autofs4: improve parameter usage

The parameter usage in the device node ioctl code uses arg1 and arg2 as
parameter names.  This patch redefines the parameter names to reflect what
they actually are in an effort to make the code more readable.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 100 insertions, 29 deletions

diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
index 63b7c7afe8df..054d6d9ad9ba 100644
--- a/fs/autofs4/dev-ioctl.c
+++ b/fs/autofs4/dev-ioctl.c
@@ -180,7 +180,7 @@ static int autofs_dev_ioctl_protover(struct file *fp,
                                      struct autofs_sb_info *sbi,
                                      struct autofs_dev_ioctl *param)
 {
-        param->arg1 = sbi->version;
+        param->protover.version = sbi->version;
         return 0;
 }
 
@@ -189,7 +189,7 @@ static int autofs_dev_ioctl_protosubver(struct file *fp,
                                         struct autofs_sb_info *sbi,
                                         struct autofs_dev_ioctl *param)
 {
-        param->arg1 = sbi->sub_version;
+        param->protosubver.sub_version = sbi->sub_version;
         return 0;
 }
 
@@ -335,13 +335,13 @@ static int autofs_dev_ioctl_openmount(struct file *fp,
         int err, fd;
 
         /* param->path has already been checked */
-        if (!param->arg1)
+        if (!param->openmount.devid)
                 return -EINVAL;
 
         param->ioctlfd = -1;
 
         path = param->path;
-        devid = param->arg1;
+        devid = param->openmount.devid;
 
         err = 0;
         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
@@ -373,7 +373,7 @@ static int autofs_dev_ioctl_ready(struct file *fp,
 {
         autofs_wqt_t token;
 
-        token = (autofs_wqt_t) param->arg1;
+        token = (autofs_wqt_t) param->ready.token;
         return autofs4_wait_release(sbi, token, 0);
 }
 
@@ -388,8 +388,8 @@ static int autofs_dev_ioctl_fail(struct file *fp,
         autofs_wqt_t token;
         int status;
 
-        token = (autofs_wqt_t) param->arg1;
-        status = param->arg2 ? param->arg2 : -ENOENT;
+        token = (autofs_wqt_t) param->fail.token;
+        status = param->fail.status ? param->fail.status : -ENOENT;
         return autofs4_wait_release(sbi, token, status);
 }
 
@@ -412,10 +412,10 @@ static int autofs_dev_ioctl_setpipefd(struct file *fp,
         int pipefd;
         int err = 0;
 
-        if (param->arg1 == -1)
+        if (param->setpipefd.pipefd == -1)
                 return -EINVAL;
 
-        pipefd = param->arg1;
+        pipefd = param->setpipefd.pipefd;
 
         mutex_lock(&sbi->wq_mutex);
         if (!sbi->catatonic) {
@@ -457,8 +457,8 @@ static int autofs_dev_ioctl_timeout(struct file *fp,
 {
         unsigned long timeout;
 
-        timeout = param->arg1;
-        param->arg1 = sbi->exp_timeout / HZ;
+        timeout = param->timeout.timeout;
+        param->timeout.timeout = sbi->exp_timeout / HZ;
         sbi->exp_timeout = timeout * HZ;
         return 0;
 }
@@ -489,7 +489,7 @@ static int autofs_dev_ioctl_requester(struct file *fp,
         path = param->path;
         devid = sbi->sb->s_dev;
 
-        param->arg1 = param->arg2 = -1;
+        param->requester.uid = param->requester.gid = -1;
 
         /* Get nameidata of the parent directory */
         err = path_lookup(path, LOOKUP_PARENT, &nd);
@@ -505,8 +505,8 @@ static int autofs_dev_ioctl_requester(struct file *fp,
                 err = 0;
                 autofs4_expire_wait(nd.path.dentry);
                 spin_lock(&sbi->fs_lock);
-                param->arg1 = ino->uid;
-                param->arg2 = ino->gid;
+                param->requester.uid = ino->uid;
+                param->requester.gid = ino->gid;
                 spin_unlock(&sbi->fs_lock);
         }
 
@@ -529,7 +529,7 @@ static int autofs_dev_ioctl_expire(struct file *fp,
         int err = -EAGAIN;
         int how;
 
-        how = param->arg1;
+        how = param->expire.how;
         mnt = fp->f_path.mnt;
 
         if (sbi->type & AUTOFS_TYPE_TRIGGER)
@@ -565,9 +565,9 @@ static int autofs_dev_ioctl_askumount(struct file *fp,
                                       struct autofs_sb_info *sbi,
                                       struct autofs_dev_ioctl *param)
 {
-        param->arg1 = 0;
+        param->askumount.may_umount = 0;
         if (may_umount(fp->f_path.mnt))
-                param->arg1 = 1;
+                param->askumount.may_umount = 1;
         return 0;
 }
 
@@ -600,6 +600,7 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp,
         struct nameidata nd;
         const char *path;
         unsigned int type;
+        unsigned int devid, magic;
         int err = -ENOENT;
 
         if (param->size <= sizeof(*param)) {
@@ -608,10 +609,10 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp,
         }
 
         path = param->path;
-        type = param->arg1;
+        type = param->ismountpoint.in.type;
 
