Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs fixes from Al Viro:
- backport-friendly part of lock_parent() race fix
- a fix for an assumption in the heurisic used by path_connected() that
is not true on NFS
- livelock fixes for d_alloc_parallel()
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: Teach path_connected to handle nfs filesystems with multiple roots.
fs: dcache: Use READ_ONCE when accessing i_dir_seq
fs: dcache: Avoid livelock between d_alloc_parallel and __d_add
lock_parent() needs to recheck if dentry got __dentry_kill'ed under it
+22
-7
+16
-5
fs/dcache.c
+16
-5
fs/dcache.c
···
647
647
spin_unlock(&parent->d_lock);
648
648
goto again;
649
649
}
650
-
rcu_read_unlock();
651
-
if (parent != dentry)
650
+
if (parent != dentry) {
652
651
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
653
-
else
652
+
if (unlikely(dentry->d_lockref.count < 0)) {
653
+
spin_unlock(&parent->d_lock);
654
+
parent = NULL;
655
+
}
656
+
} else {
654
657
parent = NULL;
658
+
}
659
+
rcu_read_unlock();
655
660
return parent;
656
661
}
657
662
···
2479
2474
2480
2475
retry:
2481
2476
rcu_read_lock();
2482
-
seq = smp_load_acquire(&parent->d_inode->i_dir_seq) & ~1;
2477
+
seq = smp_load_acquire(&parent->d_inode->i_dir_seq);
2483
2478
r_seq = read_seqbegin(&rename_lock);
2484
2479
dentry = __d_lookup_rcu(parent, name, &d_seq);
2485
2480
if (unlikely(dentry)) {
···
2500
2495
rcu_read_unlock();
2501
2496
goto retry;
2502
2497
}
2498
+
2499
+
if (unlikely(seq & 1)) {
2500
+
rcu_read_unlock();
2501
+
goto retry;
2502
+
}
2503
+
2503
2504
hlist_bl_lock(b);
2504
-
if (unlikely(parent->d_inode->i_dir_seq != seq)) {
2505
+
if (unlikely(READ_ONCE(parent->d_inode->i_dir_seq) != seq)) {
2505
2506
hlist_bl_unlock(b);
2506
2507
rcu_read_unlock();
2507
2508
goto retry;
+3
-2
fs/namei.c
+3
-2
fs/namei.c
···
559
559
static bool path_connected(const struct path *path)
560
560
{
561
561
struct vfsmount *mnt = path->mnt;
562
+
struct super_block *sb = mnt->mnt_sb;
562
563
563
-
/* Only bind mounts can have disconnected paths */
564
-
if (mnt->mnt_root == mnt->mnt_sb->s_root)
564
+
/* Bind mounts and multi-root filesystems can have disconnected paths */
565
+
if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root))
565
566
return true;
566
567
567
568
return is_subdir(path->dentry, mnt->mnt_root);
+2
fs/nfs/super.c
+2
fs/nfs/super.c
···
2631
2631
/* initial superblock/root creation */
2632
2632
mount_info->fill_super(s, mount_info);
2633
2633
nfs_get_cache_cookie(s, mount_info->parsed, mount_info->cloned);
2634
+
if (!(server->flags & NFS_MOUNT_UNSHARED))
2635
+
s->s_iflags |= SB_I_MULTIROOT;
2634
2636
}
2635
2637
2636
2638
mntroot = nfs_get_root(s, mount_info->mntfh, dev_name);
+1
include/linux/fs.h
+1
include/linux/fs.h
···
1317
1317
#define SB_I_CGROUPWB 0x00000001 /* cgroup-aware writeback enabled */
1318
1318
#define SB_I_NOEXEC 0x00000002 /* Ignore executables on this fs */
1319
1319
#define SB_I_NODEV 0x00000004 /* Ignore devices on this fs */
1320
+
#define SB_I_MULTIROOT 0x00000008 /* Multiple roots to the dentry tree */
1320
1321
1321
1322
/* sb->s_iflags to limit user namespace mounts */
1322
1323
#define SB_I_USERNS_VISIBLE 0x00000010 /* fstype already mounted */