Commit 2ca35346 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'vfs-6.16-rc1.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs 

Pull vfs mount updates from Christian Brauner:
 "This contains minor mount updates for this cycle:

   - mnt->mnt_devname can never be NULL so simplify the code handling
     that case

   - Add a comment about concurrent changes during statmount() and
     listmount()

   - Update the STATMOUNT_SUPPORTED macro

   - Convert mount flags to an enum"

* tag 'vfs-6.16-rc1.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  statmount: update STATMOUNT_SUPPORTED macro
  fs: convert mount flags to enum
  ->mnt_devname is never NULL
  mount: add a comment about concurrent changes with statmount()/listmount()
parents 8dd53535 2b3c61b8

fs/namespace.c

+33 −10
Original line number Diff line number Diff line
@@ -355,12 +355,13 @@ static struct mount *alloc_vfsmnt(const char *name) 
		if (err)

			goto out_free_cache;



		if (name) {

		if (name)

			mnt->mnt_devname = kstrdup_const(name,

							 GFP_KERNEL_ACCOUNT);

		else

			mnt->mnt_devname = "none";

		if (!mnt->mnt_devname)

			goto out_free_id;

		}



#ifdef CONFIG_SMP

		mnt->mnt_pcp = alloc_percpu(struct mnt_pcp);
@@ -1264,7 +1265,7 @@ struct vfsmount *vfs_create_mount(struct fs_context *fc) 
	if (!fc->root)

		return ERR_PTR(-EINVAL);



	mnt = alloc_vfsmnt(fc->source ?: "none");

	mnt = alloc_vfsmnt(fc->source);

	if (!mnt)

		return ERR_PTR(-ENOMEM);
@@ -5491,7 +5492,7 @@ static int statmount_sb_source(struct kstatmount *s, struct seq_file *seq) 
		seq->buf[seq->count] = '\0';

		seq->count = start;

		seq_commit(seq, string_unescape_inplace(seq->buf + start, UNESCAPE_OCTAL));

	} else if (r->mnt_devname) {

	} else {

		seq_puts(seq, r->mnt_devname);

	}

	return 0;
@@ -5804,7 +5805,9 @@ static int grab_requested_root(struct mnt_namespace *ns, struct path *root) 
			     STATMOUNT_SB_SOURCE | \

			     STATMOUNT_OPT_ARRAY | \

			     STATMOUNT_OPT_SEC_ARRAY | \

			     STATMOUNT_SUPPORTED_MASK)

			     STATMOUNT_SUPPORTED_MASK | \

			     STATMOUNT_MNT_UIDMAP | \

			     STATMOUNT_MNT_GIDMAP)



static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id,

			struct mnt_namespace *ns)
@@ -5839,13 +5842,29 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, 
		return err;



	s->root = root;

	s->idmap = mnt_idmap(s->mnt);

	if (s->mask & STATMOUNT_SB_BASIC)

		statmount_sb_basic(s);



	/*

	 * Note that mount properties in mnt->mnt_flags, mnt->mnt_idmap

	 * can change concurrently as we only hold the read-side of the

	 * namespace semaphore and mount properties may change with only

	 * the mount lock held.

	 *

	 * We could sample the mount lock sequence counter to detect

	 * those changes and retry. But it's not worth it. Worst that

	 * happens is that the mnt->mnt_idmap pointer is already changed

	 * while mnt->mnt_flags isn't or vica versa. So what.

	 *

	 * Both mnt->mnt_flags and mnt->mnt_idmap are set and retrieved

	 * via READ_ONCE()/WRITE_ONCE() and guard against theoretical

	 * torn read/write. That's all we care about right now.

	 */

	s->idmap = mnt_idmap(s->mnt);

	if (s->mask & STATMOUNT_MNT_BASIC)

		statmount_mnt_basic(s);



	if (s->mask & STATMOUNT_SB_BASIC)

		statmount_sb_basic(s);



	if (s->mask & STATMOUNT_PROPAGATE_FROM)

		statmount_propagate_from(s);
@@ -6157,6 +6176,10 @@ SYSCALL_DEFINE4(listmount, const struct mnt_id_req __user *, req, 
	    !ns_capable_noaudit(ns->user_ns, CAP_SYS_ADMIN))

		return -ENOENT;



	/*

	 * We only need to guard against mount topology changes as

	 * listmount() doesn't care about any mount properties.

