btrfs: replace barriers with explicit flush / FUA usage

Switch to the WRITE_FLUSH_FUA flag for log writes, remove the EOPNOTSUPP
detection for barriers and stop setting the barrier flag for discards.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

4 files changed, 5 insertions, 21 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 64f10082f04..5e789f4a3ed 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2063,7 +2063,7 @@ static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate)
         if (uptodate) {
                 set_buffer_uptodate(bh);
         } else {
-                if (!buffer_eopnotsupp(bh) && printk_ratelimit()) {
+                if (printk_ratelimit()) {
                         printk(KERN_WARNING "lost page write due to "
                                         "I/O error on %s\n",
                                        bdevname(bh->b_bdev, b));
@@ -2200,21 +2200,10 @@ static int write_dev_supers(struct btrfs_device *device,
                         bh->b_end_io = btrfs_end_buffer_write_sync;
                 }
 
-                if (i == last_barrier && do_barriers && device->barriers) {
-                        ret = submit_bh(WRITE_BARRIER, bh);
-                        if (ret == -EOPNOTSUPP) {
-                                printk("btrfs: disabling barriers on dev %s\n",
-                                       device->name);
-                                set_buffer_uptodate(bh);
-                                device->barriers = 0;
-                                /* one reference for submit_bh */
-                                get_bh(bh);
-                                lock_buffer(bh);
-                                ret = submit_bh(WRITE_SYNC, bh);
-                        }
-                } else {
+                if (i == last_barrier && do_barriers)
+                        ret = submit_bh(WRITE_FLUSH_FUA, bh);
+                else
                         ret = submit_bh(WRITE_SYNC, bh);
-                }
 
                 if (ret)
                         errors++;
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 32d094002a5..43dc9ea9aef 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1696,7 +1696,7 @@ static void btrfs_issue_discard(struct block_device *bdev,
                                 u64 start, u64 len)
 {
         blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_KERNEL,
-                        BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
+                        BLKDEV_IFL_WAIT);
 }
 
 static int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr,
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index dd318ff280b..e25e46a8b4e 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -398,7 +398,6 @@ static noinline int device_list_add(const char *path,
                 device->work.func = pending_bios_fn;
                 memcpy(device->uuid, disk_super->dev_item.uuid,
                        BTRFS_UUID_SIZE);
-                device->barriers = 1;
                 spin_lock_init(&device->io_lock);
                 device->name = kstrdup(path, GFP_NOFS);
                 if (!device->name) {
@@ -462,7 +461,6 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
                 device->devid = orig_dev->devid;
                 device->work.func = pending_bios_fn;
                 memcpy(device->uuid, orig_dev->uuid, sizeof(device->uuid));
-                device->barriers = 1;
                 spin_lock_init(&device->io_lock);
                 INIT_LIST_HEAD(&device->dev_list);
                 INIT_LIST_HEAD(&device->dev_alloc_list);
@@ -1489,7 +1487,6 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         trans = btrfs_start_transaction(root, 0);
         lock_chunks(root);
 
-        device->barriers = 1;
         device->writeable = 1;
         device->work.func = pending_bios_fn;
         generate_random_uuid(device->uuid);
@@ -3084,7 +3081,6 @@ static struct btrfs_device *add_missing_dev(struct btrfs_root *root,
                 return NULL;
         list_add(&device->dev_list,
                  &fs_devices->devices);
-        device->barriers = 1;
         device->dev_root = root->fs_info->dev_root;
         device->devid = devid;
         device->work.func = pending_bios_fn;
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 31b0fabdd2e..2b638b6e4ee 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -42,7 +42,6 @@ struct btrfs_device {
         int running_pending;
         u64 generation;
 
-        int barriers;
         int writeable;
         int in_fs_metadata;