6.16-stable review patch. If anyone has any objections, please let me know.
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From: Christian Brauner brauner@kernel.org
[ Upstream commit bda3f1608d993419fa247dc11263fc931ceca58a ]
* Add a callback to struct stashed_operations so it's possible to implement custom behavior for pidfs and allow for it to return errors.
* Teach stashed_dentry_get() to handle error pointers.
Link: https://lore.kernel.org/20250618-work-pidfs-persistent-v2-2-98f3456fd552@ker... Reviewed-by: Alexander Mikhalitsyn aleksandr.mikhalitsyn@canonical.com Signed-off-by: Christian Brauner brauner@kernel.org Stable-dep-of: 0b2d71a7c826 ("pidfs: Fix memory leak in pidfd_info()") Signed-off-by: Sasha Levin sashal@kernel.org --- fs/internal.h | 3 +++ fs/libfs.c | 27 ++++++++++++++++++++------- 2 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/fs/internal.h b/fs/internal.h index 393f6c5c24f6..22ba066d1dba 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -322,12 +322,15 @@ struct mnt_idmap *alloc_mnt_idmap(struct user_namespace *mnt_userns); struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap); void mnt_idmap_put(struct mnt_idmap *idmap); struct stashed_operations { + struct dentry *(*stash_dentry)(struct dentry **stashed, + struct dentry *dentry); void (*put_data)(void *data); int (*init_inode)(struct inode *inode, void *data); }; int path_from_stashed(struct dentry **stashed, struct vfsmount *mnt, void *data, struct path *path); void stashed_dentry_prune(struct dentry *dentry); +struct dentry *stash_dentry(struct dentry **stashed, struct dentry *dentry); struct dentry *stashed_dentry_get(struct dentry **stashed); /** * path_mounted - check whether path is mounted diff --git a/fs/libfs.c b/fs/libfs.c index 972b95cc7433..5b936ee71892 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -2126,6 +2126,8 @@ struct dentry *stashed_dentry_get(struct dentry **stashed) dentry = rcu_dereference(*stashed); if (!dentry) return NULL; + if (IS_ERR(dentry)) + return dentry; if (!lockref_get_not_dead(&dentry->d_lockref)) return NULL; return dentry; @@ -2174,8 +2176,7 @@ static struct dentry *prepare_anon_dentry(struct dentry **stashed, return dentry; }
-static struct dentry *stash_dentry(struct dentry **stashed, - struct dentry *dentry) +struct dentry *stash_dentry(struct dentry **stashed, struct dentry *dentry) { guard(rcu)(); for (;;) { @@ -2216,12 +2217,15 @@ static struct dentry *stash_dentry(struct dentry **stashed, int path_from_stashed(struct dentry **stashed, struct vfsmount *mnt, void *data, struct path *path) { - struct dentry *dentry; + struct dentry *dentry, *res; const struct stashed_operations *sops = mnt->mnt_sb->s_fs_info;
/* See if dentry can be reused. */ - path->dentry = stashed_dentry_get(stashed); - if (path->dentry) { + res = stashed_dentry_get(stashed); + if (IS_ERR(res)) + return PTR_ERR(res); + if (res) { + path->dentry = res; sops->put_data(data); goto out_path; } @@ -2232,8 +2236,17 @@ int path_from_stashed(struct dentry **stashed, struct vfsmount *mnt, void *data, return PTR_ERR(dentry);
/* Added a new dentry. @data is now owned by the filesystem. */ - path->dentry = stash_dentry(stashed, dentry); - if (path->dentry != dentry) + if (sops->stash_dentry) + res = sops->stash_dentry(stashed, dentry); + else + res = stash_dentry(stashed, dentry); + if (IS_ERR(res)) { + dput(dentry); + return PTR_ERR(res); + } + path->dentry = res; + /* A dentry was reused. */ + if (res != dentry) dput(dentry);
out_path: