summaryrefslogtreecommitdiff
path: root/fs/afs/dir_silly.c
diff options
context:
space:
mode:
authorDavid Howells <dhowells@redhat.com>2019-04-25 14:26:51 +0100
committerDavid Howells <dhowells@redhat.com>2019-04-25 14:26:51 +0100
commit79ddbfa500b37a94fa7501e65ebdd5c0e4c7592d (patch)
tree1521d6e9276078aaf142ea40ab0f1e156c0fc276 /fs/afs/dir_silly.c
parent99987c560046ea178eb5aea793043deea255f185 (diff)
downloadlinux-sh-79ddbfa500b37a94fa7501e65ebdd5c0e4c7592d.tar.gz
afs: Implement sillyrename for unlink and rename
Implement sillyrename for AFS unlink and rename, using the NFS variant implementation as a basis. Note that the asynchronous file locking extender/releaser has to be notified with a state change to stop it complaining if there's a race between that and the actual file deletion. A tracepoint, afs_silly_rename, is also added to note the silly rename and the cleanup. The afs_edit_dir tracepoint is given some extra reason indicators and the afs_flock_ev tracepoint is given a silly-delete file lock cancellation indicator. Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs/afs/dir_silly.c')
-rw-r--r--fs/afs/dir_silly.c239
1 files changed, 239 insertions, 0 deletions
diff --git a/fs/afs/dir_silly.c b/fs/afs/dir_silly.c
new file mode 100644
index 000000000000..f6f89fdab6b2
--- /dev/null
+++ b/fs/afs/dir_silly.c
@@ -0,0 +1,239 @@
+/* AFS silly rename handling
+ *
+ * Copyright (C) 2019 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ * - Derived from NFS's sillyrename.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/fsnotify.h>
+#include "internal.h"
+
+/*
+ * Actually perform the silly rename step.
+ */
+static int afs_do_silly_rename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
+ struct dentry *old, struct dentry *new,
+ struct key *key)
+{
+ struct afs_fs_cursor fc;
+ u64 dir_data_version = dvnode->status.data_version;
+ int ret = -ERESTARTSYS;
+
+ _enter("%pd,%pd", old, new);
+
+ trace_afs_silly_rename(vnode, false);
+ if (afs_begin_vnode_operation(&fc, dvnode, key)) {
+ while (afs_select_fileserver(&fc)) {
+ fc.cb_break = afs_calc_vnode_cb_break(dvnode);
+ afs_fs_rename(&fc, old->d_name.name,
+ dvnode, new->d_name.name,
+ dir_data_version, dir_data_version);
+ }
+
+ afs_vnode_commit_status(&fc, dvnode, fc.cb_break);
+ ret = afs_end_vnode_operation(&fc);
+ }
+
+ if (ret == 0) {
+ spin_lock(&old->d_lock);
+ old->d_flags |= DCACHE_NFSFS_RENAMED;
+ spin_unlock(&old->d_lock);
+ if (dvnode->silly_key != key) {
+ key_put(dvnode->silly_key);
+ dvnode->silly_key = key_get(key);
+ }
+
+ if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
+ afs_edit_dir_remove(dvnode, &old->d_name,
+ afs_edit_dir_for_silly_0);
+ if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
+ afs_edit_dir_add(dvnode, &new->d_name,
+ &vnode->fid, afs_edit_dir_for_silly_1);
+
+ /* vfs_unlink and the like do not issue this when a file is
+ * sillyrenamed, so do it here.
+ */
+ fsnotify_nameremove(old, 0);
+ }
+
+ _leave(" = %d", ret);
+ return ret;
+}
+
+/**
+ * afs_sillyrename - Perform a silly-rename of a dentry
+ *
+ * AFS is stateless and the server doesn't know when the client is holding a
+ * file open. To prevent application problems when a file is unlinked while
+ * it's still open, the client performs a "silly-rename". That is, it renames
+ * the file to a hidden file in the same directory, and only performs the
+ * unlink once the last reference to it is put.
+ *
+ * The final cleanup is done during dentry_iput.
+ */
+int afs_sillyrename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
+ struct dentry *dentry, struct key *key)
+{
+ static unsigned int sillycounter;
+ struct dentry *sdentry = NULL;
+ unsigned char silly[16];
+ int ret = -EBUSY;
+
+ _enter("");
+
+ /* We don't allow a dentry to be silly-renamed twice. */
+ if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
+ return -EBUSY;
+
+ sdentry = NULL;
+ do {
+ int slen;
+
+ dput(sdentry);
+ sillycounter++;
+
+ /* Create a silly name. Note that the ".__afs" prefix is
+ * understood by the salvager and must not be changed.
