Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph...

[sfrench/cifs-2.6.git] / fs / ceph / addr.c

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index aa3cd7cc3e405dab3613eb3e3065ae3dbc81c9ed..412593703d1ec0519410ee6653bd8b55be5b0e2a 100644 (file)
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -337,16 +337,15 @@ out:
 /*
  * Get ref for the oldest snapc for an inode with dirty data... that is, the
  * only snap context we are allowed to write back.
- *
- * Caller holds i_lock.
  */
-static struct ceph_snap_context *__get_oldest_context(struct inode *inode,
-                                                     u64 *snap_size)
+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(&inode->i_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);
@@ -357,21 +356,11 @@ static struct ceph_snap_context *__get_oldest_context(struct inode *inode,
                        break;
                }
        }
-       if (!snapc && ci->i_snap_realm) {
-               snapc = ceph_get_snap_context(ci->i_snap_realm->cached_context);
+       if (!snapc && ci->i_head_snapc) {
+               snapc = ceph_get_snap_context(ci->i_head_snapc);
                dout(" head snapc %p has %d dirty pages\n",
                     snapc, ci->i_wrbuffer_ref_head);
        }
-       return snapc;
-}
-
-static struct ceph_snap_context *get_oldest_context(struct inode *inode,
-                                                   u64 *snap_size)
-{
-       struct ceph_snap_context *snapc = NULL;
-
-       spin_lock(&inode->i_lock);
-       snapc = __get_oldest_context(inode, snap_size);
        spin_unlock(&inode->i_lock);
        return snapc;
 }
@@ -392,7 +381,7 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
        int len = PAGE_CACHE_SIZE;
        loff_t i_size;
        int err = 0;
-       struct ceph_snap_context *snapc;
+       struct ceph_snap_context *snapc, *oldest;
        u64 snap_size = 0;
        long writeback_stat;
 
@@ -413,13 +402,16 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
                dout("writepage %p page %p not dirty?\n", inode, page);
                goto out;
        }
-       if (snapc != get_oldest_context(inode, &snap_size)) {
+       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, (void *)page->private);
                /* 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);
 
        /* is this a partial page at end of file? */
        if (snap_size)
@@ -458,7 +450,7 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
        ClearPagePrivate(page);
        end_page_writeback(page);
        ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
-       ceph_put_snap_context(snapc);
+       ceph_put_snap_context(snapc);  /* page's reference */
 out:
        return err;
 }
@@ -558,9 +550,9 @@ static void writepages_finish(struct ceph_osd_request *req,
                        dout("inode %p skipping page %p\n", inode, page);
                        wbc->pages_skipped++;
                }
+               ceph_put_snap_context((void *)page->private);
                page->private = 0;
                ClearPagePrivate(page);
-               ceph_put_snap_context(snapc);
                dout("unlocking %d %p\n", i, page);
                end_page_writeback(page);
 
@@ -618,7 +610,7 @@ static int ceph_writepages_start(struct address_space *mapping,
        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;
+       struct ceph_snap_context *snapc = NULL, *last_snapc = NULL, *pgsnapc;
        struct pagevec pvec;
        int done = 0;
        int rc = 0;
@@ -770,9 +762,10 @@ get_more_pages:
                        }
 
                        /* only if matching snap context */
-                       if (snapc != (void *)page->private) {
-                               dout("page snapc %p != oldest %p\n",
-                                    (void *)page->private, snapc);
+                       pgsnapc = (void *)page->private;
+                       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 */
@@ -914,7 +907,10 @@ 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);
-       return !oldest || snapc->seq <= oldest->seq;
+       int ret = !oldest || snapc->seq <= oldest->seq;
+
+       ceph_put_snap_context(oldest);
+       return ret;
 }
 
 /*
@@ -936,8 +932,8 @@ static int ceph_update_writeable_page(struct file *file,
        int pos_in_page = pos & ~PAGE_CACHE_MASK;
        int end_in_page = pos_in_page + len;
        loff_t i_size;
-       struct ceph_snap_context *snapc;
        int r;
+       struct ceph_snap_context *snapc, *oldest;
 
 retry_locked:
        /* writepages currently holds page lock, but if we change that later, */
@@ -947,23 +943,24 @@ retry_locked:
        BUG_ON(!ci->i_snap_realm);
        down_read(&mdsc->snap_rwsem);
        BUG_ON(!ci->i_snap_realm->cached_context);
-       if (page->private &&
-           (void *)page->private != ci->i_snap_realm->cached_context) {
+       snapc = (void *)page->private;
+       if (snapc && snapc != ci->i_head_snapc) {
                /*
                 * this page is already dirty in another (older) snap
                 * context!  is it writeable now?
                 */
-               snapc = get_oldest_context(inode, NULL);
+               oldest = get_oldest_context(inode, NULL);
                up_read(&mdsc->snap_rwsem);
 
-               if (snapc != (void *)page->private) {
+               if (snapc->seq > oldest->seq) {
+                       ceph_put_snap_context(oldest);
                        dout(" page %p snapc %p not current or oldest\n",
-                            page, (void *)page->private);
+                            page, snapc);
                        /*
                         * queue for writeback, and wait for snapc to
                         * be writeable or written
                         */
-                       snapc = ceph_get_snap_context((void *)page->private);
+                       snapc = ceph_get_snap_context(snapc);
                        unlock_page(page);
                        ceph_queue_writeback(inode);
                        r = wait_event_interruptible(ci->i_cap_wq,
@@ -973,6 +970,7 @@ retry_locked:
                                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",