• K
    writeback: fix periodic superblock dirty inode flushing · 0e0f4fc2
    Ken Chen 提交于
    Current -mm tree has bucketful of bug fixes in periodic writeback path.
    However, we still hit a glitch where dirty pages on a given inode aren't
    completely flushed to the disk, and system will accumulate large amount of
    dirty pages beyond what dirty_expire_interval is designed for.
    
    The problem is __sync_single_inode() will move an inode to sb->s_dirty list
    even when there are more pending dirty pages on that inode.  If there is
    another inode with a small number of dirty pages, we hit a case where the loop
    iteration in wb_kupdate() terminates prematurely because wbc.nr_to_write > 0.
    Thus leaving the inode that has large amount of dirty pages behind and it has
    to wait for another dirty_writeback_interval before we flush it again.  We
    effectively only write out MAX_WRITEBACK_PAGES every dirty_writeback_interval.
    If the rate of dirtying is sufficiently high, the system will start
    accumulate a large number of dirty pages.
    
    So fix it by having another sb->s_more_io list on which to park the inode
    while we iterate through sb->s_io and to allow each dirty inode which resides
    on that sb to have an equal chance of flushing some amount of dirty pages.
    Signed-off-by: NKen Chen <kenchen@google.com>
    Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
    0e0f4fc2
super.c 22.2 KB