Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 943 insertions, 0 deletions

diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
new file mode 100644
index 000000000..31e8270d0
--- /dev/null
+++ b/fs/gfs2/aops.c
@@ -0,0 +1,943 @@
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU General Public License version 2.
+ */
+
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/completion.h>
+#include <linux/buffer_head.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+#include <linux/mpage.h>
+#include <linux/fs.h>
+#include <linux/writeback.h>
+#include <linux/swap.h>
+#include <linux/gfs2_ondisk.h>
+#include <linux/backing-dev.h>
+#include <linux/uio.h>
+#include <trace/events/writeback.h>
+#include <linux/sched/signal.h>
+
+#include "gfs2.h"
+#include "incore.h"
+#include "bmap.h"
+#include "glock.h"
+#include "inode.h"
+#include "log.h"
+#include "meta_io.h"
+#include "quota.h"
+#include "trans.h"
+#include "rgrp.h"
+#include "super.h"
+#include "util.h"
+#include "glops.h"
+#include "aops.h"
+
+
+void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
+			    unsigned int from, unsigned int len)
+{
+	struct buffer_head *head = page_buffers(page);
+	unsigned int bsize = head->b_size;
+	struct buffer_head *bh;
+	unsigned int to = from + len;
+	unsigned int start, end;
+
+	for (bh = head, start = 0; bh != head || !start;
+	     bh = bh->b_this_page, start = end) {
+		end = start + bsize;
+		if (end <= from)
+			continue;
+		if (start >= to)
+			break;
+		set_buffer_uptodate(bh);
+		gfs2_trans_add_data(ip->i_gl, bh);
+	}
+}
+
+/**
+ * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
+ * @inode: The inode
+ * @lblock: The block number to look up
+ * @bh_result: The buffer head to return the result in
+ * @create: Non-zero if we may add block to the file
+ *
+ * Returns: errno
+ */
+
+static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
+				  struct buffer_head *bh_result, int create)
+{
+	int error;
+
+	error = gfs2_block_map(inode, lblock, bh_result, 0);
+	if (error)
+		return error;
+	if (!buffer_mapped(bh_result))
+		return -EIO;
+	return 0;
+}
+
+/**
+ * gfs2_writepage_common - Common bits of writepage
+ * @page: The page to be written
+ * @wbc: The writeback control
+ *
+ * Returns: 1 if writepage is ok, otherwise an error code or zero if no error.
+ */
+
+static int gfs2_writepage_common(struct page *page,
+				 struct writeback_control *wbc)
+{
+	struct inode *inode = page->mapping->host;
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	loff_t i_size = i_size_read(inode);
+	pgoff_t end_index = i_size >> PAGE_SHIFT;
+	unsigned offset;
+
+	if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
+		goto out;
+	if (current->journal_info)
+		goto redirty;
+	/* Is the page fully outside i_size? (truncate in progress) */
+	offset = i_size & (PAGE_SIZE-1);
+	if (page->index > end_index || (page->index == end_index && !offset)) {
+		page->mapping->a_ops->invalidatepage(page, 0, PAGE_SIZE);
+		goto out;
+	}
+	return 1;
+redirty:
+	redirty_page_for_writepage(wbc, page);
+out:
+	unlock_page(page);
+	return 0;
+}
+
+/**
+ * gfs2_writepage - Write page for writeback mappings
+ * @page: The page
+ * @wbc: The writeback control
+ *
+ */
+
+static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
+{
+	int ret;
+
+	ret = gfs2_writepage_common(page, wbc);
+	if (ret <= 0)
+		return ret;
+
+	return nobh_writepage(page, gfs2_get_block_noalloc, wbc);
+}
+
+/* This is the same as calling block_write_full_page, but it also
+ * writes pages outside of i_size
+ */
+static int gfs2_write_full_page(struct page *page, get_block_t *get_block,
+				struct writeback_control *wbc)
+{
+	struct inode * const inode = page->mapping->host;
+	loff_t i_size = i_size_read(inode);
+	const pgoff_t end_index = i_size >> PAGE_SHIFT;
+	unsigned offset;
+
+	/*
+	 * The page straddles i_size.  It must be zeroed out on each and every
+	 * writepage invocation because it may be mmapped.  "A file is mapped
+	 * in multiples of the page size.  For a file that is not a multiple of
+	 * the  page size, the remaining memory is zeroed when mapped, and
+	 * writes to that region are not written out to the file."
