+/**
+ * nilfs_page_buffers_clean - check if a page has dirty buffers or not.
+ * @page: page to be checked
+ *
+ * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
+ * Otherwise, it returns non-zero value.
+ */
+int nilfs_page_buffers_clean(struct page *page)
+{
+	struct buffer_head *bh, *head;
+
+	bh = head = page_buffers(page);
+	do {
+		if (buffer_dirty(bh))
+			return 0;
+		bh = bh->b_this_page;
+	} while (bh != head);
+	return 1;
+}
+
+void nilfs_page_bug(struct page *page)
+{
+	struct address_space *m;
+	unsigned long ino = 0;
+
+	if (unlikely(!page)) {
+		printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
+		return;
+	}
+
+	m = page->mapping;
+	if (m) {
+		struct inode *inode = NILFS_AS_I(m);
+		if (inode != NULL)
+			ino = inode->i_ino;
+	}
+	printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
+	       "mapping=%p ino=%lu\n",
+	       page, atomic_read(&page->_count),
+	       (unsigned long long)page->index, page->flags, m, ino);
+
+	if (page_has_buffers(page)) {
+		struct buffer_head *bh, *head;
+		int i = 0;
+
+		bh = head = page_buffers(page);
+		do {
+			printk(KERN_CRIT
+			       " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
+			       i++, bh, atomic_read(&bh->b_count),
+			       (unsigned long long)bh->b_blocknr, bh->b_state);
+			bh = bh->b_this_page;
+		} while (bh != head);
+	}
+}
+
+/**
+ * nilfs_alloc_private_page - allocate a private page with buffer heads
+ *
+ * Return Value: On success, a pointer to the allocated page is returned.
+ * On error, NULL is returned.
+ */
+struct page *nilfs_alloc_private_page(struct block_device *bdev, int size,
+				      unsigned long state)
+{
+	struct buffer_head *bh, *head, *tail;
+	struct page *page;
+
+	page = alloc_page(GFP_NOFS); /* page_count of the returned page is 1 */
+	if (unlikely(!page))
+		return NULL;
+
+	lock_page(page);
+	head = alloc_page_buffers(page, size, 0);
+	if (unlikely(!head)) {
+		unlock_page(page);
+		__free_page(page);
+		return NULL;
+	}
+
+	bh = head;
+	do {
+		bh->b_state = (1UL << BH_NILFS_Allocated) | state;
+		tail = bh;
+		bh->b_bdev = bdev;
+		bh = bh->b_this_page;
+	} while (bh);
+
+	tail->b_this_page = head;
+	attach_page_buffers(page, head);
+
+	return page;
+}
+
+void nilfs_free_private_page(struct page *page)
+{
+	BUG_ON(!PageLocked(page));
+	BUG_ON(page->mapping);
+
+	if (page_has_buffers(page) && !try_to_free_buffers(page))
+		NILFS_PAGE_BUG(page, "failed to free page");
+
+	unlock_page(page);
+	__free_page(page);
+}
+
+/**
+ * nilfs_copy_page -- copy the page with buffers
+ * @dst: destination page
+ * @src: source page
+ * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
+ *
+ * This fuction is for both data pages and btnode pages.  The dirty flag
+ * should be treated by caller.  The page must not be under i/o.
+ * Both src and dst page must be locked
+ */
+static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
+{
+	struct buffer_head *dbh, *dbufs, *sbh, *sbufs;
+	unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
+
+	BUG_ON(PageWriteback(dst));
+
+	sbh = sbufs = page_buffers(src);
+	if (!page_has_buffers(dst))
+		create_empty_buffers(dst, sbh->b_size, 0);
+
+	if (copy_dirty)
+		mask |= (1UL << BH_Dirty);
+
+	dbh = dbufs = page_buffers(dst);
+	do {
+		lock_buffer(sbh);
+		lock_buffer(dbh);
+		dbh->b_state = sbh->b_state & mask;
+		dbh->b_blocknr = sbh->b_blocknr;
+		dbh->b_bdev = sbh->b_bdev;
+		sbh = sbh->b_this_page;
+		dbh = dbh->b_this_page;
+	} while (dbh != dbufs);
+
+	copy_highpage(dst, src);
+
+	if (PageUptodate(src) && !PageUptodate(dst))
+		SetPageUptodate(dst);
+	else if (!PageUptodate(src) && PageUptodate(dst))
+		ClearPageUptodate(dst);
+	if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
+		SetPageMappedToDisk(dst);
+	else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
+		ClearPageMappedToDisk(dst);
+
+	do {
+		unlock_buffer(sbh);
+		unlock_buffer(dbh);
+		sbh = sbh->b_this_page;
+		dbh = dbh->b_this_page;
+	} while (dbh != dbufs);
+}
+
+int nilfs_copy_dirty_pages(struct address_space *dmap,
+			   struct address_space *smap)
+{
+	struct pagevec pvec;
+	unsigned int i;
+	pgoff_t index = 0;
+	int err = 0;
+
+	pagevec_init(&pvec, 0);
+repeat:
+	if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
+				PAGEVEC_SIZE))
+		return 0;
+
+	for (i = 0; i < pagevec_count(&pvec); i++) {
+		struct page *page = pvec.pages[i], *dpage;
+
+		lock_page(page);
+		if (unlikely(!PageDirty(page)))
+			NILFS_PAGE_BUG(page, "inconsistent dirty state");
+
+		dpage = grab_cache_page(dmap, page->index);
+		if (unlikely(!dpage)) {
+			/* No empty page is added to the page cache */
+			err = -ENOMEM;
+			unlock_page(page);
+			break;
+		}
+		if (unlikely(!page_has_buffers(page)))
+			NILFS_PAGE_BUG(page,
+				       "found empty page in dat page cache");
+
+		nilfs_copy_page(dpage, page, 1);
+		__set_page_dirty_nobuffers(dpage);
+
+		unlock_page(dpage);
+		page_cache_release(dpage);
+		unlock_page(page);
+	}
+	pagevec_release(&pvec);
+	cond_resched();
+
+	if (likely(!err))
+		goto repeat;
+	return err;
+}
+
+/**
+ * nilfs_copy_back_pages -- copy back pages to orignal cache from shadow cache
+ * @dmap: destination page cache
+ * @smap: source page cache
+ *
+ * No pages must no be added to the cache during this process.
