From 387125fc722a8ed432066b85a552917343bdafca Mon Sep 17 00:00:00 2001
From: Chris Mason <chris.mason@oracle.com>
Date: Fri, 18 Nov 2011 15:07:51 -0500
Subject: Btrfs: fix barrier flushes
When btrfs is writing the super blocks, it send barrier flushes to make
sure writeback caching drives get all the metadata on disk in the
right order.
But, we have two bugs in the way these are sent down. When doing
full commits (not via the tree log), we are sending the barrier down
before the last super when it should be going down before the first.
In multi-device setups, we should be waiting for the barriers to
complete on all devices before writing any of the supers.
Both of these bugs can cause corruptions on power failures. We fix it
with some new code to send down empty barriers to all devices before
writing the first super.
Alexandre Oliva found the multi-device bug. Arne Jansen did the async
barrier loop.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Reported-by: Alexandre Oliva <oliva@lsd.ic.unicamp.br>
---
fs/btrfs/disk-io.c | 145 ++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 128 insertions(+), 17 deletions(-)
(limited to 'fs/btrfs/disk-io.c')
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index b6a5c0dd0dd..48d30138237 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2573,22 +2573,10 @@ static int write_dev_supers(struct btrfs_device *device,
int errors = 0;
u32 crc;
u64 bytenr;
- int last_barrier = 0;
if (max_mirrors == 0)
max_mirrors = BTRFS_SUPER_MIRROR_MAX;
- /* make sure only the last submit_bh does a barrier */
- if (do_barriers) {
- for (i = 0; i < max_mirrors; i++) {
- bytenr = btrfs_sb_offset(i);
- if (bytenr + BTRFS_SUPER_INFO_SIZE >=
- device->total_bytes)
- break;
- last_barrier = i;
- }
- }
-
for (i = 0; i < max_mirrors; i++) {
bytenr = btrfs_sb_offset(i);
if (bytenr + BTRFS_SUPER_INFO_SIZE >= device->total_bytes)
@@ -2634,17 +2622,136 @@ static int write_dev_supers(struct btrfs_device *device,
bh->b_end_io = btrfs_end_buffer_write_sync;
}
- if (i == last_barrier && do_barriers)
- ret = submit_bh(WRITE_FLUSH_FUA, bh);
- else
- ret = submit_bh(WRITE_SYNC, bh);
-
+ /*
+ * we fua the first super. The others we allow
+ * to go down lazy.
+ */
+ ret = submit_bh(WRITE_FUA, bh);
if (ret)
errors++;
}
return errors < i ? 0 : -1;
}
+/*
+ * endio for the write_dev_flush, this will wake anyone waiting
+ * for the barrier when it is done
+ */
+static void btrfs_end_empty_barrier(struct bio *bio, int err)
+{
+ if (err) {
+ if (err == -EOPNOTSUPP)
+ set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
+ clear_bit(BIO_UPTODATE, &bio->bi_flags);
+ }
+ if (bio->bi_private)
+ complete(bio->bi_private);
+ bio_put(bio);
+}
+
+/*
+ * trigger flushes for one the devices. If you pass wait == 0, the flushes are
+ * sent down. With wait == 1, it waits for the previous flush.
