ceph: fix race between writepages and truncate

[karo-tx-linux.git] / fs / ceph / addr.c

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 27d62070a8e9f65034ee02801006ce534da63ae6..2d6466b5fe820fa2bdb70e0349ec6b9a38184af8 100644 (file)
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -671,7 +671,7 @@ 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 = 0;
+       u64 snap_size;
 
        /*
         * Include a 'sync' in the OSD request if this is a data
@@ -717,6 +717,7 @@ 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;
        snapc = get_oldest_context(inode, &snap_size);
        if (!snapc) {
                /* hmm, why does writepages get called when there
@@ -724,6 +725,8 @@ 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);
        if (last_snapc && snapc != last_snapc) {
@@ -795,11 +798,8 @@ get_more_pages:
                                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));
+                       if (page_offset(page) >= snap_size) {
+                               dout("%p page eof %llu\n", page, snap_size);
                                done = 1;
                                unlock_page(page);
                                break;
@@ -911,7 +911,7 @@ get_more_pages:
                /* Format the osd request message and submit the write */
 
                offset = page_offset(pages[0]);
-               len = min((snap_size ? snap_size : i_size_read(inode)) - offset,
+               len = min(snap_size - offset,
                          (u64)locked_pages << PAGE_CACHE_SHIFT);
                dout("writepages got %d pages at %llu~%llu\n",
                     locked_pages, offset, len);