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Subject[PATCH 1/2] devpts: remove unneeded inode_lock in mknod_ptmx
Date
Afaict, the mknod_ptmx() call is a no-op on subsequent calls and the first
call is done before we unlock the suberblock. If I'm not mistaken this is
exactly parallel to what Al pointed out for binderfs 29ef1c8e16a
("binderfs: drop lock in binderfs_binder_ctl_create"). In both filesystems
it should not be necessary to take inode_lock() in there. Let's remove it
and remove the goto.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christian Brauner <christian@brauner.io>
---
fs/devpts/inode.c | 19 ++++++-------------
1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index c53814539070..8fa1492f9712 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -325,7 +325,6 @@ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
static int mknod_ptmx(struct super_block *sb)
{
int mode;
- int rc = -ENOMEM;
struct dentry *dentry;
struct inode *inode;
struct dentry *root = sb->s_root;
@@ -334,18 +333,14 @@ static int mknod_ptmx(struct super_block *sb)
kuid_t ptmx_uid = current_fsuid();
kgid_t ptmx_gid = current_fsgid();

- inode_lock(d_inode(root));
-
/* If we have already created ptmx node, return */
- if (fsi->ptmx_dentry) {
- rc = 0;
- goto out;
- }
+ if (fsi->ptmx_dentry)
+ return 0;

dentry = d_alloc_name(root, "ptmx");
if (!dentry) {
pr_err("Unable to alloc dentry for ptmx node\n");
- goto out;
+ return -ENOMEM;
}

/*
@@ -355,7 +350,7 @@ static int mknod_ptmx(struct super_block *sb)
if (!inode) {
pr_err("Unable to alloc inode for ptmx node\n");
dput(dentry);
- goto out;
+ return -ENOMEM;
}

inode->i_ino = 2;
@@ -369,10 +364,8 @@ static int mknod_ptmx(struct super_block *sb)
d_add(dentry, inode);

fsi->ptmx_dentry = dentry;
- rc = 0;
-out:
- inode_unlock(d_inode(root));
- return rc;
+
+ return 0;
}

static void update_ptmx_mode(struct pts_fs_info *fsi)
--
2.20.1
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