[PATCHES] several fixes from tree-in-dcache stuff

[PATCHES] several fixes from tree-in-dcache stuff

[Al Viro]

Several fixes for fairly old crap - qibfs leak, a couple
of spufs ones and a spufs double-dput() memory corruptor.

This stuff sits in viro/vfs.git#fixes; individual patches
in followups.  Review would be very welcome.

[PATCH 1/4] spufs: fix a leak on spufs_new_file() failure

[Al Viro]

It's called from spufs_fill_dir(), and caller of that will do
spufs_rmdir() in case of failure.  That does remove everything
we'd managed to create, but... the problem dentry is still
negative.  IOW, it needs to be explicitly dropped.

Fixes: 3f51dd91c807 "[PATCH] spufs: fix spufs_fill_dir error path"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/powerpc/platforms/cell/spufs/inode.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/cell/spufs/inode.c b/arch/powerpc/platforms/cell/spufs/inode.c
index 70236d1df3d3..793c005607cf 100644
--- a/arch/powerpc/platforms/cell/spufs/inode.c
+++ b/arch/powerpc/platforms/cell/spufs/inode.c
@@ -192,8 +192,10 @@ static int spufs_fill_dir(struct dentry *dir,
 			return -ENOMEM;
 		ret = spufs_new_file(dir->d_sb, dentry, files->ops,
 					files->mode & mode, files->size, ctx);
-		if (ret)
+		if (ret) {
+			dput(dentry);
 			return ret;
+		}
 		files++;
 	}
 	return 0;
-- 
2.39.5

Re: [PATCH 1/4] spufs: fix a leak on spufs_new_file() failure

[Christian Brauner]

On Thu, Mar 13, 2025 at 04:28:15AM +0000, Al Viro wrote:
> It's called from spufs_fill_dir(), and caller of that will do
> spufs_rmdir() in case of failure.  That does remove everything
> we'd managed to create, but... the problem dentry is still
> negative.  IOW, it needs to be explicitly dropped.
> 
> Fixes: 3f51dd91c807 "[PATCH] spufs: fix spufs_fill_dir error path"
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---

Reviewed-by: Christian Brauner <brauner@kernel.org>

[PATCH 2/4] spufs: fix gang directory lifetimes

[Al Viro]

prior to "[POWERPC] spufs: Fix gang destroy leaks" we used to have
a problem with gang lifetimes - creation of a gang returns opened
gang directory, which normally gets removed when that gets closed,
but if somebody has created a context belonging to that gang and
kept it alive until the gang got closed, removal failed and we
ended up with a leak.

Unfortunately, it had been fixed the wrong way.  Dentry of gang
directory was no longer pinned, and rmdir on close was gone.
One problem was that failure of open kept calling simple_rmdir()
as cleanup, which meant an unbalanced dput().  Another bug was
in the success case - gang creation incremented link count on
root directory, but that was no longer undone when gang got
destroyed.

Fix consists of
	* reverting the commit in question
	* adding a counter to gang, protected by ->i_rwsem
of gang directory inode.
	* having it set to 1 at creation time, dropped
in both spufs_dir_close() and spufs_gang_close() and bumped
in spufs_create_context(), provided that it's not 0.
	* using simple_recursive_removal() to take the gang
directory out when counter reaches zero.

Fixes: 877907d37da9 "[POWERPC] spufs: Fix gang destroy leaks"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/powerpc/platforms/cell/spufs/gang.c  |  1 +
 arch/powerpc/platforms/cell/spufs/inode.c | 54 +++++++++++++++++++----
 arch/powerpc/platforms/cell/spufs/spufs.h |  2 +
 3 files changed, 49 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/platforms/cell/spufs/gang.c b/arch/powerpc/platforms/cell/spufs/gang.c
index 827d338deaf4..2c2999de6bfa 100644
--- a/arch/powerpc/platforms/cell/spufs/gang.c
+++ b/arch/powerpc/platforms/cell/spufs/gang.c
@@ -25,6 +25,7 @@ struct spu_gang *alloc_spu_gang(void)
 	mutex_init(&gang->aff_mutex);
 	INIT_LIST_HEAD(&gang->list);
 	INIT_LIST_HEAD(&gang->aff_list_head);
+	gang->alive = 1;
 
 out:
 	return gang;
diff --git a/arch/powerpc/platforms/cell/spufs/inode.c b/arch/powerpc/platforms/cell/spufs/inode.c
index 793c005607cf..c566e7997f2c 100644
--- a/arch/powerpc/platforms/cell/spufs/inode.c
+++ b/arch/powerpc/platforms/cell/spufs/inode.c
@@ -201,6 +201,23 @@ static int spufs_fill_dir(struct dentry *dir,
 	return 0;
 }
 
