| Message ID | 1338389946-13711-3-git-send-email-jeff.liu@oracle.com |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On 05/30/2012 06:58 PM, jeff.liu@oracle.com wrote: > Introduce two functions to lock/unlock a particular mount namespace > when container quota operations is performed. > > Signed-off-by: Jie Liu<jeff.liu@oracle.com> > --- > fs/namespace.c | 17 +++++++++++++++++ > include/linux/mnt_namespace.h | 13 +++++++++++++ > 2 files changed, 30 insertions(+), 0 deletions(-) > > diff --git a/fs/namespace.c b/fs/namespace.c > index e608199..8823ba8 100644 > --- a/fs/namespace.c > +++ b/fs/namespace.c > @@ -2633,3 +2633,20 @@ bool our_mnt(struct vfsmount *mnt) > { > return check_mnt(real_mount(mnt)); > } > + > +/* > + * Lock the mount namespace when performing a particular container > + * disk quotactl operation, especially to protect removing it. > + */ > +void lock_mnt_ns(struct mnt_namespace *ns) > +{ > + down_write(&namespace_sem); > +} > + > +/* > + * Unlock the mount namespace after quotactl on that was done. > + */ > +void unlock_mnt_ns(struct mnt_namespace *ns) > +{ > + up_write(&namespace_sem); > +} > diff --git a/include/linux/mnt_namespace.h b/include/linux/mnt_namespace.h > index 5a8e390..ff72ed5 100644 > --- a/include/linux/mnt_namespace.h > +++ b/include/linux/mnt_namespace.h > @@ -9,6 +9,19 @@ extern struct mnt_namespace *copy_mnt_ns(unsigned long, struct mnt_namespace *, > struct fs_struct *); > extern void put_mnt_ns(struct mnt_namespace *ns); > > +#ifdef CONFIG_NS_QUOTA > +extern void lock_mnt_ns(struct mnt_namespace *); > +extern void unlock_mnt_ns(struct mnt_namespace *); > +#else > +void lock_mnt_ns(struct mnt_namespace *) > +{ > +} > + > +void unlock_mnt_ns(struct mnt_namespace *) > +{ > +} > +#endif > + Seems weird. There is nothing ns-quota specific in locking a namespace. Also, just grabbing a lock from an outer subsystem is quite ugly. If you are grabbing a namespace lock, this suggests you are tweaking namespace data. So you should have that file provide you with a function that does the full operation. Of course there are exceptions to that, but it rings a bell. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 05/31/2012 05:04 PM, Glauber Costa wrote: > On 05/30/2012 06:58 PM, jeff.liu@oracle.com wrote: >> Introduce two functions to lock/unlock a particular mount namespace >> when container quota operations is performed. >> >> Signed-off-by: Jie Liu<jeff.liu@oracle.com> >> --- >> fs/namespace.c | 17 +++++++++++++++++ >> include/linux/mnt_namespace.h | 13 +++++++++++++ >> 2 files changed, 30 insertions(+), 0 deletions(-) >> >> diff --git a/fs/namespace.c b/fs/namespace.c >> index e608199..8823ba8 100644 >> --- a/fs/namespace.c >> +++ b/fs/namespace.c >> @@ -2633,3 +2633,20 @@ bool our_mnt(struct vfsmount *mnt) >> { >> return check_mnt(real_mount(mnt)); >> } >> + >> +/* >> + * Lock the mount namespace when performing a particular container >> + * disk quotactl operation, especially to protect removing it. >> + */ >> +void lock_mnt_ns(struct mnt_namespace *ns) >> +{ >> + down_write(&namespace_sem); >> +} >> + >> +/* >> + * Unlock the mount namespace after quotactl on that was done. >> + */ >> +void unlock_mnt_ns(struct mnt_namespace *ns) >> +{ >> + up_write(&namespace_sem); >> +} >> diff --git a/include/linux/mnt_namespace.h >> b/include/linux/mnt_namespace.h >> index 5a8e390..ff72ed5 100644 >> --- a/include/linux/mnt_namespace.h >> +++ b/include/linux/mnt_namespace.h >> @@ -9,6 +9,19 @@ extern struct mnt_namespace *copy_mnt_ns(unsigned >> long, struct mnt_namespace *, >> struct fs_struct *); >> extern void put_mnt_ns(struct mnt_namespace *ns); >> >> +#ifdef CONFIG_NS_QUOTA >> +extern void lock_mnt_ns(struct mnt_namespace *); >> +extern void unlock_mnt_ns(struct mnt_namespace *); >> +#else >> +void lock_mnt_ns(struct mnt_namespace *) >> +{ >> +} >> + >> +void unlock_mnt_ns(struct mnt_namespace *) >> +{ >> +} >> +#endif >> + > > Seems weird. There is nothing ns-quota specific in locking a namespace. > Also, just grabbing a lock from an outer subsystem is quite ugly. If you > are grabbing a namespace lock, this suggests you are tweaking namespace > data. So you should have that file provide you with a function that does > the full operation. Maybe this can be safely removed, it is presented like a place holder, which is suggests to protect changing data inner quota info of a mount namespace. However, both quota info initialization and destroy business are all projected at mount init and put mount namespace stage, so that the lock/unlock are make less sense here. Thanks, -Jeff > > Of course there are exceptions to that, but it rings a bell. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/namespace.c b/fs/namespace.c index e608199..8823ba8 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2633,3 +2633,20 @@ bool our_mnt(struct vfsmount *mnt) { return check_mnt(real_mount(mnt)); } + +/* + * Lock the mount namespace when performing a particular container + * disk quotactl operation, especially to protect removing it. + */ +void lock_mnt_ns(struct mnt_namespace *ns) +{ + down_write(&namespace_sem); +} + +/* + * Unlock the mount namespace after quotactl on that was done. + */ +void unlock_mnt_ns(struct mnt_namespace *ns) +{ + up_write(&namespace_sem); +} diff --git a/include/linux/mnt_namespace.h b/include/linux/mnt_namespace.h index 5a8e390..ff72ed5 100644 --- a/include/linux/mnt_namespace.h +++ b/include/linux/mnt_namespace.h @@ -9,6 +9,19 @@ extern struct mnt_namespace *copy_mnt_ns(unsigned long, struct mnt_namespace *, struct fs_struct *); extern void put_mnt_ns(struct mnt_namespace *ns); +#ifdef CONFIG_NS_QUOTA +extern void lock_mnt_ns(struct mnt_namespace *); +extern void unlock_mnt_ns(struct mnt_namespace *); +#else +void lock_mnt_ns(struct mnt_namespace *) +{ +} + +void unlock_mnt_ns(struct mnt_namespace *) +{ +} +#endif + extern const struct file_operations proc_mounts_operations; extern const struct file_operations proc_mountinfo_operations; extern const struct file_operations proc_mountstats_operations;
Introduce two functions to lock/unlock a particular mount namespace when container quota operations is performed. Signed-off-by: Jie Liu <jeff.liu@oracle.com> --- fs/namespace.c | 17 +++++++++++++++++ include/linux/mnt_namespace.h | 13 +++++++++++++ 2 files changed, 30 insertions(+), 0 deletions(-)