+ *
+ * any device where the flush fails with eopnotsupp are flagged as not-barrier
+ * capable
+ */
+static int write_dev_flush(struct btrfs_device *device, int wait)
+{
+ struct bio *bio;
+ int ret = 0;
+
+ if (device->nobarriers)
+ return 0;
+
+ if (wait) {
+ bio = device->flush_bio;
+ if (!bio)
+ return 0;
+
+ wait_for_completion(&device->flush_wait);
+
+ if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
+ printk("btrfs: disabling barriers on dev %s\n",
+ device->name);
+ device->nobarriers = 1;
+ }
+ if (!bio_flagged(bio, BIO_UPTODATE)) {
+ ret = -EIO;
+ }
+
+ /* drop the reference from the wait == 0 run */
+ bio_put(bio);
+ device->flush_bio = NULL;
+
+ return ret;
+ }
+
+ /*
+ * one reference for us, and we leave it for the
+ * caller
+ */
+ device->flush_bio = NULL;;
+ bio = bio_alloc(GFP_NOFS, 0);
+ if (!bio)
+ return -ENOMEM;
+
+ bio->bi_end_io = btrfs_end_empty_barrier;
+ bio->bi_bdev = device->bdev;
+ init_completion(&device->flush_wait);
+ bio->bi_private = &device->flush_wait;
+ device->flush_bio = bio;
+
+ bio_get(bio);
+ submit_bio(WRITE_FLUSH, bio);
+
+ return 0;
+}
+
+/*
+ * send an empty flush down to each device in parallel,
+ * then wait for them
+ */
+static int barrier_all_devices(struct btrfs_fs_info *info)
+{
+ struct list_head *head;
+ struct btrfs_device *dev;
+ int errors = 0;
+ int ret;
+
+ /* send down all the barriers */
+ head = &info->fs_devices->devices;
+ list_for_each_entry_rcu(dev, head, dev_list) {
+ if (!dev->bdev) {
+ errors++;
+ continue;
+ }
+ if (!dev->in_fs_metadata || !dev->writeable)
+ continue;
+
+ ret = write_dev_flush(dev, 0);
+ if (ret)
+ errors++;
+ }
+
+ /* wait for all the barriers */
+ list_for_each_entry_rcu(dev, head, dev_list) {
+ if (!dev->bdev) {
+ errors++;
+ continue;
+ }
+ if (!dev->in_fs_metadata || !dev->writeable)
+ continue;
+
+ ret = write_dev_flush(dev, 1);
+ if (ret)
+ errors++;
+ }
+ if (errors)
+ return -EIO;
+ return 0;
+}
+
int write_all_supers(struct btrfs_root *root, int max_mirrors)
{
struct list_head *head;
@@ -2666,6 +2773,10 @@ int write_all_supers(struct btrfs_root *root, int max_mirrors)
mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
head = &root->fs_info->fs_devices->devices;
+
+ if (do_barriers)
+ barrier_all_devices(root->fs_info);
+
list_for_each_entry_rcu(dev, head, dev_list) {
if (!dev->bdev) {
total_errors++;
--
cgit v1.2.3-70-g09d2
From 32240a913d9f3a5aad42175d7696590ea1bfdb08 Mon Sep 17 00:00:00 2001
From: Jan Schmidt <list.btrfs@jan-o-sch.net>
Date: Sun, 20 Nov 2011 07:33:38 -0500
Subject: btrfs: mirror_num should be int, not u64
My previous patch introduced some u64 for failed_mirror variables, this one
makes it consistent again.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
---
fs/btrfs/disk-io.c | 2 +-
fs/btrfs/extent_io.c | 4 ++--
fs/btrfs/extent_io.h | 2 +-
3 files changed, 4 insertions(+), 4 deletions(-)
(limited to 'fs/btrfs/disk-io.c')
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 48d30138237..94abc25392f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -620,7 +620,7 @@ out:
static int btree_io_failed_hook(struct bio *failed_bio,
struct page *page, u64 start, u64 end,
- u64 mirror_num, struct extent_state *state)
+ int mirror_num, struct extent_state *state)
{
struct extent_io_tree *tree;
unsigned long len;
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 47fdba7853c..a877b8b212e 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2285,8 +2285,8 @@ static void end_bio_extent_readpage(struct bio *bio, int err)
clean_io_failure(start, page);
}
if (!uptodate) {
- u64 failed_mirror;
- failed_mirror = (unsigned long)bio->bi_bdev;
+ int failed_mirror;
+ failed_mirror = (int)(unsigned long)bio->bi_bdev;
if (tree->ops && tree->ops->readpage_io_failed_hook)
ret = tree->ops->readpage_io_failed_hook(
bio, page, start, end,
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index feb9be0e23b..7604c300132 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -70,7 +70,7 @@ struct extent_io_ops {
unsigned long bio_flags);
int (*readpage_io_hook)(struct page *page, u64 start, u64 end);
int (*readpage_io_failed_hook)(struct bio *bio, struct page *page,
- u64 start, u64 end, u64 failed_mirror,
+ u64 start, u64 end, int failed_mirror,
struct extent_state *state);
int (*writepage_io_failed_hook)(struct bio *bio, struct page *page,
u64 start, u64 end,
--
cgit v1.2.3-70-g09d2