[PATCH 4/6] fuse: return correct dentry for ->mkdir

[NeilBrown <neilb@suse.de>]

fuse already uses d_splice_alias() to ensure an appropriate dentry is
found for a newly created dentry.  Now that ->mkdir can return that
dentry we do so.

This requires changing create_new_entry() to return a dentry and
handling that change in all callers.

Note that when create_new_entry() is asked to create anything other than
a directory we can be sure it will NOT return an alternate dentry as
d_splice_alias() only returns an alternate dentry for directories.
So we don't need to check for that case when passing one the result.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neilb@suse.de>
---
 fs/fuse/dir.c | 48 +++++++++++++++++++++++++++---------------------
 1 file changed, 27 insertions(+), 21 deletions(-)

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index d0289ce068ba..2779ebf2b3b9 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -781,9 +781,9 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry,
 /*
  * Code shared between mknod, mkdir, symlink and link
  */
-static int create_new_entry(struct mnt_idmap *idmap, struct fuse_mount *fm,
-			    struct fuse_args *args, struct inode *dir,
-			    struct dentry *entry, umode_t mode)
+static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_mount *fm,
+				       struct fuse_args *args, struct inode *dir,
+				       struct dentry *entry, umode_t mode)
 {
 	struct fuse_entry_out outarg;
 	struct inode *inode;
@@ -792,11 +792,11 @@ static int create_new_entry(struct mnt_idmap *idmap, struct fuse_mount *fm,
 	struct fuse_forget_link *forget;
 
 	if (fuse_is_bad(dir))
-		return -EIO;
+		return ERR_PTR(-EIO);
 
 	forget = fuse_alloc_forget();
 	if (!forget)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	memset(&outarg, 0, sizeof(outarg));
 	args->nodeid = get_node_id(dir);
@@ -826,29 +826,27 @@ static int create_new_entry(struct mnt_idmap *idmap, struct fuse_mount *fm,
 			  &outarg.attr, ATTR_TIMEOUT(&outarg), 0, 0);
 	if (!inode) {
 		fuse_queue_forget(fm->fc, forget, outarg.nodeid, 1);
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 	}
 	kfree(forget);
 
 	d_drop(entry);
 	d = d_splice_alias(inode, entry);
 	if (IS_ERR(d))
-		return PTR_ERR(d);
+		return d;
 
-	if (d) {
+	if (d)
 		fuse_change_entry_timeout(d, &outarg);
-		dput(d);
-	} else {
+	else
 		fuse_change_entry_timeout(entry, &outarg);
-	}
 	fuse_dir_changed(dir);
-	return 0;
+	return d;
 
  out_put_forget_req:
 	if (err == -EEXIST)
 		fuse_invalidate_entry(entry);
 	kfree(forget);
-	return err;
+	return ERR_PTR(err);
 }
 
 static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
@@ -856,6 +854,7 @@ static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
 {
 	struct fuse_mknod_in inarg;
 	struct fuse_mount *fm = get_fuse_mount(dir);
+	struct dentry *de;
 	FUSE_ARGS(args);
 
 	if (!fm->fc->dont_mask)
@@ -871,7 +870,10 @@ static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
 	args.in_args[0].value = &inarg;
 	args.in_args[1].size = entry->d_name.len + 1;
 	args.in_args[1].value = entry->d_name.name;
-	return create_new_entry(idmap, fm, &args, dir, entry, mode);
+	de = create_new_entry(idmap, fm, &args, dir, entry, mode);
+	if (IS_ERR(de))
+		return PTR_ERR(de);
+	return 0;
 }
 
 static int fuse_create(struct mnt_idmap *idmap, struct inode *dir,
@@ -917,7 +919,7 @@ static struct dentry *fuse_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 	args.in_args[0].value = &inarg;
 	args.in_args[1].size = entry->d_name.len + 1;
 	args.in_args[1].value = entry->d_name.name;
-	return ERR_PTR(create_new_entry(idmap, fm, &args, dir, entry, S_IFDIR));
+	return create_new_entry(idmap, fm, &args, dir, entry, S_IFDIR);
 }
 
 static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
@@ -925,6 +927,7 @@ static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
 {
 	struct fuse_mount *fm = get_fuse_mount(dir);
 	unsigned len = strlen(link) + 1;
+	struct dentry *de;
 	FUSE_ARGS(args);
 
 	args.opcode = FUSE_SYMLINK;
@@ -934,7 +937,10 @@ static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
 	args.in_args[1].value = entry->d_name.name;
 	args.in_args[2].size = len;
 	args.in_args[2].value = link;
-	return create_new_entry(idmap, fm, &args, dir, entry, S_IFLNK);
+	de = create_new_entry(idmap, fm, &args, dir, entry, S_IFLNK);
+	if (IS_ERR(de))
+		return PTR_ERR(de);
+	return 0;
 }
 
 void fuse_flush_time_update(struct inode *inode)
@@ -1117,7 +1123,7 @@ static int fuse_rename2(struct mnt_idmap *idmap, struct inode *olddir,
 static int fuse_link(struct dentry *entry, struct inode *newdir,
 		     struct dentry *newent)
 {
-	int err;
+	struct dentry *de;
 	struct fuse_link_in inarg;
 	struct inode *inode = d_inode(entry);
 	struct fuse_mount *fm = get_fuse_mount(inode);
@@ -1131,13 +1137,13 @@ static int fuse_link(struct dentry *entry, struct inode *newdir,
 	args.in_args[0].value = &inarg;
 	args.in_args[1].size = newent->d_name.len + 1;
 	args.in_args[1].value = newent->d_name.name;
-	err = create_new_entry(&invalid_mnt_idmap, fm, &args, newdir, newent, inode->i_mode);
-	if (!err)
+	de = create_new_entry(&invalid_mnt_idmap, fm, &args, newdir, newent, inode->i_mode);
+	if (!IS_ERR(de))
 		fuse_update_ctime_in_cache(inode);
-	else if (err == -EINTR)
+	else if (PTR_ERR(de) == -EINTR)
 		fuse_invalidate_attr(inode);
 
-	return err;
+	return PTR_ERR(de);
 }
 
 static void fuse_fillattr(struct mnt_idmap *idmap, struct inode *inode,
-- 
2.48.1