From 2853908a59603118f854b813da055c26257dfa4f Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sun, 29 May 2016 13:49:56 -0400
Subject: undo "fs: allow d_instantiate to be called with negative parent
 dentry"

Background: spufs used to mangle the order in which it had been building
dentry trees.  It was broken in a lot of ways, but most of them required
the right timing to trigger until an fsnotify change had added one more
- the one that was always triggered.

Unfortunately, insteading of fixing their long-standing bug the spufs
folks had chosen to paper over the fsnotify trigger.  Eventually said
bug had been spotted and killed off, but the pointless check in
fsnotify has remained, complete with the implication that one *could*
do that kind of crap.

Again, a parent of any dentry should always be positive.  Any code
can rely upon that and anything violating that assert is a bug,
*not* something to be accomodated.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 include/linux/fsnotify_backend.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'include')

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 29f917517299..d188a107c562 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -281,7 +281,7 @@ static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
 	 * us with the new state.
 	 */
 	parent = dentry->d_parent;
-	if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode))
+	if (fsnotify_inode_watches_children(parent->d_inode))
 		dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
 	else
 		dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
-- 
cgit v1.2.3


From affda48410a5bbfd516def60bbc97f2683cd9f7b Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sun, 29 May 2016 18:35:12 -0400
Subject: trim fsnotify hooks a bit

fsnotify_d_move()/__fsnotify_d_instantiate()/__fsnotify_update_dcache_flags()
are identical to each other, regardless of the config.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/dcache.c                      |  8 ++++----
 include/linux/fsnotify.h         | 12 ------------
 include/linux/fsnotify_backend.h | 20 +++-----------------
 3 files changed, 7 insertions(+), 33 deletions(-)

(limited to 'include')

diff --git a/fs/dcache.c b/fs/dcache.c
index ad4a542e9bab..f9c63c108881 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1769,7 +1769,7 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode)
 	raw_write_seqcount_begin(&dentry->d_seq);
 	__d_set_inode_and_type(dentry, inode, add_flags);
 	raw_write_seqcount_end(&dentry->d_seq);
-	__fsnotify_d_instantiate(dentry);
+	fsnotify_update_flags(dentry);
 	spin_unlock(&dentry->d_lock);
 }
 
@@ -2563,7 +2563,7 @@ static inline void __d_add(struct dentry *dentry, struct inode *inode)
 		raw_write_seqcount_begin(&dentry->d_seq);
 		__d_set_inode_and_type(dentry, inode, add_flags);
 		raw_write_seqcount_end(&dentry->d_seq);
-		__fsnotify_d_instantiate(dentry);
+		fsnotify_update_flags(dentry);
 	}
 	_d_rehash(dentry);
 	if (dir)
@@ -2853,8 +2853,8 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
 		list_move(&target->d_child, &target->d_parent->d_subdirs);
 		list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
 		if (exchange)
-			fsnotify_d_move(target);
-		fsnotify_d_move(dentry);
+			fsnotify_update_flags(target);
+		fsnotify_update_flags(dentry);
 	}
 
 	write_seqcount_end(&target->d_seq);
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 0141f257d67b..eed9e853a06f 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -51,18 +51,6 @@ static inline int fsnotify_perm(struct file *file, int mask)
 	return fsnotify(inode, fsnotify_mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
 }
 
-/*
- * fsnotify_d_move - dentry has been moved
- */
-static inline void fsnotify_d_move(struct dentry *dentry)
-{
-	/*
-	 * On move we need to update dentry->d_flags to indicate if the new parent
-	 * cares about events from this dentry.
-	 */
-	__fsnotify_update_dcache_flags(dentry);
-}
-
 /*
  * fsnotify_link_count - inode's link count changed
  */
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index d188a107c562..58205f33af02 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -267,10 +267,8 @@ static inline int fsnotify_inode_watches_children(struct inode *inode)
  * Update the dentry with a flag indicating the interest of its parent to receive
  * filesystem events when those events happens to this dentry->d_inode.
  */
-static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
+static inline void fsnotify_update_flags(struct dentry *dentry)
 {
-	struct dentry *parent;
-
 	assert_spin_locked(&dentry->d_lock);
 
 	/*
@@ -280,21 +278,12 @@ static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
 	 * find our entry, so it will spin until we complete here, and update
 	 * us with the new state.
 	 */
-	parent = dentry->d_parent;
-	if (fsnotify_inode_watches_children(parent->d_inode))
+	if (fsnotify_inode_watches_children(dentry->d_parent->d_inode))
 		dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
 	else
 		dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
 }
 
