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authorChris Mason <chris.mason@oracle.com>2009-02-04 17:24:25 +0300
committerChris Mason <chris.mason@oracle.com>2009-02-04 17:24:25 +0300
commitc487685d7c18a8481900755aa5c56a7a74193101 (patch)
treef2ff6c059e24d7fdf2e1fff498bbef0bb90bfbfc /fs/btrfs/ctree.c
parent3935127c50c84106d654ef14962cff28c660bc62 (diff)
downloadlinux-c487685d7c18a8481900755aa5c56a7a74193101.tar.xz
Btrfs: hash_lock is no longer needed
Before metadata is written to disk, it is updated to reflect that writeout has begun. Once this update is done, the block must be cow'd before it can be modified again. This update was originally synchronized by using a per-fs spinlock. Today the buffers for the metadata blocks are locked before writeout begins, and everyone that tests the flag has the buffer locked as well. So, the per-fs spinlock (called hash_lock for no good reason) is no longer required. Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/ctree.c')
-rw-r--r--fs/btrfs/ctree.c7
1 files changed, 1 insertions, 6 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 2603ee539b7a..3b6e35aafc9e 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -388,16 +388,14 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
WARN_ON(1);
}
- spin_lock(&root->fs_info->hash_lock);
if (btrfs_header_generation(buf) == trans->transid &&
btrfs_header_owner(buf) == root->root_key.objectid &&
!btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
*cow_ret = buf;
- spin_unlock(&root->fs_info->hash_lock);
WARN_ON(prealloc_dest);
return 0;
}
- spin_unlock(&root->fs_info->hash_lock);
+
search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
ret = __btrfs_cow_block(trans, root, buf, parent,
parent_slot, cow_ret, search_start, 0,
@@ -1376,14 +1374,11 @@ again:
int wret;
/* is a cow on this block not required */
- spin_lock(&root->fs_info->hash_lock);
if (btrfs_header_generation(b) == trans->transid &&
btrfs_header_owner(b) == root->root_key.objectid &&
!btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) {
- spin_unlock(&root->fs_info->hash_lock);
goto cow_done;
}
- spin_unlock(&root->fs_info->hash_lock);
/* ok, we have to cow, is our old prealloc the right
* size?