-        param->arg1 = 0;
-        param->arg2 = 0;
+        param->ismountpoint.out.devid = devid = 0;
+        param->ismountpoint.out.magic = magic = 0;
 
         if (!fp || param->ioctlfd == -1) {
                 if (type == AUTOFS_TYPE_ANY) {
@@ -622,7 +623,7 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp,
                                 goto out;
 
                         sb = nd.path.dentry->d_sb;
-                        param->arg1 = new_encode_dev(sb->s_dev);
+                        devid = new_encode_dev(sb->s_dev);
                 } else {
                         struct autofs_info *ino;
 
@@ -635,14 +636,14 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp,
                                 goto out_release;
 
                         ino = autofs4_dentry_ino(nd.path.dentry);
-                        param->arg1 = autofs4_get_dev(ino->sbi);
+                        devid = autofs4_get_dev(ino->sbi);
                 }
 
                 err = 0;
                 if (nd.path.dentry->d_inode &&
                     nd.path.mnt->mnt_root == nd.path.dentry) {
                         err = 1;
-                        param->arg2 = nd.path.dentry->d_inode->i_sb->s_magic;
+                        magic = nd.path.dentry->d_inode->i_sb->s_magic;
                 }
         } else {
                 dev_t devid = new_encode_dev(sbi->sb->s_dev);
@@ -655,18 +656,21 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp,
                 if (err)
                         goto out_release;
 
-                param->arg1 = autofs4_get_dev(sbi);
+                devid = autofs4_get_dev(sbi);
 
                 err = have_submounts(nd.path.dentry);
 
                 if (nd.path.mnt->mnt_mountpoint != nd.path.mnt->mnt_root) {
                         if (follow_down(&nd.path.mnt, &nd.path.dentry)) {
                                 struct inode *inode = nd.path.dentry->d_inode;
-                                param->arg2 = inode->i_sb->s_magic;
+                                magic = inode->i_sb->s_magic;
                         }
                 }
         }
 
+        param->ismountpoint.out.devid = devid;
+        param->ismountpoint.out.magic = magic;
+
 out_release:
         path_put(&nd.path);
 out:
diff --git a/include/linux/auto_dev-ioctl.h b/include/linux/auto_dev-ioctl.h
index f4d05ccd731f..91a773993a5c 100644
--- a/include/linux/auto_dev-ioctl.h
+++ b/include/linux/auto_dev-ioctl.h
@@ -10,6 +10,7 @@
 #ifndef _LINUX_AUTO_DEV_IOCTL_H
 #define _LINUX_AUTO_DEV_IOCTL_H
 
+#include <linux/string.h>
 #include <linux/types.h>
 
 #define AUTOFS_DEVICE_NAME              "autofs"
@@ -25,6 +26,60 @@
  * An ioctl interface for autofs mount point control.
  */
 
+struct args_protover {
+        __u32   version;
+};
+
+struct args_protosubver {
+        __u32   sub_version;
+};
+
+struct args_openmount {
+        __u32   devid;
+};
+
+struct args_ready {
+        __u32   token;
+};
+
+struct args_fail {
+        __u32   token;
+        __s32   status;
+};
+
+struct args_setpipefd {
+        __s32   pipefd;
+};
+
+struct args_timeout {
+        __u64   timeout;
+};
+
+struct args_requester {
+        __u32   uid;
+        __u32   gid;
+};
+
+struct args_expire {
+        __u32   how;
+};
+
+struct args_askumount {
+        __u32   may_umount;
+};
+
+struct args_ismountpoint {
+        union {
+                struct args_in {
+                        __u32   type;
+                } in;
+                struct args_out {
+                        __u32   devid;
+                        __u32   magic;
+                } out;
+        };
+};
+
 /*
  * All the ioctls use this structure.
  * When sending a path size must account for the total length
@@ -39,20 +94,32 @@ struct autofs_dev_ioctl {
                                  * including this struct */
         __s32 ioctlfd;          /* automount command fd */
 
-        __u32 arg1;             /* Command parameters */
-        __u32 arg2;
+        /* Command parameters */
+
+        union {
+                struct args_protover            protover;
+                struct args_protosubver         protosubver;
+                struct args_openmount           openmount;
+                struct args_ready               ready;
+                struct args_fail                fail;
+                struct args_setpipefd           setpipefd;
+                struct args_timeout             timeout;
+                struct args_requester           requester;
+                struct args_expire              expire;
+                struct args_askumount           askumount;
+                struct args_ismountpoint        ismountpoint;
+        };
 
         char path[0];
 };
 
 static inline void init_autofs_dev_ioctl(struct autofs_dev_ioctl *in)
 {
+        memset(in, 0, sizeof(struct autofs_dev_ioctl));
         in->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
         in->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
         in->size = sizeof(struct autofs_dev_ioctl);
         in->ioctlfd = -1;
-        in->arg1 = 0;
-        in->arg2 = 0;
         return;
 }