+	 */
+	offset = i_size & (PAGE_SIZE-1);
+	if (page->index == end_index && offset)
+		zero_user_segment(page, offset, PAGE_SIZE);
+
+	return __block_write_full_page(inode, page, get_block, wbc,
+				       end_buffer_async_write);
+}
+
+/**
+ * __gfs2_jdata_writepage - The core of jdata writepage
+ * @page: The page to write
+ * @wbc: The writeback control
+ *
+ * This is shared between writepage and writepages and implements the
+ * core of the writepage operation. If a transaction is required then
+ * PageChecked will have been set and the transaction will have
+ * already been started before this is called.
+ */
+
+static int __gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct inode *inode = page->mapping->host;
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+
+	if (PageChecked(page)) {
+		ClearPageChecked(page);
+		if (!page_has_buffers(page)) {
+			create_empty_buffers(page, inode->i_sb->s_blocksize,
+					     BIT(BH_Dirty)|BIT(BH_Uptodate));
+		}
+		gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize);
+	}
+	return gfs2_write_full_page(page, gfs2_get_block_noalloc, wbc);
+}
+
+/**
+ * gfs2_jdata_writepage - Write complete page
+ * @page: Page to write
+ * @wbc: The writeback control
+ *
+ * Returns: errno
+ *
+ */
+
+static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct inode *inode = page->mapping->host;
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	int ret;
+
+	if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
+		goto out;
+	if (PageChecked(page) || current->journal_info)
+		goto out_ignore;
+	ret = __gfs2_jdata_writepage(page, wbc);
+	return ret;
+
+out_ignore:
+	redirty_page_for_writepage(wbc, page);
+out:
+	unlock_page(page);
+	return 0;
+}
+
+/**
+ * gfs2_writepages - Write a bunch of dirty pages back to disk
+ * @mapping: The mapping to write
+ * @wbc: Write-back control
+ *
+ * Used for both ordered and writeback modes.
+ */
+static int gfs2_writepages(struct address_space *mapping,
+			   struct writeback_control *wbc)
+{
+	struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
+	int ret = mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
+
+	/*
+	 * Even if we didn't write any pages here, we might still be holding
+	 * dirty pages in the ail. We forcibly flush the ail because we don't
+	 * want balance_dirty_pages() to loop indefinitely trying to write out
+	 * pages held in the ail that it can't find.
+	 */
+	if (ret == 0)
+		set_bit(SDF_FORCE_AIL_FLUSH, &sdp->sd_flags);
+
+	return ret;
+}
+
+/**
+ * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
+ * @mapping: The mapping
+ * @wbc: The writeback control
+ * @pvec: The vector of pages
+ * @nr_pages: The number of pages to write
+ * @done_index: Page index
+ *
+ * Returns: non-zero if loop should terminate, zero otherwise
+ */
+
+static int gfs2_write_jdata_pagevec(struct address_space *mapping,
+				    struct writeback_control *wbc,
+				    struct pagevec *pvec,
+				    int nr_pages,
+				    pgoff_t *done_index)
+{
+	struct inode *inode = mapping->host;
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	unsigned nrblocks = nr_pages * (PAGE_SIZE/inode->i_sb->s_blocksize);
+	int i;
+	int ret;
+
+	ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
+	if (ret < 0)
+		return ret;
+
+	for(i = 0; i < nr_pages; i++) {
+		struct page *page = pvec->pages[i];
+
+		*done_index = page->index;
+
+		lock_page(page);
+
+		if (unlikely(page->mapping != mapping)) {
+continue_unlock:
+			unlock_page(page);
+			continue;
+		}
+
+		if (!PageDirty(page)) {
+			/* someone wrote it for us */
+			goto continue_unlock;
+		}
+
+		if (PageWriteback(page)) {
+			if (wbc->sync_mode != WB_SYNC_NONE)
+				wait_on_page_writeback(page);
+			else
+				goto continue_unlock;
+		}
+
+		BUG_ON(PageWriteback(page));
+		if (!clear_page_dirty_for_io(page))
+			goto continue_unlock;
+
+		trace_wbc_writepage(wbc, inode_to_bdi(inode));
+
+		ret = __gfs2_jdata_writepage(page, wbc);
+		if (unlikely(ret)) {
+			if (ret == AOP_WRITEPAGE_ACTIVATE) {
+				unlock_page(page);
+				ret = 0;
+			} else {
+
+				/*
+				 * done_index is set past this page,
+				 * so media errors will not choke
+				 * background writeout for the entire
+				 * file. This has consequences for
+				 * range_cyclic semantics (ie. it may
+				 * not be suitable for data integrity
+				 * writeout).
