On Sat, 2023-04-08 at 19:43 +0300, Amir Goldstein wrote:
> Now that we have the entire lower stack in ovl_inode, we do not
> need to hold another reference to the lowerdata inode.
>
> Instead, use the vacant ovl_inode space as a place holder for
> lowerdata
> redirect path from the metacopy to lowerdata, which is going to be
> used
> later on for lazy lowerdata lookup.
>
> Use accessors to get the lowerdata path and dentry.
>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Reviewed-by: Alexander Larsson <alexl@xxxxxxxxxx>
> ---
> fs/overlayfs/inode.c | 4 ++--
> fs/overlayfs/namei.c | 7 +++++--
> fs/overlayfs/overlayfs.h | 3 ++-
> fs/overlayfs/ovl_entry.h | 16 +++++++++++++++-
> fs/overlayfs/super.c | 4 ++--
> fs/overlayfs/util.c | 26 ++++++++++++++++----------
> 6 files changed, 42 insertions(+), 18 deletions(-)
>
> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
> index 9f29fc3e9fa5..35d51a6dced7 100644
> --- a/fs/overlayfs/inode.c
> +++ b/fs/overlayfs/inode.c
> @@ -1006,8 +1006,7 @@ void ovl_inode_init(struct inode *inode, struct
> ovl_inode_params *oip,
> oi->__upperdentry = oip->upperdentry;
> oi->oe = *oip->oe;
> oi->redirect = oip->redirect;
> - if (oip->lowerdata)
> - oi->lowerdata = igrab(d_inode(oip->lowerdata));
> + oi->lowerdata_redirect = oip->lowerdata_redirect;
>
> realinode = ovl_inode_real(inode);
> ovl_copyattr(inode);
> @@ -1368,6 +1367,7 @@ struct inode *ovl_get_inode(struct super_block
> *sb,
> dput(upperdentry);
> ovl_destroy_entry(oip->oe);
> kfree(oip->redirect);
> + kfree(oip->lowerdata_redirect);
> goto out;
> }
>
> diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
> index cdcb2ac5d95c..b629261324f1 100644
> --- a/fs/overlayfs/namei.c
> +++ b/fs/overlayfs/namei.c
> @@ -1105,10 +1105,13 @@ struct dentry *ovl_lookup(struct inode *dir,
> struct dentry *dentry,
> .oe = &oe,
> .index = index,
> .redirect = upperredirect,
> - .lowerdata = (ctr > 1 && !d.is_dir) ?
> - stack[ctr - 1].dentry : NULL,
> };
>
> + /* Store lowerdata redirect for lazy lookup */
> + if (ctr > 1 && !d.is_dir && !stack[ctr - 1].dentry) {
> + oip.lowerdata_redirect = d.redirect;
> + d.redirect = NULL;
> + }
> inode = ovl_get_inode(dentry->d_sb, &oip);
> err = PTR_ERR(inode);
> if (IS_ERR(inode))
> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> index 32532342e56a..011b7b466f70 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -409,6 +409,7 @@ struct inode *ovl_inode_lower(struct inode
> *inode);
> struct inode *ovl_inode_lowerdata(struct inode *inode);
> struct inode *ovl_inode_real(struct inode *inode);
> struct inode *ovl_inode_realdata(struct inode *inode);
> +const char *ovl_lowerdata_redirect(struct inode *inode);
> struct ovl_dir_cache *ovl_dir_cache(struct inode *inode);
> void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache
> *cache);
> void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry);
> @@ -660,7 +661,7 @@ struct ovl_inode_params {
> struct ovl_entry *oe;
> bool index;
> char *redirect;
> - struct dentry *lowerdata;
> + char *lowerdata_redirect;
> };
> void ovl_inode_init(struct inode *inode, struct ovl_inode_params
> *oip,
> unsigned long ino, int fsid);
> diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
> index 5d95e937f555..221f0cbe748e 100644
> --- a/fs/overlayfs/ovl_entry.h
> +++ b/fs/overlayfs/ovl_entry.h
> @@ -125,6 +125,20 @@ static inline struct ovl_path
> *ovl_lowerstack(struct ovl_entry *oe)
> return oe && oe->__numlower > 1 ? oe->__lowerstack : &oe-
> >__lowerpath;
> }
>
> +static inline struct ovl_path *ovl_lowerdata(struct ovl_entry *oe)
> +{
> + struct ovl_path *lowerstack = ovl_lowerstack(oe);
> +
> + return lowerstack ? &lowerstack[oe->__numlower - 1] : NULL;
> +}
> +
> +static inline struct dentry *ovl_lowerdata_dentry(struct ovl_entry
> *oe)
> +{
