// SPDX-License-Identifier: GPL-2.0-only
/*
 * Linux v6.18, fs/fs-writeback.c: complete requeue_inode() function.
 * Copyright (C) 2002, Linus Torvalds.
 * Original file attribution: 10Apr2002 Andrew Morton, split from fs/inode.c.
 */

static void requeue_inode(struct inode *inode, struct bdi_writeback *wb,
			  struct writeback_control *wbc,
			  unsigned long dirtied_before)
{
	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 (wbc->pages_skipped) {
		/*
		 * Writeback is not making progress due to locked buffers.
		 * Skip this inode for now. Although having skipped pages
		 * is odd for clean inodes, it can happen for some
		 * filesystems so handle that gracefully.
		 */
		if (inode->i_state & I_DIRTY_ALL)
			redirty_tail_locked(inode, wb);
		else
			inode_cgwb_move_to_attached(inode, wb);
		return;
	}

	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 &&
		    !inode_dirtied_after(inode, dirtied_before)) {
			/* 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_locked(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_locked(inode, wb);
	} else if (inode->i_state & I_DIRTY_TIME) {
		inode->dirtied_when = jiffies;
		inode_io_list_move_locked(inode, wb, &wb->b_dirty_time);
		inode->i_state &= ~I_SYNC_QUEUED;
	} else {
		/* The inode is clean. Remove from writeback lists. */
		inode_cgwb_move_to_attached(inode, wb);
	}
}