+ * This must be ensured by the caller.
+ */
+void nilfs_copy_back_pages(struct address_space *dmap,
+			   struct address_space *smap)
+{
+	struct pagevec pvec;
+	unsigned int i, n;
+	pgoff_t index = 0;
+	int err;
+
+	pagevec_init(&pvec, 0);
+repeat:
+	n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
+	if (!n)
+		return;
+	index = pvec.pages[n - 1]->index + 1;
+
+	for (i = 0; i < pagevec_count(&pvec); i++) {
+		struct page *page = pvec.pages[i], *dpage;
+		pgoff_t offset = page->index;
+
+		lock_page(page);
+		dpage = find_lock_page(dmap, offset);
+		if (dpage) {
+			/* override existing page on the destination cache */
+			BUG_ON(PageDirty(dpage));
+			nilfs_copy_page(dpage, page, 0);
+			unlock_page(dpage);
+			page_cache_release(dpage);
+		} else {
+			struct page *page2;
+
+			/* move the page to the destination cache */
+			spin_lock_irq(&smap->tree_lock);
+			page2 = radix_tree_delete(&smap->page_tree, offset);
+			if (unlikely(page2 != page))
+				NILFS_PAGE_BUG(page, "page removal failed "
+					       "(offset=%lu, page2=%p)",
+					       offset, page2);
+			smap->nrpages--;
+			spin_unlock_irq(&smap->tree_lock);
+
+			spin_lock_irq(&dmap->tree_lock);
+			err = radix_tree_insert(&dmap->page_tree, offset, page);
+			if (unlikely(err < 0)) {
+				BUG_ON(err == -EEXIST);
+				page->mapping = NULL;
+				page_cache_release(page); /* for cache */
+			} else {
+				page->mapping = dmap;
+				dmap->nrpages++;
+				if (PageDirty(page))
+					radix_tree_tag_set(&dmap->page_tree,
+							   offset,
+							   PAGECACHE_TAG_DIRTY);
+			}
+			spin_unlock_irq(&dmap->tree_lock);
+		}
+		unlock_page(page);
+	}
+	pagevec_release(&pvec);
+	cond_resched();
+
+	goto repeat;
+}
+
+void nilfs_clear_dirty_pages(struct address_space *mapping)
+{
+	struct pagevec pvec;
+	unsigned int i;
+	pgoff_t index = 0;
+
+	pagevec_init(&pvec, 0);
+
+	while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
+				  PAGEVEC_SIZE)) {
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			struct page *page = pvec.pages[i];
+			struct buffer_head *bh, *head;
+
+			lock_page(page);
+			ClearPageUptodate(page);
+			ClearPageMappedToDisk(page);
+			bh = head = page_buffers(page);
+			do {
+				lock_buffer(bh);
+				clear_buffer_dirty(bh);
+				clear_buffer_nilfs_volatile(bh);
+				clear_buffer_uptodate(bh);
+				clear_buffer_mapped(bh);
+				unlock_buffer(bh);
+				bh = bh->b_this_page;
+			} while (bh != head);
+
+			__nilfs_clear_page_dirty(page);
+			unlock_page(page);
+		}
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+}
+
+unsigned nilfs_page_count_clean_buffers(struct page *page,
+					unsigned from, unsigned to)
+{
+	unsigned block_start, block_end;
+	struct buffer_head *bh, *head;
+	unsigned nc = 0;
+
+	for (bh = head = page_buffers(page), block_start = 0;
+	     bh != head || !block_start;
+	     block_start = block_end, bh = bh->b_this_page) {
+		block_end = block_start + bh->b_size;
+		if (block_end > from && block_start < to && !buffer_dirty(bh))
+			nc++;
+	}
+	return nc;
+}
+
+/*
+ * NILFS2 needs clear_page_dirty() in the following two cases:
+ *
+ * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
+ *    page dirty flags when it copies back pages from the shadow cache
+ *    (gcdat->{i_mapping,i_btnode_cache}) to its original cache
+ *    (dat->{i_mapping,i_btnode_cache}).
+ *
+ * 2) Some B-tree operations like insertion or deletion may dispose buffers
+ *    in dirty state, and this needs to cancel the dirty state of their pages.
+ */
+int __nilfs_clear_page_dirty(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+
+	if (mapping) {
+		spin_lock_irq(&mapping->tree_lock);
+		if (test_bit(PG_dirty, &page->flags)) {
+			radix_tree_tag_clear(&mapping->page_tree,
+					     page_index(page),
+					     PAGECACHE_TAG_DIRTY);
+			spin_unlock_irq(&mapping->tree_lock);
+			return clear_page_dirty_for_io(page);
+		}
+		spin_unlock_irq(&mapping->tree_lock);
+		return 0;
+	}
+	return TestClearPageDirty(page);
+}