cleanup __writeback_single_inode

There is no reason to for the split between __writeback_single_inode and
__sync_single_inode, the former just does a couple of checks before
tail-calling the latter.  So merge the two, and while we're at it split
out the I_SYNC waiting case for data integrity writers, as it's
logically separate function.  Finally rename __writeback_single_inode to
writeback_single_inode.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index caf0491..c54226b 100644 (file)
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -278,7 +278,26 @@ int sb_has_dirty_inodes(struct super_block *sb)
 EXPORT_SYMBOL(sb_has_dirty_inodes);
 
 /*
- * Write a single inode's dirty pages and inode data out to disk.
+ * Wait for writeback on an inode to complete.
+ */
+static void inode_wait_for_writeback(struct inode *inode)
+{
+       DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC);
+       wait_queue_head_t *wqh;
+
+       wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
+       do {
+               spin_unlock(&inode_lock);
+               __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE);
+               spin_lock(&inode_lock);
+       } while (inode->i_state & I_SYNC);
+}
+
+/*
+ * Write out an inode's dirty pages.  Called under inode_lock.  Either the
+ * caller has ref on the inode (either via __iget or via syscall against an fd)
+ * or the inode has I_WILL_FREE set (via generic_forget_inode)
+ *
  * If `wait' is set, wait on the writeout.
  *
  * The whole writeout design is quite complex and fragile.  We want to avoid
@@ -288,13 +307,38 @@ EXPORT_SYMBOL(sb_has_dirty_inodes);
  * Called under inode_lock.
  */
 static int
-__sync_single_inode(struct inode *inode, struct writeback_control *wbc)
+writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 {
-       unsigned dirty;
        struct address_space *mapping = inode->i_mapping;
        int wait = wbc->sync_mode == WB_SYNC_ALL;
+       unsigned dirty;
        int ret;
 
+       if (!atomic_read(&inode->i_count))
+               WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING)));
+       else
+               WARN_ON(inode->i_state & I_WILL_FREE);
+
+       if (inode->i_state & I_SYNC) {
+               /*
+                * If this inode is locked for writeback and we are not doing
+                * writeback-for-data-integrity, move it to s_more_io so that
+                * writeback can proceed with the other inodes on s_io.
+                *
+                * We'll have another go at writing back this inode when we
+                * completed a full scan of s_io.
+                */
+               if (!wait) {
+                       requeue_io(inode);
+                       return 0;
+               }
+
+               /*
+                * It's a data-integrity sync.  We must wait.
+                */
+               inode_wait_for_writeback(inode);
+       }
+
        BUG_ON(inode->i_state & I_SYNC);
 
        /* Set I_SYNC, reset I_DIRTY */
@@ -389,50 +433,6 @@ __sync_single_inode(struct inode *inode, struct writeback_control *wbc)
        return ret;
 }
 
-/*
- * Write out an inode's dirty pages.  Called under inode_lock.  Either the
- * caller has ref on the inode (either via __iget or via syscall against an fd)
- * or the inode has I_WILL_FREE set (via generic_forget_inode)
- */
-static int
-__writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
-{
-       wait_queue_head_t *wqh;
-
-       if (!atomic_read(&inode->i_count))
-               WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING)));
-       else
-               WARN_ON(inode->i_state & I_WILL_FREE);
-
-       if ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_SYNC)) {
-               /*
-                * We're skipping this inode because it's locked, and we're not
-                * doing writeback-for-data-integrity.  Move it to s_more_io so
-                * that writeback can proceed with the other inodes on s_io.
-                * We'll have another go at writing back this inode when we
-                * completed a full scan of s_io.
-                */
-               requeue_io(inode);
-               return 0;
-       }
-
-       /*
-        * It's a data-integrity sync.  We must wait.
-        */
-       if (inode->i_state & I_SYNC) {
-               DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC);
-
-               wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
-               do {
-                       spin_unlock(&inode_lock);
-                       __wait_on_bit(wqh, &wq, inode_wait,
-                                                       TASK_UNINTERRUPTIBLE);
-                       spin_lock(&inode_lock);
-               } while (inode->i_state & I_SYNC);
-       }
-       return __sync_single_inode(inode, wbc);
-}
-
 /*
  * Write out a superblock's list of dirty inodes.  A wait will be performed
  * upon no inodes, all inodes or the final one, depending upon sync_mode.
@@ -526,7 +526,7 @@ void generic_sync_sb_inodes(struct super_block *sb,
                BUG_ON(inode->i_state & (I_FREEING | I_CLEAR));
                __iget(inode);
                pages_skipped = wbc->pages_skipped;
-               __writeback_single_inode(inode, wbc);
+               writeback_single_inode(inode, wbc);
                if (current_is_pdflush())
                        writeback_release(bdi);
                if (wbc->pages_skipped != pages_skipped) {
@@ -708,7 +708,7 @@ int write_inode_now(struct inode *inode, int sync)
 
        might_sleep();
        spin_lock(&inode_lock);
-       ret = __writeback_single_inode(inode, &wbc);
+       ret = writeback_single_inode(inode, &wbc);
        spin_unlock(&inode_lock);
        if (sync)
                inode_sync_wait(inode);
@@ -732,7 +732,7 @@ int sync_inode(struct inode *inode, struct writeback_control *wbc)
        int ret;
 
        spin_lock(&inode_lock);
-       ret = __writeback_single_inode(inode, wbc);
+       ret = writeback_single_inode(inode, wbc);
        spin_unlock(&inode_lock);
        return ret;
 }