+static void unuse_gang(struct dentry *dir)
+{
+	struct inode *inode = dir->d_inode;
+	struct spu_gang *gang = SPUFS_I(inode)->i_gang;
+
+	if (gang) {
+		bool dead;
+
+		inode_lock(inode); // exclusion with spufs_create_context()
+		dead = !--gang->alive;
+		inode_unlock(inode);
+
+		if (dead)
+			simple_recursive_removal(dir, NULL);
+	}
+}
+
 static int spufs_dir_close(struct inode *inode, struct file *file)
 {
 	struct inode *parent;
@@ -215,6 +232,7 @@ static int spufs_dir_close(struct inode *inode, struct file *file)
 	inode_unlock(parent);
 	WARN_ON(ret);
 
+	unuse_gang(dir->d_parent);
 	return dcache_dir_close(inode, file);
 }
 
@@ -407,7 +425,7 @@ spufs_create_context(struct inode *inode, struct dentry *dentry,
 {
 	int ret;
 	int affinity;
-	struct spu_gang *gang;
+	struct spu_gang *gang = SPUFS_I(inode)->i_gang;
 	struct spu_context *neighbor;
 	struct path path = {.mnt = mnt, .dentry = dentry};
 
@@ -422,11 +440,15 @@ spufs_create_context(struct inode *inode, struct dentry *dentry,
 	if ((flags & SPU_CREATE_ISOLATE) && !isolated_loader)
 		return -ENODEV;
 
-	gang = NULL;
+	if (gang) {
+		if (!gang->alive)
+			return -ENOENT;
+		gang->alive++;
+	}
+
 	neighbor = NULL;
 	affinity = flags & (SPU_CREATE_AFFINITY_MEM | SPU_CREATE_AFFINITY_SPU);
 	if (affinity) {
-		gang = SPUFS_I(inode)->i_gang;
 		if (!gang)
 			return -EINVAL;
 		mutex_lock(&gang->aff_mutex);
@@ -455,6 +477,8 @@ spufs_create_context(struct inode *inode, struct dentry *dentry,
 out_aff_unlock:
 	if (affinity)
 		mutex_unlock(&gang->aff_mutex);
+	if (ret && gang)
+		gang->alive--; // can't reach 0
 	return ret;
 }
 
@@ -484,6 +508,7 @@ spufs_mkgang(struct inode *dir, struct dentry *dentry, umode_t mode)
 	inode->i_fop = &simple_dir_operations;
 
 	d_instantiate(dentry, inode);
+	dget(dentry);
 	inc_nlink(dir);
 	inc_nlink(d_inode(dentry));
 	return ret;
@@ -494,6 +519,21 @@ spufs_mkgang(struct inode *dir, struct dentry *dentry, umode_t mode)
 	return ret;
 }
 
+static int spufs_gang_close(struct inode *inode, struct file *file)
+{
+	unuse_gang(file->f_path.dentry);
+	return dcache_dir_close(inode, file);
+}
+
+static const struct file_operations spufs_gang_fops = {
+	.open		= dcache_dir_open,
+	.release	= spufs_gang_close,
+	.llseek		= dcache_dir_lseek,
+	.read		= generic_read_dir,
+	.iterate_shared	= dcache_readdir,
+	.fsync		= noop_fsync,
+};
+
 static int spufs_gang_open(const struct path *path)
 {
 	int ret;
@@ -513,7 +553,7 @@ static int spufs_gang_open(const struct path *path)
 		return PTR_ERR(filp);
 	}
 
