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33 results

addr.c

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  • addr.c 41.83 KiB
    #include <linux/ceph/ceph_debug.h>
    
    #include <linux/backing-dev.h>
    #include <linux/fs.h>
    #include <linux/mm.h>
    #include <linux/pagemap.h>
    #include <linux/writeback.h>	/* generic_writepages */
    #include <linux/slab.h>
    #include <linux/pagevec.h>
    #include <linux/task_io_accounting_ops.h>
    
    #include "super.h"
    #include "mds_client.h"
    #include "cache.h"
    #include <linux/ceph/osd_client.h>
    
    /*
     * Ceph address space ops.
     *
     * There are a few funny things going on here.
     *
     * The page->private field is used to reference a struct
     * ceph_snap_context for _every_ dirty page.  This indicates which
     * snapshot the page was logically dirtied in, and thus which snap
     * context needs to be associated with the osd write during writeback.
     *
     * Similarly, struct ceph_inode_info maintains a set of counters to
     * count dirty pages on the inode.  In the absence of snapshots,
     * i_wrbuffer_ref == i_wrbuffer_ref_head == the dirty page count.
     *
     * When a snapshot is taken (that is, when the client receives
     * notification that a snapshot was taken), each inode with caps and
     * with dirty pages (dirty pages implies there is a cap) gets a new
     * ceph_cap_snap in the i_cap_snaps list (which is sorted in ascending
     * order, new snaps go to the tail).  The i_wrbuffer_ref_head count is
     * moved to capsnap->dirty. (Unless a sync write is currently in
     * progress.  In that case, the capsnap is said to be "pending", new
     * writes cannot start, and the capsnap isn't "finalized" until the
     * write completes (or fails) and a final size/mtime for the inode for
     * that snap can be settled upon.)  i_wrbuffer_ref_head is reset to 0.
     *
     * On writeback, we must submit writes to the osd IN SNAP ORDER.  So,
     * we look for the first capsnap in i_cap_snaps and write out pages in
     * that snap context _only_.  Then we move on to the next capsnap,
     * eventually reaching the "live" or "head" context (i.e., pages that
     * are not yet snapped) and are writing the most recently dirtied
     * pages.
     *
     * Invalidate and so forth must take care to ensure the dirty page
     * accounting is preserved.
     */
    
    #define CONGESTION_ON_THRESH(congestion_kb) (congestion_kb >> (PAGE_SHIFT-10))
    #define CONGESTION_OFF_THRESH(congestion_kb)				\
    	(CONGESTION_ON_THRESH(congestion_kb) -				\
    	 (CONGESTION_ON_THRESH(congestion_kb) >> 2))
    
    static inline struct ceph_snap_context *page_snap_context(struct page *page)
    {
    	if (PagePrivate(page))
    		return (void *)page->private;
    	return NULL;
    }
    
    /*
     * Dirty a page.  Optimistically adjust accounting, on the assumption
     * that we won't race with invalidate.  If we do, readjust.
     */
    static int ceph_set_page_dirty(struct page *page)
    {
    	struct address_space *mapping = page->mapping;
    	struct inode *inode;
    	struct ceph_inode_info *ci;
    	struct ceph_snap_context *snapc;
    	int ret;
    
    	if (unlikely(!mapping))
    		return !TestSetPageDirty(page);
    
    	if (PageDirty(page)) {
    		dout("%p set_page_dirty %p idx %lu -- already dirty\n",
    		     mapping->host, page, page->index);
    		BUG_ON(!PagePrivate(page));
    		return 0;
    	}
    
    	inode = mapping->host;
    	ci = ceph_inode(inode);
    
    	/*
    	 * Note that we're grabbing a snapc ref here without holding
    	 * any locks!
    	 */
    	snapc = ceph_get_snap_context(ci->i_snap_realm->cached_context);
    
    	/* dirty the head */
    	spin_lock(&ci->i_ceph_lock);
    	if (ci->i_head_snapc == NULL)
    		ci->i_head_snapc = ceph_get_snap_context(snapc);
    	++ci->i_wrbuffer_ref_head;
    	if (ci->i_wrbuffer_ref == 0)
    		ihold(inode);
    	++ci->i_wrbuffer_ref;
    	dout("%p set_page_dirty %p idx %lu head %d/%d -> %d/%d "
    	     "snapc %p seq %lld (%d snaps)\n",
    	     mapping->host, page, page->index,
    	     ci->i_wrbuffer_ref-1, ci->i_wrbuffer_ref_head-1,
    	     ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
    	     snapc, snapc->seq, snapc->num_snaps);
    	spin_unlock(&ci->i_ceph_lock);
    
    	/*
    	 * Reference snap context in page->private.  Also set
    	 * PagePrivate so that we get invalidatepage callback.
    	 */
    	BUG_ON(PagePrivate(page));
    	page->private = (unsigned long)snapc;
    	SetPagePrivate(page);
    
    	ret = __set_page_dirty_nobuffers(page);
    	WARN_ON(!PageLocked(page));
    	WARN_ON(!page->mapping);
    
    	return ret;
    }
    
    /*
     * If we are truncating the full page (i.e. offset == 0), adjust the
     * dirty page counters appropriately.  Only called if there is private
     * data on the page.
     */
    static void ceph_invalidatepage(struct page *page, unsigned int offset,
    				unsigned int length)
    {
    	struct inode *inode;
    	struct ceph_inode_info *ci;
    	struct ceph_snap_context *snapc = page_snap_context(page);
    
    	inode = page->mapping->host;
    	ci = ceph_inode(inode);
    
    	if (offset != 0 || length != PAGE_CACHE_SIZE) {
    		dout("%p invalidatepage %p idx %lu partial dirty page %u~%u\n",
    		     inode, page, page->index, offset, length);
    		return;
    	}
    
    	ceph_invalidate_fscache_page(inode, page);
    
    	if (!PagePrivate(page))
    		return;
    
    	/*
    	 * We can get non-dirty pages here due to races between
    	 * set_page_dirty and truncate_complete_page; just spit out a
    	 * warning, in case we end up with accounting problems later.
    	 */
    	if (!PageDirty(page))
    		pr_err("%p invalidatepage %p page not dirty\n", inode, page);
    
    	ClearPageChecked(page);
    
    	dout("%p invalidatepage %p idx %lu full dirty page\n",
    	     inode, page, page->index);
    
    	ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
    	ceph_put_snap_context(snapc);
    	page->private = 0;
    	ClearPagePrivate(page);
    }
    
    static int ceph_releasepage(struct page *page, gfp_t g)
    {
    	struct inode *inode = page->mapping ? page->mapping->host : NULL;
    	dout("%p releasepage %p idx %lu\n", inode, page, page->index);
    	WARN_ON(PageDirty(page));
    
    	/* Can we release the page from the cache? */
    	if (!ceph_release_fscache_page(page, g))
    		return 0;
    
    	return !PagePrivate(page);
    }
    
    /*
     * read a single page, without unlocking it.
     */
    static int readpage_nounlock(struct file *filp, struct page *page)
    {
    	struct inode *inode = file_inode(filp);
    	struct ceph_inode_info *ci = ceph_inode(inode);
    	struct ceph_osd_client *osdc =
    		&ceph_inode_to_client(inode)->client->osdc;
    	int err = 0;
    	u64 off = page_offset(page);
    	u64 len = PAGE_CACHE_SIZE;
    
    	if (off >= i_size_read(inode)) {
    		zero_user_segment(page, err, PAGE_CACHE_SIZE);
    		SetPageUptodate(page);
    		return 0;
    	}
    
    	/*
    	 * Uptodate inline data should have been added into page cache
    	 * while getting Fcr caps.
    	 */
    	if (ci->i_inline_version != CEPH_INLINE_NONE)
    		return -EINVAL;
    
    	err = ceph_readpage_from_fscache(inode, page);
    	if (err == 0)
    		goto out;
    
    	dout("readpage inode %p file %p page %p index %lu\n",
    	     inode, filp, page, page->index);
    	err = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
    				  off, &len,
    				  ci->i_truncate_seq, ci->i_truncate_size,
    				  &page, 1, 0);
    	if (err == -ENOENT)
    		err = 0;
    	if (err < 0) {
    		SetPageError(page);
    		ceph_fscache_readpage_cancel(inode, page);
    		goto out;
    	}
    	if (err < PAGE_CACHE_SIZE)
    		/* zero fill remainder of page */
    		zero_user_segment(page, err, PAGE_CACHE_SIZE);
    	else
    		flush_dcache_page(page);
    
    	SetPageUptodate(page);
    	ceph_readpage_to_fscache(inode, page);
    
    out:
    	return err < 0 ? err : 0;
    }
    
    static int ceph_readpage(struct file *filp, struct page *page)
    {
    	int r = readpage_nounlock(filp, page);
    	unlock_page(page);
    	return r;
    }
    
    /*
     * Finish an async read(ahead) op.
     */
    static void finish_read(struct ceph_osd_request *req, struct ceph_msg *msg)
    {
    	struct inode *inode = req->r_inode;
    	struct ceph_osd_data *osd_data;
    	int rc = req->r_result;
    	int bytes = le32_to_cpu(msg->hdr.data_len);
    	int num_pages;
    	int i;
    
    	dout("finish_read %p req %p rc %d bytes %d\n", inode, req, rc, bytes);
    
    	/* unlock all pages, zeroing any data we didn't read */
    	osd_data = osd_req_op_extent_osd_data(req, 0);
    	BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);
    	num_pages = calc_pages_for((u64)osd_data->alignment,
    					(u64)osd_data->length);
    	for (i = 0; i < num_pages; i++) {
    		struct page *page = osd_data->pages[i];
    
    		if (rc < 0)
    			goto unlock;
    		if (bytes < (int)PAGE_CACHE_SIZE) {
    			/* zero (remainder of) page */
    			int s = bytes < 0 ? 0 : bytes;
    			zero_user_segment(page, s, PAGE_CACHE_SIZE);
    		}
     		dout("finish_read %p uptodate %p idx %lu\n", inode, page,
    		     page->index);
    		flush_dcache_page(page);
    		SetPageUptodate(page);
    		ceph_readpage_to_fscache(inode, page);
    unlock:
    		unlock_page(page);
    		page_cache_release(page);
    		bytes -= PAGE_CACHE_SIZE;
    	}
    	kfree(osd_data->pages);
    }
    
    static void ceph_unlock_page_vector(struct page **pages, int num_pages)
    {
    	int i;
    
    	for (i = 0; i < num_pages; i++)
    		unlock_page(pages[i]);
    }
    
    /*
     * start an async read(ahead) operation.  return nr_pages we submitted
     * a read for on success, or negative error code.
     */
    static int start_read(struct inode *inode, struct list_head *page_list, int max)
    {
    	struct ceph_osd_client *osdc =
    		&ceph_inode_to_client(inode)->client->osdc;
    	struct ceph_inode_info *ci = ceph_inode(inode);
    	struct page *page = list_entry(page_list->prev, struct page, lru);
    	struct ceph_vino vino;
    	struct ceph_osd_request *req;
    	u64 off;
    	u64 len;
    	int i;
    	struct page **pages;
    	pgoff_t next_index;
    	int nr_pages = 0;
    	int ret;
    
    	off = (u64) page_offset(page);
    
    	/* count pages */
    	next_index = page->index;
    	list_for_each_entry_reverse(page, page_list, lru) {
    		if (page->index != next_index)
    			break;
    		nr_pages++;
    		next_index++;
    		if (max && nr_pages == max)
    			break;
    	}
    	len = nr_pages << PAGE_CACHE_SHIFT;
    	dout("start_read %p nr_pages %d is %lld~%lld\n", inode, nr_pages,
    	     off, len);
    	vino = ceph_vino(inode);
    	req = ceph_osdc_new_request(osdc, &ci->i_layout, vino, off, &len,
    				    0, 1, CEPH_OSD_OP_READ,
    				    CEPH_OSD_FLAG_READ, NULL,
    				    ci->i_truncate_seq, ci->i_truncate_size,
    				    false);
    	if (IS_ERR(req))
    		return PTR_ERR(req);
    
    	/* build page vector */
    	nr_pages = calc_pages_for(0, len);
    	pages = kmalloc(sizeof(*pages) * nr_pages, GFP_NOFS);
    	ret = -ENOMEM;
    	if (!pages)
    		goto out;
    	for (i = 0; i < nr_pages; ++i) {
    		page = list_entry(page_list->prev, struct page, lru);
    		BUG_ON(PageLocked(page));
    		list_del(&page->lru);
    
     		dout("start_read %p adding %p idx %lu\n", inode, page,
    		     page->index);
    		if (add_to_page_cache_lru(page, &inode->i_data, page->index,
    					  GFP_NOFS)) {
    			ceph_fscache_uncache_page(inode, page);
    			page_cache_release(page);
    			dout("start_read %p add_to_page_cache failed %p\n",
    			     inode, page);
    			nr_pages = i;
    			goto out_pages;
    		}
    		pages[i] = page;
    	}
    	osd_req_op_extent_osd_data_pages(req, 0, pages, len, 0, false, false);
    	req->r_callback = finish_read;
    	req->r_inode = inode;
    
    	ceph_osdc_build_request(req, off, NULL, vino.snap, NULL);
    
    	dout("start_read %p starting %p %lld~%lld\n", inode, req, off, len);
    	ret = ceph_osdc_start_request(osdc, req, false);
    	if (ret < 0)
    		goto out_pages;
    	ceph_osdc_put_request(req);
    	return nr_pages;
    
    out_pages:
    	ceph_unlock_page_vector(pages, nr_pages);
    	ceph_release_page_vector(pages, nr_pages);
    out:
    	ceph_osdc_put_request(req);
    	return ret;
    }
    
