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authorJosef Bacik <jbacik@fusionio.com>2012-09-14 12:59:20 -0400
committerChris Mason <chris.mason@fusionio.com>2012-10-04 09:39:58 -0400
commitff44c6e36dc9dcc02652a1105b120bdf08cea9f7 (patch)
treee3be38a3bc4fc628aacc35a361446da8694c1301 /fs/btrfs/tree-log.c
parent98114659e0d467e2c0ee6f24f2429329328fc312 (diff)
Btrfs: do not hold the write_lock on the extent tree while logging
Dave Sterba pointed out a sleeping while atomic bug while doing fsync. This is because I'm an idiot and didn't realize that rwlock's were spin locks, so we've been holding this thing while doing allocations and such which is not good. This patch fixes this by dropping the write lock before we do anything heavy and re-acquire it when it is done. We also need to take a ref on the em's in case their corresponding pages are evicted and mark them as being logged so that releasepage does not remove them and doesn't remove them from our local list. Thanks, Reported-by: Dave Sterba <dave@jikos.cz> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Diffstat (limited to 'fs/btrfs/tree-log.c')
-rw-r--r--fs/btrfs/tree-log.c21
1 files changed, 17 insertions, 4 deletions
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 038a5229404..ed1f7ce7219 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2945,6 +2945,9 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
list_del_init(&em->list);
if (em->generation <= test_gen)
continue;
+ /* Need a ref to keep it from getting evicted from cache */
+ atomic_inc(&em->refs);
+ set_bit(EXTENT_FLAG_LOGGING, &em->flags);
list_add_tail(&em->list, &extents);
}
@@ -2954,13 +2957,18 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
em = list_entry(extents.next, struct extent_map, list);
list_del_init(&em->list);
+ clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
/*
* If we had an error we just need to delete everybody from our
* private list.
*/
- if (ret)
+ if (ret) {
+ free_extent_map(em);
continue;
+ }
+
+ write_unlock(&tree->lock);
/*
* If the previous EM and the last extent we left off on aren't
@@ -2971,21 +2979,26 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
ret = copy_items(trans, inode, dst_path, args.src,
args.start_slot, args.nr,
LOG_INODE_ALL);
- if (ret)
+ if (ret) {
+ free_extent_map(em);
+ write_lock(&tree->lock);
continue;
+ }
btrfs_release_path(path);
args.nr = 0;
}
ret = log_one_extent(trans, inode, root, em, path, dst_path, &args);
+ free_extent_map(em);
+ write_lock(&tree->lock);
}
+ WARN_ON(!list_empty(&extents));
+ write_unlock(&tree->lock);
if (!ret && args.nr)
ret = copy_items(trans, inode, dst_path, args.src,
args.start_slot, args.nr, LOG_INODE_ALL);
btrfs_release_path(path);
- WARN_ON(!list_empty(&extents));
- write_unlock(&tree->lock);
return ret;
}