+				 */
+				*done_index = page->index + 1;
+				ret = 1;
+				break;
+			}
+		}
+
+		/*
+		 * We stop writing back only if we are not doing
+		 * integrity sync. In case of integrity sync we have to
+		 * keep going until we have written all the pages
+		 * we tagged for writeback prior to entering this loop.
+		 */
+		if (--wbc->nr_to_write <= 0 && wbc->sync_mode == WB_SYNC_NONE) {
+			ret = 1;
+			break;
+		}
+
+	}
+	gfs2_trans_end(sdp);
+	return ret;
+}
+
+/**
+ * gfs2_write_cache_jdata - Like write_cache_pages but different
+ * @mapping: The mapping to write
+ * @wbc: The writeback control
+ *
+ * The reason that we use our own function here is that we need to
+ * start transactions before we grab page locks. This allows us
+ * to get the ordering right.
+ */
+
+static int gfs2_write_cache_jdata(struct address_space *mapping,
+				  struct writeback_control *wbc)
+{
+	int ret = 0;
+	int done = 0;
+	struct pagevec pvec;
+	int nr_pages;
+	pgoff_t uninitialized_var(writeback_index);
+	pgoff_t index;
+	pgoff_t end;
+	pgoff_t done_index;
+	int cycled;
+	int range_whole = 0;
+	int tag;
+
+	pagevec_init(&pvec);
+	if (wbc->range_cyclic) {
+		writeback_index = mapping->writeback_index; /* prev offset */
+		index = writeback_index;
+		if (index == 0)
+			cycled = 1;
+		else
+			cycled = 0;
+		end = -1;
+	} else {
+		index = wbc->range_start >> PAGE_SHIFT;
+		end = wbc->range_end >> PAGE_SHIFT;
+		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
+			range_whole = 1;
+		cycled = 1; /* ignore range_cyclic tests */
+	}
+	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
+		tag = PAGECACHE_TAG_TOWRITE;
+	else
+		tag = PAGECACHE_TAG_DIRTY;
+
+retry:
+	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
+		tag_pages_for_writeback(mapping, index, end);
+	done_index = index;
+	while (!done && (index <= end)) {
+		nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
+				tag);
+		if (nr_pages == 0)
+			break;
+
+		ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, &done_index);
+		if (ret)
+			done = 1;
+		if (ret > 0)
+			ret = 0;
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+
+	if (!cycled && !done) {
+		/*
+		 * range_cyclic:
+		 * We hit the last page and there is more work to be done: wrap
+		 * back to the start of the file
+		 */
+		cycled = 1;
+		index = 0;
+		end = writeback_index - 1;
+		goto retry;
+	}
+
+	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
+		mapping->writeback_index = done_index;
+
+	return ret;
+}
+
+
+/**
+ * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
+ * @mapping: The mapping to write
+ * @wbc: The writeback control
+ * 
+ */
+
+static int gfs2_jdata_writepages(struct address_space *mapping,
+				 struct writeback_control *wbc)
+{
+	struct gfs2_inode *ip = GFS2_I(mapping->host);
+	struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
+	int ret;
+
+	ret = gfs2_write_cache_jdata(mapping, wbc);
+	if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
+		gfs2_log_flush(sdp, ip->i_gl, GFS2_LOG_HEAD_FLUSH_NORMAL |
+			       GFS2_LFC_JDATA_WPAGES);
+		ret = gfs2_write_cache_jdata(mapping, wbc);
+	}
+	return ret;
+}
+
+/**
+ * stuffed_readpage - Fill in a Linux page with stuffed file data
+ * @ip: the inode
+ * @page: the page
+ *
+ * Returns: errno
+ */
+
+int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
+{
+	struct buffer_head *dibh;
+	u64 dsize = i_size_read(&ip->i_inode);
+	void *kaddr;
+	int error;
+
+	/*
+	 * Due to the order of unstuffing files and ->fault(), we can be
+	 * asked for a zero page in the case of a stuffed file being extended,
+	 * so we need to supply one here. It doesn't happen often.
