diff --git a/fs/autofs/expire.c b/fs/autofs/expire.c index cdff0567aacb..2866fabf497f 100644 --- a/fs/autofs/expire.c +++ b/fs/autofs/expire.c @@ -70,6 +70,27 @@ static int autofs_mount_busy(struct vfsmount *mnt, return status; } +/* p->d_lock held */ +static struct dentry *positive_after(struct dentry *p, struct dentry *child) +{ + if (child) + child = list_next_entry(child, d_child); + else + child = list_first_entry(&p->d_subdirs, struct dentry, d_child); + + list_for_each_entry_from(child, &p->d_subdirs, d_child) { + spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); + if (simple_positive(child)) { + dget_dlock(child); + spin_unlock(&child->d_lock); + return child; + } + spin_unlock(&child->d_lock); + } + + return NULL; +} + /* * Calculate and dget next entry in the subdirs list under root. */ @@ -77,43 +98,14 @@ static struct dentry *get_next_positive_subdir(struct dentry *prev, struct dentry *root) { struct autofs_sb_info *sbi = autofs_sbi(root->d_sb); - struct list_head *next; struct dentry *q; spin_lock(&sbi->lookup_lock); spin_lock(&root->d_lock); - - if (prev) - next = prev->d_child.next; - else { - prev = dget_dlock(root); - next = prev->d_subdirs.next; - } - -cont: - if (next == &root->d_subdirs) { - spin_unlock(&root->d_lock); - spin_unlock(&sbi->lookup_lock); - dput(prev); - return NULL; - } - - q = list_entry(next, struct dentry, d_child); - - spin_lock_nested(&q->d_lock, DENTRY_D_LOCK_NESTED); - /* Already gone or negative dentry (under construction) - try next */ - if (!d_count(q) || !simple_positive(q)) { - spin_unlock(&q->d_lock); - next = q->d_child.next; - goto cont; - } - dget_dlock(q); - spin_unlock(&q->d_lock); + q = positive_after(root, prev); spin_unlock(&root->d_lock); spin_unlock(&sbi->lookup_lock); - dput(prev); - return q; } @@ -124,59 +116,28 @@ static struct dentry *get_next_positive_dentry(struct dentry *prev, struct dentry *root) { struct autofs_sb_info *sbi = autofs_sbi(root->d_sb); - struct list_head *next; - struct dentry *p, *ret; + struct dentry *p = prev, *ret = NULL, *d = NULL; if (prev == NULL) return dget(root); spin_lock(&sbi->lookup_lock); -relock: - p = prev; spin_lock(&p->d_lock); -again: - next = p->d_subdirs.next; - if (next == &p->d_subdirs) { - while (1) { - struct dentry *parent; - - if (p == root) { - spin_unlock(&p->d_lock); - spin_unlock(&sbi->lookup_lock); - dput(prev); - return NULL; - } + while (1) { + struct dentry *parent; - parent = p->d_parent; - if (!spin_trylock(&parent->d_lock)) { - spin_unlock(&p->d_lock); - cpu_relax(); - goto relock; - } - spin_unlock(&p->d_lock); - next = p->d_child.next; - p = parent; - if (next != &parent->d_subdirs) - break; - } - } - ret = list_entry(next, struct dentry, d_child); - - spin_lock_nested(&ret->d_lock, DENTRY_D_LOCK_NESTED); - /* Negative dentry - try next */ - if (!simple_positive(ret)) { + ret = positive_after(p, d); + if (ret || p == root) + break; + parent = p->d_parent; spin_unlock(&p->d_lock); - lock_set_subclass(&ret->d_lock.dep_map, 0, _RET_IP_); - p = ret; - goto again; + spin_lock(&parent->d_lock); + d = p; + p = parent; } - dget_dlock(ret); - spin_unlock(&ret->d_lock); spin_unlock(&p->d_lock); spin_unlock(&sbi->lookup_lock); - dput(prev); - return ret; }