fs: add ksys_ioctl() helper; remove in-kernel calls to sys_ioctl()

Using this helper allows us to avoid the in-kernel calls to the
sys_ioctl() syscall. The ksys_ prefix denotes that this function
is meant as a drop-in replacement for the syscall. In particular, it
uses the same calling convention as sys_ioctl().

After careful review, at least some of these calls could be converted
to do_vfs_ioctl() in future.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 5ace7efb0d04d2c0d4201e0fa24176be43b6e69c..4823431d1c9d4dc26f35df2327215ef56c94792e 100644 (file)
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -689,7 +689,7 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
        return error;
 }
 
-SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
+int ksys_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg)
 {
        int error;
        struct fd f = fdget(fd);
@@ -702,3 +702,8 @@ SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
        fdput(f);
        return error;
 }
+
+SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
+{
+       return ksys_ioctl(fd, cmd, arg);
+}

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index c056aff6d7ad9075cb9ccd74b8ed21fc24d04bdd..5a959efd8fb76e28c1b7fc54b8ae2e6e5712fd2c 100644 (file)
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -957,6 +957,7 @@ int ksys_fchmod(unsigned int fd, umode_t mode);
 int ksys_fchown(unsigned int fd, uid_t user, gid_t group);
 int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,
                    unsigned int count);
+int ksys_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg);
 
 /*
  * The following kernel syscall equivalents are just wrappers to fs-internal

diff --git a/init/do_mounts.c b/init/do_mounts.c
index cc11034770714e48f00e0ddb9ed8e8a6f3b3a503..b17e0095eb4edc37d876d790ae7d1c6ce21a0c1a 100644 (file)
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -491,18 +491,18 @@ void __init change_floppy(char *fmt, ...)
        va_end(args);
        fd = ksys_open("/dev/root", O_RDWR | O_NDELAY, 0);
        if (fd >= 0) {
-               sys_ioctl(fd, FDEJECT, 0);
+               ksys_ioctl(fd, FDEJECT, 0);
                ksys_close(fd);
        }
        printk(KERN_NOTICE "VFS: Insert %s and press ENTER\n", buf);
        fd = ksys_open("/dev/console", O_RDWR, 0);
        if (fd >= 0) {
-               sys_ioctl(fd, TCGETS, (long)&termios);
+               ksys_ioctl(fd, TCGETS, (long)&termios);
                termios.c_lflag &= ~ICANON;
-               sys_ioctl(fd, TCSETSF, (long)&termios);
+               ksys_ioctl(fd, TCSETSF, (long)&termios);
                sys_read(fd, &c, 1);
                termios.c_lflag |= ICANON;
-               sys_ioctl(fd, TCSETSF, (long)&termios);
+               ksys_ioctl(fd, TCSETSF, (long)&termios);
                ksys_close(fd);
        }
 }

diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index cedca8fd25901fba0fc137a4c959cafcbec0ad35..03ec0c1b75530fd7c2c84f8cd1a9b5ab162d0896 100644 (file)
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -110,7 +110,7 @@ static void __init handle_initrd(void)
                if (fd < 0) {
                        error = fd;
                } else {
-                       error = sys_ioctl(fd, BLKFLSBUF, 0);
+                       error = ksys_ioctl(fd, BLKFLSBUF, 0);
                        ksys_close(fd);
                }
                printk(!error ? "okay\n" : "failed\n");

