addr.c 32.8 KB
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#include <linux/ceph/ceph_debug.h>
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#include <linux/backing-dev.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/writeback.h>	/* generic_writepages */
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#include <linux/slab.h>
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#include <linux/pagevec.h>
#include <linux/task_io_accounting_ops.h>

#include "super.h"
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#include "mds_client.h"
#include <linux/ceph/osd_client.h>
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/*
 * 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
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 * count dirty pages on the inode.  In the absence of snapshots,
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 * 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.
 */

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#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))


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/*
 * 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;
	int undo = 0;
	struct ceph_snap_context *snapc;

	if (unlikely(!mapping))
		return !TestSetPageDirty(page);

	if (TestSetPageDirty(page)) {
		dout("%p set_page_dirty %p idx %lu -- already dirty\n",
		     mapping->host, page, page->index);
		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(&inode->i_lock);
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	if (ci->i_head_snapc == NULL)
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		ci->i_head_snapc = ceph_get_snap_context(snapc);
	++ci->i_wrbuffer_ref_head;
	if (ci->i_wrbuffer_ref == 0)
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		ihold(inode);
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	++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(&inode->i_lock);

	/* now adjust page */
	spin_lock_irq(&mapping->tree_lock);
	if (page->mapping) {	/* Race with truncate? */
		WARN_ON_ONCE(!PageUptodate(page));
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		account_page_dirtied(page, page->mapping);
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		radix_tree_tag_set(&mapping->page_tree,
				page_index(page), PAGECACHE_TAG_DIRTY);

		/*
		 * Reference snap context in page->private.  Also set
		 * PagePrivate so that we get invalidatepage callback.
		 */
		page->private = (unsigned long)snapc;
		SetPagePrivate(page);
	} else {
		dout("ANON set_page_dirty %p (raced truncate?)\n", page);
		undo = 1;
	}

	spin_unlock_irq(&mapping->tree_lock);

	if (undo)
		/* whoops, we failed to dirty the page */
		ceph_put_wrbuffer_cap_refs(ci, 1, snapc);

	__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);

	BUG_ON(!PageDirty(page));
	return 1;
}

/*
 * 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 long offset)
{
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	struct inode *inode;
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	struct ceph_inode_info *ci;
	struct ceph_snap_context *snapc = (void *)page->private;

	BUG_ON(!PageLocked(page));
	BUG_ON(!page->private);
	BUG_ON(!PagePrivate(page));
	BUG_ON(!page->mapping);

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	inode = page->mapping->host;

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	/*
	 * 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);

	if (offset == 0)
		ClearPageChecked(page);

	ci = ceph_inode(inode);
	if (offset == 0) {
		dout("%p invalidatepage %p idx %lu full dirty page %lu\n",
		     inode, page, page->index, offset);
		ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
		ceph_put_snap_context(snapc);
		page->private = 0;
		ClearPagePrivate(page);
	} else {
		dout("%p invalidatepage %p idx %lu partial dirty page\n",
		     inode, page, page->index);
	}
}

/* just a sanity check */
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));
	WARN_ON(page->private);
	WARN_ON(PagePrivate(page));
	return 0;
}

/*
 * read a single page, without unlocking it.
 */
static int readpage_nounlock(struct file *filp, struct page *page)
{
	struct inode *inode = filp->f_dentry->d_inode;
	struct ceph_inode_info *ci = ceph_inode(inode);
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	struct ceph_osd_client *osdc = 
		&ceph_inode_to_client(inode)->client->osdc;
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	int err = 0;
	u64 len = PAGE_CACHE_SIZE;

	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,
				  page->index << PAGE_CACHE_SHIFT, &len,
				  ci->i_truncate_seq, ci->i_truncate_size,
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				  &page, 1, 0);
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	if (err == -ENOENT)
		err = 0;
	if (err < 0) {
		SetPageError(page);
		goto out;
	} else if (err < PAGE_CACHE_SIZE) {
		/* zero fill remainder of page */
		zero_user_segment(page, err, PAGE_CACHE_SIZE);
	}
	SetPageUptodate(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;
}

