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    SubjectRe: [PATCH 3/6] writeback: sync expired inodes first in background writeback
    > > Still, given wb_writeback() is the only caller of both
    > > __writeback_inodes_sb and writeback_inodes_wb(), I'm wondering if
    > > moving the queue_io calls up into wb_writeback() would clean up this
    > > logic somewhat. I think Jan mentioned doing something like this as
    > > well elsewhere in the thread...
    >
    > Unfortunately they call queue_io() inside the lock..

    OK, let's try moving up the lock too. Do you like this change? :)

    Thanks,
    Fengguang
    ---
    fs/fs-writeback.c | 22 ++++++----------------
    mm/backing-dev.c | 4 ++++
    2 files changed, 10 insertions(+), 16 deletions(-)

    --- linux-next.orig/fs/fs-writeback.c 2011-04-21 12:04:02.000000000 +0800
    +++ linux-next/fs/fs-writeback.c 2011-04-21 12:05:54.000000000 +0800
    @@ -591,7 +591,6 @@ void writeback_inodes_wb(struct bdi_writ

    if (!wbc->wb_start)
    wbc->wb_start = jiffies; /* livelock avoidance */
    - spin_lock(&inode_wb_list_lock);

    if (list_empty(&wb->b_io))
    queue_io(wb, wbc);
    @@ -610,22 +609,9 @@ void writeback_inodes_wb(struct bdi_writ
    if (ret)
    break;
    }
    - spin_unlock(&inode_wb_list_lock);
    /* Leave any unwritten inodes on b_io */
    }

    -static void __writeback_inodes_sb(struct super_block *sb,
    - struct bdi_writeback *wb, struct writeback_control *wbc)
    -{
    - WARN_ON(!rwsem_is_locked(&sb->s_umount));
    -
    - spin_lock(&inode_wb_list_lock);
    - if (list_empty(&wb->b_io))
    - queue_io(wb, wbc);
    - writeback_sb_inodes(sb, wb, wbc, true);
    - spin_unlock(&inode_wb_list_lock);
    -}
    -
    static inline bool over_bground_thresh(void)
    {
    unsigned long background_thresh, dirty_thresh;
    @@ -652,7 +638,7 @@ static unsigned long writeback_chunk_siz
    * The intended call sequence for WB_SYNC_ALL writeback is:
    *
    * wb_writeback()
    - * __writeback_inodes_sb() <== called only once
    + * writeback_sb_inodes() <== called only once
    * write_cache_pages() <== called once for each inode
    * (quickly) tag currently dirty pages
    * (maybe slowly) sync all tagged pages
    @@ -742,10 +728,14 @@ static long wb_writeback(struct bdi_writ

    retry:
    trace_wbc_writeback_start(&wbc, wb->bdi);
    + spin_lock(&inode_wb_list_lock);
    + if (list_empty(&wb->b_io))
    + queue_io(wb, wbc);
    if (work->sb)
    - __writeback_inodes_sb(work->sb, wb, &wbc);
    + writeback_sb_inodes(work->sb, wb, &wbc, true);
    else
    writeback_inodes_wb(wb, &wbc);
    + spin_unlock(&inode_wb_list_lock);
    trace_wbc_writeback_written(&wbc, wb->bdi);

    bdi_update_write_bandwidth(wb->bdi, wbc.wb_start);
    --- linux-next.orig/mm/backing-dev.c 2011-04-21 12:06:02.000000000 +0800
    +++ linux-next/mm/backing-dev.c 2011-04-21 12:06:31.000000000 +0800
    @@ -268,7 +268,11 @@ static void bdi_flush_io(struct backing_
    .nr_to_write = 1024,
    };

    + spin_lock(&inode_wb_list_lock);
    + if (list_empty(&wb->b_io))
    + queue_io(wb, wbc);
    writeback_inodes_wb(&bdi->wb, &wbc);
    + spin_unlock(&inode_wb_list_lock);
    }

    /*

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      Last update: 2011-04-21 06:13    [W:0.023 / U:1.972 seconds]
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