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SubjectRe: [PATCH 08/11] vfs: Merge check_submounts_and_drop and d_invalidate
On Sat, Feb 15, 2014 at 01:39:22PM -0800, Eric W. Biederman wrote:
>
> Now that d_invalidate is the only caller of check_submounts_and_drop,
> expand check_submounts_and_drop inline in d_invalidate.
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
> fs/dcache.c | 55 +++++++++++++++++++----------------------------
> include/linux/dcache.h | 1 -
> 2 files changed, 22 insertions(+), 34 deletions(-)
>
> diff --git a/fs/dcache.c b/fs/dcache.c
> index 27585b1dd6f1..5b41205cbf33 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -608,32 +608,6 @@ kill_it:
> }
> EXPORT_SYMBOL(dput);
>
> -/**
> - * d_invalidate - invalidate a dentry
> - * @dentry: dentry to invalidate
> - *
> - * Try to invalidate the dentry if it turns out to be
> - * possible. If there are reasons not to delete it
> - * return -EBUSY. On success return 0.
> - *
> - * no dcache lock.
> - */
> -
> -int d_invalidate(struct dentry * dentry)
> -{
> - /*
> - * If it's already been dropped, return OK.
> - */
> - spin_lock(&dentry->d_lock);
> - if (d_unhashed(dentry)) {
> - spin_unlock(&dentry->d_lock);
> - return 0;
> - }
> - spin_unlock(&dentry->d_lock);
> -
> - return check_submounts_and_drop(dentry);
> -}
> -EXPORT_SYMBOL(d_invalidate);
>
> /* This must be called with d_lock held */
> static inline void __dget_dlock(struct dentry *dentry)
> @@ -1175,7 +1149,7 @@ EXPORT_SYMBOL(have_submounts);
> * reachable (e.g. NFS can unhash a directory dentry and then the complete
> * subtree can become unreachable).
> *
> - * Only one of check_submounts_and_drop() and d_set_mounted() must succeed. For
> + * Only one of d_invalidate() and d_set_mounted() must succeed. For
> * this reason take rename_lock and d_lock on dentry and ancestors.
> */
> int d_set_mounted(struct dentry *dentry)
> @@ -1184,7 +1158,7 @@ int d_set_mounted(struct dentry *dentry)
> int ret = -ENOENT;
> write_seqlock(&rename_lock);
> for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) {
> - /* Need exclusion wrt. check_submounts_and_drop() */
> + /* Need exclusion wrt. d_invalidate() */
> spin_lock(&p->d_lock);
> if (unlikely(d_unhashed(p))) {
> spin_unlock(&p->d_lock);
> @@ -1400,18 +1374,33 @@ static void check_and_drop(void *_data)
> }
>
> /**
> - * check_submounts_and_drop - detach submounts, prune dcache, and drop
> + * d_invalidate - detach submounts, prune dcache, and drop
> + * @dentry: dentry to invalidate (aka detach, prune and drop)
> + *
> + * Try to invalidate the dentry if it turns out to be
> + * possible. If there are reasons not to delete it
> + * return -EBUSY. On success return 0.
> + *
> + * no dcache lock.
> *
> * The final d_drop is done as an atomic operation relative to
> * rename_lock ensuring there are no races with d_set_mounted. This
> * ensures there are no unhashed dentries on the path to a mountpoint.
> - *
> - * @dentry: dentry to detach, prune and drop
> */
> -int check_submounts_and_drop(struct dentry *dentry)
> +int d_invalidate(struct dentry *dentry)
> {
> int ret = 0;
>
> + /*
> + * If it's already been dropped, return OK.
> + */
> + spin_lock(&dentry->d_lock);
> + if (d_unhashed(dentry)) {
> + spin_unlock(&dentry->d_lock);
> + return 0;
> + }
> + spin_unlock(&dentry->d_lock);
> +
> /* Negative dentries can be dropped without further checks */
> if (!dentry->d_inode) {
> d_drop(dentry);


You can optimize this by including the negative check within the above d_locked
region and calling __d_drop() instead.

> @@ -1445,7 +1434,7 @@ int check_submounts_and_drop(struct dentry *dentry)
> out:
> return ret;
> }
> -EXPORT_SYMBOL(check_submounts_and_drop);
> +EXPORT_SYMBOL(d_invalidate);
>
> /**
> * __d_alloc - allocate a dcache entry
> diff --git a/include/linux/dcache.h b/include/linux/dcache.h
> index bf72e9ac6de0..ae77222c3e86 100644
> --- a/include/linux/dcache.h
> +++ b/include/linux/dcache.h
> @@ -265,7 +265,6 @@ extern void d_prune_aliases(struct inode *);
>
> /* test whether we have any submounts in a subdir tree */
> extern int have_submounts(struct dentry *);
> -extern int check_submounts_and_drop(struct dentry *);
>
> /*
> * This adds the entry to the hash queues.
> --
> 1.7.5.4
>


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