On Sat, 2007-02-03 at 00:33 -0500, J. Bruce Fields wrote:
> From: J. Bruce Fields <bfields@xxxxxxxxxxxxxxxxxxxxx> - unquoted
>
> Factor out the code that switches between generic and filesystem-specific lock
> methods; eventually we want to call this from lock managers (lockd and nfsd)
> too; currently they only call the generic methods.
>
> This patch does that for test_lock.
>
> Note that this hasn't been necessary until recently, because the few
> filesystems that define ->lock() (nfs, cifs...) aren't exportable via NFS.
> However GFS (and, in the future, other cluster filesystems) need to implement
> their own locking to get cluster-coherent locking, and also want to be able to
> export locking to NFS (lockd and NFSv4).
>
> So we accomplish this by factoring out code such as this and exporting it for
> the use of lockd and nfsd.
>
> Signed-off-by: "J. Bruce Fields" <bfields@xxxxxxxxxxxxxx>
> ---
> fs/locks.c | 59 ++++++++++++++++++++++++++-----------------
> include/linux/lockd/bind.h | 2 +
> 2 files changed, 38 insertions(+), 23 deletions(-)
>
> diff --git a/fs/locks.c b/fs/locks.c
> index 4390a95..95246dc 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -1611,6 +1611,33 @@ asmlinkage long sys_flock(unsigned int fd, unsigned int cmd)
> return error;
> }
>
> +/**
> + * vfs_test_lock - test file byte range lock
> + * @filp: The file to test lock for
> + * @fl: The lock to test
> + * @conf: Place to return a copy of the conflicting lock, if found
> + *
> + * Returns -ERRNO on failure. Indicates presence of conflicting lock by
> + * setting conf->fl_type to something other than F_UNLCK.
> + */
> +int vfs_test_lock(struct file *filp, struct file_lock *fl, struct file_lock *conf)
> +{
> + int error;
> +
> + conf->fl_type = F_UNLCK;
> + if (filp->f_op && filp->f_op->lock) {
> + __locks_copy_lock(conf, fl);
> + error = filp->f_op->lock(filp, F_GETLK, conf);
> + if (conf->fl_ops && conf->fl_ops->fl_release_private)
> + conf->fl_ops->fl_release_private(conf);
Why are you adding in a "release" call here? Is there any reason why a
GETLK would want to return private data from the filesystem to the VFS?
> + return error;
> + } else {
> + posix_test_lock(filp, fl, conf);
> + return 0;
> + }
> +}
> +EXPORT_SYMBOL(vfs_test_lock);
> +
> /* Report the first existing lock that would conflict with l.
> * This implements the F_GETLK command of fcntl().
> */
> @@ -1631,17 +1658,10 @@ int fcntl_getlk(struct file *filp, struct flock __user *l)
> if (error)
> goto out;
>
> - if (filp->f_op && filp->f_op->lock) {
> - error = filp->f_op->lock(filp, F_GETLK, &file_lock);
> - if (file_lock.fl_ops && file_lock.fl_ops->fl_release_private)
> - file_lock.fl_ops->fl_release_private(&file_lock);
> - if (error < 0)
> - goto out;
> - else
> - fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock);
> - } else {
> - fl = (posix_test_lock(filp, &file_lock, &cfl) ? &cfl : NULL);
> - }
> + error = vfs_test_lock(filp, &file_lock, &cfl);
> + if (error)
> + goto out;
> + fl = (cfl.fl_type == F_UNLCK ? NULL : &cfl);
>
> flock.l_type = F_UNLCK;
> if (fl != NULL) {
> @@ -1785,18 +1805,11 @@ int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
> if (error)
> goto out;
>
> - if (filp->f_op && filp->f_op->lock) {
> - error = filp->f_op->lock(filp, F_GETLK, &file_lock);
> - if (file_lock.fl_ops && file_lock.fl_ops->fl_release_private)
> - file_lock.fl_ops->fl_release_private(&file_lock);
> - if (error < 0)
> - goto out;
> - else
> - fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock);
> - } else {
> - fl = (posix_test_lock(filp, &file_lock, &cfl) ? &cfl : NULL);
> - }
> -
> + error = vfs_test_lock(filp, &file_lock, &cfl);
> + if (error)
> + goto out;
> + fl = (cfl.fl_type == F_UNLCK ? NULL : &cfl);
> +
> flock.l_type = F_UNLCK;
> if (fl != NULL) {
> flock.l_pid = fl->fl_pid;
> diff --git a/include/linux/lockd/bind.h b/include/linux/lockd/bind.h
> index 246de1d..f78b24a 100644
> --- a/include/linux/lockd/bind.h
> +++ b/include/linux/lockd/bind.h
> @@ -38,4 +38,6 @@ extern int nlmclnt_proc(struct inode *, int, struct file_lock *);
> extern int lockd_up(int proto);
> extern void lockd_down(void);
>
> +extern int vfs_test_lock(struct file *, struct file_lock *, struct file_lock *);
> +
> #endif /* LINUX_LOCKD_BIND_H */
> --
> 1.5.0.rc1.g72fe
>
>
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