+ */
+ slen = scnprintf(silly, sizeof(silly), ".__afs%04X", sillycounter);
+ sdentry = lookup_one_len(silly, dentry->d_parent, slen);
+
+ /* N.B. Better to return EBUSY here ... it could be dangerous
+ * to delete the file while it's in use.
+ */
+ if (IS_ERR(sdentry))
+ goto out;
+ } while (!d_is_negative(sdentry));
+
+ ihold(&vnode->vfs_inode);
+
+ ret = afs_do_silly_rename(dvnode, vnode, dentry, sdentry, key);
+ switch (ret) {
+ case 0:
+ /* The rename succeeded. */
+ d_move(dentry, sdentry);
+ break;
+ case -ERESTARTSYS:
+ /* The result of the rename is unknown. Play it safe by forcing
+ * a new lookup.
+ */
+ d_drop(dentry);
+ d_drop(sdentry);
+ }
+
+ iput(&vnode->vfs_inode);
+ dput(sdentry);
+out:
+ _leave(" = %d", ret);
+ return ret;
+}
+
+/*
+ * Tell the server to remove a sillyrename file.
+ */
+static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode,
+ struct dentry *dentry, struct key *key)
+{
+ struct afs_fs_cursor fc;
+ u64 dir_data_version = dvnode->status.data_version;
+ int ret = -ERESTARTSYS;
+
+ _enter("");
+
+ trace_afs_silly_rename(vnode, true);
+ if (afs_begin_vnode_operation(&fc, dvnode, key)) {
+ while (afs_select_fileserver(&fc)) {
+ fc.cb_break = afs_calc_vnode_cb_break(dvnode);
+
+ if (test_bit(AFS_SERVER_FL_IS_YFS, &fc.cbi->server->flags) &&
+ !test_bit(AFS_SERVER_FL_NO_RM2, &fc.cbi->server->flags)) {
+ yfs_fs_remove_file2(&fc, vnode, dentry->d_name.name,
+ dir_data_version);
+ if (fc.ac.error != -ECONNABORTED ||
+ fc.ac.abort_code != RXGEN_OPCODE)
+ continue;
+ set_bit(AFS_SERVER_FL_NO_RM2, &fc.cbi->server->flags);
+ }
+
+ afs_fs_remove(&fc, vnode, dentry->d_name.name, false,
+ dir_data_version);
+ }
+
+ afs_vnode_commit_status(&fc, dvnode, fc.cb_break);
+ ret = afs_end_vnode_operation(&fc);
+ if (ret == 0) {
+ drop_nlink(&vnode->vfs_inode);
+ if (vnode->vfs_inode.i_nlink == 0) {
+ set_bit(AFS_VNODE_DELETED, &vnode->flags);
+ clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
+ }
+ }
+ if (ret == 0 &&
+ test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
+ afs_edit_dir_remove(dvnode, &dentry->d_name,
+ afs_edit_dir_for_unlink);
+ }
+
+ _leave(" = %d", ret);
+ return ret;
+}
+
+/*
+ * Remove sillyrename file on iput.
+ */
+int afs_silly_iput(struct dentry *dentry, struct inode *inode)
+{
+ struct afs_vnode *dvnode = AFS_FS_I(d_inode(dentry->d_parent));
+ struct afs_vnode *vnode = AFS_FS_I(inode);
+ struct dentry *alias;
+ int ret;
+
+ DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+
+ _enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode);
+
+ down_read(&dvnode->rmdir_lock);
+
+ alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq);
+ if (IS_ERR(alias)) {
+ up_read(&dvnode->rmdir_lock);
+ return 0;
+ }
+
+ if (!d_in_lookup(alias)) {
+ /* We raced with lookup... See if we need to transfer the
+ * sillyrename information to the aliased dentry.
+ */
+ ret = 0;
+ spin_lock(&alias->d_lock);
+ if (d_really_is_positive(alias) &&
+ !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
+ alias->d_flags |= DCACHE_NFSFS_RENAMED;
+ ret = 1;
+ }
+ spin_unlock(&alias->d_lock);
+ up_read(&dvnode->rmdir_lock);
+ dput(alias);
+ return ret;
+ }
+
+ /* Stop lock-release from complaining. */
+ spin_lock(&vnode->lock);
+ vnode->lock_state = AFS_VNODE_LOCK_DELETED;
+ trace_afs_flock_ev(vnode, NULL, afs_flock_silly_delete, 0);
+ spin_unlock(&vnode->lock);
+
+ afs_do_silly_unlink(dvnode, vnode, dentry, dvnode->silly_key);
+ up_read(&dvnode->rmdir_lock);
+ d_lookup_done(alias);
+ dput(alias);
+ return 1;
+}