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    Subject[PATCH v2 32/35] Partially revert "locks: fix file locking on overlayfs"
    Date
    This partially reverts commit c568d68341be7030f5647def68851e469b21ca11.

    Overlayfs files will now automatically get the correct locks, no need to
    hack overlay support in VFS.

    It is a partial revert, because it leaves the locks_inode() calls in place
    and defines locks_inode() to file_inode(). We could revert those as well,
    but it would be unnecessary code churn and it makes sense to document that
    we are getting the inode for locking purposes.

    Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
    ---
    fs/locks.c | 17 ++++++-----------
    fs/overlayfs/super.c | 2 +-
    include/linux/fs.h | 13 +------------
    include/uapi/linux/fs.h | 1 -
    4 files changed, 8 insertions(+), 25 deletions(-)

    diff --git a/fs/locks.c b/fs/locks.c
    index 9c0e5f3da66c..40bcbaaa3f52 100644
    --- a/fs/locks.c
    +++ b/fs/locks.c
    @@ -139,11 +139,6 @@
    #define IS_OFDLCK(fl) (fl->fl_flags & FL_OFDLCK)
    #define IS_REMOTELCK(fl) (fl->fl_pid <= 0)

    -static inline bool is_remote_lock(struct file *filp)
    -{
    - return likely(!(filp->f_path.dentry->d_sb->s_flags & SB_NOREMOTELOCK));
    -}
    -
    static bool lease_breaking(struct file_lock *fl)
    {
    return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
    @@ -1875,7 +1870,7 @@ EXPORT_SYMBOL(generic_setlease);
    int
    vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv)
    {
    - if (filp->f_op->setlease && is_remote_lock(filp))
    + if (filp->f_op->setlease)
    return filp->f_op->setlease(filp, arg, lease, priv);
    else
    return generic_setlease(filp, arg, lease, priv);
    @@ -2022,7 +2017,7 @@ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
    if (error)
    goto out_free;

    - if (f.file->f_op->flock && is_remote_lock(f.file))
    + if (f.file->f_op->flock)
    error = f.file->f_op->flock(f.file,
    (can_sleep) ? F_SETLKW : F_SETLK,
    lock);
    @@ -2048,7 +2043,7 @@ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
    */
    int vfs_test_lock(struct file *filp, struct file_lock *fl)
    {
    - if (filp->f_op->lock && is_remote_lock(filp))
    + if (filp->f_op->lock)
    return filp->f_op->lock(filp, F_GETLK, fl);
    posix_test_lock(filp, fl);
    return 0;
    @@ -2191,7 +2186,7 @@ int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock *flock)
    */
    int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
    {
    - if (filp->f_op->lock && is_remote_lock(filp))
    + if (filp->f_op->lock)
    return filp->f_op->lock(filp, cmd, fl);
    else
    return posix_lock_file(filp, fl, conf);
    @@ -2513,7 +2508,7 @@ locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
    if (list_empty(&flctx->flc_flock))
    return;

    - if (filp->f_op->flock && is_remote_lock(filp))
    + if (filp->f_op->flock)
    filp->f_op->flock(filp, F_SETLKW, &fl);
    else
    flock_lock_inode(inode, &fl);
    @@ -2600,7 +2595,7 @@ EXPORT_SYMBOL(posix_unblock_lock);
    */
    int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
    {
    - if (filp->f_op->lock && is_remote_lock(filp))
    + if (filp->f_op->lock)
    return filp->f_op->lock(filp, F_CANCELLK, fl);
    return 0;
    }
    diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
    index 7779fc610767..f2a83fabe2eb 100644
    --- a/fs/overlayfs/super.c
    +++ b/fs/overlayfs/super.c
    @@ -1479,7 +1479,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
    sb->s_op = &ovl_super_operations;
    sb->s_xattr = ovl_xattr_handlers;
    sb->s_fs_info = ofs;
    - sb->s_flags |= SB_POSIXACL | SB_NOREMOTELOCK;
    + sb->s_flags |= SB_POSIXACL;

    err = -ENOMEM;
    root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));
    diff --git a/include/linux/fs.h b/include/linux/fs.h
    index ba3078693d4a..417e692a606a 100644
    --- a/include/linux/fs.h
    +++ b/include/linux/fs.h
    @@ -1050,17 +1050,7 @@ struct file_lock_context {

    extern void send_sigio(struct fown_struct *fown, int fd, int band);

    -/*
    - * Return the inode to use for locking
    - *
    - * For overlayfs this should be the overlay inode, not the real inode returned
    - * by file_inode(). For any other fs file_inode(filp) and locks_inode(filp) are
    - * equal.
    - */
    -static inline struct inode *locks_inode(const struct file *f)
    -{
    - return f->f_path.dentry->d_inode;
    -}
    +#define locks_inode(f) file_inode(f)

    #ifdef CONFIG_FILE_LOCKING
    extern int fcntl_getlk(struct file *, unsigned int, struct flock *);
    @@ -1300,7 +1290,6 @@ extern int send_sigurg(struct fown_struct *fown);

    /* These sb flags are internal to the kernel */
    #define SB_SUBMOUNT (1<<26)
    -#define SB_NOREMOTELOCK (1<<27)
    #define SB_NOSEC (1<<28)
    #define SB_BORN (1<<29)
    #define SB_ACTIVE (1<<30)
    diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
    index d2a8313fabd7..2840ddcece73 100644
    --- a/include/uapi/linux/fs.h
    +++ b/include/uapi/linux/fs.h
    @@ -134,7 +134,6 @@ struct inodes_stat_t {

    /* These sb flags are internal to the kernel */
    #define MS_SUBMOUNT (1<<26)
    -#define MS_NOREMOTELOCK (1<<27)
    #define MS_NOSEC (1<<28)
    #define MS_BORN (1<<29)
    #define MS_ACTIVE (1<<30)
    --
    2.14.3
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