[PATCH 20/30] btrfs: replace barriers with explicit flush / FUA usage

From: Tejun Heo
Date: Wed Aug 25 2010 - 12:05:03 EST


From: Christoph Hellwig <hch@xxxxxxxxxxxxx>

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@xxxxxx>
Acked-by: Chris Mason <chris.mason@xxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
fs/btrfs/disk-io.c | 19 ++++---------------
fs/btrfs/extent-tree.c | 2 +-
fs/btrfs/volumes.c | 4 ----
fs/btrfs/volumes.h | 1 -
4 files changed, 5 insertions(+), 21 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 64f1008..5e789f4 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 32d0940..43dc9ea 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 dd318ff..e25e46a 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 31b0fab..2b638b6 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;

--
1.7.1

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