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kernel: fix an overlayfs deadlock on rmdir

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SVN-Revision: 26215
This commit is contained in:
Felix Fietkau 2011-03-17 23:14:17 +00:00
parent 4e2339b032
commit 473ac1f87d
2 changed files with 152 additions and 0 deletions
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76
target/linux/generic/patches-2.6.37/212-overlayfs_fix_readdir_unlink_deadlock.patch Normal file
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@ -0,0 +1,76 @@
--- a/fs/overlayfs/overlayfs.c
+++ b/fs/overlayfs/overlayfs.c
@@ -1686,37 +1686,56 @@ static int ovl_check_empty_dir(struct de
return err;
}
-static int ovl_unlink_whiteout(void *buf, const char *name, int namelen,
- loff_t offset, u64 ino, unsigned int d_type)
+static int ovl_fill_links(void *buf, const char *name, int namelen,
+ loff_t offset, u64 ino, unsigned int d_type)
{
struct ovl_readdir_data *rdd = buf;
+ struct ovl_cache_entry *p;
- rdd->count++;
- /* check d_type to filter out "." and ".." */
- if (d_type == DT_LNK) {
- struct dentry *dentry;
+ if (d_type != DT_LNK)
+ return 0;
- dentry = lookup_one_len(name, rdd->dir, namelen);
- if (IS_ERR(dentry)) {
- rdd->err = PTR_ERR(dentry);
- } else {
- rdd->err = vfs_unlink(rdd->dir->d_inode, dentry);
- dput(dentry);
- }
- }
+ p = ovl_cache_entry_new(name, namelen, ino, d_type);
+ if (!p)
+ return -ENOMEM;
- return rdd->err;
+ list_add(&p->l_node, rdd->list);
+ return 0;
}
static int ovl_remove_whiteouts(struct dentry *dentry)
{
struct path upperpath;
- struct ovl_readdir_data rdd = { .list = NULL };
+ LIST_HEAD(list);
+ struct ovl_readdir_data rdd = { .list = &list };
+ struct ovl_cache_entry *p, *t;
+ int ret;
ovl_path_upper(dentry, &upperpath);
rdd.dir = upperpath.dentry;
- return ovl_dir_read(&upperpath, &rdd, ovl_unlink_whiteout);
+ ret = ovl_dir_read(&upperpath, &rdd, ovl_fill_links);
+
+ mutex_lock(&rdd.dir->d_inode->i_mutex);
+ list_for_each_entry_safe(p, t, &list, l_node) {
+ struct dentry *dentry;
+
+ if (!ret) {
+ dentry = lookup_one_len(p->name, rdd.dir, p->len);
+ if (IS_ERR(dentry)) {
+ ret = PTR_ERR(dentry);
+ } else {
+ ret = vfs_unlink(rdd.dir->d_inode, dentry);
+ dput(dentry);
+ }
+ }
+
+ list_del(&p->l_node);
+ kfree(p);
+ }
+ mutex_unlock(&rdd.dir->d_inode->i_mutex);
+
+ return ret;
}
static int ovl_rmdir(struct inode *dir, struct dentry *dentry)

76
target/linux/generic/patches-2.6.38/211-overlayfs_fix_readdir_unlink_deadlock.patch Normal file
View file

@ -0,0 +1,76 @@
--- a/fs/overlayfs/overlayfs.c
+++ b/fs/overlayfs/overlayfs.c
@@ -1700,37 +1700,56 @@ static int ovl_check_empty_dir(struct de
return err;
}
-static int ovl_unlink_whiteout(void *buf, const char *name, int namelen,
- loff_t offset, u64 ino, unsigned int d_type)
+static int ovl_fill_links(void *buf, const char *name, int namelen,
+ loff_t offset, u64 ino, unsigned int d_type)
{
struct ovl_readdir_data *rdd = buf;
+ struct ovl_cache_entry *p;
- rdd->count++;
- /* check d_type to filter out "." and ".." */
- if (d_type == DT_LNK) {
- struct dentry *dentry;
+ if (d_type != DT_LNK)
+ return 0;
- dentry = lookup_one_len(name, rdd->dir, namelen);
- if (IS_ERR(dentry)) {
- rdd->err = PTR_ERR(dentry);
- } else {
- rdd->err = vfs_unlink(rdd->dir->d_inode, dentry);
- dput(dentry);
- }
- }
+ p = ovl_cache_entry_new(name, namelen, ino, d_type);
+ if (!p)
+ return -ENOMEM;
- return rdd->err;
+ list_add(&p->l_node, rdd->list);
+ return 0;
}
static int ovl_remove_whiteouts(struct dentry *dentry)
{
struct path upperpath;
- struct ovl_readdir_data rdd = { .list = NULL };
+ LIST_HEAD(list);
+ struct ovl_readdir_data rdd = { .list = &list };
+ struct ovl_cache_entry *p, *t;
+ int ret;
ovl_path_upper(dentry, &upperpath);
rdd.dir = upperpath.dentry;
- return ovl_dir_read(&upperpath, &rdd, ovl_unlink_whiteout);
+ ret = ovl_dir_read(&upperpath, &rdd, ovl_fill_links);
+
+ mutex_lock(&rdd.dir->d_inode->i_mutex);
+ list_for_each_entry_safe(p, t, &list, l_node) {
+ struct dentry *dentry;
+
+ if (!ret) {
+ dentry = lookup_one_len(p->name, rdd.dir, p->len);
+ if (IS_ERR(dentry)) {
+ ret = PTR_ERR(dentry);
+ } else {
+ ret = vfs_unlink(rdd.dir->d_inode, dentry);
+ dput(dentry);
+ }
+ }
+
+ list_del(&p->l_node);
+ kfree(p);
+ }
+ mutex_unlock(&rdd.dir->d_inode->i_mutex);
+
+ return ret;
}
static int ovl_rmdir(struct inode *dir, struct dentry *dentry)