From bda3f1608d993419fa247dc11263fc931ceca58a Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 18 Jun 2025 22:53:36 +0200 Subject: libfs: massage path_from_stashed() to allow custom stashing behavior * 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@kernel.org Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner --- fs/libfs.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) (limited to 'fs/libfs.c') diff --git a/fs/libfs.c b/fs/libfs.c index 9ea0ecc325a8..3541e22c87b5 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -2128,6 +2128,8 @@ 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; @@ -2176,8 +2178,7 @@ 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 (;;) { @@ -2218,12 +2219,15 @@ 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; } @@ -2234,8 +2238,17 @@ 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: -- cgit v1.2.3 From 23cdee615c4fdad1a8ec6f317b3c294cb37d662d Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 18 Jun 2025 22:53:37 +0200 Subject: libfs: massage path_from_stashed() Make it a littler easier to follow. Link: https://lore.kernel.org/20250618-work-pidfs-persistent-v2-3-98f3456fd552@kernel.org Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner --- fs/libfs.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) (limited to 'fs/libfs.c') diff --git a/fs/libfs.c b/fs/libfs.c index 3541e22c87b5..997d3a363ce6 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -2227,9 +2227,8 @@ int path_from_stashed(struct dentry **stashed, struct vfsmount *mnt, void *data, if (IS_ERR(res)) return PTR_ERR(res); if (res) { - path->dentry = res; sops->put_data(data); - goto out_path; + goto make_path; } /* Allocate a new dentry. */ @@ -2246,15 +2245,14 @@ int path_from_stashed(struct dentry **stashed, struct vfsmount *mnt, void *data, dput(dentry); return PTR_ERR(res); } - path->dentry = res; - /* A dentry was reused. */ if (res != dentry) dput(dentry); -out_path: - WARN_ON_ONCE(path->dentry->d_fsdata != stashed); - WARN_ON_ONCE(d_inode(path->dentry)->i_private != data); +make_path: + path->dentry = res; path->mnt = mntget(mnt); + VFS_WARN_ON_ONCE(path->dentry->d_fsdata != stashed); + VFS_WARN_ON_ONCE(d_inode(path->dentry)->i_private != data); return 0; } -- cgit v1.2.3 From c007d95221397eda24e7d6b4ac5a5d699ea2f1ca Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 18 Jun 2025 22:53:44 +0200 Subject: libfs: prepare to allow for non-immutable pidfd inodes Allow for S_IMMUTABLE to be stripped so that we can support xattrs. Link: https://lore.kernel.org/20250618-work-pidfs-persistent-v2-10-98f3456fd552@kernel.org Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner --- fs/libfs.c | 1 - 1 file changed, 1 deletion(-) (limited to 'fs/libfs.c') diff --git a/fs/libfs.c b/fs/libfs.c index 997d3a363ce6..c5b520df9032 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -2162,7 +2162,6 @@ static struct dentry *prepare_anon_dentry(struct dentry **stashed, /* Notice when this is changed. */ WARN_ON_ONCE(!S_ISREG(inode->i_mode)); - WARN_ON_ONCE(!IS_IMMUTABLE(inode)); dentry = d_alloc_anon(sb); if (!dentry) { -- cgit v1.2.3