    
    /*
     * Read multiple pages.  Leave pages we don't read + unlock in page_list;
     * the caller (VM) cleans them up.
     */
    static int ceph_readpages(struct file *file, struct address_space *mapping,
    			  struct list_head *page_list, unsigned nr_pages)
    {
    	struct inode *inode = file_inode(file);
    	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
    	int rc = 0;
    	int max = 0;
    
    	if (ceph_inode(inode)->i_inline_version != CEPH_INLINE_NONE)
    		return -EINVAL;
    
    	rc = ceph_readpages_from_fscache(mapping->host, mapping, page_list,
    					 &nr_pages);
    
    	if (rc == 0)
    		goto out;
    
    	if (fsc->mount_options->rsize >= PAGE_CACHE_SIZE)
    		max = (fsc->mount_options->rsize + PAGE_CACHE_SIZE - 1)
    			>> PAGE_SHIFT;
    
    	dout("readpages %p file %p nr_pages %d max %d\n", inode,
    		file, nr_pages,
    	     max);
    	while (!list_empty(page_list)) {
    		rc = start_read(inode, page_list, max);
    		if (rc < 0)
    			goto out;
    		BUG_ON(rc == 0);
    	}
    out:
    	ceph_fscache_readpages_cancel(inode, page_list);
    
    	dout("readpages %p file %p ret %d\n", inode, file, rc);
    	return rc;
    }
    
    /*
     * Get ref for the oldest snapc for an inode with dirty data... that is, the
     * only snap context we are allowed to write back.
     */
    static struct ceph_snap_context *get_oldest_context(struct inode *inode,
    						    u64 *snap_size)
    {
    	struct ceph_inode_info *ci = ceph_inode(inode);
    	struct ceph_snap_context *snapc = NULL;
    	struct ceph_cap_snap *capsnap = NULL;
    
    	spin_lock(&ci->i_ceph_lock);
    	list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
    		dout(" cap_snap %p snapc %p has %d dirty pages\n", capsnap,
    		     capsnap->context, capsnap->dirty_pages);
    		if (capsnap->dirty_pages) {
    			snapc = ceph_get_snap_context(capsnap->context);
    			if (snap_size)
    				*snap_size = capsnap->size;
    			break;
    		}
    	}
    	if (!snapc && ci->i_wrbuffer_ref_head) {
    		snapc = ceph_get_snap_context(ci->i_head_snapc);
    		dout(" head snapc %p has %d dirty pages\n",
    		     snapc, ci->i_wrbuffer_ref_head);
    	}
    	spin_unlock(&ci->i_ceph_lock);
    	return snapc;
    }
    
    /*
     * Write a single page, but leave the page locked.
     *
     * If we get a write error, set the page error bit, but still adjust the
     * dirty page accounting (i.e., page is no longer dirty).
     */
    static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
    {
    	struct inode *inode;
    	struct ceph_inode_info *ci;
    	struct ceph_fs_client *fsc;
    	struct ceph_osd_client *osdc;
    	struct ceph_snap_context *snapc, *oldest;
    	loff_t page_off = page_offset(page);
    	long writeback_stat;
    	u64 truncate_size, snap_size = 0;
    	u32 truncate_seq;
    	int err = 0, len = PAGE_CACHE_SIZE;
    
    	dout("writepage %p idx %lu\n", page, page->index);
    
    	if (!page->mapping || !page->mapping->host) {
    		dout("writepage %p - no mapping\n", page);
    		return -EFAULT;
    	}
    	inode = page->mapping->host;
    	ci = ceph_inode(inode);
    	fsc = ceph_inode_to_client(inode);
    	osdc = &fsc->client->osdc;
    
    	/* verify this is a writeable snap context */
    	snapc = page_snap_context(page);
    	if (snapc == NULL) {
    		dout("writepage %p page %p not dirty?\n", inode, page);
    		goto out;
    	}
    	oldest = get_oldest_context(inode, &snap_size);
    	if (snapc->seq > oldest->seq) {
    		dout("writepage %p page %p snapc %p not writeable - noop\n",
    		     inode, page, snapc);
    		/* we should only noop if called by kswapd */
    		WARN_ON((current->flags & PF_MEMALLOC) == 0);
    		ceph_put_snap_context(oldest);
    		goto out;
    	}
    	ceph_put_snap_context(oldest);
    
    	spin_lock(&ci->i_ceph_lock);
    	truncate_seq = ci->i_truncate_seq;
    	truncate_size = ci->i_truncate_size;
    	if (!snap_size)
    		snap_size = i_size_read(inode);
    	spin_unlock(&ci->i_ceph_lock);
    
    	/* is this a partial page at end of file? */
    	if (page_off >= snap_size) {
    		dout("%p page eof %llu\n", page, snap_size);
    		goto out;
    	}
    	if (snap_size < page_off + len)
    		len = snap_size - page_off;
    
    	dout("writepage %p page %p index %lu on %llu~%u snapc %p\n",
    	     inode, page, page->index, page_off, len, snapc);
    
    	writeback_stat = atomic_long_inc_return(&fsc->writeback_count);
    	if (writeback_stat >
    	    CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb))
    		set_bdi_congested(&fsc->backing_dev_info, BLK_RW_ASYNC);
    
    	ceph_readpage_to_fscache(inode, page);
    
    	set_page_writeback(page);
    	err = ceph_osdc_writepages(osdc, ceph_vino(inode),
    				   &ci->i_layout, snapc,
    				   page_off, len,
    				   truncate_seq, truncate_size,
    				   &inode->i_mtime, &page, 1);
    	if (err < 0) {
    		dout("writepage setting page/mapping error %d %p\n", err, page);
    		SetPageError(page);
    		mapping_set_error(&inode->i_data, err);
    		if (wbc)
    			wbc->pages_skipped++;
    	} else {
    		dout("writepage cleaned page %p\n", page);
    		err = 0;  /* vfs expects us to return 0 */
    	}
    	page->private = 0;
    	ClearPagePrivate(page);
    	end_page_writeback(page);
    	ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
    	ceph_put_snap_context(snapc);  /* page's reference */
    out:
    	return err;
    }
    
    static int ceph_writepage(struct page *page, struct writeback_control *wbc)
    {
    	int err;
    	struct inode *inode = page->mapping->host;
    	BUG_ON(!inode);
    	ihold(inode);
    	err = writepage_nounlock(page, wbc);
    	unlock_page(page);
    	iput(inode);
    	return err;
    }
    
    
    /*
     * lame release_pages helper.  release_pages() isn't exported to
     * modules.
     */
    static void ceph_release_pages(struct page **pages, int num)
    {
    	struct pagevec pvec;
    	int i;
    
    	pagevec_init(&pvec, 0);
    	for (i = 0; i < num; i++) {
    		if (pagevec_add(&pvec, pages[i]) == 0)
    			pagevec_release(&pvec);
    	}
    	pagevec_release(&pvec);
    }
    