-/*
- * fsnotify_d_instantiate - instantiate a dentry for inode
- */
-static inline void __fsnotify_d_instantiate(struct dentry *dentry)
-{
-	__fsnotify_update_dcache_flags(dentry);
-}
-
 /* called from fsnotify listeners, such as fanotify or dnotify */
 
 /* create a new group */
@@ -386,10 +375,7 @@ static inline void __fsnotify_inode_delete(struct inode *inode)
 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
 {}
 
-static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
-{}
-
-static inline void __fsnotify_d_instantiate(struct dentry *dentry)
+static inline void fsnotify_update_flags(struct dentry *dentry)
 {}
 
 static inline u32 fsnotify_get_cookie(void)
-- 
cgit v1.2.3


From 2d902671ce1cd98cdc88d78c481889a1b2996101 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Thu, 30 Jun 2016 08:53:27 +0200
Subject: vfs: merge .d_select_inode() into .d_real()

The two methods essentially do the same: find the real dentry/inode
belonging to an overlay dentry.  The difference is in the usage:

vfs_open() uses ->d_select_inode() and expects the function to perform
copy-up if necessary based on the open flags argument.

file_dentry() uses ->d_real() passing in the overlay dentry as well as the
underlying inode.

vfs_rename() uses ->d_select_inode() but passes zero flags.  ->d_real()
with a zero inode would have worked just as well here.

This patch merges the functionality of ->d_select_inode() into ->d_real()
by adding an 'open_flags' argument to the latter.

[Al Viro] Make the signature of d_real() match that of ->d_real() again.
And constify the inode argument, while we are at it.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/dcache.c              |  3 ---
 fs/namei.c               |  2 +-
 fs/open.c                |  8 ++++----
 fs/overlayfs/inode.c     | 31 ++++++++++---------------------
 fs/overlayfs/overlayfs.h |  2 +-
 fs/overlayfs/super.c     | 20 ++++++++++++++------
 include/linux/dcache.h   | 28 ++++++++--------------------
 include/linux/fs.h       |  7 +------
 8 files changed, 39 insertions(+), 62 deletions(-)

(limited to 'include')

diff --git a/fs/dcache.c b/fs/dcache.c
index d6847d7b123d..5405b89fe8ec 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1729,7 +1729,6 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
 				DCACHE_OP_REVALIDATE	|
 				DCACHE_OP_WEAK_REVALIDATE	|
 				DCACHE_OP_DELETE	|
-				DCACHE_OP_SELECT_INODE	|
 				DCACHE_OP_REAL));
 	dentry->d_op = op;
 	if (!op)
@@ -1746,8 +1745,6 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
 		dentry->d_flags |= DCACHE_OP_DELETE;
 	if (op->d_prune)
 		dentry->d_flags |= DCACHE_OP_PRUNE;
-	if (op->d_select_inode)
-		dentry->d_flags |= DCACHE_OP_SELECT_INODE;
 	if (op->d_real)
 		dentry->d_flags |= DCACHE_OP_REAL;
 
diff --git a/fs/namei.c b/fs/namei.c
index 70580ab1445c..bb7a2e0b959c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4328,7 +4328,7 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	 * Check source == target.
 	 * On overlayfs need to look at underlying inodes.
 	 */
-	if (vfs_select_inode(old_dentry, 0) == vfs_select_inode(new_dentry, 0))
+	if (d_real_inode(old_dentry) == d_real_inode(new_dentry))
 		return 0;
 
 	error = may_delete(old_dir, old_dentry, is_dir);
diff --git a/fs/open.c b/fs/open.c
index 93ae3cdee4ab..bf66cf1a9f5c 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -840,13 +840,13 @@ EXPORT_SYMBOL(file_path);
 int vfs_open(const struct path *path, struct file *file,
 	     const struct cred *cred)
 {
-	struct inode *inode = vfs_select_inode(path->dentry, file->f_flags);
+	struct dentry *dentry = d_real(path->dentry, NULL, file->f_flags);
 
-	if (IS_ERR(inode))
-		return PTR_ERR(inode);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
 
 	file->f_path = *path;
-	return do_dentry_open(file, inode, NULL, cred);
+	return do_dentry_open(file, d_backing_inode(dentry), NULL, cred);
 }
 
 struct file *dentry_open(const struct path *path, int flags,
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 1dbeab6cf96e..e08cd94d7b26 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -325,36 +325,25 @@ static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
 	return true;
 }
 
-struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags)
+int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags)
 {
-	int err;
+	int err = 0;
 	struct path realpath;
 	enum ovl_path_type type;
 
-	if (d_is_dir(dentry))
-		return d_backing_inode(dentry);
-
 	type = ovl_path_real(dentry, &realpath);
 	if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) {
 		err = ovl_want_write(dentry);
-		if (err)
-			return ERR_PTR(err);
-
-		if (file_flags & O_TRUNC)
-			err = ovl_copy_up_truncate(dentry);
-		else
-			err = ovl_copy_up(dentry);
-		ovl_drop_write(dentry);
-		if (err)
-			return ERR_PTR(err);
-
-		ovl_path_upper(dentry, &realpath);
+		if (!err) {
+			if (file_flags & O_TRUNC)
+				err = ovl_copy_up_truncate(dentry);
+			else
+				err = ovl_copy_up(dentry);
+			ovl_drop_write(dentry);
+		}
 	}
 
-	if (realpath.dentry->d_flags & DCACHE_OP_SELECT_INODE)
-		return realpath.dentry->d_op->d_select_inode(realpath.dentry, file_flags);
-
-	return d_backing_inode(realpath.dentry);
+	return err;
 }
 
 static const struct inode_operations ovl_file_inode_operations = {
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 4bd9b5ba8f42..6b9fd25c5ad4 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -179,7 +179,7 @@ ssize_t ovl_getxattr(struct dentry *dentry, struct inode *inode,
 		     const char *name, void *value, size_t size);
 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
 int ovl_removexattr(struct dentry *dentry, const char *name);
-struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags);
+int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags);
 
 struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
 			    struct ovl_entry *oe);
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index ce02f46029da..035c176edf00 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -304,7 +304,9 @@ static void ovl_dentry_release(struct dentry *dentry)
 	}
 }
 
-static struct dentry *ovl_d_real(struct dentry *dentry, struct inode *inode)
+static struct dentry *ovl_d_real(struct dentry *dentry,
+				 const struct inode *inode,
+				 unsigned int open_flags)
 {
 	struct dentry *real;
 
@@ -314,6 +316,16 @@ static struct dentry *ovl_d_real(struct dentry *dentry, struct inode *inode)
 		goto bug;
 	}
 
+	if (d_is_negative(dentry))
+		return dentry;
+
+	if (open_flags) {
+		int err = ovl_open_maybe_copy_up(dentry, open_flags);
+
+		if (err)
+			return ERR_PTR(err);
+	}
+
 	real = ovl_dentry_upper(dentry);
 	if (real && (!inode || inode == d_inode(real)))
 		return real;
@@ -326,9 +338,7 @@ static struct dentry *ovl_d_real(struct dentry *dentry, struct inode *inode)
 		return real;
 
 	/* Handle recursion */
-	if (real->d_flags & DCACHE_OP_REAL)
-		return real->d_op->d_real(real, inode);
-
+	return d_real(real, inode, open_flags);
 bug:
 	WARN(1, "ovl_d_real(%pd4, %s:%lu\n): real dentry not found\n", dentry,
 	     inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0);
@@ -378,13 +388,11 @@ static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
 
 static const struct dentry_operations ovl_dentry_operations = {
 	.d_release = ovl_dentry_release,
-	.d_select_inode = ovl_d_select_inode,
 	.d_real = ovl_d_real,
 };
 
 static const struct dentry_operations ovl_reval_dentry_operations = {
 	.d_release = ovl_dentry_release,
-	.d_select_inode = ovl_d_select_inode,
 	.d_real = ovl_d_real,
 	.d_revalidate = ovl_dentry_revalidate,
 	.d_weak_revalidate = ovl_dentry_weak_revalidate,
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index f53fa055021a..45b22de15ede 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -139,8 +139,7 @@ struct dentry_operations {
 	char *(*d_dname)(struct dentry *, char *, int);
 	struct vfsmount *(*d_automount)(struct path *);
 	int (*d_manage)(struct dentry *, bool);
-	struct inode *(*d_select_inode)(struct dentry *, unsigned);
-	struct dentry *(*d_real)(struct dentry *, struct inode *);
+	struct dentry *(*d_real)(struct dentry *, const struct inode *, unsigned int);
 } ____cacheline_aligned;
 
