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authorLinus Torvalds <torvalds@linux-foundation.org>2019-09-19 20:14:22 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-09-19 20:14:22 +0300
commit8e6ee05d8aa9c802d999c79aa22f3f6ca92d7d27 (patch)
tree739d2f62c631b31ceb4ec85f2e30f9bbe644d17d /fs
parentbc7d9aee3f3ce0c0633c20ea55b81efb3ca7984d (diff)
parent5f68056ca50fdd3954a93ae66fea7452abddb66f (diff)
downloadlinux-8e6ee05d8aa9c802d999c79aa22f3f6ca92d7d27.tar.xz
Merge branch 'work.autofs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull autofs updates from Al Viro: "The most interesting part here is getting rid of the last trylock loop on dentry->d_lock. The ones in fs/dcache.c had been dealt with several years ago, but there'd been leftovers in fs/autofs/expire.c" * 'work.autofs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: autofs_lookup(): hold ->d_lock over playing with ->d_flags get rid of autofs_info->active_count autofs: simplify get_next_positive_...(), get rid of trylocks
Diffstat (limited to 'fs')
-rw-r--r--fs/autofs/autofs_i.h1
-rw-r--r--fs/autofs/expire.c103
-rw-r--r--fs/autofs/root.c44
3 files changed, 44 insertions, 104 deletions
diff --git a/fs/autofs/autofs_i.h b/fs/autofs/autofs_i.h
index 8c0c11181fad..8bcec8dcabb6 100644
--- a/fs/autofs/autofs_i.h
+++ b/fs/autofs/autofs_i.h
@@ -58,7 +58,6 @@ struct autofs_info {
struct completion expire_complete;
struct list_head active;
- int active_count;
struct list_head expiring;
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 @@ done:
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;
}
diff --git a/fs/autofs/root.c b/fs/autofs/root.c
index e646569c75ed..29abafc0ce31 100644
--- a/fs/autofs/root.c
+++ b/fs/autofs/root.c
@@ -60,38 +60,15 @@ const struct dentry_operations autofs_dentry_operations = {
.d_release = autofs_dentry_release,
};
-static void autofs_add_active(struct dentry *dentry)
-{
- struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
- struct autofs_info *ino;
-
- ino = autofs_dentry_ino(dentry);
- if (ino) {
- spin_lock(&sbi->lookup_lock);
- if (!ino->active_count) {
- if (list_empty(&ino->active))
- list_add(&ino->active, &sbi->active_list);
- }
- ino->active_count++;
- spin_unlock(&sbi->lookup_lock);
- }
-}
-
static void autofs_del_active(struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
struct autofs_info *ino;
ino = autofs_dentry_ino(dentry);
- if (ino) {
- spin_lock(&sbi->lookup_lock);
- ino->active_count--;
- if (!ino->active_count) {
- if (!list_empty(&ino->active))
- list_del_init(&ino->active);
- }
- spin_unlock(&sbi->lookup_lock);
- }
+ spin_lock(&sbi->lookup_lock);
+ list_del_init(&ino->active);
+ spin_unlock(&sbi->lookup_lock);
}
static int autofs_dir_open(struct inode *inode, struct file *file)
@@ -527,19 +504,22 @@ static struct dentry *autofs_lookup(struct inode *dir,
if (!autofs_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
return ERR_PTR(-ENOENT);
- /* Mark entries in the root as mount triggers */
- if (IS_ROOT(dentry->d_parent) &&
- autofs_type_indirect(sbi->type))
- __managed_dentry_set_managed(dentry);
-
ino = autofs_new_ino(sbi);
if (!ino)
return ERR_PTR(-ENOMEM);
+ spin_lock(&sbi->lookup_lock);
+ spin_lock(&dentry->d_lock);
+ /* Mark entries in the root as mount triggers */
+ if (IS_ROOT(dentry->d_parent) &&
+ autofs_type_indirect(sbi->type))
+ __managed_dentry_set_managed(dentry);
dentry->d_fsdata = ino;
ino->dentry = dentry;
- autofs_add_active(dentry);
+ list_add(&ino->active, &sbi->active_list);
+ spin_unlock(&sbi->lookup_lock);
+ spin_unlock(&dentry->d_lock);
}
return NULL;
}