    /*
     * async writeback completion handler.
     *
     * If we get an error, set the mapping error bit, but not the individual
     * page error bits.
     */
    static void writepages_finish(struct ceph_osd_request *req,
    			      struct ceph_msg *msg)
    {
    	struct inode *inode = req->r_inode;
    	struct ceph_inode_info *ci = ceph_inode(inode);
    	struct ceph_osd_data *osd_data;
    	unsigned wrote;
    	struct page *page;
    	int num_pages;
    	int i;
    	struct ceph_snap_context *snapc = req->r_snapc;
    	struct address_space *mapping = inode->i_mapping;
    	int rc = req->r_result;
    	u64 bytes = req->r_ops[0].extent.length;
    	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
    	long writeback_stat;
    	unsigned issued = ceph_caps_issued(ci);
    
    	osd_data = osd_req_op_extent_osd_data(req, 0);
    	BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);
    	num_pages = calc_pages_for((u64)osd_data->alignment,
    					(u64)osd_data->length);
    	if (rc >= 0) {
    		/*
    		 * Assume we wrote the pages we originally sent.  The
    		 * osd might reply with fewer pages if our writeback
    		 * raced with a truncation and was adjusted at the osd,
    		 * so don't believe the reply.
    		 */
    		wrote = num_pages;
    	} else {
    		wrote = 0;
    		mapping_set_error(mapping, rc);
    	}
    	dout("writepages_finish %p rc %d bytes %llu wrote %d (pages)\n",
    	     inode, rc, bytes, wrote);
    
    	/* clean all pages */
    	for (i = 0; i < num_pages; i++) {
    		page = osd_data->pages[i];
    		BUG_ON(!page);
    		WARN_ON(!PageUptodate(page));
    
    		writeback_stat =
    			atomic_long_dec_return(&fsc->writeback_count);
    		if (writeback_stat <
    		    CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
    			clear_bdi_congested(&fsc->backing_dev_info,
    					    BLK_RW_ASYNC);
    
    		ceph_put_snap_context(page_snap_context(page));
    		page->private = 0;
    		ClearPagePrivate(page);
    		dout("unlocking %d %p\n", i, page);
    		end_page_writeback(page);
    
    		/*
    		 * We lost the cache cap, need to truncate the page before
    		 * it is unlocked, otherwise we'd truncate it later in the
    		 * page truncation thread, possibly losing some data that
    		 * raced its way in
    		 */
    		if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0)
    			generic_error_remove_page(inode->i_mapping, page);
    
    		unlock_page(page);
    	}
    	dout("%p wrote+cleaned %d pages\n", inode, wrote);
    	ceph_put_wrbuffer_cap_refs(ci, num_pages, snapc);
    
    	ceph_release_pages(osd_data->pages, num_pages);
    	if (osd_data->pages_from_pool)
    		mempool_free(osd_data->pages,
    			     ceph_sb_to_client(inode->i_sb)->wb_pagevec_pool);
    	else
    		kfree(osd_data->pages);
    	ceph_osdc_put_request(req);
    }
    
    /*
     * initiate async writeback
     */
    static int ceph_writepages_start(struct address_space *mapping,
    				 struct writeback_control *wbc)
    {
    	struct inode *inode = mapping->host;
    	struct ceph_inode_info *ci = ceph_inode(inode);
    	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
    	struct ceph_vino vino = ceph_vino(inode);
    	pgoff_t index, start, end;
    	int range_whole = 0;
    	int should_loop = 1;
    	pgoff_t max_pages = 0, max_pages_ever = 0;
    	struct ceph_snap_context *snapc = NULL, *last_snapc = NULL, *pgsnapc;
    	struct pagevec pvec;
    	int done = 0;
    	int rc = 0;
    	unsigned wsize = 1 << inode->i_blkbits;
    	struct ceph_osd_request *req = NULL;
    	int do_sync;
    	u64 truncate_size, snap_size;
    	u32 truncate_seq;
    
    	/*
    	 * Include a 'sync' in the OSD request if this is a data
    	 * integrity write (e.g., O_SYNC write or fsync()), or if our
    	 * cap is being revoked.
    	 */
    	if ((wbc->sync_mode == WB_SYNC_ALL) ||
    		ceph_caps_revoking(ci, CEPH_CAP_FILE_BUFFER))
    		do_sync = 1;
    	dout("writepages_start %p dosync=%d (mode=%s)\n",
    	     inode, do_sync,
    	     wbc->sync_mode == WB_SYNC_NONE ? "NONE" :
    	     (wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD"));
    
    	if (fsc->mount_state == CEPH_MOUNT_SHUTDOWN) {
    		pr_warn("writepage_start %p on forced umount\n", inode);
    		return -EIO; /* we're in a forced umount, don't write! */
    	}
    	if (fsc->mount_options->wsize && fsc->mount_options->wsize < wsize)
    		wsize = fsc->mount_options->wsize;
    	if (wsize < PAGE_CACHE_SIZE)
    		wsize = PAGE_CACHE_SIZE;
    	max_pages_ever = wsize >> PAGE_CACHE_SHIFT;
    
    	pagevec_init(&pvec, 0);
    
    	/* where to start/end? */
    	if (wbc->range_cyclic) {
    		start = mapping->writeback_index; /* Start from prev offset */
    		end = -1;
    		dout(" cyclic, start at %lu\n", start);
    	} else {
    		start = wbc->range_start >> PAGE_CACHE_SHIFT;
    		end = wbc->range_end >> PAGE_CACHE_SHIFT;
    		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
    			range_whole = 1;
    		should_loop = 0;
    		dout(" not cyclic, %lu to %lu\n", start, end);
    	}
    	index = start;
    
    retry:
    	/* find oldest snap context with dirty data */
    	ceph_put_snap_context(snapc);
    	snap_size = 0;
    	snapc = get_oldest_context(inode, &snap_size);
    	if (!snapc) {
    		/* hmm, why does writepages get called when there
    		   is no dirty data? */
    		dout(" no snap context with dirty data?\n");
    		goto out;
    	}
    	if (snap_size == 0)
    		snap_size = i_size_read(inode);
    	dout(" oldest snapc is %p seq %lld (%d snaps)\n",
    	     snapc, snapc->seq, snapc->num_snaps);
    
    	spin_lock(&ci->i_ceph_lock);
    	truncate_seq = ci->i_truncate_seq;
    	truncate_size = ci->i_truncate_size;
    	if (!snap_size)
    		snap_size = i_size_read(inode);
    	spin_unlock(&ci->i_ceph_lock);
    
    	if (last_snapc && snapc != last_snapc) {
    		/* if we switched to a newer snapc, restart our scan at the
    		 * start of the original file range. */
    		dout("  snapc differs from last pass, restarting at %lu\n",
    		     index);
    		index = start;
    	}
    	last_snapc = snapc;
    