+	 */
+	if (unlikely(page->index)) {
+		zero_user(page, 0, PAGE_SIZE);
+		SetPageUptodate(page);
+		return 0;
+	}
+
+	error = gfs2_meta_inode_buffer(ip, &dibh);
+	if (error)
+		return error;
+
+	kaddr = kmap_atomic(page);
+	if (dsize > gfs2_max_stuffed_size(ip))
+		dsize = gfs2_max_stuffed_size(ip);
+	memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
+	memset(kaddr + dsize, 0, PAGE_SIZE - dsize);
+	kunmap_atomic(kaddr);
+	flush_dcache_page(page);
+	brelse(dibh);
+	SetPageUptodate(page);
+
+	return 0;
+}
+
+
+/**
+ * __gfs2_readpage - readpage
+ * @file: The file to read a page for
+ * @page: The page to read
+ *
+ * This is the core of gfs2's readpage. It's used by the internal file
+ * reading code as in that case we already hold the glock. Also it's
+ * called by gfs2_readpage() once the required lock has been granted.
+ */
+
+static int __gfs2_readpage(void *file, struct page *page)
+{
+	struct gfs2_inode *ip = GFS2_I(page->mapping->host);
+	struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
+
+	int error;
+
+	if (i_blocksize(page->mapping->host) == PAGE_SIZE &&
+	    !page_has_buffers(page)) {
+		error = iomap_readpage(page, &gfs2_iomap_ops);
+	} else if (gfs2_is_stuffed(ip)) {
+		error = stuffed_readpage(ip, page);
+		unlock_page(page);
+	} else {
+		error = mpage_readpage(page, gfs2_block_map);
+	}
+
+	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+		return -EIO;
+
+	return error;
+}
+
+/**
+ * gfs2_readpage - read a page of a file
+ * @file: The file to read
+ * @page: The page of the file
+ *
+ * This deals with the locking required. We have to unlock and
+ * relock the page in order to get the locking in the right
+ * order.
