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path: root/fs/autofs4/waitq.c
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Diffstat (limited to 'fs/autofs4/waitq.c')
-rw-r--r--fs/autofs4/waitq.c135
1 files changed, 97 insertions, 38 deletions
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 55aac10cf328..cd3b2a671696 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -215,19 +215,106 @@ autofs4_find_wait(struct autofs_sb_info *sbi, struct qstr *qstr)
return wq;
}
+/*
+ * Check if we have a valid request.
+ * Returns
+ * 1 if the request should continue.
+ * In this case we can return an autofs_wait_queue entry if one is
+ * found or NULL to idicate a new wait needs to be created.
+ * 0 or a negative errno if the request shouldn't continue.
+ */
+static int validate_request(struct autofs_wait_queue **wait,
+ struct autofs_sb_info *sbi,
+ struct qstr *qstr,
+ struct dentry*dentry, enum autofs_notify notify)
+{
+ struct autofs_wait_queue *wq;
+ struct autofs_info *ino;
+
+ /* Wait in progress, continue; */
+ wq = autofs4_find_wait(sbi, qstr);
+ if (wq) {
+ *wait = wq;
+ return 1;
+ }
+
+ *wait = NULL;
+
+ /* If we don't yet have any info this is a new request */
+ ino = autofs4_dentry_ino(dentry);
+ if (!ino)
+ return 1;
+
+ /*
+ * If we've been asked to wait on an existing expire (NFY_NONE)
+ * but there is no wait in the queue ...
+ */
+ if (notify == NFY_NONE) {
+ /*
+ * Either we've betean the pending expire to post it's
+ * wait or it finished while we waited on the mutex.
+ * So we need to wait till either, the wait appears
+ * or the expire finishes.
+ */
+
+ while (ino->flags & AUTOFS_INF_EXPIRING) {
+ mutex_unlock(&sbi->wq_mutex);
+ schedule_timeout_interruptible(HZ/10);
+ if (mutex_lock_interruptible(&sbi->wq_mutex))
+ return -EINTR;
+
+ wq = autofs4_find_wait(sbi, qstr);
+ if (wq) {
+ *wait = wq;
+ return 1;
+ }
+ }
+
+ /*
+ * Not ideal but the status has already gone. Of the two
+ * cases where we wait on NFY_NONE neither depend on the
+ * return status of the wait.
+ */
+ return 0;
+ }
+
+ /*
+ * If we've been asked to trigger a mount and the request
+ * completed while we waited on the mutex ...
+ */
+ if (notify == NFY_MOUNT) {
+ /*
+ * If the dentry isn't hashed just go ahead and try the
+ * mount again with a new wait (not much else we can do).
+ */
+ if (!d_unhashed(dentry)) {
+ /*
+ * But if the dentry is hashed, that means that we
+ * got here through the revalidate path. Thus, we
+ * need to check if the dentry has been mounted
+ * while we waited on the wq_mutex. If it has,
+ * simply return success.
+ */
+ if (d_mountpoint(dentry))
+ return 0;
+ }
+ }
+
+ return 1;
+}
+
int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
enum autofs_notify notify)
{
- struct autofs_info *ino;
struct autofs_wait_queue *wq;
struct qstr qstr;
char *name;
- int status, type;
+ int status, ret, type;
/* In catatonic mode, we don't wait for nobody */
if (sbi->catatonic)
return -ENOENT;
-
+
name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
if (!name)
return -ENOMEM;
@@ -245,43 +332,15 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
qstr.name = name;
qstr.hash = full_name_hash(name, qstr.len);
- if (mutex_lock_interruptible(&sbi->wq_mutex)) {
- kfree(qstr.name);
+ if (mutex_lock_interruptible(&sbi->wq_mutex))
return -EINTR;
- }
-
- wq = autofs4_find_wait(sbi, &qstr);
- ino = autofs4_dentry_ino(dentry);
- if (!wq && ino && notify == NFY_NONE) {
- /*
- * Either we've betean the pending expire to post it's
- * wait or it finished while we waited on the mutex.
- * So we need to wait till either, the wait appears
- * or the expire finishes.
- */
- while (ino->flags & AUTOFS_INF_EXPIRING) {
- mutex_unlock(&sbi->wq_mutex);
- schedule_timeout_interruptible(HZ/10);
- if (mutex_lock_interruptible(&sbi->wq_mutex)) {
- kfree(qstr.name);
- return -EINTR;
- }
- wq = autofs4_find_wait(sbi, &qstr);
- if (wq)
- break;
- }
-
- /*
- * Not ideal but the status has already gone. Of the two
- * cases where we wait on NFY_NONE neither depend on the
- * return status of the wait.
- */
- if (!wq) {
- kfree(qstr.name);
+ ret = validate_request(&wq, sbi, &qstr, dentry, notify);
+ if (ret <= 0) {
+ if (ret == 0)
mutex_unlock(&sbi->wq_mutex);
- return 0;
- }
+ kfree(qstr.name);
+ return ret;
}
if (!wq) {
@@ -392,9 +451,9 @@ int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_tok
}
*wql = wq->next; /* Unlink from chain */
- mutex_unlock(&sbi->wq_mutex);
kfree(wq->name.name);
wq->name.name = NULL; /* Do not wait on this queue */
+ mutex_unlock(&sbi->wq_mutex);
wq->status = status;