    	while (!done && index <= end) {
    		unsigned i;
    		int first;
    		pgoff_t next;
    		int pvec_pages, locked_pages;
    		struct page **pages = NULL;
    		mempool_t *pool = NULL;	/* Becomes non-null if mempool used */
    		struct page *page;
    		int want;
    		u64 offset, len;
    		long writeback_stat;
    
    		next = 0;
    		locked_pages = 0;
    		max_pages = max_pages_ever;
    
    get_more_pages:
    		first = -1;
    		want = min(end - index,
    			   min((pgoff_t)PAGEVEC_SIZE,
    			       max_pages - (pgoff_t)locked_pages) - 1)
    			+ 1;
    		pvec_pages = pagevec_lookup_tag(&pvec, mapping, &index,
    						PAGECACHE_TAG_DIRTY,
    						want);
    		dout("pagevec_lookup_tag got %d\n", pvec_pages);
    		if (!pvec_pages && !locked_pages)
    			break;
    		for (i = 0; i < pvec_pages && locked_pages < max_pages; i++) {
    			page = pvec.pages[i];
    			dout("? %p idx %lu\n", page, page->index);
    			if (locked_pages == 0)
    				lock_page(page);  /* first page */
    			else if (!trylock_page(page))
    				break;
    
    			/* only dirty pages, or our accounting breaks */
    			if (unlikely(!PageDirty(page)) ||
    			    unlikely(page->mapping != mapping)) {
    				dout("!dirty or !mapping %p\n", page);
    				unlock_page(page);
    				break;
    			}
    			if (!wbc->range_cyclic && page->index > end) {
    				dout("end of range %p\n", page);
    				done = 1;
    				unlock_page(page);
    				break;
    			}
    			if (next && (page->index != next)) {
    				dout("not consecutive %p\n", page);
    				unlock_page(page);
    				break;
    			}
    			if (wbc->sync_mode != WB_SYNC_NONE) {
    				dout("waiting on writeback %p\n", page);
    				wait_on_page_writeback(page);
    			}
    			if (page_offset(page) >= snap_size) {
    				dout("%p page eof %llu\n", page, snap_size);
    				done = 1;
    				unlock_page(page);
    				break;
    			}
    			if (PageWriteback(page)) {
    				dout("%p under writeback\n", page);
    				unlock_page(page);
    				break;
    			}
    
    			/* only if matching snap context */
    			pgsnapc = page_snap_context(page);
    			if (pgsnapc->seq > snapc->seq) {
    				dout("page snapc %p %lld > oldest %p %lld\n",
    				     pgsnapc, pgsnapc->seq, snapc, snapc->seq);
    				unlock_page(page);
    				if (!locked_pages)
    					continue; /* keep looking for snap */
    				break;
    			}
    
    			if (!clear_page_dirty_for_io(page)) {
    				dout("%p !clear_page_dirty_for_io\n", page);
    				unlock_page(page);
    				break;
    			}
    
    			/*
    			 * We have something to write.  If this is
    			 * the first locked page this time through,
    			 * allocate an osd request and a page array
    			 * that it will use.
    			 */
    			if (locked_pages == 0) {
    				BUG_ON(pages);
    				/* prepare async write request */
    				offset = (u64)page_offset(page);
    				len = wsize;
    				req = ceph_osdc_new_request(&fsc->client->osdc,
    							&ci->i_layout, vino,
    							offset, &len, 0,
    							do_sync ? 2 : 1,
    							CEPH_OSD_OP_WRITE,
    							CEPH_OSD_FLAG_WRITE |
    							CEPH_OSD_FLAG_ONDISK,
    							snapc, truncate_seq,
    							truncate_size, true);
    				if (IS_ERR(req)) {
    					rc = PTR_ERR(req);
    					unlock_page(page);
    					break;
    				}
    
    				if (do_sync)
    					osd_req_op_init(req, 1, CEPH_OSD_OP_STARTSYNC);
    
    				req->r_callback = writepages_finish;
    				req->r_inode = inode;
    
    				max_pages = calc_pages_for(0, (u64)len);
    				pages = kmalloc(max_pages * sizeof (*pages),
    						GFP_NOFS);
    				if (!pages) {
    					pool = fsc->wb_pagevec_pool;
    					pages = mempool_alloc(pool, GFP_NOFS);
    					BUG_ON(!pages);
    				}
    			}
    
    			/* note position of first page in pvec */
    			if (first < 0)
    				first = i;
    			dout("%p will write page %p idx %lu\n",
    			     inode, page, page->index);
    
    			writeback_stat =
    			       atomic_long_inc_return(&fsc->writeback_count);
    			if (writeback_stat > CONGESTION_ON_THRESH(
    				    fsc->mount_options->congestion_kb)) {
    				set_bdi_congested(&fsc->backing_dev_info,
    						  BLK_RW_ASYNC);
    			}
    
    			set_page_writeback(page);
    			pages[locked_pages] = page;
    			locked_pages++;
    			next = page->index + 1;
    		}
    
    		/* did we get anything? */
    		if (!locked_pages)
    			goto release_pvec_pages;
    		if (i) {
    			int j;
    			BUG_ON(!locked_pages || first < 0);
    
    			if (pvec_pages && i == pvec_pages &&
    			    locked_pages < max_pages) {
    				dout("reached end pvec, trying for more\n");
    				pagevec_reinit(&pvec);
    				goto get_more_pages;
    			}
    
    			/* shift unused pages over in the pvec...  we
    			 * will need to release them below. */
    			for (j = i; j < pvec_pages; j++) {
    				dout(" pvec leftover page %p\n",
    				     pvec.pages[j]);
    				pvec.pages[j-i+first] = pvec.pages[j];
    			}
    			pvec.nr -= i-first;
    		}
    
    		/* Format the osd request message and submit the write */
    
    		offset = page_offset(pages[0]);
    		len = min(snap_size - offset,
    			  (u64)locked_pages << PAGE_CACHE_SHIFT);
    		dout("writepages got %d pages at %llu~%llu\n",
    		     locked_pages, offset, len);
    
    		osd_req_op_extent_osd_data_pages(req, 0, pages, len, 0,
    							!!pool, false);
    
    		pages = NULL;	/* request message now owns the pages array */
    		pool = NULL;
    
    		/* Update the write op length in case we changed it */
    
    		osd_req_op_extent_update(req, 0, len);
    
    		vino = ceph_vino(inode);
    		ceph_osdc_build_request(req, offset, snapc, vino.snap,
    					&inode->i_mtime);
    
    		rc = ceph_osdc_start_request(&fsc->client->osdc, req, true);
    		BUG_ON(rc);
    		req = NULL;
    
    		/* continue? */
    		index = next;
    		wbc->nr_to_write -= locked_pages;
    		if (wbc->nr_to_write <= 0)
    			done = 1;
    
    release_pvec_pages:
    		dout("pagevec_release on %d pages (%p)\n", (int)pvec.nr,
    		     pvec.nr ? pvec.pages[0] : NULL);
    		pagevec_release(&pvec);
    
    		if (locked_pages && !done)
    			goto retry;
    	}
    
    	if (should_loop && !done) {
    		/* more to do; loop back to beginning of file */
    		dout("writepages looping back to beginning of file\n");
    		should_loop = 0;
    		index = 0;
    		goto retry;
    	}
    