> + struct ovl_path *lowerdata = ovl_lowerdata(oe);
> +
> + return lowerdata ? lowerdata->dentry : NULL;
> +}
> +
> /* private information held for every overlayfs dentry */
> static inline unsigned long *OVL_E_FLAGS(struct dentry *dentry)
> {
> @@ -134,7 +148,7 @@ static inline unsigned long *OVL_E_FLAGS(struct
> dentry *dentry)
> struct ovl_inode {
> union {
> struct ovl_dir_cache *cache; /* directory */
> - struct inode *lowerdata; /* regular file */
> + const char *lowerdata_redirect; /* regular file */
> };
> const char *redirect;
> u64 version;
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index e01a76de787c..6e4231799b86 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -172,7 +172,7 @@ static struct inode *ovl_alloc_inode(struct
> super_block *sb)
> oi->flags = 0;
> oi->__upperdentry = NULL;
> ovl_init_entry(&oi->oe, NULL, 0);
> - oi->lowerdata = NULL;
> + oi->lowerdata_redirect = NULL;
> mutex_init(&oi->lock);
>
> return &oi->vfs_inode;
> @@ -196,7 +196,7 @@ static void ovl_destroy_inode(struct inode
> *inode)
> if (S_ISDIR(inode->i_mode))
> ovl_dir_cache_free(inode);
> else
> - iput(oi->lowerdata);
> + kfree(oi->lowerdata_redirect);
> }
>
> static void ovl_free_fs(struct ovl_fs *ofs)
> diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
> index 540819ac9b9c..fe2e5a8b216b 100644
> --- a/fs/overlayfs/util.c
> +++ b/fs/overlayfs/util.c
> @@ -245,11 +245,12 @@ void ovl_path_lower(struct dentry *dentry,
> struct path *path)
> void ovl_path_lowerdata(struct dentry *dentry, struct path *path)
> {
> struct ovl_entry *oe = OVL_E(dentry);
> - struct ovl_path *lowerstack = ovl_lowerstack(oe);
> + struct ovl_path *lowerdata = ovl_lowerdata(oe);
> + struct dentry *lowerdata_dentry = ovl_lowerdata_dentry(oe);
>
> - if (ovl_numlower(oe)) {
> - path->mnt = lowerstack[ovl_numlower(oe) - 1].layer-
> >mnt;
> - path->dentry = lowerstack[ovl_numlower(oe) -
> 1].dentry;
> + if (lowerdata_dentry) {
> + path->dentry = lowerdata_dentry;
> + path->mnt = lowerdata->layer->mnt;
> } else {
> *path = (struct path) { };
> }
> @@ -308,10 +309,7 @@ const struct ovl_layer *ovl_layer_lower(struct
> dentry *dentry)
> */
> struct dentry *ovl_dentry_lowerdata(struct dentry *dentry)
> {
> - struct ovl_entry *oe = OVL_E(dentry);
> -
> - return ovl_numlower(oe) ?
> - ovl_lowerstack(oe)[ovl_numlower(oe) - 1].dentry :
> NULL;
> + return ovl_lowerdata_dentry(OVL_E(dentry));
> }
>
> struct dentry *ovl_dentry_real(struct dentry *dentry)
> @@ -359,10 +357,12 @@ struct inode *ovl_inode_real(struct inode
> *inode)
> /* Return inode which contains lower data. Do not return metacopy */
> struct inode *ovl_inode_lowerdata(struct inode *inode)
> {
> + struct dentry *lowerdata =
> ovl_lowerdata_dentry(OVL_I_E(inode));
> +
> if (WARN_ON(!S_ISREG(inode->i_mode)))
> return NULL;
>
> - return OVL_I(inode)->lowerdata ?: ovl_inode_lower(inode);
> + return lowerdata ? d_inode(lowerdata) : NULL;
> }
>
> /* Return real inode which contains data. Does not return metacopy
> inode */
> @@ -377,9 +377,15 @@ struct inode *ovl_inode_realdata(struct inode
> *inode)
> return ovl_inode_lowerdata(inode);
> }
>
> +const char *ovl_lowerdata_redirect(struct inode *inode)
> +{
> + return inode && S_ISREG(inode->i_mode) ?
> + OVL_I(inode)->lowerdata_redirect : NULL;
> +}
> +
> struct ovl_dir_cache *ovl_dir_cache(struct inode *inode)
> {
> - return OVL_I(inode)->cache;
> + return inode && S_ISDIR(inode->i_mode) ? OVL_I(inode)->cache
> : NULL;
> }
>
> void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache
> *cache)
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
=-=-=
Alexander Larsson Red Hat,
Inc
alexl@xxxxxxxxxx alexander.larsson@xxxxxxxxx
He's a shy one-eyed hairdresser with a robot buddy named Sparky. She's
a
mentally unstable communist bodyguard with the soul of a mighty
warrior.
They fight crime!
