--- /dev/null
+/*
+ * 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 <linux/gfp.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_Checked))
+
+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;
+}
+
+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;
+ struct buffer_head *bh;
+
+ 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;
+ }
+ 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;
+ const unsigned long clear_bits =
+ (1 << BH_Uptodate | 1 << BH_Dirty | 1 << BH_Mapped |
+ 1 << BH_Async_Write | 1 << BH_NILFS_Volatile |
+ 1 << BH_NILFS_Checked | 1 << BH_NILFS_Redirected);
+
+ lock_buffer(bh);
+ set_mask_bits(&bh->b_state, clear_bits, 0);
+ if (nilfs_page_buffers_clean(page))
+ __nilfs_clear_page_dirty(page);
+
+ 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);
+ kaddr1 = kmap_atomic(dpage);
+ memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
+ kunmap_atomic(kaddr1);
+ kunmap_atomic(kaddr0);
+
+ 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;
+
+ if (unlikely(!page)) {
+ printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
+ return;
+ }
+
+ m = page->mapping;
+ ino = m ? m->host->i_ino : 0;
+
+ 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_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 function 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 original 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 */
+ WARN_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);
+ WARN_ON(page2 != page);
+
+ 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)) {
+ WARN_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;
+}
+
+/**
+ * nilfs_clear_dirty_pages - discard dirty pages in address space
+ * @mapping: address space with dirty pages for discarding
+ * @silent: suppress [true] or print [false] warning messages
+ */
+void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
+{
+ 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];
+
+ lock_page(page);
+ nilfs_clear_dirty_page(page, silent);
+ unlock_page(page);
+ }
+ pagevec_release(&pvec);
+ cond_resched();
+ }
+}
+
+/**
+ * nilfs_clear_dirty_page - discard dirty page
+ * @page: dirty page that will be discarded
+ * @silent: suppress [true] or print [false] warning messages
+ */
+void nilfs_clear_dirty_page(struct page *page, bool silent)
+{
+ struct inode *inode = page->mapping->host;
+ struct super_block *sb = inode->i_sb;
+
+ BUG_ON(!PageLocked(page));
+
+ if (!silent) {
+ nilfs_warning(sb, __func__,
+ "discard page: offset %lld, ino %lu",
+ page_offset(page), inode->i_ino);
+ }
+
+ ClearPageUptodate(page);
+ ClearPageMappedToDisk(page);
+
+ if (page_has_buffers(page)) {
+ struct buffer_head *bh, *head;
+ const unsigned long clear_bits =
+ (1 << BH_Uptodate | 1 << BH_Dirty | 1 << BH_Mapped |
+ 1 << BH_Async_Write | 1 << BH_NILFS_Volatile |
+ 1 << BH_NILFS_Checked | 1 << BH_NILFS_Redirected);
+
+ bh = head = page_buffers(page);
+ do {
+ lock_buffer(bh);
+ if (!silent) {
+ nilfs_warning(sb, __func__,
+ "discard block %llu, size %zu",
+ (u64)bh->b_blocknr, bh->b_size);
+ }
+ set_mask_bits(&bh->b_state, clear_bits, 0);
+ unlock_buffer(bh);
+ } while (bh = bh->b_this_page, bh != head);
+ }
+
+ __nilfs_clear_page_dirty(page);
+}
+
+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;
+}
+
+void nilfs_mapping_init(struct address_space *mapping, struct inode *inode)
+{
+ mapping->host = inode;
+ mapping->flags = 0;
+ mapping_set_gfp_mask(mapping, GFP_NOFS);
+ mapping->private_data = NULL;
+ mapping->a_ops = &empty_aops;
+}
+
+/*
+ * 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);
+}
+
+/**
+ * nilfs_find_uncommitted_extent - find extent of uncommitted data
+ * @inode: inode
+ * @start_blk: start block offset (in)
+ * @blkoff: start offset of the found extent (out)
+ *
+ * This function searches an extent of buffers marked "delayed" which
+ * starts from a block offset equal to or larger than @start_blk. If
+ * such an extent was found, this will store the start offset in
+ * @blkoff and return its length in blocks. Otherwise, zero is
+ * returned.
+ */
+unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
+ sector_t start_blk,
+ sector_t *blkoff)
+{
+ unsigned int i;
+ pgoff_t index;
+ unsigned int nblocks_in_page;
+ unsigned long length = 0;
+ sector_t b;
+ struct pagevec pvec;
+ struct page *page;
+
+ if (inode->i_mapping->nrpages == 0)
+ return 0;
+
+ index = start_blk >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
+ nblocks_in_page = 1U << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+
+ pagevec_init(&pvec, 0);
+
+repeat:
+ pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
+ pvec.pages);
+ if (pvec.nr == 0)
+ return length;
+
+ if (length > 0 && pvec.pages[0]->index > index)
+ goto out;
+
+ b = pvec.pages[0]->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+ i = 0;
+ do {
+ page = pvec.pages[i];
+
+ lock_page(page);
+ if (page_has_buffers(page)) {
+ struct buffer_head *bh, *head;
+
+ bh = head = page_buffers(page);
+ do {
+ if (b < start_blk)
+ continue;
+ if (buffer_delay(bh)) {
+ if (length == 0)
+ *blkoff = b;
+ length++;
+ } else if (length > 0) {
+ goto out_locked;
+ }
+ } while (++b, bh = bh->b_this_page, bh != head);
+ } else {
+ if (length > 0)
+ goto out_locked;
+
+ b += nblocks_in_page;
+ }
+ unlock_page(page);
+
+ } while (++i < pagevec_count(&pvec));
+
+ index = page->index + 1;
+ pagevec_release(&pvec);
+ cond_resched();
+ goto repeat;
+
+out_locked:
+ unlock_page(page);
+out:
+ pagevec_release(&pvec);
+ return length;
+}
Code Review / kvmfornfv.git / blobdiff