linux-kernel - [PATCH 18/45] fs/quota: add kernel_quotactl() helper; remove in-kernel call to syscall

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Date:   Thu, 22 Mar 2018 10:00:32 +0100
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
        viro@...IV.linux.org.uk, arnd@...db.de, linux-arch@...r.kernel.org
Cc:     Jan Kara <jack@...e.com>
Subject: [PATCH 18/45] fs/quota: add kernel_quotactl() helper; remove in-kernel call to syscall

Using the fs-internal kernel_quotactl() helper allows us to get rid of
the fs-internal call to the sys_quotactl() syscall.

This patch is part of a series which tries to remove in-kernel calls to
syscalls. On this basis, the syscall entry path can be streamlined.

Cc: Jan Kara <jack@...e.com>
Signed-off-by: Dominik Brodowski <linux@...inikbrodowski.net>
---
 fs/quota/compat.c        |  8 ++++----
 fs/quota/quota.c         | 10 ++++++++--
 include/linux/quotaops.h |  3 +++
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/fs/quota/compat.c b/fs/quota/compat.c
index 779caed4f078..1577a2fd51f4 100644
--- a/fs/quota/compat.c
+++ b/fs/quota/compat.c
@@ -59,7 +59,7 @@ asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
 	case Q_GETQUOTA:
 		dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
 		compat_dqblk = addr;
-		ret = sys_quotactl(cmd, special, id, dqblk);
+		ret = kernel_quotactl(cmd, special, id, dqblk);
 		if (ret)
 			break;
 		if (copy_in_user(compat_dqblk, dqblk, sizeof(*compat_dqblk)) ||
@@ -75,12 +75,12 @@ asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
 			get_user(data, &compat_dqblk->dqb_valid) ||
 			put_user(data, &dqblk->dqb_valid))
 			break;
-		ret = sys_quotactl(cmd, special, id, dqblk);
+		ret = kernel_quotactl(cmd, special, id, dqblk);
 		break;
 	case Q_XGETQSTAT:
 		fsqstat = compat_alloc_user_space(sizeof(struct fs_quota_stat));
 		compat_fsqstat = addr;
-		ret = sys_quotactl(cmd, special, id, fsqstat);
+		ret = kernel_quotactl(cmd, special, id, fsqstat);
 		if (ret)
 			break;
 		ret = -EFAULT;
@@ -113,7 +113,7 @@ asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
 		ret = 0;
 		break;
 	default:
-		ret = sys_quotactl(cmd, special, id, addr);
+		ret = kernel_quotactl(cmd, special, id, addr);
 	}
 	return ret;
 }
diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index 43612e2a73af..860bfbe7a07a 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -833,8 +833,8 @@ static struct super_block *quotactl_block(const char __user *special, int cmd)
  * calls. Maybe we need to add the process quotas etc. in the future,
  * but we probably should use rlimits for that.
  */
-SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
-		qid_t, id, void __user *, addr)
+int kernel_quotactl(unsigned int cmd, const char __user *special,
+		    qid_t id, void __user *addr)
 {
 	uint cmds, type;
 	struct super_block *sb = NULL;
@@ -885,3 +885,9 @@ SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 		path_put(pathp);
 	return ret;
 }
+
+SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
+		qid_t, id, void __user *, addr)
+{
+	return kernel_quotactl(cmd, special, id, addr);
+}
diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
index 2fb6fb11132e..ff63eac16a79 100644
--- a/include/linux/quotaops.h
+++ b/include/linux/quotaops.h
@@ -105,6 +105,9 @@ int dquot_set_dqblk(struct super_block *sb, struct kqid id,
 int __dquot_transfer(struct inode *inode, struct dquot **transfer_to);
 int dquot_transfer(struct inode *inode, struct iattr *iattr);
 
+int kernel_quotactl(unsigned int cmd, const char __user *special,
+		    qid_t id, void __user *addr);
+
 static inline struct mem_dqinfo *sb_dqinfo(struct super_block *sb, int type)
 {
 	return sb_dqopt(sb)->info + type;
-- 
2.16.2