On Wed, Aug 21, 2019 at 5:09 PM Khazhismel Kumykov <khazhy@xxxxxxxxxx> wrote:
>
> Implements the optimization noted in f75fdf22b0a8 ("fuse: don't use
> ->d_time"), as the additional memory can be significant. (In particular,
> on SLAB configurations this 8-byte alloc becomes 32 bytes). Per-dentry,
> this can consume significant memory.
>
> Signed-off-by: Khazhismel Kumykov <khazhy@xxxxxxxxxx>
Actually we are seeing this in production where a job creating a lot
of fuse files cause a lot of extra system level overhead.
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
> ---
> fs/fuse/dir.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
> index dd0f64f7bc06..f9c59a296568 100644
> --- a/fs/fuse/dir.c
> +++ b/fs/fuse/dir.c
> @@ -24,6 +24,18 @@ static void fuse_advise_use_readdirplus(struct inode *dir)
> set_bit(FUSE_I_ADVISE_RDPLUS, &fi->state);
> }
>
> +#if BITS_PER_LONG >= 64
> +static inline void fuse_dentry_settime(struct dentry *entry, u64 time)
> +{
> + entry->d_fsdata = (void *) time;
> +}
> +
> +static inline u64 fuse_dentry_time(struct dentry *entry)
> +{
> + return (u64)entry->d_fsdata;
> +}
> +
> +#else
> union fuse_dentry {
> u64 time;
> struct rcu_head rcu;
> @@ -38,6 +50,7 @@ static inline u64 fuse_dentry_time(struct dentry *entry)
> {
> return ((union fuse_dentry *) entry->d_fsdata)->time;
> }
> +#endif
>
> /*
> * FUSE caches dentries and attributes with separate timeout. The
> @@ -242,6 +255,7 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
> goto out;
> }
>
> +#if BITS_PER_LONG < 64
> static int fuse_dentry_init(struct dentry *dentry)
> {
> dentry->d_fsdata = kzalloc(sizeof(union fuse_dentry), GFP_KERNEL);
> @@ -254,16 +268,21 @@ static void fuse_dentry_release(struct dentry *dentry)
>
> kfree_rcu(fd, rcu);
> }
> +#endif
>
> const struct dentry_operations fuse_dentry_operations = {
> .d_revalidate = fuse_dentry_revalidate,
> +#if BITS_PER_LONG < 64
> .d_init = fuse_dentry_init,
> .d_release = fuse_dentry_release,
> +#endif
> };
>
> const struct dentry_operations fuse_root_dentry_operations = {
> +#if BITS_PER_LONG < 64
> .d_init = fuse_dentry_init,
> .d_release = fuse_dentry_release,
> +#endif
> };
>
> int fuse_valid_type(int m)
> --
> 2.23.0.187.g17f5b7556c-goog
>
