On Wed, Aug 18, 2010 at 04:37:31AM +1000, Nick Piggin wrote:
> fs: dentry allocation consolidation
>
> There are 2 duplicate copies of code in dentry allocation in path lookup.
> Consolidate them into a single function.
>
> Signed-off-by: Nick Piggin <npiggin@xxxxxxxxx>
>
> ---
> fs/namei.c | 70 ++++++++++++++++++++++++++++---------------------------------
> 1 file changed, 33 insertions(+), 37 deletions(-)
>
> Index: linux-2.6/fs/namei.c
> ===================================================================
> --- linux-2.6.orig/fs/namei.c 2010-08-18 04:04:29.000000000 +1000
> +++ linux-2.6/fs/namei.c 2010-08-18 04:05:12.000000000 +1000
> @@ -686,6 +686,35 @@ static __always_inline void follow_dotdo
> }
>
> /*
> + * Allocate a dentry with name and parent, and perform a parent
> + * directory ->lookup on it. Returns the new dentry, or ERR_PTR
> + * on error. parent->d_inode->i_mutex must be held. d_lookup must
> + * have verified that no child exists while under i_mutex.
> + */
> +static struct dentry *d_alloc_and_lookup(struct dentry *parent,
> + struct qstr *name, struct nameidata *nd)
> +{
> + struct inode *inode = parent->d_inode;
> + struct dentry *dentry;
> + struct dentry *old;
> +
> + /* Don't create child dentry for a dead directory. */
> + if (unlikely(IS_DEADDIR(inode)))
> + return ERR_PTR(-ENOENT);
> +
> + dentry = d_alloc(parent, name);
> + if (unlikely(!dentry))
> + return ERR_PTR(-ENOMEM);
> +
> + old = inode->i_op->lookup(inode, dentry, nd);
> + if (unlikely(old)) {
> + dput(dentry);
> + dentry = old;
> + }
> + return dentry;
> +}
> +
> +/*
> * It's more convoluted than I'd like it to be, but... it's still fairly
> * small and for now I'd prefer to have fast path as straight as possible.
> * It _is_ time-critical.
> @@ -738,30 +767,13 @@ need_lookup:
> * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
> */
> dentry = d_lookup(parent, name);
> - if (!dentry) {
> - struct dentry *new;
> -
> - /* Don't create child dentry for a dead directory. */
> - dentry = ERR_PTR(-ENOENT);
> - if (IS_DEADDIR(dir))
> - goto out_unlock;
> -
> - new = d_alloc(parent, name);
> - dentry = ERR_PTR(-ENOMEM);
> - if (new) {
> - dentry = dir->i_op->lookup(dir, new, nd);
> - if (dentry)
> - dput(new);
> - else
> - dentry = new;
> - }
> -out_unlock:
> + if (likely(!dentry)) {
> + dentry = d_alloc_and_lookup(parent, name, nd);
> mutex_unlock(&dir->i_mutex);
> if (IS_ERR(dentry))
> goto fail;
> goto done;
> }
> -
> /*
> * Uhhuh! Nasty case: the cache was re-populated while
> * we waited on the semaphore. Need to revalidate.
> @@ -1135,24 +1147,8 @@ static struct dentry *__lookup_hash(stru
> if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
> dentry = do_revalidate(dentry, nd);
>
> - if (!dentry) {
> - struct dentry *new;
> -
> - /* Don't create child dentry for a dead directory. */
> - dentry = ERR_PTR(-ENOENT);
> - if (IS_DEADDIR(inode))
> - goto out;
> -
> - new = d_alloc(base, name);
> - dentry = ERR_PTR(-ENOMEM);
> - if (!new)
> - goto out;
> - dentry = inode->i_op->lookup(inode, new, nd);
> - if (!dentry)
> - dentry = new;
> - else
> - dput(new);
> - }
> + if (!dentry)
> + dentry = d_alloc_and_lookup(base, name, nd);
> out:
> return dentry;
> }
Looks good.
Reviewed-by: Valerie Aurora <vaurora@xxxxxxxxxx>
-VAL
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