fs/fs-writeback.c: restore lost comment

I had to go back to a 2.6.20 tree to work out why we're adding a
number-of-inodes into a number-of-pages count.  Restore the lost comment.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 97d2951bd4d1..b5aae4bd0aca 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -721,6 +721,10 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb)
                 return 0;
 
         wb->last_old_flush = jiffies;
+        /*
+         * Add in the number of potentially dirty inodes, because each inode
+         * write can dirty pagecache in the underlying blockdev.
+         */
         nr_pages = global_page_state(NR_FILE_DIRTY) +
                         global_page_state(NR_UNSTABLE_NFS) +
                         (inodes_stat.nr_inodes - inodes_stat.nr_unused);