    	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
    		mapping->writeback_index = index;
    
    out:
    	if (req)
    		ceph_osdc_put_request(req);
    	ceph_put_snap_context(snapc);
    	dout("writepages done, rc = %d\n", rc);
    	return rc;
    }
    
    
    
    /*
     * See if a given @snapc is either writeable, or already written.
     */
    static int context_is_writeable_or_written(struct inode *inode,
    					   struct ceph_snap_context *snapc)
    {
    	struct ceph_snap_context *oldest = get_oldest_context(inode, NULL);
    	int ret = !oldest || snapc->seq <= oldest->seq;
    
    	ceph_put_snap_context(oldest);
    	return ret;
    }
    
    /*
     * We are only allowed to write into/dirty the page if the page is
     * clean, or already dirty within the same snap context.
     *
     * called with page locked.
     * return success with page locked,
     * or any failure (incl -EAGAIN) with page unlocked.
     */
    static int ceph_update_writeable_page(struct file *file,
    			    loff_t pos, unsigned len,
    			    struct page *page)
    {
    	struct inode *inode = file_inode(file);
    	struct ceph_inode_info *ci = ceph_inode(inode);
    	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
    	loff_t page_off = pos & PAGE_CACHE_MASK;
    	int pos_in_page = pos & ~PAGE_CACHE_MASK;
    	int end_in_page = pos_in_page + len;
    	loff_t i_size;
    	int r;
    	struct ceph_snap_context *snapc, *oldest;
    
    retry_locked:
    	/* writepages currently holds page lock, but if we change that later, */
    	wait_on_page_writeback(page);
    
    	/* check snap context */
    	BUG_ON(!ci->i_snap_realm);
    	down_read(&mdsc->snap_rwsem);
    	BUG_ON(!ci->i_snap_realm->cached_context);
    	snapc = page_snap_context(page);
    	if (snapc && snapc != ci->i_head_snapc) {
    		/*
    		 * this page is already dirty in another (older) snap
    		 * context!  is it writeable now?
    		 */
    		oldest = get_oldest_context(inode, NULL);
    		up_read(&mdsc->snap_rwsem);
    
    		if (snapc->seq > oldest->seq) {
    			ceph_put_snap_context(oldest);
    			dout(" page %p snapc %p not current or oldest\n",
    			     page, snapc);
    			/*
    			 * queue for writeback, and wait for snapc to
    			 * be writeable or written
    			 */
    			snapc = ceph_get_snap_context(snapc);
    			unlock_page(page);
    			ceph_queue_writeback(inode);
    			r = wait_event_interruptible(ci->i_cap_wq,
    			       context_is_writeable_or_written(inode, snapc));
    			ceph_put_snap_context(snapc);
    			if (r == -ERESTARTSYS)
    				return r;
    			return -EAGAIN;
    		}
    		ceph_put_snap_context(oldest);
    
    		/* yay, writeable, do it now (without dropping page lock) */
    		dout(" page %p snapc %p not current, but oldest\n",
    		     page, snapc);
    		if (!clear_page_dirty_for_io(page))
    			goto retry_locked;
    		r = writepage_nounlock(page, NULL);
    		if (r < 0)
    			goto fail_nosnap;
    		goto retry_locked;
    	}
    
    	if (PageUptodate(page)) {
    		dout(" page %p already uptodate\n", page);
    		return 0;
    	}
    
    	/* full page? */
    	if (pos_in_page == 0 && len == PAGE_CACHE_SIZE)
    		return 0;
    
    	/* past end of file? */
    	i_size = inode->i_size;   /* caller holds i_mutex */
    
    	if (page_off >= i_size ||
    	    (pos_in_page == 0 && (pos+len) >= i_size &&
    	     end_in_page - pos_in_page != PAGE_CACHE_SIZE)) {
    		dout(" zeroing %p 0 - %d and %d - %d\n",
    		     page, pos_in_page, end_in_page, (int)PAGE_CACHE_SIZE);
    		zero_user_segments(page,
    				   0, pos_in_page,
    				   end_in_page, PAGE_CACHE_SIZE);
    		return 0;
    	}
    
    	/* we need to read it. */
    	up_read(&mdsc->snap_rwsem);
    	r = readpage_nounlock(file, page);
    	if (r < 0)
    		goto fail_nosnap;
    	goto retry_locked;
    fail_nosnap:
    	unlock_page(page);
    	return r;
    }
    
    /*
     * We are only allowed to write into/dirty the page if the page is
     * clean, or already dirty within the same snap context.
     */
    static int ceph_write_begin(struct file *file, struct address_space *mapping,
    			    loff_t pos, unsigned len, unsigned flags,
    			    struct page **pagep, void **fsdata)
    {
    	struct inode *inode = file_inode(file);
    	struct page *page;
    	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
    	int r;
    
    	do {
    		/* get a page */
    		page = grab_cache_page_write_begin(mapping, index, 0);
    		if (!page)
    			return -ENOMEM;
    		*pagep = page;
    
    		dout("write_begin file %p inode %p page %p %d~%d\n", file,
    		     inode, page, (int)pos, (int)len);
    
    		r = ceph_update_writeable_page(file, pos, len, page);
    	} while (r == -EAGAIN);
    
    	return r;
    }
    
    /*
     * we don't do anything in here that simple_write_end doesn't do
     * except adjust dirty page accounting and drop read lock on
     * mdsc->snap_rwsem.
     */
    static int ceph_write_end(struct file *file, struct address_space *mapping,
    			  loff_t pos, unsigned len, unsigned copied,
    			  struct page *page, void *fsdata)
    {
    	struct inode *inode = file_inode(file);
    	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
    	struct ceph_mds_client *mdsc = fsc->mdsc;
    	unsigned from = pos & (PAGE_CACHE_SIZE - 1);
    	int check_cap = 0;
    
    	dout("write_end file %p inode %p page %p %d~%d (%d)\n", file,
    	     inode, page, (int)pos, (int)copied, (int)len);
    
    	/* zero the stale part of the page if we did a short copy */
    	if (copied < len)
    		zero_user_segment(page, from+copied, len);
    
