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authorJens Axboe <axboe@fb.com>2016-04-12 21:32:46 +0300
committerJens Axboe <axboe@fb.com>2016-04-13 00:46:27 +0300
commit93e9d8e836cb1a9a58b33eb6643bf061c6119ef2 (patch)
tree17a50abdadaa58686983510230932323bf5d123c /block/blk-settings.c
parente0489487ec9cd79ee1fa0dc5d3789c08b0e51a2c (diff)
downloadlinux-93e9d8e836cb1a9a58b33eb6643bf061c6119ef2.tar.xz
block: add ability to flag write back caching on a device
Add an internal helper and flag for setting whether a queue has write back caching, or write through (or none). Add a sysfs file to show this as well, and make it changeable from user space. This will replace the (awkward) blk_queue_flush() interface that drivers currently use to inform the block layer of write cache state and capabilities. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'block/blk-settings.c')
-rw-r--r--block/blk-settings.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 331e4eee0dda..c903bee43cf8 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -846,6 +846,32 @@ void blk_queue_flush_queueable(struct request_queue *q, bool queueable)
}
EXPORT_SYMBOL_GPL(blk_queue_flush_queueable);
+/**
+ * blk_queue_write_cache - configure queue's write cache
+ * @q: the request queue for the device
+ * @wc: write back cache on or off
+ * @fua: device supports FUA writes, if true
+ *
+ * Tell the block layer about the write cache of @q.
+ */
+void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua)
+{
+ spin_lock_irq(q->queue_lock);
+ if (wc) {
+ queue_flag_set(QUEUE_FLAG_WC, q);
+ q->flush_flags = REQ_FLUSH;
+ } else
+ queue_flag_clear(QUEUE_FLAG_WC, q);
+ if (fua) {
+ if (wc)
+ q->flush_flags |= REQ_FUA;
+ queue_flag_set(QUEUE_FLAG_FUA, q);
+ } else
+ queue_flag_clear(QUEUE_FLAG_FUA, q);
+ spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL_GPL(blk_queue_write_cache);
+
static int __init blk_settings_init(void)
{
blk_max_low_pfn = max_low_pfn - 1;