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authorJosef Bacik <josef@redhat.com>2011-05-27 12:06:11 -0400
committerJosef Bacik <josef@redhat.com>2011-07-11 09:58:45 -0400
commitfa09200b8334f9a6af3f656edae924a98d85630f (patch)
tree9213ac48212f70d86fb60834beb464d68be332ba /fs/btrfs/xattr.c
parent149e2d76b4886c4c7ff5e077646a8ba3563c8026 (diff)
downloadlwn-fa09200b8334f9a6af3f656edae924a98d85630f.tar.gz
lwn-fa09200b8334f9a6af3f656edae924a98d85630f.zip
Btrfs: try to only do one btrfs_search_slot in do_setxattr
I've been watching how many btrfs_search_slot()'s we do and I noticed that when we create a file with selinux enabled we were doing 2 each time we initialize the security context. That's because we lookup the xattr first so we can delete it if we're setting a new value to an existing xattr. But in the create case we don't have any xattrs, so it is completely useless to have the extra lookup. So re-arrange things so that we only lookup first if we specifically have XATTR_REPLACE. That way in the basic case we only do 1 search, and in the more complicated case we do the normal 2 lookups. Thanks, Signed-off-by: Josef Bacik <josef@redhat.com>
Diffstat (limited to 'fs/btrfs/xattr.c')
-rw-r--r--fs/btrfs/xattr.c66
1 files changed, 40 insertions, 26 deletions
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 5366fe452ab0..d733b9cfea34 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -102,43 +102,57 @@ static int do_setxattr(struct btrfs_trans_handle *trans,
if (!path)
return -ENOMEM;
- /* first lets see if we already have this xattr */
- di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name,
- strlen(name), -1);
- if (IS_ERR(di)) {
- ret = PTR_ERR(di);
- goto out;
- }
-
- /* ok we already have this xattr, lets remove it */
- if (di) {
- /* if we want create only exit */
- if (flags & XATTR_CREATE) {
- ret = -EEXIST;
+ if (flags & XATTR_REPLACE) {
+ di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name,
+ name_len, -1);
+ if (IS_ERR(di)) {
+ ret = PTR_ERR(di);
+ goto out;
+ } else if (!di) {
+ ret = -ENODATA;
goto out;
}
-
ret = btrfs_delete_one_dir_name(trans, root, path, di);
- BUG_ON(ret);
+ if (ret)
+ goto out;
btrfs_release_path(path);
+ }
- /* if we don't have a value then we are removing the xattr */
- if (!value)
+again:
+ ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode),
+ name, name_len, value, size);
+ if (ret == -EEXIST) {
+ if (flags & XATTR_CREATE)
goto out;
- } else {
+ /*
+ * We can't use the path we already have since we won't have the
+ * proper locking for a delete, so release the path and
+ * re-lookup to delete the thing.
+ */
btrfs_release_path(path);
+ di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode),
+ name, name_len, -1);
+ if (IS_ERR(di)) {
+ ret = PTR_ERR(di);
+ goto out;
+ } else if (!di) {
+ /* Shouldn't happen but just in case... */
+ btrfs_release_path(path);
+ goto again;
+ }
- if (flags & XATTR_REPLACE) {
- /* we couldn't find the attr to replace */
- ret = -ENODATA;
+ ret = btrfs_delete_one_dir_name(trans, root, path, di);
+ if (ret)
goto out;
+
+ /*
+ * We have a value to set, so go back and try to insert it now.
+ */
+ if (value) {
+ btrfs_release_path(path);
+ goto again;
}
}
-
- /* ok we have to create a completely new xattr */
- ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode),
- name, name_len, value, size);
- BUG_ON(ret);
out:
btrfs_free_path(path);
return ret;