    	/* did file size increase? */
    	/* (no need for i_size_read(); we caller holds i_mutex */
    	if (pos+copied > inode->i_size)
    		check_cap = ceph_inode_set_size(inode, pos+copied);
    
    	if (!PageUptodate(page))
    		SetPageUptodate(page);
    
    	set_page_dirty(page);
    
    	unlock_page(page);
    	up_read(&mdsc->snap_rwsem);
    	page_cache_release(page);
    
    	if (check_cap)
    		ceph_check_caps(ceph_inode(inode), CHECK_CAPS_AUTHONLY, NULL);
    
    	return copied;
    }
    
    /*
     * we set .direct_IO to indicate direct io is supported, but since we
     * intercept O_DIRECT reads and writes early, this function should
     * never get called.
     */
    static ssize_t ceph_direct_io(int rw, struct kiocb *iocb,
    			      struct iov_iter *iter,
    			      loff_t pos)
    {
    	WARN_ON(1);
    	return -EINVAL;
    }
    
    const struct address_space_operations ceph_aops = {
    	.readpage = ceph_readpage,
    	.readpages = ceph_readpages,
    	.writepage = ceph_writepage,
    	.writepages = ceph_writepages_start,
    	.write_begin = ceph_write_begin,
    	.write_end = ceph_write_end,
    	.set_page_dirty = ceph_set_page_dirty,
    	.invalidatepage = ceph_invalidatepage,
    	.releasepage = ceph_releasepage,
    	.direct_IO = ceph_direct_io,
    };
    
    
    /*
     * vm ops
     */
    static int ceph_filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
    {
    	struct inode *inode = file_inode(vma->vm_file);
    	struct ceph_inode_info *ci = ceph_inode(inode);
    	struct ceph_file_info *fi = vma->vm_file->private_data;
    	struct page *pinned_page = NULL;
    	loff_t off = vmf->pgoff << PAGE_CACHE_SHIFT;
    	int want, got, ret;
    
    	dout("filemap_fault %p %llx.%llx %llu~%zd trying to get caps\n",
    	     inode, ceph_vinop(inode), off, (size_t)PAGE_CACHE_SIZE);
    	if (fi->fmode & CEPH_FILE_MODE_LAZY)
    		want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;
    	else
    		want = CEPH_CAP_FILE_CACHE;
    	while (1) {
    		got = 0;
    		ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, want,
    				    -1, &got, &pinned_page);
    		if (ret == 0)
    			break;
    		if (ret != -ERESTARTSYS) {
    			WARN_ON(1);
    			return VM_FAULT_SIGBUS;
    		}
    	}
    	dout("filemap_fault %p %llu~%zd got cap refs on %s\n",
    	     inode, off, (size_t)PAGE_CACHE_SIZE, ceph_cap_string(got));
    
    	if ((got & (CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO)) ||
    	    ci->i_inline_version == CEPH_INLINE_NONE)
    		ret = filemap_fault(vma, vmf);
    	else
    		ret = -EAGAIN;
    
    	dout("filemap_fault %p %llu~%zd dropping cap refs on %s ret %d\n",
    	     inode, off, (size_t)PAGE_CACHE_SIZE, ceph_cap_string(got), ret);
    	if (pinned_page)
    		page_cache_release(pinned_page);
    	ceph_put_cap_refs(ci, got);
    
    	if (ret != -EAGAIN)
    		return ret;
    
    	/* read inline data */
    	if (off >= PAGE_CACHE_SIZE) {
    		/* does not support inline data > PAGE_SIZE */
    		ret = VM_FAULT_SIGBUS;
    	} else {
    		int ret1;
    		struct address_space *mapping = inode->i_mapping;
    		struct page *page = find_or_create_page(mapping, 0,
    						mapping_gfp_mask(mapping) &
    						~__GFP_FS);
    		if (!page) {
    			ret = VM_FAULT_OOM;
    			goto out;
    		}
    		ret1 = __ceph_do_getattr(inode, page,
    					 CEPH_STAT_CAP_INLINE_DATA, true);
    		if (ret1 < 0 || off >= i_size_read(inode)) {
    			unlock_page(page);
    			page_cache_release(page);
    			ret = VM_FAULT_SIGBUS;
    			goto out;
    		}
    		if (ret1 < PAGE_CACHE_SIZE)
    			zero_user_segment(page, ret1, PAGE_CACHE_SIZE);
    		else
    			flush_dcache_page(page);
    		SetPageUptodate(page);
    		vmf->page = page;
    		ret = VM_FAULT_MAJOR | VM_FAULT_LOCKED;
    	}
    out:
    	dout("filemap_fault %p %llu~%zd read inline data ret %d\n",
    	     inode, off, (size_t)PAGE_CACHE_SIZE, ret);
    	return ret;
    }
    
    /*
     * Reuse write_begin here for simplicity.
     */
    static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
    {
    	struct inode *inode = file_inode(vma->vm_file);
    	struct ceph_inode_info *ci = ceph_inode(inode);
    	struct ceph_file_info *fi = vma->vm_file->private_data;
    	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
    	struct page *page = vmf->page;
    	loff_t off = page_offset(page);
    	loff_t size = i_size_read(inode);
    	size_t len;
    	int want, got, ret;
    
    	if (ci->i_inline_version != CEPH_INLINE_NONE) {
    		struct page *locked_page = NULL;
    		if (off == 0) {
    			lock_page(page);
    			locked_page = page;
    		}
    		ret = ceph_uninline_data(vma->vm_file, locked_page);
    		if (locked_page)
    			unlock_page(locked_page);
    		if (ret < 0)
    			return VM_FAULT_SIGBUS;
    	}
    
    	if (off + PAGE_CACHE_SIZE <= size)
    		len = PAGE_CACHE_SIZE;
    	else
    		len = size & ~PAGE_CACHE_MASK;
    
    	dout("page_mkwrite %p %llx.%llx %llu~%zd getting caps i_size %llu\n",
    	     inode, ceph_vinop(inode), off, len, size);
    	if (fi->fmode & CEPH_FILE_MODE_LAZY)
    		want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
    	else
    		want = CEPH_CAP_FILE_BUFFER;
    	while (1) {
    		got = 0;
    		ret = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, off + len,
    				    &got, NULL);
    		if (ret == 0)
    			break;
    		if (ret != -ERESTARTSYS) {
    			WARN_ON(1);
    			return VM_FAULT_SIGBUS;
    		}
    	}
    	dout("page_mkwrite %p %llu~%zd got cap refs on %s\n",
    	     inode, off, len, ceph_cap_string(got));
    