 /*
@@ -206,10 +205,8 @@ struct dentry_operations {
 
 #define DCACHE_MAY_FREE			0x00800000
 #define DCACHE_FALLTHRU			0x01000000 /* Fall through to lower layer */
-#define DCACHE_OP_SELECT_INODE		0x02000000 /* Unioned entry: dcache op selects inode */
-
-#define DCACHE_ENCRYPTED_WITH_KEY	0x04000000 /* dir is encrypted with a valid key */
-#define DCACHE_OP_REAL			0x08000000
+#define DCACHE_ENCRYPTED_WITH_KEY	0x02000000 /* dir is encrypted with a valid key */
+#define DCACHE_OP_REAL			0x04000000
 
 #define DCACHE_PAR_LOOKUP		0x10000000 /* being looked up (with parent locked shared) */
 #define DCACHE_DENTRY_CURSOR		0x20000000
@@ -557,25 +554,16 @@ static inline struct dentry *d_backing_dentry(struct dentry *upper)
 	return upper;
 }
 
-static inline struct dentry *d_real(struct dentry *dentry)
+static inline struct dentry *d_real(struct dentry *dentry,
+				    const struct inode *inode,
+				    unsigned int flags)
 {
 	if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
-		return dentry->d_op->d_real(dentry, NULL);
+		return dentry->d_op->d_real(dentry, inode, flags);
 	else
 		return dentry;
 }
 
-static inline struct inode *vfs_select_inode(struct dentry *dentry,
-					     unsigned open_flags)
-{
-	struct inode *inode = d_inode(dentry);
-
-	if (inode && unlikely(dentry->d_flags & DCACHE_OP_SELECT_INODE))
-		inode = dentry->d_op->d_select_inode(dentry, open_flags);
-
-	return inode;
-}
-
 /**
  * d_real_inode - Return the real inode
  * @dentry: The dentry to query
@@ -585,7 +573,7 @@ static inline struct inode *vfs_select_inode(struct dentry *dentry,
  */
 static inline struct inode *d_real_inode(struct dentry *dentry)
 {
-	return d_backing_inode(d_real(dentry));
+	return d_backing_inode(d_real(dentry, NULL, 0));
 }
 
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index dd288148a6b1..bacc0733663c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1272,12 +1272,7 @@ static inline struct inode *file_inode(const struct file *f)
 
 static inline struct dentry *file_dentry(const struct file *file)
 {
-	struct dentry *dentry = file->f_path.dentry;
-
-	if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
-		return dentry->d_op->d_real(dentry, file_inode(file));
-	else
-		return dentry;
+	return d_real(file->f_path.dentry, file_inode(file), 0);
 }
 
 static inline int locks_lock_file_wait(struct file *filp, struct file_lock *fl)
-- 
cgit v1.2.3


From e698b8a43659f9ece192fcab215abcadac8f88d7 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Thu, 30 Jun 2016 08:53:27 +0200
Subject: vfs: document ->d_real()

Add missing documentation for the d_op->d_real() method and d_real()
helper.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 Documentation/filesystems/Locking |  3 +++
 Documentation/filesystems/vfs.txt | 20 ++++++++++++++++++++
 include/linux/dcache.h            | 14 +++++++++++++-
 3 files changed, 36 insertions(+), 1 deletion(-)

(limited to 'include')

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 75eea7ce3d7c..898d3cecd8a6 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -20,6 +20,8 @@ prototypes:
 	char *(*d_dname)((struct dentry *dentry, char *buffer, int buflen);
 	struct vfsmount *(*d_automount)(struct path *path);
 	int (*d_manage)(struct dentry *, bool);
+	struct dentry *(*d_real)(struct dentry *, const struct inode *,
+				 unsigned int);
 
 locking rules:
 		rename_lock	->d_lock	may block	rcu-walk
@@ -34,6 +36,7 @@ d_iput:		no		no		yes		no
 d_dname:	no		no		no		no
 d_automount:	no		no		yes		no
 d_manage:	no		no		yes (ref-walk)	maybe
+d_real		no		no		yes 		no
 
 --------------------------- inode_operations --------------------------- 
 prototypes:
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index c61a223ef3ff..1c934dd2c47d 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -938,6 +938,8 @@ struct dentry_operations {
 	char *(*d_dname)(struct dentry *, char *, int);
 	struct vfsmount *(*d_automount)(struct path *);
 	int (*d_manage)(struct dentry *, bool);
+	struct dentry *(*d_real)(struct dentry *, const struct inode *,
+				 unsigned int);
 };
 
   d_revalidate: called when the VFS needs to revalidate a dentry. This
@@ -1060,6 +1062,24 @@ struct dentry_operations {
 	This function is only used if DCACHE_MANAGE_TRANSIT is set on the
 	dentry being transited from.
 