/*
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 * Finish an async read(ahead) op.
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 */
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static void finish_read(struct ceph_osd_request *req, struct ceph_msg *msg)
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{
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	struct inode *inode = req->r_inode;
	struct ceph_osd_reply_head *replyhead;
	int rc, bytes;
	int i;
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	/* parse reply */
	replyhead = msg->front.iov_base;
	WARN_ON(le32_to_cpu(replyhead->num_ops) == 0);
	rc = le32_to_cpu(replyhead->result);
	bytes = le32_to_cpu(msg->hdr.data_len);
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	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 */
	for (i = 0; i < req->r_num_pages; i++, bytes -= PAGE_CACHE_SIZE) {
		struct page *page = req->r_pages[i];

		if (bytes < (int)PAGE_CACHE_SIZE) {
			/* zero (remainder of) page */
			int s = bytes < 0 ? 0 : bytes;
			zero_user_segment(page, s, PAGE_CACHE_SIZE);
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		}
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 		dout("finish_read %p uptodate %p idx %lu\n", inode, page,
		     page->index);
		flush_dcache_page(page);
		SetPageUptodate(page);
		unlock_page(page);
		page_cache_release(page);
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	}
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	kfree(req->r_pages);
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}

/*
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 * start an async read(ahead) operation.  return nr_pages we submitted
 * a read for on success, or negative error code.
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 */
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static int start_read(struct inode *inode, struct list_head *page_list)
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{
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	struct ceph_osd_client *osdc =
		&ceph_inode_to_client(inode)->client->osdc;
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	struct ceph_inode_info *ci = ceph_inode(inode);
	struct page *page = list_entry(page_list->prev, struct page, lru);
	struct ceph_osd_request *req;
	u64 off;
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	u64 len;
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	int i;
	struct page **pages;
	pgoff_t next_index;
	int nr_pages = 0;
	int ret;
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	off = page->index << PAGE_CACHE_SHIFT;
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	/* 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++;
	}
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	len = nr_pages << PAGE_CACHE_SHIFT;
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	dout("start_read %p nr_pages %d is %lld~%lld\n", inode, nr_pages,
	     off, len);

	req = ceph_osdc_new_request(osdc, &ci->i_layout, ceph_vino(inode),
				    off, &len,
				    CEPH_OSD_OP_READ, CEPH_OSD_FLAG_READ,
				    NULL, 0,
				    ci->i_truncate_seq, ci->i_truncate_size,
				    NULL, false, 1, 0);
	if (!req)
		return -ENOMEM;
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	/* build page vector */
	nr_pages = len >> PAGE_CACHE_SHIFT;
	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));
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		list_del(&page->lru);
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 		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,
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					  GFP_NOFS)) {
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			page_cache_release(page);
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			dout("start_read %p add_to_page_cache failed %p\n",
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			     inode, page);
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			nr_pages = i;
			goto out_pages;
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		}
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		pages[i] = page;
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	}
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	req->r_pages = pages;
	req->r_num_pages = nr_pages;
	req->r_callback = finish_read;
	req->r_inode = inode;

	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_release_page_vector(pages, nr_pages);
	kfree(pages);
out:
	ceph_osdc_put_request(req);
	return ret;
}
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/*
 * 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->f_dentry->d_inode;
	int rc = 0;

	dout("readpages %p file %p nr_pages %d\n", inode, file, nr_pages);
	while (!list_empty(page_list)) {
		rc = start_read(inode, page_list);
		if (rc < 0)
			goto out;
		BUG_ON(rc == 0);
	}
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out:
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	dout("readpages %p file %p ret %d\n", inode, file, rc);
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	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.
 */
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static struct ceph_snap_context *get_oldest_context(struct inode *inode,
						    u64 *snap_size)
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{
	struct ceph_inode_info *ci = ceph_inode(inode);
	struct ceph_snap_context *snapc = NULL;
	struct ceph_cap_snap *capsnap = NULL;

