Convert to requeue_io_wait() for case: - kupdate cannot write all pages due to some blocking condition; - during sync, a file is being written to too fast, starving other files. In the case of sync, requeue_io_wait() can break the starvation because the inode requeued into s_more_io_wait will be served _after_ normal inodes, hence won't stand in the way of other inodes in the next run. Cc: Michael Rubin Cc: Peter Zijlstra Signed-off-by: Fengguang Wu --- fs/fs-writeback.c | 33 ++++++++------------------------- 1 files changed, 8 insertions(+), 25 deletions(-) --- linux-mm.orig/fs/fs-writeback.c +++ linux-mm/fs/fs-writeback.c @@ -275,37 +275,20 @@ __sync_single_inode(struct inode *inode, mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { /* * We didn't write back all the pages. nfs_writepages() - * sometimes bales out without doing anything. Redirty - * the inode; Move it from s_io onto s_more_io/s_dirty. + * sometimes bales out without doing anything. */ - /* - * akpm: if the caller was the kupdate function we put - * this inode at the head of s_dirty so it gets first - * consideration. Otherwise, move it to the tail, for - * the reasons described there. I'm not really sure - * how much sense this makes. Presumably I had a good - * reasons for doing it this way, and I'd rather not - * muck with it at present. - */ - if (wbc->for_kupdate) { + inode->i_state |= I_DIRTY_PAGES; + if (wbc->for_kupdate && wbc->nr_to_write <= 0) /* - * For the kupdate function we move the inode - * to s_more_io so it will get more writeout as - * soon as the queue becomes uncongested. + * slice used up: queue for next turn */ - inode->i_state |= I_DIRTY_PAGES; requeue_io(inode); - } else { + else /* - * Otherwise fully redirty the inode so that - * other inodes on this superblock will get some - * writeout. Otherwise heavy writing to one - * file would indefinitely suspend writeout of - * all the other files. + * 1) somehow blocked in kupdate: retry later + * 2) fast writer during sync: give others a try */ - inode->i_state |= I_DIRTY_PAGES; - redirty_tail(inode); - } + requeue_io_wait(inode); } else if (inode->i_state & I_DIRTY) { /* * Someone redirtied the inode while were writing back -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/