From: Andrew Morton NFS needs to be able to distinguish between single-page ->writepage() calls and multipage ->writepages() calls. For the single-page writepage calls NFS can kick off the I/O within the context of ->writepage(). For multipage ->writepages calls, nfs_writepage() will leave the I/O pending and nfs_writepages() will kick off the I/O when it all has been queued up within NFS. Cc: Trond Myklebust Signed-off-by: Andrew Morton --- include/linux/writeback.h | 9 +++++---- mm/page-writeback.c | 10 ++++++++-- 2 files changed, 13 insertions(+), 6 deletions(-) diff -puN include/linux/writeback.h~writeback_control-flag-writepages include/linux/writeback.h --- devel/include/linux/writeback.h~writeback_control-flag-writepages 2005-11-16 16:13:32.000000000 -0800 +++ devel-akpm/include/linux/writeback.h 2005-11-16 16:13:32.000000000 -0800 @@ -53,10 +53,11 @@ struct writeback_control { loff_t start; loff_t end; - unsigned nonblocking:1; /* Don't get stuck on request queues */ - unsigned encountered_congestion:1; /* An output: a queue is full */ - unsigned for_kupdate:1; /* A kupdate writeback */ - unsigned for_reclaim:1; /* Invoked from the page allocator */ + unsigned nonblocking:1; /* Don't get stuck on request queues */ + unsigned encountered_congestion:1; /* An output: a queue is full */ + unsigned for_kupdate:1; /* A kupdate writeback */ + unsigned for_reclaim:1; /* Invoked from the page allocator */ + unsigned for_writepages:1; /* This is a writepages() call */ }; /* diff -puN mm/page-writeback.c~writeback_control-flag-writepages mm/page-writeback.c --- devel/mm/page-writeback.c~writeback_control-flag-writepages 2005-11-16 16:13:32.000000000 -0800 +++ devel-akpm/mm/page-writeback.c 2005-11-16 16:13:32.000000000 -0800 @@ -550,11 +550,17 @@ void __init page_writeback_init(void) int do_writepages(struct address_space *mapping, struct writeback_control *wbc) { + int ret; + if (wbc->nr_to_write <= 0) return 0; + wbc->for_writepages = 1; if (mapping->a_ops->writepages) - return mapping->a_ops->writepages(mapping, wbc); - return generic_writepages(mapping, wbc); + ret = mapping->a_ops->writepages(mapping, wbc); + else + ret = generic_writepages(mapping, wbc); + wbc->for_writepages = 0; + return ret; } /** _