+  d_real: overlay/union type filesystems implement this method to return one of
+	the underlying dentries hidden by the overlay.  It is used in three
+	different modes:
+
+	Called from open it may need to copy-up the file depending on the
+	supplied open flags.  This mode is selected with a non-zero flags
+	argument.  In this mode the d_real method can return an error.
+
+	Called from file_dentry() it returns the real dentry matching the inode
+	argument.  The real dentry may be from a lower layer already copied up,
+	but still referenced from the file.  This mode is selected with a
+	non-NULL inode argument.  This will always succeed.
+
+	With NULL inode and zero flags the topmost real underlying dentry is
+	returned.  This will always succeed.
+
+	This method is never called with both non-NULL inode and non-zero flags.
+
 Example :
 
 static char *pipefs_dname(struct dentry *dent, char *buffer, int buflen)
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 45b22de15ede..14df83609c7f 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -139,7 +139,8 @@ struct dentry_operations {
 	char *(*d_dname)(struct dentry *, char *, int);
 	struct vfsmount *(*d_automount)(struct path *);
 	int (*d_manage)(struct dentry *, bool);
-	struct dentry *(*d_real)(struct dentry *, const struct inode *, unsigned int);
+	struct dentry *(*d_real)(struct dentry *, const struct inode *,
+				 unsigned int);
 } ____cacheline_aligned;
 
 /*
@@ -554,6 +555,17 @@ static inline struct dentry *d_backing_dentry(struct dentry *upper)
 	return upper;
 }
 
+/**
+ * d_real - Return the real dentry
+ * @dentry: the dentry to query
+ * @inode: inode to select the dentry from multiple layers (can be NULL)
+ * @flags: open flags to control copy-up behavior
+ *
+ * If dentry is on an union/overlay, then return the underlying, real dentry.
+ * Otherwise return the dentry itself.
+ *
+ * See also: Documentation/filesystems/vfs.txt
+ */
 static inline struct dentry *d_real(struct dentry *dentry,
 				    const struct inode *inode,
 				    unsigned int flags)
-- 
cgit v1.2.3


From a4a4f9439c73b921ef246368fc6f2d7c0281e99d Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Tue, 19 Jul 2016 13:16:52 -0400
Subject: bdev: get rid of ->bd_inodes

Since 2006 we have ->i_bdev pinning bdev in question, so there's no
way to get to bdev ->evict_inode() while there's an aliasing inode
anywhere.  In other words, the only place walking the list of aliases
is guaranteed to do it only when the list is empty...

Remove the detritus; it should've been done in "[PATCH] Fix a race
condition between ->i_mapping and iput()", but nobody had noticed it
back then.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/block_dev.c     | 16 ++--------------
 include/linux/fs.h |  1 -
 2 files changed, 2 insertions(+), 15 deletions(-)

(limited to 'include')

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 71ccab1d22c6..73130dad30e4 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -614,7 +614,6 @@ static void init_once(void *foo)
 
 	memset(bdev, 0, sizeof(*bdev));
 	mutex_init(&bdev->bd_mutex);
-	INIT_LIST_HEAD(&bdev->bd_inodes);
 	INIT_LIST_HEAD(&bdev->bd_list);
 #ifdef CONFIG_SYSFS
 	INIT_LIST_HEAD(&bdev->bd_holder_disks);
@@ -624,24 +623,13 @@ static void init_once(void *foo)
 	mutex_init(&bdev->bd_fsfreeze_mutex);
 }
 
-static inline void __bd_forget(struct inode *inode)
-{
-	list_del_init(&inode->i_devices);
-	inode->i_bdev = NULL;
-	inode->i_mapping = &inode->i_data;
-}
-
 static void bdev_evict_inode(struct inode *inode)
 {
 	struct block_device *bdev = &BDEV_I(inode)->bdev;
-	struct list_head *p;
 	truncate_inode_pages_final(&inode->i_data);
 	invalidate_inode_buffers(inode); /* is it needed here? */
 	clear_inode(inode);
 	spin_lock(&bdev_lock);
-	while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
-		__bd_forget(list_entry(p, struct inode, i_devices));
-	}
 	list_del_init(&bdev->bd_list);
 	spin_unlock(&bdev_lock);
 }
@@ -805,7 +793,6 @@ static struct block_device *bd_acquire(struct inode *inode)
 			bdgrab(bdev);
 			inode->i_bdev = bdev;
 			inode->i_mapping = bdev->bd_inode->i_mapping;
-			list_add(&inode->i_devices, &bdev->bd_inodes);
 		}
 		spin_unlock(&bdev_lock);
 	}
@@ -821,7 +808,8 @@ void bd_forget(struct inode *inode)
 	spin_lock(&bdev_lock);
 	if (!sb_is_blkdev_sb(inode->i_sb))
 		bdev = inode->i_bdev;
-	__bd_forget(inode);
+	inode->i_bdev = NULL;
+	inode->i_mapping = &inode->i_data;
 	spin_unlock(&bdev_lock);
 