-	filp->f_op = &simple_dir_operations;
+	filp->f_op = &spufs_gang_fops;
 	fd_install(ret, filp);
 	return ret;
 }
@@ -528,10 +568,8 @@ static int spufs_create_gang(struct inode *inode,
 	ret = spufs_mkgang(inode, dentry, mode & 0777);
 	if (!ret) {
 		ret = spufs_gang_open(&path);
-		if (ret < 0) {
-			int err = simple_rmdir(inode, dentry);
-			WARN_ON(err);
-		}
+		if (ret < 0)
+			unuse_gang(dentry);
 	}
 	return ret;
 }
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index 84958487f696..d33787c57c39 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -151,6 +151,8 @@ struct spu_gang {
 	int aff_flags;
 	struct spu *aff_ref_spu;
 	atomic_t aff_sched_count;
+
+	int alive;
 };
 
 /* Flag bits for spu_gang aff_flags */
-- 
2.39.5

Re: [PATCH 2/4] spufs: fix gang directory lifetimes

[Christian Brauner]

On Thu, Mar 13, 2025 at 04:29:01AM +0000, Al Viro wrote:
> prior to "[POWERPC] spufs: Fix gang destroy leaks" we used to have
> a problem with gang lifetimes - creation of a gang returns opened
> gang directory, which normally gets removed when that gets closed,
> but if somebody has created a context belonging to that gang and
> kept it alive until the gang got closed, removal failed and we
> ended up with a leak.
> 
> Unfortunately, it had been fixed the wrong way.  Dentry of gang
> directory was no longer pinned, and rmdir on close was gone.
> One problem was that failure of open kept calling simple_rmdir()
> as cleanup, which meant an unbalanced dput().  Another bug was
> in the success case - gang creation incremented link count on
> root directory, but that was no longer undone when gang got
> destroyed.
> 
> Fix consists of
> 	* reverting the commit in question
> 	* adding a counter to gang, protected by ->i_rwsem
> of gang directory inode.
> 	* having it set to 1 at creation time, dropped
> in both spufs_dir_close() and spufs_gang_close() and bumped
> in spufs_create_context(), provided that it's not 0.
> 	* using simple_recursive_removal() to take the gang
> directory out when counter reaches zero.
> 
> Fixes: 877907d37da9 "[POWERPC] spufs: Fix gang destroy leaks"
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---

Reviewed-by: Christian Brauner <brauner@kernel.org>

[PATCH 3/4] spufs: fix a leak in spufs_create_context()

[Al Viro]

Leak fixes back in 2008 missed one case - if we are trying to set affinity
and spufs_mkdir() fails, we need to drop the reference to neighbor.

Fixes: 58119068cb27 "[POWERPC] spufs: Fix memory leak on SPU affinity"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/powerpc/platforms/cell/spufs/inode.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/cell/spufs/inode.c b/arch/powerpc/platforms/cell/spufs/inode.c
index c566e7997f2c..9f9e4b871627 100644
--- a/arch/powerpc/platforms/cell/spufs/inode.c
+++ b/arch/powerpc/platforms/cell/spufs/inode.c
@@ -460,8 +460,11 @@ spufs_create_context(struct inode *inode, struct dentry *dentry,
 	}
 
 	ret = spufs_mkdir(inode, dentry, flags, mode & 0777);
-	if (ret)
+	if (ret) {
+		if (neighbor)
+			put_spu_context(neighbor);
 		goto out_aff_unlock;
+	}
 
 	if (affinity) {
 		spufs_set_affinity(flags, SPUFS_I(d_inode(dentry))->i_ctx,
-- 
2.39.5

Re: [PATCH 3/4] spufs: fix a leak in spufs_create_context()

[Christian Brauner]

On Thu, Mar 13, 2025 at 04:29:32AM +0000, Al Viro wrote:
> Leak fixes back in 2008 missed one case - if we are trying to set affinity
> and spufs_mkdir() fails, we need to drop the reference to neighbor.
> 
> Fixes: 58119068cb27 "[POWERPC] spufs: Fix memory leak on SPU affinity"
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---

Reviewed-by: Christian Brauner <brauner@kernel.org>