Re: [RFC] NFS Support

Balaji Rao R
2008-06-30T15:20:46Z

On Mon, Jun 30, 2008 at 8:20 PM, Josef Bacik <jbacik@redhat.com> wrote:
> On Sun, Jun 29, 2008 at 05:05:31AM +0530, Balaji Rao wrote:
>> Hello,
>>
>> Here's a quick implementation of NFS support for btrfs. It works mostly. But
>> its still a bit buggy. I suspect it has to do something with inode locking.
>> When I unmount and mount a couple of times, it stops working i.e, when I do an
>> 'ls', it keeps waiting indefinitely. This is seen when accessing the filesystem
>> from a local mount point as well.
>>
>> Can anybody please review and tell me what stupid mistake I'm committing ?
>>
>
> You may want to send things in patch form. I'd recommend using the hg quilt
> plugin, its nice for adding patches easily.
Yes, since this was just an RFC, i thought it would be better to send
just the file I created.
>
>>
>> #include <linux/fs.h>
>> #include <linux/types.h>
>> #include "ctree.h"
>> #include "disk-io.h"
>> #include "btrfs_inode.h"
>> #include "print-tree.h"
>> #include "export.h"
>>
>> static int btrfs_encode_fh(struct dentry *dentry, u32 *fh_in, int *max_len,
>> int connectable)
>> { struct inode *inode = dentry->d_inode;
>> int len = *max_len;
>> u64 objectid, root_objectid;
>> u32 generation;
>> __le32 *fh = (__force __le32 *) fh_in;
>>
>> if ((len < 5 )|| (connectable && len < 8)) {
>> return 255;
>> }
>
> Magic numbers are a no-no.
OK :) Will change
>
>>
>> objectid = BTRFS_I(inode)->location.objectid;
>> root_objectid = BTRFS_I(inode)->root->objectid;
>> generation = inode->i_generation;
>>
>> len = 5;
>> fh[0] = cpu_to_le32((u32)(objectid >> 32));
>> fh[1] = cpu_to_le32((u32)(objectid & 0xffffffff));
>> fh[2] = cpu_to_le32((u32)(root_objectid >> 32));
>> fh[3] = cpu_to_le32((u32)(root_objectid & 0xffffffff));
>> fh[4] = cpu_to_le32(generation);
>>
>> if (connectable && !S_ISDIR(inode->i_mode)) {
>> struct inode *parent;
>>
>> spin_lock(&dentry->d_lock);
>>
>> parent = dentry->d_parent->d_inode;
>> objectid = BTRFS_I(parent)->location.objectid;
>> generation = parent->i_generation;
>>
>> fh[5] = cpu_to_le32((u32)(objectid >> 32));
>> fh[6] = cpu_to_le32((u32)(objectid & 0xffffffff));
>> fh[7] = cpu_to_le32(generation);
>>
>> spin_unlock(&dentry->d_lock);
>>
>> len += 3;
>
> there is no need to take the d_lock here.
OK. Will remove it. It was done at fs/ocfs2/export.c. So probably i
thought it was necessary.

<snip>

>> static struct dentry *btrfs_get_parent(struct dentry *child)
>> {
>> struct inode *dir = child->d_inode;
>> struct inode *inode;
>> struct dentry *parent;
>> struct btrfs_root *root = BTRFS_I(dir)->root;
>> struct btrfs_key key;
>> struct btrfs_path *path;
>> struct extent_buffer *leaf;
>> u32 nritems;
>> int slot;
>> u64 objectid;
>> int ret;
>>
>> path = btrfs_alloc_path();
>>
>> key.objectid = dir->i_ino;
>> btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
>> key.offset = 0;
>> ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
>> BUG_ON(ret == 0);
>> ret = 0;
>>
>> leaf = path->nodes[0];
>> slot = path->slots[0];
>> nritems = btrfs_header_nritems(leaf);
>> if (slot >= nritems)
>> return ERR_PTR(-EINVAL);
>>
>> btrfs_item_key_to_cpu(leaf, &key, slot);
>> if (key.objectid != dir->i_ino ||
>> key.type != BTRFS_INODE_REF_KEY) {
>> return ERR_PTR(-EINVAL);
>> }
>>
>
> in both of the above error cases you don't free the path, you need to do that.
Yes. Will do.

Thanks for the review!
--
warm regards

Balaji Rao