diff --git a/init/do_mounts_md.c b/init/do_mounts_md.c
index 76dcfaada3edcce82e834d1e333049552d0253a7..7d85d172bc7e265ae2e4541a95d495799ee6446e 100644 (file)
--- a/init/do_mounts_md.c
+++ b/init/do_mounts_md.c
@@ -187,7 +187,7 @@ static void __init md_setup_drive(void)
                                        "array %s\n", name);
                        continue;
                }
-               if (sys_ioctl(fd, SET_ARRAY_INFO, 0) == -EBUSY) {
+               if (ksys_ioctl(fd, SET_ARRAY_INFO, 0) == -EBUSY) {
                        printk(KERN_WARNING
                               "md: Ignoring md=%d, already autodetected. (Use raid=noautodetect)\n",
                               minor);
@@ -210,7 +210,7 @@ static void __init md_setup_drive(void)
                        ainfo.state = (1 << MD_SB_CLEAN);
                        ainfo.layout = 0;
                        ainfo.chunk_size = md_setup_args[ent].chunk;
-                       err = sys_ioctl(fd, SET_ARRAY_INFO, (long)&ainfo);
+                       err = ksys_ioctl(fd, SET_ARRAY_INFO, (long)&ainfo);
                        for (i = 0; !err && i <= MD_SB_DISKS; i++) {
                                dev = devices[i];
                                if (!dev)
@@ -220,7 +220,8 @@ static void __init md_setup_drive(void)
                                dinfo.state = (1<<MD_DISK_ACTIVE)|(1<<MD_DISK_SYNC);
                                dinfo.major = MAJOR(dev);
                                dinfo.minor = MINOR(dev);
-                               err = sys_ioctl(fd, ADD_NEW_DISK, (long)&dinfo);
+                               err = ksys_ioctl(fd, ADD_NEW_DISK,
+                                                (long)&dinfo);
                        }
                } else {
                        /* persistent */
@@ -230,11 +231,11 @@ static void __init md_setup_drive(void)
                                        break;
                                dinfo.major = MAJOR(dev);
                                dinfo.minor = MINOR(dev);
-                               sys_ioctl(fd, ADD_NEW_DISK, (long)&dinfo);
+                               ksys_ioctl(fd, ADD_NEW_DISK, (long)&dinfo);
                        }
                }
                if (!err)
-                       err = sys_ioctl(fd, RUN_ARRAY, 0);
+                       err = ksys_ioctl(fd, RUN_ARRAY, 0);
                if (err)
                        printk(KERN_WARNING "md: starting md%d failed\n", minor);
                else {
@@ -245,7 +246,7 @@ static void __init md_setup_drive(void)
                         */
                        ksys_close(fd);
                        fd = ksys_open(name, 0, 0);
-                       sys_ioctl(fd, BLKRRPART, 0);
+                       ksys_ioctl(fd, BLKRRPART, 0);
                }
                ksys_close(fd);
        }
@@ -296,7 +297,7 @@ static void __init autodetect_raid(void)
 
        fd = ksys_open("/dev/md0", 0, 0);
        if (fd >= 0) {
-               sys_ioctl(fd, RAID_AUTORUN, raid_autopart);
+               ksys_ioctl(fd, RAID_AUTORUN, raid_autopart);
                ksys_close(fd);
        }
 }

diff --git a/init/do_mounts_rd.c b/init/do_mounts_rd.c
index a6706314baa75a88c90c8b5b7c7d1b78b9108f31..4dafaed5736f20f3807510cb5b096168c2348895 100644 (file)
--- a/init/do_mounts_rd.c
+++ b/init/do_mounts_rd.c
@@ -218,7 +218,7 @@ int __init rd_load_image(char *from)
         * NOTE NOTE: nblocks is not actually blocks but
         * the number of kibibytes of data to load into a ramdisk.
         */
-       if (sys_ioctl(out_fd, BLKGETSIZE, (unsigned long)&rd_blocks) < 0)
+       if (ksys_ioctl(out_fd, BLKGETSIZE, (unsigned long)&rd_blocks) < 0)
                rd_blocks = 0;
        else
                rd_blocks >>= 1;
@@ -232,7 +232,7 @@ int __init rd_load_image(char *from)
        /*
         * OK, time to copy in the data
         */
-       if (sys_ioctl(in_fd, BLKGETSIZE, (unsigned long)&devblocks) < 0)
+       if (ksys_ioctl(in_fd, BLKGETSIZE, (unsigned long)&devblocks) < 0)
                devblocks = 0;
        else
                devblocks >>= 1;