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authorAl Viro <viro@zeniv.linux.org.uk>2019-11-18 17:43:10 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2019-12-11 06:29:58 +0300
commita3d1e7eb5abe3aa1095bc75d1a6760d3809bd672 (patch)
tree1dce9bdc1052f0a94dffe67526e38f5a8202164f /fs/libfs.c
parente42617b825f8073569da76dc4510bfa019b1c35a (diff)
downloadlinux-a3d1e7eb5abe3aa1095bc75d1a6760d3809bd672.tar.xz
simple_recursive_removal(): kernel-side rm -rf for ramfs-style filesystems
two requirements: no file creations in IS_DEADDIR and no cross-directory renames whatsoever. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/libfs.c')
-rw-r--r--fs/libfs.c70
1 files changed, 70 insertions, 0 deletions
diff --git a/fs/libfs.c b/fs/libfs.c
index 1463b038ffc4..c686bd9caac6 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -19,6 +19,7 @@
#include <linux/buffer_head.h> /* sync_mapping_buffers */
#include <linux/fs_context.h>
#include <linux/pseudo_fs.h>
+#include <linux/fsnotify.h>
#include <linux/uaccess.h>
@@ -239,6 +240,75 @@ const struct inode_operations simple_dir_inode_operations = {
};
EXPORT_SYMBOL(simple_dir_inode_operations);
+static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev)
+{
+ struct dentry *child = NULL;
+ struct list_head *p = prev ? &prev->d_child : &parent->d_subdirs;
+
+ spin_lock(&parent->d_lock);
+ while ((p = p->next) != &parent->d_subdirs) {
+ struct dentry *d = container_of(p, struct dentry, d_child);
+ if (simple_positive(d)) {
+ spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
+ if (simple_positive(d))
+ child = dget_dlock(d);
+ spin_unlock(&d->d_lock);
+ if (likely(child))
+ break;
+ }
+ }
+ spin_unlock(&parent->d_lock);
+ dput(prev);
+ return child;
+}
+
+void simple_recursive_removal(struct dentry *dentry,
+ void (*callback)(struct dentry *))
+{
+ struct dentry *this = dget(dentry);
+ while (true) {
+ struct dentry *victim = NULL, *child;
+ struct inode *inode = this->d_inode;
+
+ inode_lock(inode);
+ if (d_is_dir(this))
+ inode->i_flags |= S_DEAD;
+ while ((child = find_next_child(this, victim)) == NULL) {
+ // kill and ascend
+ // update metadata while it's still locked
+ inode->i_ctime = current_time(inode);
+ clear_nlink(inode);
+ inode_unlock(inode);
+ victim = this;
+ this = this->d_parent;
+ inode = this->d_inode;
+ inode_lock(inode);
+ if (simple_positive(victim)) {
+ d_invalidate(victim); // avoid lost mounts
+ if (d_is_dir(victim))
+ fsnotify_rmdir(inode, victim);
+ else
+ fsnotify_unlink(inode, victim);
+ if (callback)
+ callback(victim);
+ dput(victim); // unpin it
+ }
+ if (victim == dentry) {
+ inode->i_ctime = inode->i_mtime =
+ current_time(inode);
+ if (d_is_dir(dentry))
+ drop_nlink(inode);
+ inode_unlock(inode);
+ dput(dentry);
+ return;
+ }
+ }
+ inode_unlock(inode);
+ this = child;
+ }
+}
+EXPORT_SYMBOL(simple_recursive_removal);
+
static const struct super_operations simple_super_operations = {
.statfs = simple_statfs,
};