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autofs - dont hold spin lock over direct mount expire

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Commit 7cbdb4a286 altered the autofs indirect mount expire to
not hold a spin lock during the expire check.

The direct mount expire needs the same treatment because to
make autofs expires namespace aware may_umount_tree() needs to
to use a similar method to may_umount() when checking if a mount
tree is in use.

This means may_umount_tree() will end up taking the namespace_sem
for the check so the autofs direct mount expire won't be allowed
to hold a spin lock over the check.

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Ian Kent 2016-11-28 10:12:14 +08:00 committed by Al Viro
parent 455e8f1030
commit 1c4344a50d
1 changed files with 10 additions and 7 deletions
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17
fs/autofs4/expire.c
View File

@ -310,26 +310,29 @@ struct dentry *autofs4_expire_direct(struct super_block *sb,
now = jiffies;
timeout = sbi->exp_timeout;
spin_lock(&sbi->fs_lock);
ino = autofs4_dentry_ino(root);
/* No point expiring a pending mount */
if (ino->flags & AUTOFS_INF_PENDING)
goto out;
if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
spin_lock(&sbi->fs_lock);
ino = autofs4_dentry_ino(root);
/* No point expiring a pending mount */
if (ino->flags & AUTOFS_INF_PENDING) {
spin_unlock(&sbi->fs_lock);
goto out;
}
ino->flags |= AUTOFS_INF_WANT_EXPIRE;
spin_unlock(&sbi->fs_lock);
synchronize_rcu();
spin_lock(&sbi->fs_lock);
if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
spin_lock(&sbi->fs_lock);
ino->flags |= AUTOFS_INF_EXPIRING;
init_completion(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
return root;
}
spin_lock(&sbi->fs_lock);
ino->flags &= ~AUTOFS_INF_WANT_EXPIRE;
spin_unlock(&sbi->fs_lock);
}
out:
spin_unlock(&sbi->fs_lock);
dput(root);
return NULL;