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Subject: [PATCH 24/67] cachefiles: Remove separate backer dentry from
 cachefiles_object
From:   David Howells <dhowells@redhat.com>
To:     linux-cachefs@redhat.com
Cc:     dhowells@redhat.com, Trond Myklebust <trondmy@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        Steve French <sfrench@samba.org>,
        Dominique Martinet <asmadeus@codewreck.org>,
        Jeff Layton <jlayton@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Omar Sandoval <osandov@osandov.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org,
        linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org,
        v9fs-developer@lists.sourceforge.net,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Mon, 18 Oct 2021 15:56:54 +0100
Message-ID: <163456901488.2614702.3877237088238450861.stgit@warthog.procyon.org.uk>
In-Reply-To: <163456861570.2614702.14754548462706508617.stgit@warthog.procyon.org.uk>
References: <163456861570.2614702.14754548462706508617.stgit@warthog.procyon.org.uk>
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The cachefiles_object struct has two dentry pointers - one for the
file/directory representing the object and a second one in case a data
object is a directory with a file inside of it that contains the data (the
idea being that there might be another file, say, containing a journal of
local changes that need committing or a list of cached xattrs).

At the moment, this isn't implemented, so remove it and always use the main
dentry pointer.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/cachefiles/bind.c      |    2 --
 fs/cachefiles/interface.c |   28 +++++++++-------------------
 fs/cachefiles/internal.h  |    1 -
 fs/cachefiles/io.c        |    4 ++--
 fs/cachefiles/namei.c     |    1 -
 5 files changed, 11 insertions(+), 25 deletions(-)

diff --git a/fs/cachefiles/bind.c b/fs/cachefiles/bind.c
index fbc8577477c1..cb3296814056 100644
--- a/fs/cachefiles/bind.c
+++ b/fs/cachefiles/bind.c
@@ -101,8 +101,6 @@ static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
 	if (!fsdef)
 		goto error_root_object;
 
-	ASSERTCMP(fsdef->backer, ==, NULL);
-
 	atomic_set(&fsdef->usage, 1);
 	fsdef->type = FSCACHE_COOKIE_TYPE_INDEX;
 
diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index 2083aca6bd0c..92bb3ba78c41 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -31,8 +31,6 @@ static struct fscache_object *cachefiles_alloc_object(
 	if (!object)
 		goto nomem_object;
 
-	ASSERTCMP(object->backer, ==, NULL);
-
 	atomic_set(&object->usage, 1);
 
 	fscache_object_init(&object->fscache, cookie, &cache->cache);
@@ -191,10 +189,6 @@ static void cachefiles_drop_object(struct fscache_object *_object)
 		}
 
 		/* close the filesystem stuff attached to the object */
-		if (object->backer != object->dentry)
-			dput(object->backer);
-		object->backer = NULL;
-
 		cachefiles_unmark_inode_in_use(object);
 		dput(object->dentry);
 		object->dentry = NULL;
@@ -235,7 +229,6 @@ void cachefiles_put_object(struct fscache_object *_object,
 		_debug("- kill object OBJ%x", object->fscache.debug_id);
 
 		ASSERTCMP(object->fscache.parent, ==, NULL);
-		ASSERTCMP(object->backer, ==, NULL);
 		ASSERTCMP(object->dentry, ==, NULL);
 		ASSERTCMP(object->fscache.n_ops, ==, 0);
 		ASSERTCMP(object->fscache.n_children, ==, 0);
@@ -303,17 +296,14 @@ static int cachefiles_attr_changed(struct cachefiles_object *object)
 	if (ni_size == object->i_size)
 		return 0;
 
-	if (!object->backer)
-		return -ENOBUFS;
+	ASSERT(d_is_reg(object->dentry));
 
-	ASSERT(d_is_reg(object->backer));
-
-	oi_size = i_size_read(d_backing_inode(object->backer));
+	oi_size = i_size_read(d_backing_inode(object->dentry));
 	if (oi_size == ni_size)
 		return 0;
 
 	cachefiles_begin_secure(cache, &saved_cred);
-	inode_lock(d_inode(object->backer));
+	inode_lock(d_inode(object->dentry));
 
 	/* if there's an extension to a partial page at the end of the backing
 	 * file, we need to discard the partial page so that we pick up new
@@ -322,17 +312,17 @@ static int cachefiles_attr_changed(struct cachefiles_object *object)
 		_debug("discard tail %llx", oi_size);
 		newattrs.ia_valid = ATTR_SIZE;
 		newattrs.ia_size = oi_size & PAGE_MASK;
-		ret = notify_change(&init_user_ns, object->backer, &newattrs, NULL);
+		ret = notify_change(&init_user_ns, object->dentry, &newattrs, NULL);
 		if (ret < 0)
 			goto truncate_failed;
 	}
 
 	newattrs.ia_valid = ATTR_SIZE;
 	newattrs.ia_size = ni_size;
-	ret = notify_change(&init_user_ns, object->backer, &newattrs, NULL);
+	ret = notify_change(&init_user_ns, object->dentry, &newattrs, NULL);
 
 truncate_failed:
-	inode_unlock(d_inode(object->backer));
+	inode_unlock(d_inode(object->dentry));
 	cachefiles_end_secure(cache, saved_cred);
 
 	if (ret == -EIO) {
@@ -365,10 +355,10 @@ static void cachefiles_invalidate_object(struct fscache_object *_object)
 	_enter("{OBJ%x},[%llu]",
 	       object->fscache.debug_id, (unsigned long long)ni_size);
 
-	if (object->backer) {
-		ASSERT(d_is_reg(object->backer));
+	if (object->dentry) {
+		ASSERT(d_is_reg(object->dentry));
 
-		path.dentry = object->backer;
+		path.dentry = object->dentry;
 		path.mnt = cache->mnt;
 
 		cachefiles_begin_secure(cache, &saved_cred);
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 83911cf24769..9f2f837027e0 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -36,7 +36,6 @@ struct cachefiles_object {
 	struct fscache_object		fscache;	/* fscache handle */
 	char				*d_name;	/* Filename */
 	struct dentry			*dentry;	/* the file/dir representing this object */
-	struct dentry			*backer;	/* backing file */
 	loff_t				i_size;		/* object size */
 	atomic_t			usage;		/* object usage count */
 	uint8_t				type;		/* object type */
diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
index 534c81a05918..920ca48eecfa 100644
--- a/fs/cachefiles/io.c
+++ b/fs/cachefiles/io.c
@@ -426,9 +426,9 @@ int cachefiles_begin_operation(struct netfs_cache_resources *cres)
 			     struct cachefiles_cache, cache);
 
 	path.mnt = cache->mnt;
-	path.dentry = object->backer;
+	path.dentry = object->dentry;
 	file = open_with_fake_path(&path, O_RDWR | O_LARGEFILE | O_DIRECT,
-				   d_inode(object->backer), cache->cache_cred);
+				   d_inode(object->dentry), cache->cache_cred);
 	if (IS_ERR(file))
 		return PTR_ERR(file);
 	if (!S_ISREG(file_inode(file)->i_mode))
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index b5a0aec529af..7f02fcb34b1e 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -459,7 +459,6 @@ int cachefiles_walk_to_object(struct cachefiles_object *parent,
 	if (ret < 0)
 		goto check_error;
 
-	object->backer = object->dentry;
 	object->new = false;
 	fscache_obtained_object(&object->fscache);
 	_leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);