	 */

	scoped_guard(rwsem_read, &namespace_sem)

		ret = do_listmount(ns, kreq.mnt_id, last_mnt_id, kmnt_ids,

				   nr_mnt_ids, (flags & LISTMOUNT_REVERSE));

fs/proc_namespace.c

+4 −8
Original line number Diff line number Diff line
@@ -111,7 +111,7 @@ static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt) 
		if (err)

			goto out;

	} else {

		mangle(m, r->mnt_devname ? r->mnt_devname : "none");

		mangle(m, r->mnt_devname);

	}

	seq_putc(m, ' ');

	/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
@@ -177,7 +177,7 @@ static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt) 
		if (err)

			goto out;

	} else {

		mangle(m, r->mnt_devname ? r->mnt_devname : "none");

		mangle(m, r->mnt_devname);

	}

	seq_puts(m, sb_rdonly(sb) ? " ro" : " rw");

	err = show_sb_opts(m, sb);
@@ -199,17 +199,13 @@ static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt) 
	int err;



	/* device */

	if (sb->s_op->show_devname) {

	seq_puts(m, "device ");

	if (sb->s_op->show_devname) {

		err = sb->s_op->show_devname(m, mnt_path.dentry);

		if (err)

			goto out;

	} else {

		if (r->mnt_devname) {

			seq_puts(m, "device ");

		mangle(m, r->mnt_devname);

		} else

			seq_puts(m, "no device");

	}



	/* mount point */

include/linux/mount.h

+45 −42
Original line number Diff line number Diff line
@@ -22,20 +22,35 @@ struct fs_context; 
struct file;

struct path;



#define MNT_NOSUID	0x01

#define MNT_NODEV	0x02

#define MNT_NOEXEC	0x04

#define MNT_NOATIME	0x08

#define MNT_NODIRATIME	0x10

#define MNT_RELATIME	0x20

#define MNT_READONLY	0x40	/* does the user want this to be r/o? */

#define MNT_NOSYMFOLLOW	0x80



#define MNT_SHRINKABLE	0x100

#define MNT_WRITE_HOLD	0x200



#define MNT_SHARED	0x1000	/* if the vfsmount is a shared mount */

#define MNT_UNBINDABLE	0x2000	/* if the vfsmount is a unbindable mount */

enum mount_flags {

	MNT_NOSUID	= 0x01,

	MNT_NODEV	= 0x02,

	MNT_NOEXEC	= 0x04,

	MNT_NOATIME	= 0x08,

	MNT_NODIRATIME	= 0x10,

	MNT_RELATIME	= 0x20,

	MNT_READONLY	= 0x40, /* does the user want this to be r/o? */

	MNT_NOSYMFOLLOW	= 0x80,



	MNT_SHRINKABLE	= 0x100,

	MNT_WRITE_HOLD	= 0x200,



	MNT_SHARED	= 0x1000, /* if the vfsmount is a shared mount */

	MNT_UNBINDABLE	= 0x2000, /* if the vfsmount is a unbindable mount */



	MNT_INTERNAL	= 0x4000,



	MNT_LOCK_ATIME		= 0x040000,

	MNT_LOCK_NOEXEC		= 0x080000,

	MNT_LOCK_NOSUID		= 0x100000,

	MNT_LOCK_NODEV		= 0x200000,

	MNT_LOCK_READONLY	= 0x400000,

	MNT_LOCKED		= 0x800000,

	MNT_DOOMED		= 0x1000000,

	MNT_SYNC_UMOUNT		= 0x2000000,

	MNT_MARKED		= 0x4000000,

	MNT_UMOUNT		= 0x8000000,



	/*

	 * MNT_SHARED_MASK is the set of flags that should be cleared when a

	 * mount becomes shared.  Currently, this is only the flag that says a
@@ -43,27 +58,15 @@ struct path; 
	 * that shares events with another mount.  If you add a new MNT_*

	 * flag, consider how it interacts with shared mounts.

	 */

#define MNT_SHARED_MASK	(MNT_UNBINDABLE)

#define MNT_USER_SETTABLE_MASK  (MNT_NOSUID | MNT_NODEV | MNT_NOEXEC \

				 | MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME \

				 | MNT_READONLY | MNT_NOSYMFOLLOW)

#define MNT_ATIME_MASK (MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME )



#define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \

			    MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED)



#define MNT_INTERNAL	0x4000



#define MNT_LOCK_ATIME		0x040000

#define MNT_LOCK_NOEXEC		0x080000

#define MNT_LOCK_NOSUID		0x100000

#define MNT_LOCK_NODEV		0x200000

#define MNT_LOCK_READONLY	0x400000

#define MNT_LOCKED		0x800000

#define MNT_DOOMED		0x1000000

#define MNT_SYNC_UMOUNT		0x2000000

#define MNT_MARKED		0x4000000

#define MNT_UMOUNT		0x8000000

	MNT_SHARED_MASK	= MNT_UNBINDABLE,

	MNT_USER_SETTABLE_MASK  = MNT_NOSUID | MNT_NODEV | MNT_NOEXEC

				  | MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME

				  | MNT_READONLY | MNT_NOSYMFOLLOW,

	MNT_ATIME_MASK = MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME,



	MNT_INTERNAL_FLAGS = MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL |

			     MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED,

};



struct vfsmount {

	struct dentry *mnt_root;	/* root of the mounted tree */