Revert "Revert "writeback: Refactor writeback_single_inode()""

This reverts commit 08b1ca0719e0fce7f2b17d9862cae24b3bb83b50.
Revert "Revert "vfs: Move waiting for inode writeback from end_writeback() to evict_inode()""

This reverts commit f8484108c2a7b37d7e98efcb0b75b805453971b0.
Revert "Revert "vfs: Rename end_writeback() to clear_inode()""

This reverts commit 627826bd0b5a2a307cb17dba2e8e89aa9d8b2880.
Revert "Revert "writeback: Avoid iput() from flusher thread""

This reverts commit 6d97d3b3d30264677668b0d741d4339385236e75.
fs: f2fs: Use clear_inode vfs

Signed-off-by: LaboDJ <jacopolabardi@gmail.com>