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authorJosef Bacik <josef@redhat.com>2011-04-11 17:25:13 -0400
committerJosef Bacik <josef@redhat.com>2011-05-23 13:00:57 -0400
commita4abeea41adfa3c143c289045f4625dfaeba2212 (patch)
tree792e2a398d8ba77447ba3f9f2c4266a1ce2f611c /fs/btrfs/relocation.c
parent2a1eb4614d984d5cd4c928784e9afcf5c07f93be (diff)
downloadlinux-a4abeea41adfa3c143c289045f4625dfaeba2212.tar.gz
Btrfs: kill trans_mutex
We use trans_mutex for lots of things, here's a basic list 1) To serialize trans_handles joining the currently running transaction 2) To make sure that no new trans handles are started while we are committing 3) To protect the dead_roots list and the transaction lists Really the serializing trans_handles joining is not too hard, and can really get bogged down in acquiring a reference to the transaction. So replace the trans_mutex with a trans_lock spinlock and use it to do the following 1) Protect fs_info->running_transaction. All trans handles have to do is check this, and then take a reference of the transaction and keep on going. 2) Protect the fs_info->trans_list. This doesn't get used too much, basically it just holds the current transactions, which will usually just be the currently committing transaction and the currently running transaction at most. 3) Protect the dead roots list. This is only ever processed by splicing the list so this is relatively simple. 4) Protect the fs_info->reloc_ctl stuff. This is very lightweight and was using the trans_mutex before, so this is a pretty straightforward change. 5) Protect fs_info->no_trans_join. Because we don't hold the trans_lock over the entirety of the commit we need to have a way to block new people from creating a new transaction while we're doing our work. So we set no_trans_join and in join_transaction we test to see if that is set, and if it is we do a wait_on_commit. 6) Make the transaction use count atomic so we don't need to take locks to modify it when we're dropping references. 7) Add a commit_lock to the transaction to make sure multiple people trying to commit the same transaction don't race and commit at the same time. 8) Make open_ioctl_trans an atomic so we don't have to take any locks for ioctl trans. I have tested this with xfstests, but obviously it is a pretty hairy change so lots of testing is greatly appreciated. Thanks, Signed-off-by: Josef Bacik <josef@redhat.com>
Diffstat (limited to 'fs/btrfs/relocation.c')
-rw-r--r--fs/btrfs/relocation.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 8bb256667f2..09c30d37d43 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2136,10 +2136,10 @@ int prepare_to_merge(struct reloc_control *rc, int err)
u64 num_bytes = 0;
int ret;
- mutex_lock(&root->fs_info->trans_mutex);
+ spin_lock(&root->fs_info->trans_lock);
rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
rc->merging_rsv_size += rc->nodes_relocated * 2;
- mutex_unlock(&root->fs_info->trans_mutex);
+ spin_unlock(&root->fs_info->trans_lock);
again:
if (!err) {
num_bytes = rc->merging_rsv_size;
@@ -2208,9 +2208,9 @@ int merge_reloc_roots(struct reloc_control *rc)
int ret;
again:
root = rc->extent_root;
- mutex_lock(&root->fs_info->trans_mutex);
+ spin_lock(&root->fs_info->trans_lock);
list_splice_init(&rc->reloc_roots, &reloc_roots);
- mutex_unlock(&root->fs_info->trans_mutex);
+ spin_unlock(&root->fs_info->trans_lock);
while (!list_empty(&reloc_roots)) {
found = 1;
@@ -3583,17 +3583,17 @@ next:
static void set_reloc_control(struct reloc_control *rc)
{
struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
- mutex_lock(&fs_info->trans_mutex);
+ spin_lock(&fs_info->trans_lock);
fs_info->reloc_ctl = rc;
- mutex_unlock(&fs_info->trans_mutex);
+ spin_unlock(&fs_info->trans_lock);
}
static void unset_reloc_control(struct reloc_control *rc)
{
struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
- mutex_lock(&fs_info->trans_mutex);
+ spin_lock(&fs_info->trans_lock);
fs_info->reloc_ctl = NULL;
- mutex_unlock(&fs_info->trans_mutex);
+ spin_unlock(&fs_info->trans_lock);
}
static int check_extent_flags(u64 flags)