From 60292bcc1b240a6708aa531c8ece1da2a78d560a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 18 Aug 2015 14:54:54 -0700 Subject: [PATCH] writeback: explain why @inode is allowed to be NULL for inode_congested() Signed-off-by: Tejun Heo Suggested-by: Jan Kara Signed-off-by: Jens Axboe --- fs/fs-writeback.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 38e103506484..128404310fc0 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -701,7 +701,7 @@ EXPORT_SYMBOL_GPL(wbc_account_io); /** * inode_congested - test whether an inode is congested - * @inode: inode to test for congestion + * @inode: inode to test for congestion (may be NULL) * @cong_bits: mask of WB_[a]sync_congested bits to test * * Tests whether @inode is congested. @cong_bits is the mask of congestion @@ -711,6 +711,9 @@ EXPORT_SYMBOL_GPL(wbc_account_io); * determined by whether the cgwb (cgroup bdi_writeback) for the blkcg * associated with @inode is congested; otherwise, the root wb's congestion * state is used. + * + * @inode is allowed to be NULL as this function is often called on + * mapping->host which is NULL for the swapper space. */ int inode_congested(struct inode *inode, int cong_bits) {