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    Subject[PATCH 082/109] fs: add ksys_ftruncate() wrapper; remove in-kernel calls to sys_ftruncate()
    Date
    Using the ksys_ftruncate() wrapper allows us to get rid of in-kernel
    calls to the sys_ftruncate() 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_ftruncate().

    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>
    ---
    arch/mips/kernel/linux32.c | 2 +-
    arch/parisc/kernel/sys_parisc.c | 4 ++--
    arch/powerpc/kernel/sys_ppc32.c | 2 +-
    arch/s390/kernel/compat_linux.c | 2 +-
    arch/sparc/kernel/sys_sparc32.c | 2 +-
    arch/x86/ia32/sys_ia32.c | 2 +-
    fs/internal.h | 1 +
    fs/open.c | 2 +-
    include/linux/syscalls.h | 7 +++++++
    init/initramfs.c | 2 +-
    10 files changed, 17 insertions(+), 9 deletions(-)

    diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
    index b332f6fc1e72..3c90449742a0 100644
    --- a/arch/mips/kernel/linux32.c
    +++ b/arch/mips/kernel/linux32.c
    @@ -88,7 +88,7 @@ SYSCALL_DEFINE4(32_truncate64, const char __user *, path,
    SYSCALL_DEFINE4(32_ftruncate64, unsigned long, fd, unsigned long, __dummy,
    unsigned long, a2, unsigned long, a3)
    {
    - return sys_ftruncate(fd, merge_64(a2, a3));
    + return ksys_ftruncate(fd, merge_64(a2, a3));
    }

    SYSCALL_DEFINE5(32_llseek, unsigned int, fd, unsigned int, offset_high,
    diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
    index 378a754ca186..6d2a64859c22 100644
    --- a/arch/parisc/kernel/sys_parisc.c
    +++ b/arch/parisc/kernel/sys_parisc.c
    @@ -298,7 +298,7 @@ asmlinkage long parisc_truncate64(const char __user * path,
    asmlinkage long parisc_ftruncate64(unsigned int fd,
    unsigned int high, unsigned int low)
    {
    - return sys_ftruncate(fd, (long)high << 32 | low);
    + return ksys_ftruncate(fd, (long)high << 32 | low);
    }

    /* stubs for the benefit of the syscall_table since truncate64 and truncate
    @@ -309,7 +309,7 @@ asmlinkage long sys_truncate64(const char __user * path, unsigned long length)
    }
    asmlinkage long sys_ftruncate64(unsigned int fd, unsigned long length)
    {
    - return sys_ftruncate(fd, length);
    + return ksys_ftruncate(fd, length);
    }
    asmlinkage long sys_fcntl64(unsigned int fd, unsigned int cmd, unsigned long arg)
    {
    diff --git a/arch/powerpc/kernel/sys_ppc32.c b/arch/powerpc/kernel/sys_ppc32.c
    index 15f216d022e2..e0c9b7f1bf38 100644
    --- a/arch/powerpc/kernel/sys_ppc32.c
    +++ b/arch/powerpc/kernel/sys_ppc32.c
    @@ -107,7 +107,7 @@ asmlinkage long compat_sys_fallocate(int fd, int mode, u32 offhi, u32 offlo,
    asmlinkage int compat_sys_ftruncate64(unsigned int fd, u32 reg4, unsigned long high,
    unsigned long low)
    {
    - return sys_ftruncate(fd, (high << 32) | low);
    + return ksys_ftruncate(fd, (high << 32) | low);
    }

    long ppc32_fadvise64(int fd, u32 unused, u32 offset_high, u32 offset_low,
    diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c
    index 9a9bb395359c..9c5e975f71a6 100644
    --- a/arch/s390/kernel/compat_linux.c
    +++ b/arch/s390/kernel/compat_linux.c
    @@ -307,7 +307,7 @@ COMPAT_SYSCALL_DEFINE3(s390_truncate64, const char __user *, path, u32, high, u3