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	spin_lock(&inode->i_lock);
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	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;
		}
	}
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	if (!snapc && ci->i_wrbuffer_ref_head) {
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		snapc = ceph_get_snap_context(ci->i_head_snapc);
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		dout(" head snapc %p has %d dirty pages\n",
		     snapc, ci->i_wrbuffer_ref_head);
	}
	spin_unlock(&inode->i_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;
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	struct ceph_fs_client *fsc;
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	struct ceph_osd_client *osdc;
	loff_t page_off = page->index << PAGE_CACHE_SHIFT;
	int len = PAGE_CACHE_SIZE;
	loff_t i_size;
	int err = 0;
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	struct ceph_snap_context *snapc, *oldest;
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	u64 snap_size = 0;
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	long writeback_stat;
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	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);
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	fsc = ceph_inode_to_client(inode);
	osdc = &fsc->client->osdc;
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	/* verify this is a writeable snap context */
	snapc = (void *)page->private;
	if (snapc == NULL) {
		dout("writepage %p page %p not dirty?\n", inode, page);
		goto out;
	}
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	oldest = get_oldest_context(inode, &snap_size);
	if (snapc->seq > oldest->seq) {
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		dout("writepage %p page %p snapc %p not writeable - noop\n",
		     inode, page, (void *)page->private);
		/* we should only noop if called by kswapd */
		WARN_ON((current->flags & PF_MEMALLOC) == 0);
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		ceph_put_snap_context(oldest);
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		goto out;
	}
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	ceph_put_snap_context(oldest);
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	/* is this a partial page at end of file? */
	if (snap_size)
		i_size = snap_size;
	else
		i_size = i_size_read(inode);
	if (i_size < page_off + len)
		len = i_size - page_off;

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	dout("writepage %p page %p index %lu on %llu~%u snapc %p\n",
	     inode, page, page->index, page_off, len, snapc);
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	writeback_stat = atomic_long_inc_return(&fsc->writeback_count);
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	if (writeback_stat >
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	    CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb))
		set_bdi_congested(&fsc->backing_dev_info, BLK_RW_ASYNC);
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	set_page_writeback(page);
	err = ceph_osdc_writepages(osdc, ceph_vino(inode),
				   &ci->i_layout, snapc,
				   page_off, len,
				   ci->i_truncate_seq, ci->i_truncate_size,
				   &inode->i_mtime,
				   &page, 1, 0, 0, true);
	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);
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	ceph_put_snap_context(snapc);  /* page's reference */
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out:
	return err;
}

static int ceph_writepage(struct page *page, struct writeback_control *wbc)
{
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	int err;
	struct inode *inode = page->mapping->host;
	BUG_ON(!inode);
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	ihold(inode);
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	err = writepage_nounlock(page, wbc);
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	unlock_page(page);
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	iput(inode);
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	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_osd_reply_head *replyhead;
	struct ceph_osd_op *op;
	struct ceph_inode_info *ci = ceph_inode(inode);
	unsigned wrote;
	struct page *page;
	int i;
	struct ceph_snap_context *snapc = req->r_snapc;
	struct address_space *mapping = inode->i_mapping;
	__s32 rc = -EIO;
	u64 bytes = 0;
547
	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
Y
Yehuda Sadeh 已提交
548
	long writeback_stat;
S
Sage Weil 已提交
549
	unsigned issued = ceph_caps_issued(ci);
S
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550 551 552 553 554 555 556 557 558

	/* parse reply */
	replyhead = msg->front.iov_base;
	WARN_ON(le32_to_cpu(replyhead->num_ops) == 0);
	op = (void *)(replyhead + 1);
	rc = le32_to_cpu(replyhead->result);
	bytes = le64_to_cpu(op->extent.length);

	if (rc >= 0) {
559 560 561 562 563 564 565
		/*
		 * 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 = req->r_num_pages;
S
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566 567 568 569 570 571 572 573 574 575 576 577 578
	} 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 < req->r_num_pages; i++) {
		page = req->r_pages[i];
		BUG_ON(!page);
		WARN_ON(!PageUptodate(page));

