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Commit e1966b49 authored by Yan, Zheng's avatar Yan, Zheng Committed by Ilya Dryomov
Browse files

ceph: fix ceph_writepages_start() 



Before a page get locked, someone else can write data to the page
and increase the i_size. So we should re-check the i_size after
pages are locked.

Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
parent d3834fef

fs/ceph/addr.c

+23 −14
Original line number Diff line number Diff line
@@ -440,7 +440,7 @@ out: 
 * only snap context we are allowed to write back.

 */

static struct ceph_snap_context *get_oldest_context(struct inode *inode,

						    u64 *snap_size)

						    loff_t *snap_size)

{

	struct ceph_inode_info *ci = ceph_inode(inode);

	struct ceph_snap_context *snapc = NULL;
@@ -480,8 +480,9 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc) 
	struct ceph_osd_client *osdc;

	struct ceph_snap_context *snapc, *oldest;

	loff_t page_off = page_offset(page);

	loff_t snap_size = -1;

	long writeback_stat;

	u64 truncate_size, snap_size = 0;

	u64 truncate_size;

	u32 truncate_seq;

	int err = 0, len = PAGE_CACHE_SIZE;
@@ -516,7 +517,7 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc) 
	spin_lock(&ci->i_ceph_lock);

	truncate_seq = ci->i_truncate_seq;

	truncate_size = ci->i_truncate_size;

	if (!snap_size)

	if (snap_size == -1)

		snap_size = i_size_read(inode);

	spin_unlock(&ci->i_ceph_lock);
@@ -699,7 +700,8 @@ static int ceph_writepages_start(struct address_space *mapping, 
	unsigned wsize = 1 << inode->i_blkbits;

	struct ceph_osd_request *req = NULL;

	int do_sync = 0;

	u64 truncate_size, snap_size;

	loff_t snap_size, i_size;

	u64 truncate_size;

	u32 truncate_seq;



	/*
@@ -745,7 +747,7 @@ static int ceph_writepages_start(struct address_space *mapping, 
retry:

	/* find oldest snap context with dirty data */

	ceph_put_snap_context(snapc);

	snap_size = 0;

	snap_size = -1;

	snapc = get_oldest_context(inode, &snap_size);

	if (!snapc) {

		/* hmm, why does writepages get called when there
@@ -753,16 +755,13 @@ retry: 
		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);

	i_size = i_size_read(inode);

	spin_unlock(&ci->i_ceph_lock);



	if (last_snapc && snapc != last_snapc) {
@@ -832,8 +831,10 @@ get_more_pages: 
				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);

			if (page_offset(page) >=

			    (snap_size == -1 ? i_size : snap_size)) {

				dout("%p page eof %llu\n", page,

				     (snap_size == -1 ? i_size : snap_size));

				done = 1;

				unlock_page(page);

				break;
@@ -949,10 +950,18 @@ get_more_pages: 
		}



		/* 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);

		len = (u64)locked_pages << PAGE_CACHE_SHIFT;

		if (snap_size == -1) {

			len = min(len, (u64)i_size_read(inode) - offset);

			 /* writepages_finish() clears writeback pages

			  * according to the data length, so make sure

			  * data length covers all locked pages */

			len = max(len, 1 +

				((u64)(locked_pages - 1) << PAGE_CACHE_SHIFT));

		} else {

			len = min(len, snap_size - offset);

		}

		dout("writepages got %d pages at %llu~%llu\n",

		     locked_pages, offset, len);