The patch titled Subject: block-document-blk-plug-v3 has been removed from the -mm tree. Its filename was block-document-blk-plug-v3.patch This patch was dropped because it was folded into block-document-blk-plug.patch The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ From: Suresh Jayaraman <sjayaraman@xxxxxxx> Subject: block-document-blk-plug-v3 * clarify why we need not disable preemption while modifying the plug list. Signed-off-by: Suresh Jayaraman <sjayaraman@xxxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> Cc: Shaohua Li <shaohua.li@xxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxx> --- block/blk-core.c | 2 +- include/linux/blkdev.h | 16 ++++++++-------- 2 files changed, 9 insertions(+), 9 deletions(-) diff -puN block/blk-core.c~block-document-blk-plug-v3 block/blk-core.c --- a/block/blk-core.c~block-document-blk-plug-v3 +++ a/block/blk-core.c @@ -2641,7 +2641,7 @@ EXPORT_SYMBOL(kblockd_schedule_delayed_w * for a memory allocation, memory reclaim could end up wanting to free a * page belonging to that request that is currently residing in our private * plug. By flushing the pending I/O when the process goes to sleep, we avoid - * this kind of deadlock. + * this kind of deadlocks. */ void blk_start_plug(struct blk_plug *plug) { diff -puN include/linux/blkdev.h~block-document-blk-plug-v3 include/linux/blkdev.h --- a/include/linux/blkdev.h~block-document-blk-plug-v3 +++ a/include/linux/blkdev.h @@ -863,16 +863,16 @@ struct request_queue *blk_alloc_queue_no extern void blk_put_queue(struct request_queue *); /* - * blk_plug permits building a queue of related requests by holding the I/O + * blk_plug allows to build up a queue of related requests by holding the I/O * fragments for a short period. This allows merging of sequential requests - * into single larger request. As the requests are moved from a per-task list to - * the device's request_queue in a batch, this results in improved scalability - * as the lock contention for request_queue lock is reduced. + * into single larger request. As the requests are moved from per-task list to + * the device's request_queue in a batch, this results in improved + * scalability as the lock contention for request_queue lock is reduced. * - * Note: code in between changing the blk_plug list/cb_list or an element of - * these lists is preemptible, but such code cannot sleep (or must be very - * careful), otherwise data is corrupted. For details, please check schedule() - * where blk_schedule_flush_plug() is called. + * It is ok not to disable preemption when adding the request to the plug list + * or when attempting merge, because blk_schedule_flush_list() will only flush + * the plug list when the task sleeps by itself. For details, please check + * schedule() where blk_schedule_flush_plug() is called. */ struct blk_plug { unsigned long magic; /* detect uninitialized use-cases */ _ Patches currently in -mm which might be from sjayaraman@xxxxxxx are block-document-blk-plug.patch block-document-blk-plug-v3-fix.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html