+ */
+
+static int gfs2_readpage(struct file *file, struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct gfs2_inode *ip = GFS2_I(mapping->host);
+	struct gfs2_holder gh;
+	int error;
+
+	unlock_page(page);
+	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
+	error = gfs2_glock_nq(&gh);
+	if (unlikely(error))
+		goto out;
+	error = AOP_TRUNCATED_PAGE;
+	lock_page(page);
+	if (page->mapping == mapping && !PageUptodate(page))
+		error = __gfs2_readpage(file, page);
+	else
+		unlock_page(page);
+	gfs2_glock_dq(&gh);
+out:
+	gfs2_holder_uninit(&gh);
+	if (error && error != AOP_TRUNCATED_PAGE)
+		lock_page(page);
+	return error;
+}
+
+/**
+ * gfs2_internal_read - read an internal file
+ * @ip: The gfs2 inode
+ * @buf: The buffer to fill
+ * @pos: The file position
+ * @size: The amount to read
+ *
+ */
+
+int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
+                       unsigned size)
+{
+	struct address_space *mapping = ip->i_inode.i_mapping;
+	unsigned long index = *pos / PAGE_SIZE;
+	unsigned offset = *pos & (PAGE_SIZE - 1);
+	unsigned copied = 0;
+	unsigned amt;
+	struct page *page;
+	void *p;
+
+	do {
+		amt = size - copied;
+		if (offset + size > PAGE_SIZE)
+			amt = PAGE_SIZE - offset;
+		page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
+		if (IS_ERR(page))
+			return PTR_ERR(page);
+		p = kmap_atomic(page);
+		memcpy(buf + copied, p + offset, amt);
+		kunmap_atomic(p);
+		put_page(page);
+		copied += amt;
+		index++;
+		offset = 0;
+	} while(copied < size);
+	(*pos) += size;
+	return size;
+}
+
+/**
+ * gfs2_readpages - Read a bunch of pages at once
+ * @file: The file to read from
+ * @mapping: Address space info
+ * @pages: List of pages to read
+ * @nr_pages: Number of pages to read
+ *
+ * Some notes:
+ * 1. This is only for readahead, so we can simply ignore any things
+ *    which are slightly inconvenient (such as locking conflicts between
+ *    the page lock and the glock) and return having done no I/O. Its
+ *    obviously not something we'd want to do on too regular a basis.
+ *    Any I/O we ignore at this time will be done via readpage later.
+ * 2. We don't handle stuffed files here we let readpage do the honours.
+ * 3. mpage_readpages() does most of the heavy lifting in the common case.
+ * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
+ */
+
+static int gfs2_readpages(struct file *file, struct address_space *mapping,
+			  struct list_head *pages, unsigned nr_pages)
+{
+	struct inode *inode = mapping->host;
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	struct gfs2_holder gh;
+	int ret;
+
+	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
+	ret = gfs2_glock_nq(&gh);
+	if (unlikely(ret))
+		goto out_uninit;
+	if (!gfs2_is_stuffed(ip))
+		ret = mpage_readpages(mapping, pages, nr_pages, gfs2_block_map);
+	gfs2_glock_dq(&gh);
+out_uninit:
+	gfs2_holder_uninit(&gh);
+	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+		ret = -EIO;
+	return ret;
+}
+
+/**
+ * adjust_fs_space - Adjusts the free space available due to gfs2_grow
+ * @inode: the rindex inode
+ */
+void adjust_fs_space(struct inode *inode)
+{
+	struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
+	struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
+	struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
+	struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
+	struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
+	struct buffer_head *m_bh, *l_bh;
+	u64 fs_total, new_free;
+
+	/* Total up the file system space, according to the latest rindex. */
+	fs_total = gfs2_ri_total(sdp);
+	if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
+		return;
+
+	spin_lock(&sdp->sd_statfs_spin);
+	gfs2_statfs_change_in(m_sc, m_bh->b_data +
+			      sizeof(struct gfs2_dinode));
+	if (fs_total > (m_sc->sc_total + l_sc->sc_total))
+		new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
+	else
+		new_free = 0;
+	spin_unlock(&sdp->sd_statfs_spin);
+	fs_warn(sdp, "File system extended by %llu blocks.\n",
+		(unsigned long long)new_free);
+	gfs2_statfs_change(sdp, new_free, new_free, 0);
+
+	if (gfs2_meta_inode_buffer(l_ip, &l_bh) != 0)
+		goto out;
+	update_statfs(sdp, m_bh, l_bh);
+	brelse(l_bh);
+out:
+	brelse(m_bh);
+}
+
+/**
+ * gfs2_stuffed_write_end - Write end for stuffed files
+ * @inode: The inode
+ * @dibh: The buffer_head containing the on-disk inode
+ * @pos: The file position
+ * @copied: How much was actually copied by the VFS
+ * @page: The page
+ *
+ * This copies the data from the page into the inode block after
+ * the inode data structure itself.