Y
Yehuda Sadeh 已提交
579
		writeback_stat =
580
			atomic_long_dec_return(&fsc->writeback_count);
Y
Yehuda Sadeh 已提交
581
		if (writeback_stat <
582 583
		    CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
			clear_bdi_congested(&fsc->backing_dev_info,
Y
Yehuda Sadeh 已提交
584 585
					    BLK_RW_ASYNC);

586
		ceph_put_snap_context((void *)page->private);
S
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587 588 589 590
		page->private = 0;
		ClearPagePrivate(page);
		dout("unlocking %d %p\n", i, page);
		end_page_writeback(page);
591 592 593 594 595 596 597

		/*
		 * 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
		 */
598
		if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0)
599 600
			generic_error_remove_page(inode->i_mapping, page);

S
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601 602 603 604 605 606 607 608
		unlock_page(page);
	}
	dout("%p wrote+cleaned %d pages\n", inode, wrote);
	ceph_put_wrbuffer_cap_refs(ci, req->r_num_pages, snapc);

	ceph_release_pages(req->r_pages, req->r_num_pages);
	if (req->r_pages_from_pool)
		mempool_free(req->r_pages,
609
			     ceph_sb_to_client(inode->i_sb)->wb_pagevec_pool);
S
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610 611 612 613 614 615 616 617 618 619
	else
		kfree(req->r_pages);
	ceph_osdc_put_request(req);
}

/*
 * allocate a page vec, either directly, or if necessary, via a the
 * mempool.  we avoid the mempool if we can because req->r_num_pages
 * may be less than the maximum write size.
 */
620
static void alloc_page_vec(struct ceph_fs_client *fsc,
S
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621 622 623 624 625
			   struct ceph_osd_request *req)
{
	req->r_pages = kmalloc(sizeof(struct page *) * req->r_num_pages,
			       GFP_NOFS);
	if (!req->r_pages) {
626
		req->r_pages = mempool_alloc(fsc->wb_pagevec_pool, GFP_NOFS);
S
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627 628 629 630 631 632 633 634 635 636 637 638 639
		req->r_pages_from_pool = 1;
		WARN_ON(!req->r_pages);
	}
}

/*
 * 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);
640
	struct ceph_fs_client *fsc;
S
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641 642 643 644
	pgoff_t index, start, end;
	int range_whole = 0;
	int should_loop = 1;
	pgoff_t max_pages = 0, max_pages_ever = 0;
645
	struct ceph_snap_context *snapc = NULL, *last_snapc = NULL, *pgsnapc;
S
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646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666
	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 snap_size = 0;

	/*
	 * 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.
	 */
	do_sync = wbc->sync_mode == WB_SYNC_ALL;
	if (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"));

667 668
	fsc = ceph_inode_to_client(inode);
	if (fsc->mount_state == CEPH_MOUNT_SHUTDOWN) {
S
Sage Weil 已提交
669 670 671
		pr_warning("writepage_start %p on forced umount\n", inode);
		return -EIO; /* we're in a forced umount, don't write! */
	}
672 673
	if (fsc->mount_options->wsize && fsc->mount_options->wsize < wsize)
		wsize = fsc->mount_options->wsize;
S
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674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725
	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);
	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;
	}
	dout(" oldest snapc is %p seq %lld (%d snaps)\n",
	     snapc, snapc->seq, snapc->num_snaps);
	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 *page;
		int want;
		u64 offset, len;
		struct ceph_osd_request_head *reqhead;
		struct ceph_osd_op *op;
Y
Yehuda Sadeh 已提交
726
		long writeback_stat;
S
Sage Weil 已提交
727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789

		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 ((snap_size && page_offset(page) > snap_size) ||
			    (!snap_size &&
			     page_offset(page) > i_size_read(inode))) {
				dout("%p page eof %llu\n", page, snap_size ?
				     snap_size : i_size_read(inode));
				done = 1;
				unlock_page(page);
				break;
			}
			if (PageWriteback(page)) {
				dout("%p under writeback\n", page);
				unlock_page(page);
				break;
			}

