get_old_root needs its lock on the root node only to clone that buffer.
However, when we call read_tree_block, we know already that we're not
going to clone the root node. Thus we can safely unlock before, to avoid
issues where read_tree_block makes potentially sleeping allocations.
Signed-off-by: Jan Schmidt <list.btrfs@xxxxxxxxxxxxx>
---
Thanks for pointing that out, liubo!
I added this additional patch on top of my patch staple at:
git://git.jan-o-sch.net/btrfs-unstable for-chris
I also made a second branch, because this last commit actually fixes
that's introduced by one of the patches in the patch set. So I folded
it into the respective commit:
git://git.jan-o-sch.net/btrfs-unstable for-chris-fixed
I made sure that the resulting code is the same.
Chris: please pull either one for rc3.
-Jan
---
fs/btrfs/ctree.c | 9 +++++++--
1 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index c608b3c..eba44b0 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1261,6 +1261,8 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
tm = tree_mod_log_search(root->fs_info, logical, time_seq);
if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
+ btrfs_tree_read_unlock(root->node);
+ free_extent_buffer(root->node);
blocksize = btrfs_level_size(root, old_root->level);
eb = read_tree_block(root, logical, blocksize, 0);
if (!eb) {
@@ -1271,12 +1273,15 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
eb = btrfs_clone_extent_buffer(eb);
}
} else if (old_root) {
+ btrfs_tree_read_unlock(root->node);
+ free_extent_buffer(root->node);
eb = alloc_dummy_extent_buffer(logical, root->nodesize);
} else {
eb = btrfs_clone_extent_buffer(root->node);
+ btrfs_tree_read_unlock(root->node);
+ free_extent_buffer(root->node);
}
- btrfs_tree_read_unlock(root->node);
- free_extent_buffer(root->node);
+
if (!eb)
return NULL;
extent_buffer_get(eb);
--
1.7.1
--
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