+ *
+ * Returns: copied bytes or errno
+ */
+int gfs2_stuffed_write_end(struct inode *inode, struct buffer_head *dibh,
+			   loff_t pos, unsigned copied,
+			   struct page *page)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	u64 to = pos + copied;
+	void *kaddr;
+	unsigned char *buf = dibh->b_data + sizeof(struct gfs2_dinode);
+
+	BUG_ON(pos + copied > gfs2_max_stuffed_size(ip));
+
+	kaddr = kmap_atomic(page);
+	memcpy(buf + pos, kaddr + pos, copied);
+	flush_dcache_page(page);
+	kunmap_atomic(kaddr);
+
+	WARN_ON(!PageUptodate(page));
+	unlock_page(page);
+	put_page(page);
+
+	if (copied) {
+		if (inode->i_size < to)
+			i_size_write(inode, to);
+		mark_inode_dirty(inode);
+	}
+	return copied;
+}
+
+/**
+ * jdata_set_page_dirty - Page dirtying function
+ * @page: The page to dirty
+ *
+ * Returns: 1 if it dirtyed the page, or 0 otherwise
+ */
+ 
+static int jdata_set_page_dirty(struct page *page)
+{
+	SetPageChecked(page);
+	return __set_page_dirty_buffers(page);
+}
+
+/**
+ * gfs2_bmap - Block map function
+ * @mapping: Address space info
+ * @lblock: The block to map
+ *
+ * Returns: The disk address for the block or 0 on hole or error
+ */
+
+static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
+{
+	struct gfs2_inode *ip = GFS2_I(mapping->host);
+	struct gfs2_holder i_gh;
+	sector_t dblock = 0;
+	int error;
+
+	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
+	if (error)
+		return 0;
+
+	if (!gfs2_is_stuffed(ip))
+		dblock = generic_block_bmap(mapping, lblock, gfs2_block_map);
+
+	gfs2_glock_dq_uninit(&i_gh);
+
+	return dblock;
+}
+
+static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
+{
+	struct gfs2_bufdata *bd;
+
+	lock_buffer(bh);
+	gfs2_log_lock(sdp);
+	clear_buffer_dirty(bh);
+	bd = bh->b_private;
+	if (bd) {
+		if (!list_empty(&bd->bd_list) && !buffer_pinned(bh))
+			list_del_init(&bd->bd_list);
+		else
+			gfs2_remove_from_journal(bh, REMOVE_JDATA);
+	}
+	bh->b_bdev = NULL;
+	clear_buffer_mapped(bh);
+	clear_buffer_req(bh);
+	clear_buffer_new(bh);
+	gfs2_log_unlock(sdp);
+	unlock_buffer(bh);
+}
+
+static void gfs2_invalidatepage(struct page *page, unsigned int offset,
+				unsigned int length)
+{
+	struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
+	unsigned int stop = offset + length;
+	int partial_page = (offset || length < PAGE_SIZE);
+	struct buffer_head *bh, *head;
+	unsigned long pos = 0;
+
+	BUG_ON(!PageLocked(page));
+	if (!partial_page)
+		ClearPageChecked(page);
+	if (!page_has_buffers(page))
+		goto out;
+
+	bh = head = page_buffers(page);
+	do {
+		if (pos + bh->b_size > stop)
+			return;
+
+		if (offset <= pos)
+			gfs2_discard(sdp, bh);
+		pos += bh->b_size;
+		bh = bh->b_this_page;
+	} while (bh != head);
+out:
+	if (!partial_page)
+		try_to_release_page(page, 0);
+}
+
+/**
+ * gfs2_releasepage - free the metadata associated with a page
+ * @page: the page that's being released
+ * @gfp_mask: passed from Linux VFS, ignored by us
+ *
+ * Call try_to_free_buffers() if the buffers in this page can be
+ * released.
+ *
+ * Returns: 0
+ */
+
+int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
+{
+	struct address_space *mapping = page->mapping;
+	struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
+	struct buffer_head *bh, *head;
+	struct gfs2_bufdata *bd;
+
+	if (!page_has_buffers(page))
+		return 0;
+
+	/*
+	 * From xfs_vm_releasepage: mm accommodates an old ext3 case where
+	 * clean pages might not have had the dirty bit cleared.  Thus, it can
+	 * send actual dirty pages to ->releasepage() via shrink_active_list().
