[PATCH v2] block: remove plugging at buffered write time
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From: Wu Fengguang <hidden>
Date: 2012-02-10 13:15:39
Also in:
lkml
Buffered write(2) is not directly tied to IO, so it's not suitable to handle plug in generic_file_aio_write(). Also moves unplugging for direct I/O from around ->direct_IO() down to do_blockdev_direct_IO(). Note that plugging for O_SYNC writes is also removed. The user may pass arbitrary @size arguments, which may be much larger than the preferable I/O size, or may cross extent/device boundaries. Let the lower layers handle the plugging. The plugging code here actually turns them into no-ops. CC: Jens Axboe <axboe@kernel.dk> CC: Li Shaohua <redacted> Signed-off-by: Wu Fengguang <redacted> --- fs/direct-io.c | 5 +++++ fs/sync.c | 11 ++++++++++- mm/filemap.c | 7 ------- 3 files changed, 15 insertions(+), 8 deletions(-)
--- linux-next.orig/mm/filemap.c 2012-02-08 19:33:29.000000000 +0800
+++ linux-next/mm/filemap.c 2012-02-09 15:59:47.000000000 +0800@@ -1421,12 +1421,8 @@ generic_file_aio_read(struct kiocb *iocb retval = filemap_write_and_wait_range(mapping, pos, pos + iov_length(iov, nr_segs) - 1); if (!retval) { - struct blk_plug plug; - - blk_start_plug(&plug); retval = mapping->a_ops->direct_IO(READ, iocb, iov, pos, nr_segs); - blk_finish_plug(&plug); } if (retval > 0) { *ppos = pos + retval;
@@ -2610,13 +2606,11 @@ ssize_t generic_file_aio_write(struct ki { struct file *file = iocb->ki_filp; struct inode *inode = file->f_mapping->host; - struct blk_plug plug; ssize_t ret; BUG_ON(iocb->ki_pos != pos); mutex_lock(&inode->i_mutex); - blk_start_plug(&plug); ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); mutex_unlock(&inode->i_mutex);
@@ -2627,7 +2621,6 @@ ssize_t generic_file_aio_write(struct ki if (err < 0 && ret > 0) ret = err; } - blk_finish_plug(&plug); return ret; } EXPORT_SYMBOL(generic_file_aio_write); --- linux-next.orig/fs/direct-io.c 2012-02-08 19:33:29.000000000 +0800 +++ linux-next/fs/direct-io.c 2012-02-09 16:03:04.000000000 +0800
@@ -1106,6 +1106,7 @@ do_blockdev_direct_IO(int rw, struct kio unsigned long user_addr; size_t bytes; struct buffer_head map_bh = { 0, }; + struct blk_plug plug; if (rw & WRITE) rw = WRITE_ODIRECT;
@@ -1221,6 +1222,8 @@ do_blockdev_direct_IO(int rw, struct kio PAGE_SIZE - user_addr / PAGE_SIZE); } + blk_start_plug(&plug); + for (seg = 0; seg < nr_segs; seg++) { user_addr = (unsigned long)iov[seg].iov_base; sdio.size += bytes = iov[seg].iov_len;
@@ -1279,6 +1282,8 @@ do_blockdev_direct_IO(int rw, struct kio if (sdio.bio) dio_bio_submit(dio, &sdio); + blk_finish_plug(&plug); + /* * It is possible that, we return short IO due to end of file. * In that case, we need to release all the pages we got hold on.