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Date: Tue, 08 May 2018 11:15:47 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Miklos Szeredi <mszeredi@...hat.com>, linux-unionfs@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH v2 32/35] Partially revert "locks: fix file locking on
overlayfs"
On Mon, 2018-05-07 at 10:38 +0200, Miklos Szeredi wrote:
> 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@...hat.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)
Acked-by: Jeff Layton <jlayton@...nel.org>
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