 	if (bdev)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index bacc0733663c..1878c8461622 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -459,7 +459,6 @@ struct block_device {
 	struct inode *		bd_inode;	/* will die */
 	struct super_block *	bd_super;
 	struct mutex		bd_mutex;	/* open/close mutex */
-	struct list_head	bd_inodes;
 	void *			bd_claiming;
 	void *			bd_holder;
 	int			bd_holders;
-- 
cgit v1.2.3


From 285b102d3b745f3c2c110c9c327741d87e64aacc Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Tue, 28 Jun 2016 11:47:32 +0200
Subject: vfs: new d_init method

Allow filesystem to initialize dentry at allocation time.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 Documentation/filesystems/Locking |  2 ++
 Documentation/filesystems/vfs.txt |  3 +++
 fs/dcache.c                       | 11 +++++++++++
 include/linux/dcache.h            |  1 +
 4 files changed, 17 insertions(+)

(limited to 'include')

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index a38da93865c2..794adbe55399 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -15,6 +15,7 @@ prototypes:
 	int (*d_compare)(const struct dentry *, const struct dentry *,
 			unsigned int, const char *, const struct qstr *);
 	int (*d_delete)(struct dentry *);
+	int (*d_init)(struct dentry *);
 	void (*d_release)(struct dentry *);
 	void (*d_iput)(struct dentry *, struct inode *);
 	char *(*d_dname)((struct dentry *dentry, char *buffer, int buflen);
@@ -30,6 +31,7 @@ d_weak_revalidate:no		no		yes	 	no
 d_hash		no		no		no		maybe
 d_compare:	yes		no		no		maybe
 d_delete:	no		yes		no		no
+d_init:	no		no		yes		no
 d_release:	no		no		yes		no
 d_prune:        no              yes             no              no
 d_iput:		no		no		yes		no
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 70a056fe51a3..15c3fa7c89cc 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -923,6 +923,7 @@ struct dentry_operations {
 	int (*d_compare)(const struct dentry *, const struct dentry *,
 			unsigned int, const char *, const struct qstr *);
 	int (*d_delete)(const struct dentry *);
+	int (*d_init)(struct dentry *);
 	void (*d_release)(struct dentry *);
 	void (*d_iput)(struct dentry *, struct inode *);
 	char *(*d_dname)(struct dentry *, char *, int);
@@ -995,6 +996,8 @@ struct dentry_operations {
 	always cache a reachable dentry. d_delete must be constant and
 	idempotent.
 
+  d_init: called when a dentry is allocated
+
   d_release: called when a dentry is really deallocated
 
   d_iput: called when a dentry loses its inode (just prior to its
diff --git a/fs/dcache.c b/fs/dcache.c
index d5beef01cdfc..6d60a764c848 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1569,6 +1569,7 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
 {
 	struct dentry *dentry;
 	char *dname;
+	int err;
 
 	dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
 	if (!dentry)
@@ -1627,6 +1628,16 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
 	INIT_LIST_HEAD(&dentry->d_child);
 	d_set_d_op(dentry, dentry->d_sb->s_d_op);
 
+	if (dentry->d_op && dentry->d_op->d_init) {
+		err = dentry->d_op->d_init(dentry);
+		if (err) {
+			if (dname_external(dentry))
+				kfree(external_name(dentry));
+			kmem_cache_free(dentry_cache, dentry);
+			return NULL;
+		}
+	}
+
 	this_cpu_inc(nr_dentry);
 
 	return dentry;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 14df83609c7f..98044a8d1487 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -133,6 +133,7 @@ struct dentry_operations {
 	int (*d_compare)(const struct dentry *, const struct dentry *,
 			unsigned int, const char *, const struct qstr *);
 	int (*d_delete)(const struct dentry *);
+	int (*d_init)(struct dentry *);
 	void (*d_release)(struct dentry *);
 	void (*d_prune)(struct dentry *);
 	void (*d_iput)(struct dentry *, struct inode *);
-- 
cgit v1.2.3