writeback: split wbc_attach_and_unlock_inode

Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 77db1f10023e117e34aafe8c698422c36036e6be..2b0b2a81d5655fe3313c5aa612c0cd1f58527fe9 100644 (file)
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -721,23 +721,21 @@ bool cleanup_offline_cgwb(struct bdi_writeback *wb)
 }
 
 /**
- * wbc_attach_and_unlock_inode - associate wbc with target inode and unlock it
+ * wbc_attach_inode - associate wbc with target inode
  * @wbc: writeback_control of interest
  * @inode: target inode
  *
  * @inode is locked and about to be written back under the control of @wbc.
- * Record @inode's writeback context into @wbc and unlock the i_lock.  On
- * writeback completion, wbc_detach_inode() should be called.  This is used
- * to track the cgroup writeback context.
+ * Record @inode's writeback context into @wbc.  On writeback completion,
+ * wbc_detach_inode() should be called.  This is used to track the cgroup
+ * writeback context.
  */
-static void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
-               struct inode *inode)
-       __releases(&inode->i_lock)
+static void wbc_attach_inode(struct writeback_control *wbc, struct inode *inode)
 {
-       if (!inode_cgwb_enabled(inode)) {
-               spin_unlock(&inode->i_lock);
+       if (!inode_cgwb_enabled(inode))
                return;
-       }
+
+       lockdep_assert_held(&inode->i_lock);
 
        wbc->wb = inode_to_wb(inode);
        wbc->inode = inode;
@@ -750,15 +748,17 @@ static void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
        wbc->wb_tcand_bytes = 0;
 
        wb_get(wbc->wb);
-       spin_unlock(&inode->i_lock);
+}
 
-       /*
-        * A dying wb indicates that either the blkcg associated with the
-        * memcg changed or the associated memcg is dying.  In the first
-        * case, a replacement wb should already be available and we should
-        * refresh the wb immediately.  In the second case, trying to
-        * refresh will keep failing.
-        */
+/*
+ * A dying wb indicates that either the blkcg associated with the memcg changed
+ * or the associated memcg is dying.  In the first case, a replacement wb should
+ * already be available and we should refresh the wb immediately.  In the second
+ * case, trying to refresh will keep failing.
+ */
+static void wbc_switch_dying_wb(struct writeback_control *wbc,
+               struct inode *inode)
+{
        if (unlikely(wb_dying(wbc->wb) && !css_is_dying(wbc->wb->memcg_css)))
                inode_switch_wbs(inode, wbc->wb_id);
 }
@@ -777,7 +777,10 @@ void wbc_attach_fdatawrite_inode(struct writeback_control *wbc,
 {
        spin_lock(&inode->i_lock);
        inode_attach_wb(inode, NULL);
-       wbc_attach_and_unlock_inode(wbc, inode);
+       wbc_attach_inode(wbc, inode);
+       spin_unlock(&inode->i_lock);
+
+       wbc_switch_dying_wb(wbc, inode);
 }
 EXPORT_SYMBOL_GPL(wbc_attach_fdatawrite_inode);
 
@@ -786,7 +789,7 @@ EXPORT_SYMBOL_GPL(wbc_attach_fdatawrite_inode);
  * @wbc: writeback_control of the just finished writeback
  *
  * To be called after a writeback attempt of an inode finishes and undoes
- * wbc_attach_and_unlock_inode().  Can be called under any context.
+ * wbc_attach_inode().  Can be called under any context.
  *
  * As concurrent write sharing of an inode is expected to be very rare and
  * memcg only tracks page ownership on first-use basis severely confining
@@ -1244,11 +1247,14 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,
        }
 }
 
-static inline void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
-                                              struct inode *inode)
-       __releases(&inode->i_lock)
+static inline void wbc_attach_inode(struct writeback_control *wbc,
+               struct inode *inode)
+{
+}
+
+static void wbc_switch_dying_wb(struct writeback_control *wbc,
+               struct inode *inode)
 {
-       spin_unlock(&inode->i_lock);
 }
 
 #endif /* CONFIG_CGROUP_WRITEBACK */
@@ -1798,7 +1804,10 @@ static int writeback_single_inode(struct inode *inode,
             !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK)))
                goto out;
        inode->i_state |= I_SYNC;
-       wbc_attach_and_unlock_inode(wbc, inode);
+       wbc_attach_inode(wbc, inode);
+       spin_unlock(&inode->i_lock);
+
+       wbc_switch_dying_wb(wbc, inode);
 
        ret = __writeback_single_inode(inode, wbc);
 
@@ -1965,7 +1974,10 @@ static long writeback_sb_inodes(struct super_block *sb,
                        continue;
                }
                inode->i_state |= I_SYNC;
-               wbc_attach_and_unlock_inode(&wbc, inode);
+               wbc_attach_inode(&wbc, inode);
+               spin_unlock(&inode->i_lock);
+
+               wbc_switch_dying_wb(&wbc, inode);
 
                write_chunk = writeback_chunk_size(wb, work);
                wbc.nr_to_write = write_chunk;