			/* only if matching snap context */
790 791 792 793
			pgsnapc = (void *)page->private;
			if (pgsnapc->seq > snapc->seq) {
				dout("page snapc %p %lld > oldest %p %lld\n",
				     pgsnapc, pgsnapc->seq, snapc, snapc->seq);
S
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794 795 796 797 798 799 800 801 802 803 804 805 806 807 808
				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;
			}

			/* ok */
			if (locked_pages == 0) {
				/* prepare async write request */
809 810
				offset = (unsigned long long)page->index
					<< PAGE_CACHE_SHIFT;
S
Sage Weil 已提交
811
				len = wsize;
812
				req = ceph_osdc_new_request(&fsc->client->osdc,
S
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813 814 815 816 817 818 819 820 821
					    &ci->i_layout,
					    ceph_vino(inode),
					    offset, &len,
					    CEPH_OSD_OP_WRITE,
					    CEPH_OSD_FLAG_WRITE |
						    CEPH_OSD_FLAG_ONDISK,
					    snapc, do_sync,
					    ci->i_truncate_seq,
					    ci->i_truncate_size,
822
					    &inode->i_mtime, true, 1, 0);
823 824 825 826 827 828 829

				if (!req) {
					rc = -ENOMEM;
					unlock_page(page);
					break;
				}

S
Sage Weil 已提交
830 831
				max_pages = req->r_num_pages;

832
				alloc_page_vec(fsc, req);
S
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833 834 835 836 837 838 839 840 841
				req->r_callback = writepages_finish;
				req->r_inode = inode;
			}

			/* 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);
Y
Yehuda Sadeh 已提交
842

S
Sage Weil 已提交
843
			writeback_stat =
844
			       atomic_long_inc_return(&fsc->writeback_count);
S
Sage Weil 已提交
845
			if (writeback_stat > CONGESTION_ON_THRESH(
846 847
				    fsc->mount_options->congestion_kb)) {
				set_bdi_congested(&fsc->backing_dev_info,
S
Sage Weil 已提交
848
						  BLK_RW_ASYNC);
Y
Yehuda Sadeh 已提交
849 850
			}

S
Sage Weil 已提交
851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895
			set_page_writeback(page);
			req->r_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;
		}

		/* submit the write */
		offset = req->r_pages[0]->index << PAGE_CACHE_SHIFT;
		len = min((snap_size ? snap_size : i_size_read(inode)) - offset,
			  (u64)locked_pages << PAGE_CACHE_SHIFT);
		dout("writepages got %d pages at %llu~%llu\n",
		     locked_pages, offset, len);

		/* revise final length, page count */
		req->r_num_pages = locked_pages;
		reqhead = req->r_request->front.iov_base;
		op = (void *)(reqhead + 1);
		op->extent.length = cpu_to_le64(len);
		op->payload_len = cpu_to_le32(len);
		req->r_request->hdr.data_len = cpu_to_le32(len);

896 897
		rc = ceph_osdc_start_request(&fsc->client->osdc, req, true);
		BUG_ON(rc);
S
Sage Weil 已提交
898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942
		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);
943 944 945 946
	int ret = !oldest || snapc->seq <= oldest->seq;

	ceph_put_snap_context(oldest);
	return ret;
S
Sage Weil 已提交
947 948 949 950 951
}

/*
 * We are only allowed to write into/dirty the page if the page is
 * clean, or already dirty within the same snap context.
952 953 954 955
 *
 * called with page locked.
 * return success with page locked,
 * or any failure (incl -EAGAIN) with page unlocked.
S
Sage Weil 已提交
956
 */
957 958 959
static int ceph_update_writeable_page(struct file *file,
			    loff_t pos, unsigned len,
			    struct page *page)
S
Sage Weil 已提交
960 961 962
{
	struct inode *inode = file->f_dentry->d_inode;
	struct ceph_inode_info *ci = ceph_inode(inode);
963
	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
S
Sage Weil 已提交
964 965 966 967 968
	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;
969
	struct ceph_snap_context *snapc, *oldest;
S
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970 971 972 973 974 975 976 977 978

