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Commit fc2744aa authored by Yan, Zheng's avatar Yan, Zheng Committed by Sage Weil
Browse files

ceph: fix race between page writeback and truncate 



The client can receive truncate request from MDS at any time.
So the page writeback code need to get i_size, truncate_seq and
truncate_size atomically

Signed-off-by: default avatarYan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: default avatarSage Weil <sage@inktank.com>
parent 3803da49

fs/ceph/addr.c

+40 −44
Original line number Diff line number Diff line
@@ -438,13 +438,12 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc) 
	struct ceph_inode_info *ci;

	struct ceph_fs_client *fsc;

	struct ceph_osd_client *osdc;

	loff_t page_off = page_offset(page);

	int len = PAGE_CACHE_SIZE;

	loff_t i_size;

	int err = 0;

	struct ceph_snap_context *snapc, *oldest;

	u64 snap_size = 0;

	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);
@@ -474,13 +473,20 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc) 
	}

	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 (snap_size)

		i_size = snap_size;

	else

		i_size = i_size_read(inode);

	if (i_size < page_off + len)

		len = i_size - page_off;

	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);
@@ -494,7 +500,7 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc) 
	err = ceph_osdc_writepages(osdc, ceph_vino(inode),

				   &ci->i_layout, snapc,

				   page_off, len,

				   ci->i_truncate_seq, ci->i_truncate_size,

				   truncate_seq, truncate_size,

				   &inode->i_mtime, &page, 1);

	if (err < 0) {

		dout("writepage setting page/mapping error %d %p\n", err, page);
@@ -631,25 +637,6 @@ static void writepages_finish(struct ceph_osd_request *req, 
	ceph_osdc_put_request(req);

}



static struct ceph_osd_request *

ceph_writepages_osd_request(struct inode *inode, u64 offset, u64 *len,

				struct ceph_snap_context *snapc, int num_ops)

{

	struct ceph_fs_client *fsc;

	struct ceph_inode_info *ci;

	struct ceph_vino vino;



	fsc = ceph_inode_to_client(inode);

	ci = ceph_inode(inode);

	vino = ceph_vino(inode);

	/* BUG_ON(vino.snap != CEPH_NOSNAP); */



	return ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,

			vino, offset, len, num_ops, CEPH_OSD_OP_WRITE,

			CEPH_OSD_FLAG_WRITE|CEPH_OSD_FLAG_ONDISK,

			snapc, ci->i_truncate_seq, ci->i_truncate_size, true);

}



/*

 * initiate async writeback

 */
@@ -658,7 +645,8 @@ static int ceph_writepages_start(struct address_space *mapping, 
{

	struct inode *inode = mapping->host;

	struct ceph_inode_info *ci = ceph_inode(inode);

	struct ceph_fs_client *fsc;

	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;
@@ -670,7 +658,8 @@ static int ceph_writepages_start(struct address_space *mapping, 
	unsigned wsize = 1 << inode->i_blkbits;

	struct ceph_osd_request *req = NULL;

	int do_sync;

	u64 snap_size;

	u64 truncate_size, snap_size;

	u32 truncate_seq;



	/*

	 * Include a 'sync' in the OSD request if this is a data
@@ -685,7 +674,6 @@ static int ceph_writepages_start(struct address_space *mapping, 
	     wbc->sync_mode == WB_SYNC_NONE ? "NONE" :

	     (wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD"));



	fsc = ceph_inode_to_client(inode);

	if (fsc->mount_state == CEPH_MOUNT_SHUTDOWN) {

		pr_warning("writepage_start %p on forced umount\n", inode);

		return -EIO; /* we're in a forced umount, don't write! */
@@ -728,6 +716,14 @@ retry: 
		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. */
@@ -739,7 +735,6 @@ retry: 


	while (!done && index <= end) {

		int num_ops = do_sync ? 2 : 1;

		struct ceph_vino vino;

		unsigned i;

		int first;

		pgoff_t next;
@@ -833,17 +828,18 @@ get_more_pages: 
			 * that it will use.

			 */

			if (locked_pages == 0) {

				size_t size;



				BUG_ON(pages);



				/* prepare async write request */

				offset = (u64)page_offset(page);

				len = wsize;

				req = ceph_writepages_osd_request(inode,

							offset, &len, snapc,

							num_ops);



				req = ceph_osdc_new_request(&fsc->client->osdc,

							&ci->i_layout, vino,

							offset, &len, num_ops,

							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);
@@ -854,8 +850,8 @@ get_more_pages: 
				req->r_inode = inode;



				max_pages = calc_pages_for(0, (u64)len);

				size = max_pages * sizeof (*pages);

				pages = kmalloc(size, GFP_NOFS);

				pages = kmalloc(max_pages * sizeof (*pages),

						GFP_NOFS);

				if (!pages) {

					pool = fsc->wb_pagevec_pool;

					pages = mempool_alloc(pool, GFP_NOFS);