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authorNikanth Karthikesan <knikanth@suse.de>2009-03-24 12:29:54 +0100
committerJens Axboe <jens.axboe@oracle.com>2009-03-24 12:35:18 +0100
commit68db1961bbf4e16c220ccec4a780e966bc1fece3 (patch)
tree8101ee12fb24abd2e794ecadfedbc0e0c6859891 /drivers/block
parent05378940caf979a8655c18b18a17213dcfa52412 (diff)
loop: support barrier writes
Honour barrier requests in the loop back block device driver. In case of barrier bios, flush the backing file once before processing the barrier and once after to guarantee ordering. In case of filesystems that does not support fsync, barrier bios would be failed with -EOPNOTSUPP. Signed-off-by: Nikanth Karthikesan <knikanth@suse.de> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/loop.c32
1 files changed, 30 insertions, 2 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index bf034557767..9721d100caf 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -474,10 +474,35 @@ static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
int ret;
pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
- if (bio_rw(bio) == WRITE)
+
+ if (bio_rw(bio) == WRITE) {
+ int barrier = bio_barrier(bio);
+ struct file *file = lo->lo_backing_file;
+
+ if (barrier) {
+ if (unlikely(!file->f_op->fsync)) {
+ ret = -EOPNOTSUPP;
+ goto out;
+ }
+
+ ret = vfs_fsync(file, file->f_path.dentry, 0);
+ if (unlikely(ret)) {
+ ret = -EIO;
+ goto out;
+ }
+ }
+
ret = lo_send(lo, bio, pos);
- else
+
+ if (barrier && !ret) {
+ ret = vfs_fsync(file, file->f_path.dentry, 0);
+ if (unlikely(ret))
+ ret = -EIO;
+ }
+ } else
ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
+
+out:
return ret;
}
@@ -826,6 +851,9 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
lo->lo_queue->queuedata = lo;
lo->lo_queue->unplug_fn = loop_unplug;
+ if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
+ blk_queue_ordered(lo->lo_queue, QUEUE_ORDERED_DRAIN, NULL);
+
set_capacity(lo->lo_disk, size);
bd_set_size(bdev, size << 9);