On Mon 11-11-19 11:08:07, Sascha Hauer wrote:
> On Fri, Nov 01, 2019 at 05:07:06PM +0100, Jan Kara wrote:
> > On Wed 30-10-19 16:26:56, Sascha Hauer wrote:
> > > This patch introduces the Q_PATH flag to the quotactl cmd argument.
> > > When given, the path given in the special argument to quotactl will
> > > be the mount path where the filesystem is mounted, instead of a path
> > > to the block device.
> > > This is necessary for filesystems which do not have a block device as
> > > backing store. Particularly this is done for upcoming UBIFS support.
> > >
> > > Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> >
> > Thanks for the patch! Some smaller comments below...
> >
> > > ---
> > > fs/quota/quota.c | 37 ++++++++++++++++++++++++++++---------
> > > include/uapi/linux/quota.h | 1 +
> > > 2 files changed, 29 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/fs/quota/quota.c b/fs/quota/quota.c
> > > index cb13fb76dbee..035cdd1b022b 100644
> > > --- a/fs/quota/quota.c
> > > +++ b/fs/quota/quota.c
> > > @@ -19,6 +19,7 @@
> > > #include <linux/types.h>
> > > #include <linux/writeback.h>
> > > #include <linux/nospec.h>
> > > +#include <linux/mount.h>
> > >
> > > static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
> > > qid_t id)
> > > @@ -825,12 +826,16 @@ int kernel_quotactl(unsigned int cmd, const char __user *special,
> > > {
> > > uint cmds, type;
> > > struct super_block *sb = NULL;
> > > - struct path path, *pathp = NULL;
> > > + struct path path, *pathp = NULL, qpath;
> >
> > Maybe call these two 'file_path', 'file_pathp', and 'sb_path' to make it
> > clearer which path is which?
> >
> > > int ret;
> > > + bool q_path;
> > >
> > > cmds = cmd >> SUBCMDSHIFT;
> > > type = cmd & SUBCMDMASK;
> > >
> > > + q_path = cmds & Q_PATH;
> > > + cmds &= ~Q_PATH;
> > > +
> > > /*
> > > * As a special case Q_SYNC can be called without a specific device.
> > > * It will iterate all superblocks that have quota enabled and call
> > > @@ -855,19 +860,33 @@ int kernel_quotactl(unsigned int cmd, const char __user *special,
> > > pathp = &path;
> > > }
> > >
> > > - sb = quotactl_block(special, cmds);
> > > - if (IS_ERR(sb)) {
> > > - ret = PTR_ERR(sb);
> > > - goto out;
> > > + if (q_path) {
> > > + ret = user_path_at(AT_FDCWD, special, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT,
> > > + &qpath);
> > > + if (ret)
> > > + goto out1;
> > > +
> > > + sb = qpath.mnt->mnt_sb;
> > > + } else {
> > > + sb = quotactl_block(special, cmds);
> > > + if (IS_ERR(sb)) {
> > > + ret = PTR_ERR(sb);
> > > + goto out;
> > > + }
> > > }
> > >
> > > ret = do_quotactl(sb, type, cmds, id, addr, pathp);
> > >
> > > - if (!quotactl_cmd_onoff(cmds))
> > > - drop_super(sb);
> > > - else
> > > - drop_super_exclusive(sb);
> > > + if (!q_path) {
> > > + if (!quotactl_cmd_onoff(cmds))
> > > + drop_super(sb);
> > > + else
> > > + drop_super_exclusive(sb);
> > > + }
> > > out:
> > > + if (q_path)
> > > + path_put(&qpath);
> > > +out1:
> >
> > Why do you need out1? If you leave 'out' as is, things should just work.
> > And you can also combine the above if like:
>
> See above where out1 is used. In this case qpath is not valid and I
> cannot call path_put() on it.
Right. But you also don't need to do path_put(&qpath) in case
quotactl_block() failed. So you can just jump to out1 there as well and
then 'out' is unused...
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
