On Sun, Jan 08, 2012 at 11:50:40PM +0000, Al Viro wrote:
>
> WTF is ext4_symlink() doing in case of long symlinks? Look:
> drop_nlink(inode);
> err = ext4_orphan_add(handle, inode);
> ext4_journal_stop(handle);
> [write symlink body]
> inc_nlink(inode);
> err = ext4_orphan_del(handle, inode);
> oh, I see... The comment above that re deadlocks and inability to do that
> in a single transaction ;-/
>
> OK, try this; that's equivalent to what they are doing and will not WARN_ON();
> I hadn't checked other filesystems for similar tricks yet, so this has a good
> chance of being incomplete.
>
> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> index 86edc45..2043f48 100644
> --- a/fs/ext4/namei.c
> +++ b/fs/ext4/namei.c
> @@ -2315,7 +2315,7 @@ retry:
> err = PTR_ERR(handle);
> goto err_drop_inode;
> }
> - inc_nlink(inode);
> + set_nlink(inode, 1);
> err = ext4_orphan_del(handle, inode);
> if (err) {
> ext4_journal_stop(handle);
Thanks, looks good to me.
Acked-by: "Theodore Ts'o" <tytso@xxxxxxx>
What's there is a bit of kludge, granted. But an attempt to optimize
out placing the inode on and off the orphan list (either by deferring
the start of the ext3/4 journal handle, or by special casing the block
used for the long symlink) would add a lot of complexity, and creating
long symlinks is not common case in most workloads...
- Ted
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