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Subject[PATCH 083/109] fs: add ksys_close() wrapper; remove in-kernel calls to sys_close()
Date
Using the ksys_close() wrapper allows us to get rid of in-kernel calls
to the sys_close() 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_close(), with one subtle
difference:

The few places which checked the return value did not care about the return
value re-writing in sys_close(), so simply use a wrapper around
__close_fd().

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: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
---
fs/autofs4/dev-ioctl.c | 2 +-
fs/binfmt_misc.c | 2 +-
fs/file.c | 1 +
fs/open.c | 1 -
include/linux/syscalls.h | 12 ++++++++++++
init/do_mounts.c | 4 ++--
init/do_mounts_initrd.c | 2 +-
init/do_mounts_md.c | 8 ++++----
init/do_mounts_rd.c | 6 +++---
init/initramfs.c | 8 ++++----
10 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
index b7c816f39404..26f6b4f41ce6 100644
--- a/fs/autofs4/dev-ioctl.c
+++ b/fs/autofs4/dev-ioctl.c
@@ -310,7 +310,7 @@ static int autofs_dev_ioctl_closemount(struct file *fp,
struct autofs_sb_info *sbi,
struct autofs_dev_ioctl *param)
{
- return sys_close(param->ioctlfd);
+ return ksys_close(param->ioctlfd);
}

/*
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index a7c5a9861bef..a41b48f82a70 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -241,7 +241,7 @@ static int load_misc_binary(struct linux_binprm *bprm)
return retval;
error:
if (fd_binary > 0)
- sys_close(fd_binary);
+ ksys_close(fd_binary);
bprm->interp_flags = 0;
bprm->interp_data = 0;
goto ret;
diff --git a/fs/file.c b/fs/file.c
index d304004f0b65..7ffd6e9d103d 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -638,6 +638,7 @@ int __close_fd(struct files_struct *files, unsigned fd)
spin_unlock(&files->file_lock);
return -EBADF;
}
+EXPORT_SYMBOL(__close_fd); /* for ksys_close() */

void do_close_on_exec(struct files_struct *files)
{
diff --git a/fs/open.c b/fs/open.c
index b3f3b2cd9f19..710102fc262b 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1200,7 +1200,6 @@ SYSCALL_DEFINE1(close, unsigned int, fd)

return retval;
}
-EXPORT_SYMBOL(sys_close);

/*
* This routine simulates a hangup on the tty, to arrange that users
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 41023177c8ec..38805f3447ea 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1045,4 +1045,16 @@ static inline long ksys_ftruncate(unsigned int fd, unsigned long length)
return do_sys_ftruncate(fd, length, 1);
}

+extern int __close_fd(struct files_struct *files, unsigned int fd);
+
+/*
+ * In contrast to sys_close(), this stub does not check whether the syscall
+ * should or should not be restarted, but returns the raw error codes from
+ * __close_fd().
+ */
+static inline int ksys_close(unsigned int fd)
+{
+ return __close_fd(current->files, fd);
+}
+
#endif
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 89f18985fa90..a28dd42d1f84 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -492,7 +492,7 @@ void __init change_floppy(char *fmt, ...)
fd = sys_open("/dev/root", O_RDWR | O_NDELAY, 0);
if (fd >= 0) {
sys_ioctl(fd, FDEJECT, 0);
- sys_close(fd);
+ ksys_close(fd);
}
printk(KERN_NOTICE "VFS: Insert %s and press ENTER\n", buf);
fd = sys_open("/dev/console", O_RDWR, 0);
@@ -503,7 +503,7 @@ void __init change_floppy(char *fmt, ...)
sys_read(fd, &c, 1);
termios.c_lflag |= ICANON;
sys_ioctl(fd, TCSETSF, (long)&termios);
- sys_close(fd);
+ ksys_close(fd);
}
}
#endif
diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index 99922d1ebfe6..6907c6dbc443 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -111,7 +111,7 @@ static void __init handle_initrd(void)
error = fd;
} else {
error = sys_ioctl(fd, BLKFLSBUF, 0);
- sys_close(fd);
+ ksys_close(fd);
}
printk(!error ? "okay\n" : "failed\n");
}
diff --git a/init/do_mounts_md.c b/init/do_mounts_md.c
index 3f733c760a8c..ebd4013d589e 100644
--- a/init/do_mounts_md.c
+++ b/init/do_mounts_md.c
@@ -191,7 +191,7 @@ static void __init md_setup_drive(void)
printk(KERN_WARNING
"md: Ignoring md=%d, already autodetected. (Use raid=noautodetect)\n",
minor);
- sys_close(fd);
+ ksys_close(fd);
continue;
}

@@ -243,11 +243,11 @@ static void __init md_setup_drive(void)
* boot a kernel with devfs compiled in from partitioned md
* array without it
*/
- sys_close(fd);
+ ksys_close(fd);
fd = sys_open(name, 0, 0);
sys_ioctl(fd, BLKRRPART, 0);
}
- sys_close(fd);
+ ksys_close(fd);
}
}

@@ -297,7 +297,7 @@ static void __init autodetect_raid(void)
fd = sys_open("/dev/md0", 0, 0);
if (fd >= 0) {
sys_ioctl(fd, RAID_AUTORUN, raid_autopart);
- sys_close(fd);
+ ksys_close(fd);
}
}

diff --git a/init/do_mounts_rd.c b/init/do_mounts_rd.c
index 5b69056f610a..f1aa341862d3 100644
--- a/init/do_mounts_rd.c
+++ b/init/do_mounts_rd.c
@@ -257,7 +257,7 @@ int __init rd_load_image(char *from)
if (i && (i % devblocks == 0)) {
printk("done disk #%d.\n", disk++);
rotate = 0;
- if (sys_close(in_fd)) {
+ if (ksys_close(in_fd)) {
printk("Error closing the disk.\n");
goto noclose_input;
}
@@ -283,9 +283,9 @@ int __init rd_load_image(char *from)
successful_load:
res = 1;
done:
- sys_close(in_fd);
+ ksys_close(in_fd);
noclose_input:
- sys_close(out_fd);
+ ksys_close(out_fd);
out:
kfree(buf);
ksys_unlink("/dev/ram");
diff --git a/init/initramfs.c b/init/initramfs.c
index 0d3b001b0dc5..ce2bcad97cdf 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -373,7 +373,7 @@ static int __init do_copy(void)
if (byte_count >= body_len) {
if (xwrite(wfd, victim, body_len) != body_len)
error("write error");
- sys_close(wfd);
+ ksys_close(wfd);
do_utime(vcollected, mtime);
kfree(vcollected);
eat(body_len);
@@ -574,7 +574,7 @@ static void __init clean_rootfs(void)
buf = kzalloc(BUF_SIZE, GFP_KERNEL);
WARN_ON(!buf);
if (!buf) {
- sys_close(fd);
+ ksys_close(fd);
return;
}

@@ -602,7 +602,7 @@ static void __init clean_rootfs(void)
num = sys_getdents64(fd, dirp, BUF_SIZE);
}

- sys_close(fd);
+ ksys_close(fd);
kfree(buf);
}
#endif
@@ -639,7 +639,7 @@ static int __init populate_rootfs(void)
pr_err("/initrd.image: incomplete write (%zd != %ld)\n",
written, initrd_end - initrd_start);

- sys_close(fd);
+ ksys_close(fd);
free_initrd();
}
done:
--
2.16.3
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