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Diffstat (limited to 'fs/dcache.c')
-rw-r--r--fs/dcache.c60
1 files changed, 33 insertions, 27 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 8150e4e9e88b..484114a4db93 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1343,36 +1343,39 @@ void shrink_dcache_for_umount(struct super_block *sb)
}
}
-static enum d_walk_ret check_and_collect(void *_data, struct dentry *dentry)
+struct detach_data {
+ struct select_data select;
+ struct dentry *mountpoint;
+};
+static enum d_walk_ret detach_and_collect(void *_data, struct dentry *dentry)
{
- struct select_data *data = _data;
+ struct detach_data *data = _data;
if (d_mountpoint(dentry)) {
- data->found = -EBUSY;
+ __dget_dlock(dentry);
+ data->mountpoint = dentry;
return D_WALK_QUIT;
}
- return select_collect(_data, dentry);
+ return select_collect(&data->select, dentry);
}
static void check_and_drop(void *_data)
{
- struct select_data *data = _data;
+ struct detach_data *data = _data;
- if (d_mountpoint(data->start))
- data->found = -EBUSY;
- if (!data->found)
- __d_drop(data->start);
+ if (!data->mountpoint && !data->select.found)
+ __d_drop(data->select.start);
}
/**
- * check_submounts_and_drop - prune dcache, check for submounts and drop
+ * check_submounts_and_drop - detach submounts, prune dcache, and drop
*
- * All done as a single atomic operation relative to has_unlinked_ancestor().
- * Returns 0 if successfully unhashed @parent. If there were submounts then
- * return -EBUSY.
+ * The final d_drop is done as an atomic operation relative to
+ * rename_lock ensuring there are no races with d_set_mounted. This
+ * ensures there are no unhashed dentries on the path to a mountpoint.
*
- * @dentry: dentry to prune and drop
+ * @dentry: dentry to detach, prune and drop
*/
int check_submounts_and_drop(struct dentry *dentry)
{
@@ -1385,19 +1388,24 @@ int check_submounts_and_drop(struct dentry *dentry)
}
for (;;) {
- struct select_data data;
+ struct detach_data data;
- INIT_LIST_HEAD(&data.dispose);
- data.start = dentry;
- data.found = 0;
+ data.mountpoint = NULL;
+ INIT_LIST_HEAD(&data.select.dispose);
+ data.select.start = dentry;
+ data.select.found = 0;
+
+ d_walk(dentry, &data, detach_and_collect, check_and_drop);
- d_walk(dentry, &data, check_and_collect, check_and_drop);
- ret = data.found;
+ if (data.select.found)
+ shrink_dentry_list(&data.select.dispose);
- if (!list_empty(&data.dispose))
- shrink_dentry_list(&data.dispose);
+ if (data.mountpoint) {
+ detach_mounts(data.mountpoint);
+ dput(data.mountpoint);
+ }
- if (ret <= 0)
+ if (!data.mountpoint && !data.select.found)
break;
cond_resched();
@@ -2639,10 +2647,8 @@ static struct dentry *__d_unalias(struct inode *inode,
goto out_err;
m2 = &alias->d_parent->d_inode->i_mutex;
out_unalias:
- if (likely(!d_mountpoint(alias))) {
- __d_move(alias, dentry, false);
- ret = alias;
- }
+ __d_move(alias, dentry, false);
+ ret = alias;
out_err:
spin_unlock(&inode->i_lock);
if (m2)