    COMPAT_SYSCALL_DEFINE3(s390_ftruncate64, unsigned int, fd, u32, high, u32, low)
    {
    - return sys_ftruncate(fd, (unsigned long)high << 32 | low);
    + return ksys_ftruncate(fd, (unsigned long)high << 32 | low);
    }

    COMPAT_SYSCALL_DEFINE5(s390_pread64, unsigned int, fd, char __user *, ubuf,
    diff --git a/arch/sparc/kernel/sys_sparc32.c b/arch/sparc/kernel/sys_sparc32.c
    index 6d964bdefbaa..d64b425fff93 100644
    --- a/arch/sparc/kernel/sys_sparc32.c
    +++ b/arch/sparc/kernel/sys_sparc32.c
    @@ -65,7 +65,7 @@ asmlinkage long sys32_ftruncate64(unsigned int fd, unsigned long high, unsigned
    if ((int)high < 0)
    return -EINVAL;
    else
    - return sys_ftruncate(fd, (high << 32) | low);
    + return ksys_ftruncate(fd, (high << 32) | low);
    }

    static int cp_compat_stat64(struct kstat *stat,
    diff --git a/arch/x86/ia32/sys_ia32.c b/arch/x86/ia32/sys_ia32.c
    index 23a5260eae67..1979e5b4ad9a 100644
    --- a/arch/x86/ia32/sys_ia32.c
    +++ b/arch/x86/ia32/sys_ia32.c
    @@ -61,7 +61,7 @@ COMPAT_SYSCALL_DEFINE3(x86_truncate64, const char __user *, filename,
    COMPAT_SYSCALL_DEFINE3(x86_ftruncate64, unsigned int, fd,
    unsigned long, offset_low, unsigned long, offset_high)
    {
    - return sys_ftruncate(fd, ((loff_t) offset_high << 32) | offset_low);
    + return ksys_ftruncate(fd, ((loff_t) offset_high << 32) | offset_low);
    }

    /*
    diff --git a/fs/internal.h b/fs/internal.h
    index c797480cbd6f..980d005b21b4 100644
    --- a/fs/internal.h
    +++ b/fs/internal.h
    @@ -119,6 +119,7 @@ extern struct file *do_filp_open(int dfd, struct filename *pathname,
    extern struct file *do_file_open_root(struct dentry *, struct vfsmount *,
    const char *, const struct open_flags *);

    +long do_sys_ftruncate(unsigned int fd, loff_t length, int small);
    long do_faccessat(int dfd, const char __user *filename, int mode);
    int do_fchmodat(int dfd, const char __user *filename, umode_t mode);
    int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
    diff --git a/fs/open.c b/fs/open.c
    index 7b2eccb541f2..b3f3b2cd9f19 100644
    --- a/fs/open.c
    +++ b/fs/open.c
    @@ -162,7 +162,7 @@ COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length
    }
    #endif

    -static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
    +long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
    {
    struct inode *inode;
    struct dentry *dentry;
    diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
    index df0d1e818a6e..41023177c8ec 100644
    --- a/include/linux/syscalls.h
    +++ b/include/linux/syscalls.h
    @@ -1038,4 +1038,11 @@ static inline long ksys_lchown(const char __user *filename, uid_t user,
    AT_SYMLINK_NOFOLLOW);
    }

    +extern long do_sys_ftruncate(unsigned int fd, loff_t length, int small);
    +
    +static inline long ksys_ftruncate(unsigned int fd, unsigned long length)
    +{
    + return do_sys_ftruncate(fd, length, 1);
    +}
    +
    #endif
    diff --git a/init/initramfs.c b/init/initramfs.c
    index 35173bef7c00..0d3b001b0dc5 100644
    --- a/init/initramfs.c
    +++ b/init/initramfs.c
    @@ -346,7 +346,7 @@ static int __init do_name(void)
    ksys_fchown(wfd, uid, gid);
    ksys_fchmod(wfd, mode);
    if (body_len)
    - sys_ftruncate(wfd, body_len);
    + ksys_ftruncate(wfd, body_len);
    vcollected = kstrdup(collected, GFP_KERNEL);
    state = CopyFile;
    }
    --
    2.16.3
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