On Thu, 2007-05-31 at 17:40 -0400, J. Bruce Fields wrote:
> From: J. Bruce Fields <[EMAIL PROTECTED]>
>
> Currently leases are only kept locally, so there's no way for a distributed
> filesystem to enforce them against multiple clients. We're particularly
> interested in the case of nfsd exporting a cluster filesystem, in which
> case nfsd needs cluster-coherent leases in order to implement delegations
> correctly.
>
> Signed-off-by: J. Bruce Fields <[EMAIL PROTECTED]>
> ---
> fs/locks.c | 5 ++++-
> include/linux/fs.h | 4 ++++
> 2 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/fs/locks.c b/fs/locks.c
> index 3f366e1..40a7f39 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -1444,7 +1444,10 @@ int setlease(struct file *filp, long arg, struct
> file_lock **lease)
> return error;
>
> lock_kernel();
> - error = __setlease(filp, arg, lease);
> + if (filp->f_op && filp->f_op->set_lease)
> + error = filp->f_op->set_lease(filp, arg, lease);
> + else
> + error = __setlease(filp, arg, lease);
> unlock_kernel();
>
> return error;
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 7cf0c54..09aefb4 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1112,6 +1112,7 @@ struct file_operations {
> int (*flock) (struct file *, int, struct file_lock *);
> ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t
> *, size_t, unsigned int);
> ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info
> *, size_t, unsigned int);
> + int (*set_lease)(struct file *, long, struct file_lock **);
> };
>
> struct inode_operations {
> @@ -1137,6 +1138,7 @@ struct inode_operations {
> ssize_t (*listxattr) (struct dentry *, char *, size_t);
> int (*removexattr) (struct dentry *, const char *);
> void (*truncate_range)(struct inode *, loff_t, loff_t);
> + int (*break_lease)(struct inode *, unsigned int);
Splitting the lease into a file_operation part and an inode_operation
part looks really ugly. It also means that you're calling twice down
into the filesystem for every call to may_open() (once for
vfs_permission() and once for break_lease()) and 3 times in
do_sys_truncate().
Would it perhaps make sense to package up the call to vfs_permission()
and break_lease() as a single 'may_open()' inode operation that could be
called by may_open(), do_sys_truncate() and nfsd?
Trond
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