+	 *
+	 * As a workaround, we skip pages that contain dirty buffers below.
+	 * Once ->releasepage isn't called on dirty pages anymore, we can warn
+	 * on dirty buffers like we used to here again.
+	 */
+
+	gfs2_log_lock(sdp);
+	spin_lock(&sdp->sd_ail_lock);
+	head = bh = page_buffers(page);
+	do {
+		if (atomic_read(&bh->b_count))
+			goto cannot_release;
+		bd = bh->b_private;
+		if (bd && bd->bd_tr)
+			goto cannot_release;
+		if (buffer_dirty(bh) || WARN_ON(buffer_pinned(bh)))
+			goto cannot_release;
+		bh = bh->b_this_page;
+	} while(bh != head);
+	spin_unlock(&sdp->sd_ail_lock);
+
+	head = bh = page_buffers(page);
+	do {
+		bd = bh->b_private;
+		if (bd) {
+			gfs2_assert_warn(sdp, bd->bd_bh == bh);
+			if (!list_empty(&bd->bd_list))
+				list_del_init(&bd->bd_list);
+			bd->bd_bh = NULL;
+			bh->b_private = NULL;
+			kmem_cache_free(gfs2_bufdata_cachep, bd);
+		}
+
+		bh = bh->b_this_page;
+	} while (bh != head);
+	gfs2_log_unlock(sdp);
+
+	return try_to_free_buffers(page);
+
+cannot_release:
+	spin_unlock(&sdp->sd_ail_lock);
+	gfs2_log_unlock(sdp);
+	return 0;
+}
+
+static const struct address_space_operations gfs2_writeback_aops = {
+	.writepage = gfs2_writepage,
+	.writepages = gfs2_writepages,
+	.readpage = gfs2_readpage,
+	.readpages = gfs2_readpages,
+	.bmap = gfs2_bmap,
+	.invalidatepage = gfs2_invalidatepage,
+	.releasepage = gfs2_releasepage,
+	.direct_IO = noop_direct_IO,
+	.migratepage = buffer_migrate_page,
+	.is_partially_uptodate = block_is_partially_uptodate,
+	.error_remove_page = generic_error_remove_page,
+};
+
+static const struct address_space_operations gfs2_ordered_aops = {
+	.writepage = gfs2_writepage,
+	.writepages = gfs2_writepages,
+	.readpage = gfs2_readpage,
+	.readpages = gfs2_readpages,
+	.set_page_dirty = __set_page_dirty_buffers,
+	.bmap = gfs2_bmap,
+	.invalidatepage = gfs2_invalidatepage,
+	.releasepage = gfs2_releasepage,
+	.direct_IO = noop_direct_IO,
+	.migratepage = buffer_migrate_page,
+	.is_partially_uptodate = block_is_partially_uptodate,
+	.error_remove_page = generic_error_remove_page,
+};
+
+static const struct address_space_operations gfs2_jdata_aops = {
+	.writepage = gfs2_jdata_writepage,
+	.writepages = gfs2_jdata_writepages,
+	.readpage = gfs2_readpage,
+	.readpages = gfs2_readpages,
+	.set_page_dirty = jdata_set_page_dirty,
+	.bmap = gfs2_bmap,
+	.invalidatepage = gfs2_invalidatepage,
+	.releasepage = gfs2_releasepage,
+	.is_partially_uptodate = block_is_partially_uptodate,
+	.error_remove_page = generic_error_remove_page,
+};
+
+void gfs2_set_aops(struct inode *inode)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+
+	if (gfs2_is_writeback(ip))
+		inode->i_mapping->a_ops = &gfs2_writeback_aops;
+	else if (gfs2_is_ordered(ip))
+		inode->i_mapping->a_ops = &gfs2_ordered_aops;
+	else if (gfs2_is_jdata(ip))
+		inode->i_mapping->a_ops = &gfs2_jdata_aops;
+	else
+		BUG();
+}
+