writeback: Separate inode requeueing after writeback (ccb26b5a) · Commits · EulixOS / Software / Kernel

fs/fs-writeback.c

+55 −47

Original line number	Diff line number	Diff line
		@@ -344,6 +344,60 @@ static void inode_wait_for_writeback(struct inode *inode,
		}
		}

		/*
		* Find proper writeback list for the inode depending on its current state and
		* possibly also change of its state while we were doing writeback. Here we
		* handle things such as livelock prevention or fairness of writeback among
		* inodes. This function can be called only by flusher thread - noone else
		* processes all inodes in writeback lists and requeueing inodes behind flusher
		* thread's back can have unexpected consequences.
		*/
		static void requeue_inode(struct inode inode, struct bdi_writeback wb,
		struct writeback_control *wbc)
		{
		if (inode->i_state & I_FREEING)
		return;

		/*
		* Sync livelock prevention. Each inode is tagged and synced in one
		* shot. If still dirty, it will be redirty_tail()'ed below. Update
		* the dirty time to prevent enqueue and sync it again.
		*/
		if ((inode->i_state & I_DIRTY) &&
		(wbc->sync_mode == WB_SYNC_ALL \|\| wbc->tagged_writepages))
		inode->dirtied_when = jiffies;

		if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) {
		/*
		* We didn't write back all the pages. nfs_writepages()
		* sometimes bales out without doing anything.
		*/
		if (wbc->nr_to_write <= 0) {
		/* Slice used up. Queue for next turn. */
		requeue_io(inode, wb);
		} else {
		/*
		* Writeback blocked by something other than
		* congestion. Delay the inode for some time to
		* avoid spinning on the CPU (100% iowait)
		* retrying writeback of the dirty page/inode
		* that cannot be performed immediately.
		*/
		redirty_tail(inode, wb);
		}
		} else if (inode->i_state & I_DIRTY) {
		/*
		* Filesystems can dirty the inode during writeback operations,
		* such as delayed allocation during submission or metadata
		* updates after data IO completion.
		*/
		redirty_tail(inode, wb);
		} else {
		/* The inode is clean. Remove from writeback lists. */
		list_del_init(&inode->i_wb_list);
		}
		}

		/*
		* Write out an inode's dirty pages. Called under wb->list_lock and
		* inode->i_lock. Either the caller has an active reference on the inode or
		@@ -422,53 +476,7 @@ writeback_single_inode(struct inode inode, struct bdi_writeback wb,

		spin_lock(&wb->list_lock);
		spin_lock(&inode->i_lock);
		if (!(inode->i_state & I_FREEING)) {
		/*
		* Sync livelock prevention. Each inode is tagged and synced in
		* one shot. If still dirty, it will be redirty_tail()'ed below.
		* Update the dirty time to prevent enqueue and sync it again.
		*/
		if ((inode->i_state & I_DIRTY) &&
		(wbc->sync_mode == WB_SYNC_ALL \|\| wbc->tagged_writepages))
		inode->dirtied_when = jiffies;

		if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
		/*
		* We didn't write back all the pages. nfs_writepages()
		* sometimes bales out without doing anything.
		*/
		if (wbc->nr_to_write <= 0) {
		/*
		* slice used up: queue for next turn
		*/
		requeue_io(inode, wb);
		} else {
		/*
		* Writeback blocked by something other than
		* congestion. Delay the inode for some time to
		* avoid spinning on the CPU (100% iowait)
		* retrying writeback of the dirty page/inode
		* that cannot be performed immediately.
		*/
		redirty_tail(inode, wb);
		}
		} else if (inode->i_state & I_DIRTY) {
		/*
		* Filesystems can dirty the inode during writeback
		* operations, such as delayed allocation during
		* submission or metadata updates after data IO
		* completion.
		*/
		redirty_tail(inode, wb);
		} else {
		/*
		* The inode is clean. At this point we either have
		* a reference to the inode or it's on it's way out.
		* No need to add it back to the LRU.
		*/
		list_del_init(&inode->i_wb_list);
		}
		}
		requeue_inode(inode, wb, wbc);
		inode_sync_complete(inode);
		trace_writeback_single_inode(inode, wbc, nr_to_write);
		return ret;