2 files changed, 618 insertions, 0 deletions

diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c
new file mode 100644
index 000000000000..7b18be8cd47a
--- /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);
+}
diff --git a/fs/nilfs2/page.h b/fs/nilfs2/page.h
new file mode 100644
index 000000000000..8abca4d1c1f8
--- /dev/null
+++ b/fs/nilfs2/page.h
@@ -0,0 +1,76 @@
+/*
+ * page.h - 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>.
+ */
+
+#ifndef _NILFS_PAGE_H
+#define _NILFS_PAGE_H
+
+#include <linux/buffer_head.h>
+#include "nilfs.h"
+
+/*
+ * Extended buffer state bits
+ */
+enum {
+        BH_NILFS_Allocated = BH_PrivateStart,
+        BH_NILFS_Node,
+        BH_NILFS_Volatile,
+};
+
+BUFFER_FNS(NILFS_Allocated, nilfs_allocated)    /* nilfs private buffers */
+BUFFER_FNS(NILFS_Node, nilfs_node)              /* nilfs node buffers */
+BUFFER_FNS(NILFS_Volatile, nilfs_volatile)
+
+
+void nilfs_mark_buffer_dirty(struct buffer_head *bh);
+int __nilfs_clear_page_dirty(struct page *);
+
+struct buffer_head *nilfs_grab_buffer(struct inode *, struct address_space *,
+                                      unsigned long, unsigned long);
+void nilfs_forget_buffer(struct buffer_head *);
+void nilfs_copy_buffer(struct buffer_head *, struct buffer_head *);
+int nilfs_page_buffers_clean(struct page *);
+void nilfs_page_bug(struct page *);
+struct page *nilfs_alloc_private_page(struct block_device *, int,
+                                      unsigned long);
+void nilfs_free_private_page(struct page *);
+
+int nilfs_copy_dirty_pages(struct address_space *, struct address_space *);
+void nilfs_copy_back_pages(struct address_space *, struct address_space *);
+void nilfs_clear_dirty_pages(struct address_space *);
+unsigned nilfs_page_count_clean_buffers(struct page *, unsigned, unsigned);
+
+#define NILFS_PAGE_BUG(page, m, a...) \
+        do { nilfs_page_bug(page); BUG(); } while (0)
+
+static inline struct buffer_head *
+nilfs_page_get_nth_block(struct page *page, unsigned int count)
+{
+        struct buffer_head *bh = page_buffers(page);
+
+        while (count-- > 0)
+                bh = bh->b_this_page;
+        get_bh(bh);
+        return bh;
+}
+
+#endif /* _NILFS_PAGE_H */