    	/* Update time before taking page lock */
    	file_update_time(vma->vm_file);
    
    	lock_page(page);
    
    	ret = VM_FAULT_NOPAGE;
    	if ((off > size) ||
    	    (page->mapping != inode->i_mapping))
    		goto out;
    
    	ret = ceph_update_writeable_page(vma->vm_file, off, len, page);
    	if (ret == 0) {
    		/* success.  we'll keep the page locked. */
    		set_page_dirty(page);
    		up_read(&mdsc->snap_rwsem);
    		ret = VM_FAULT_LOCKED;
    	} else {
    		if (ret == -ENOMEM)
    			ret = VM_FAULT_OOM;
    		else
    			ret = VM_FAULT_SIGBUS;
    	}
    out:
    	if (ret != VM_FAULT_LOCKED)
    		unlock_page(page);
    	if (ret == VM_FAULT_LOCKED ||
    	    ci->i_inline_version != CEPH_INLINE_NONE) {
    		int dirty;
    		spin_lock(&ci->i_ceph_lock);
    		ci->i_inline_version = CEPH_INLINE_NONE;
    		dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR);
    		spin_unlock(&ci->i_ceph_lock);
    		if (dirty)
    			__mark_inode_dirty(inode, dirty);
    	}
    
    	dout("page_mkwrite %p %llu~%zd dropping cap refs on %s ret %d\n",
    	     inode, off, len, ceph_cap_string(got), ret);
    	ceph_put_cap_refs(ci, got);
    
    	return ret;
    }
    
    void ceph_fill_inline_data(struct inode *inode, struct page *locked_page,
    			   char	*data, size_t len)
    {
    	struct address_space *mapping = inode->i_mapping;
    	struct page *page;
    
    	if (locked_page) {
    		page = locked_page;
    	} else {
    		if (i_size_read(inode) == 0)
    			return;
    		page = find_or_create_page(mapping, 0,
    					   mapping_gfp_mask(mapping) & ~__GFP_FS);
    		if (!page)
    			return;
    		if (PageUptodate(page)) {
    			unlock_page(page);
    			page_cache_release(page);
    			return;
    		}
    	}
    
    	dout("fill_inline_data %p %llx.%llx len %lu locked_page %p\n",
    	     inode, ceph_vinop(inode), len, locked_page);
    
    	if (len > 0) {
    		void *kaddr = kmap_atomic(page);
    		memcpy(kaddr, data, len);
    		kunmap_atomic(kaddr);
    	}
    
    	if (page != locked_page) {
    		if (len < PAGE_CACHE_SIZE)
    			zero_user_segment(page, len, PAGE_CACHE_SIZE);
    		else
    			flush_dcache_page(page);
    
    		SetPageUptodate(page);
    		unlock_page(page);
    		page_cache_release(page);
    	}
    }
    
    int ceph_uninline_data(struct file *filp, struct page *locked_page)
    {
    	struct inode *inode = file_inode(filp);
    	struct ceph_inode_info *ci = ceph_inode(inode);
    	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
    	struct ceph_osd_request *req;
    	struct page *page = NULL;
    	u64 len, inline_version;
    	int err = 0;
    	bool from_pagecache = false;
    
    	spin_lock(&ci->i_ceph_lock);
    	inline_version = ci->i_inline_version;
    	spin_unlock(&ci->i_ceph_lock);
    
    	dout("uninline_data %p %llx.%llx inline_version %llu\n",
    	     inode, ceph_vinop(inode), inline_version);
    
    	if (inline_version == 1 || /* initial version, no data */
    	    inline_version == CEPH_INLINE_NONE)
    		goto out;
    
    	if (locked_page) {
    		page = locked_page;
    		WARN_ON(!PageUptodate(page));
    	} else if (ceph_caps_issued(ci) &
    		   (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) {
    		page = find_get_page(inode->i_mapping, 0);
    		if (page) {
    			if (PageUptodate(page)) {
    				from_pagecache = true;
    				lock_page(page);
    			} else {
    				page_cache_release(page);
    				page = NULL;
    			}
    		}
    	}
    
    	if (page) {
    		len = i_size_read(inode);
    		if (len > PAGE_CACHE_SIZE)
    			len = PAGE_CACHE_SIZE;
    	} else {
    		page = __page_cache_alloc(GFP_NOFS);
    		if (!page) {
    			err = -ENOMEM;
    			goto out;
    		}
    		err = __ceph_do_getattr(inode, page,
    					CEPH_STAT_CAP_INLINE_DATA, true);
    		if (err < 0) {
    			/* no inline data */
    			if (err == -ENODATA)
    				err = 0;
    			goto out;
    		}
    		len = err;
    	}
    
    	req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
    				    ceph_vino(inode), 0, &len, 0, 1,
    				    CEPH_OSD_OP_CREATE,
    				    CEPH_OSD_FLAG_ONDISK | CEPH_OSD_FLAG_WRITE,
    				    ci->i_snap_realm->cached_context,
    				    0, 0, false);
    	if (IS_ERR(req)) {
    		err = PTR_ERR(req);
    		goto out;
    	}
    
    	ceph_osdc_build_request(req, 0, NULL, CEPH_NOSNAP, &inode->i_mtime);
    	err = ceph_osdc_start_request(&fsc->client->osdc, req, false);
    	if (!err)
    		err = ceph_osdc_wait_request(&fsc->client->osdc, req);
    	ceph_osdc_put_request(req);
    	if (err < 0)
    		goto out;
    
    	req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
    				    ceph_vino(inode), 0, &len, 1, 3,
    				    CEPH_OSD_OP_WRITE,
    				    CEPH_OSD_FLAG_ONDISK | CEPH_OSD_FLAG_WRITE,
    				    ci->i_snap_realm->cached_context,
    				    ci->i_truncate_seq, ci->i_truncate_size,
    				    false);
    	if (IS_ERR(req)) {
    		err = PTR_ERR(req);
    		goto out;
    	}
    
    	osd_req_op_extent_osd_data_pages(req, 1, &page, len, 0, false, false);
    
    	err = osd_req_op_xattr_init(req, 0, CEPH_OSD_OP_CMPXATTR,
    				    "inline_version", &inline_version,
    				    sizeof(inline_version),
    				    CEPH_OSD_CMPXATTR_OP_GT,
    				    CEPH_OSD_CMPXATTR_MODE_U64);
    	if (err)
    		goto out_put;
    
    	err = osd_req_op_xattr_init(req, 2, CEPH_OSD_OP_SETXATTR,
    				    "inline_version", &inline_version,
    				    sizeof(inline_version), 0, 0);
    	if (err)
    		goto out_put;
    
    	ceph_osdc_build_request(req, 0, NULL, CEPH_NOSNAP, &inode->i_mtime);
    	err = ceph_osdc_start_request(&fsc->client->osdc, req, false);
    	if (!err)
    		err = ceph_osdc_wait_request(&fsc->client->osdc, req);
    out_put:
    	ceph_osdc_put_request(req);
    	if (err == -ECANCELED)
    		err = 0;
    out:
    	if (page && page != locked_page) {
    		if (from_pagecache) {
    			unlock_page(page);
    			page_cache_release(page);
    		} else
    			__free_pages(page, 0);
    	}
    
    	dout("uninline_data %p %llx.%llx inline_version %llu = %d\n",
    	     inode, ceph_vinop(inode), inline_version, err);
    	return err;
    }
    
    static struct vm_operations_struct ceph_vmops = {
    	.fault		= ceph_filemap_fault,
    	.page_mkwrite	= ceph_page_mkwrite,
    	.remap_pages	= generic_file_remap_pages,
    };
    
    int ceph_mmap(struct file *file, struct vm_area_struct *vma)
    {
    	struct address_space *mapping = file->f_mapping;
    
    	if (!mapping->a_ops->readpage)
    		return -ENOEXEC;
    	file_accessed(file);
    	vma->vm_ops = &ceph_vmops;
    	return 0;
    }