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);
979 980
	snapc = (void *)page->private;
	if (snapc && snapc != ci->i_head_snapc) {
S
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981 982 983 984
		/*
		 * this page is already dirty in another (older) snap
		 * context!  is it writeable now?
		 */
985
		oldest = get_oldest_context(inode, NULL);
S
Sage Weil 已提交
986 987
		up_read(&mdsc->snap_rwsem);

988
		if (snapc->seq > oldest->seq) {
989
			ceph_put_snap_context(oldest);
S
Sage Weil 已提交
990
			dout(" page %p snapc %p not current or oldest\n",
991
			     page, snapc);
S
Sage Weil 已提交
992 993 994 995
			/*
			 * queue for writeback, and wait for snapc to
			 * be writeable or written
			 */
996
			snapc = ceph_get_snap_context(snapc);
S
Sage Weil 已提交
997
			unlock_page(page);
998
			ceph_queue_writeback(inode);
999
			r = wait_event_interruptible(ci->i_cap_wq,
S
Sage Weil 已提交
1000 1001
			       context_is_writeable_or_written(inode, snapc));
			ceph_put_snap_context(snapc);
1002 1003
			if (r == -ERESTARTSYS)
				return r;
1004
			return -EAGAIN;
S
Sage Weil 已提交
1005
		}
1006
		ceph_put_snap_context(oldest);
S
Sage Weil 已提交
1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061

		/* 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 (i_size + len > inode->i_sb->s_maxbytes) {
		/* file is too big */
		r = -EINVAL;
		goto fail;
	}

	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:
	up_read(&mdsc->snap_rwsem);
fail_nosnap:
	unlock_page(page);
	return r;
}

1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075
/*
 * 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->f_dentry->d_inode;
	struct page *page;
	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
	int r;

	do {
1076
		/* get a page */
1077 1078 1079 1080 1081 1082
		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,
S
Sage Weil 已提交
1083
		     inode, page, (int)pos, (int)len);
1084 1085 1086 1087 1088 1089 1090

		r = ceph_update_writeable_page(file, pos, len, page);
	} while (r == -EAGAIN);

	return r;
}

S
Sage Weil 已提交
1091 1092 1093 1094 1095 1096 1097 1098 1099 1100
/*
 * 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->f_dentry->d_inode;
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	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
	struct ceph_mds_client *mdsc = fsc->mdsc;
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	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,
			      const struct iovec *iov,
			      loff_t pos, unsigned long nr_segs)
{
	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
 */

/*
 * Reuse write_begin here for simplicity.
 */
static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	struct inode *inode = vma->vm_file->f_dentry->d_inode;
	struct page *page = vmf->page;
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	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
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	loff_t off = page->index << PAGE_CACHE_SHIFT;
	loff_t size, len;
	int ret;

	size = i_size_read(inode);
	if (off + PAGE_CACHE_SIZE <= size)
		len = PAGE_CACHE_SIZE;
	else
		len = size & ~PAGE_CACHE_MASK;

	dout("page_mkwrite %p %llu~%llu page %p idx %lu\n", inode,
	     off, len, page, page->index);
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	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. */
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		set_page_dirty(page);
		up_read(&mdsc->snap_rwsem);
		ret = VM_FAULT_LOCKED;
	} else {
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		if (ret == -ENOMEM)
			ret = VM_FAULT_OOM;
		else
			ret = VM_FAULT_SIGBUS;
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	}
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out:
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	dout("page_mkwrite %p %llu~%llu = %d\n", inode, off, len, ret);
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	if (ret != VM_FAULT_LOCKED)
		unlock_page(page);
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	return ret;
}

static struct vm_operations_struct ceph_vmops = {
	.fault		= filemap_fault,
	.page_mkwrite	= ceph_page_mkwrite,
};

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;
	vma->vm_flags |= VM_CAN_NONLINEAR;
	return 0;
}