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afs: Fix silly rename

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Fix AFS's silly rename by the following means:

 (1) Set the destination directory in afs_do_silly_rename() so as to avoid
     misbehaviour and indicate that the directory data version will
     increment by 1 so as to avoid warnings about unexpected changes in the
     DV.  Also indicate that the ctime should be updated to avoid xfstest
     grumbling.

 (2) Note when the server indicates that a directory changed more than we
     expected (AFS_OPERATION_DIR_CONFLICT), indicating a conflict with a
     third party change, checking on successful completion of unlink and
     rename.

     The problem is that the FS.RemoveFile RPC op doesn't report the status
     of the unlinked file, though YFS.RemoveFile2 does.  This can be
     mitigated by the assumption that if the directory DV cranked by
     exactly 1, we can be sure we removed one link from the file; further,
     ordinarily in AFS, files cannot be hardlinked across directories, so
     if we reduce nlink to 0, the file is deleted.

     However, if the directory DV jumps by more than 1, we cannot know if a
     third party intervened by adding or removing a link on the file we
     just removed a link from.

     The same also goes for any vnode that is at the destination of the
     FS.Rename RPC op.

 (3) Make afs_vnode_commit_status() apply the nlink drop inside the cb_lock
     section along with the other attribute updates if ->op_unlinked is set
     on the descriptor for the appropriate vnode.

 (4) Issue a follow up status fetch to the unlinked file in the event of a
     third party conflict that makes it impossible for us to know if we
     actually deleted the file or not.

 (5) Provide a flag, AFS_VNODE_SILLY_DELETED, to make afs_getattr() lie to
     the user about the nlink of a silly deleted file so that it appears as
     0, not 1.

Found with the generic/035 and generic/084 xfstests.

Fixes: e49c7b2f6d ("afs: Build an abstraction around an "operation" concept")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells
2020-06-15 17:36:58 +01:00
parent 7c295eec1e
commit b6489a49f7
4 changed files with 80 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

36
fs/afs/dir_silly.c
View File

@@ -16,6 +16,7 @@ static void afs_silly_rename_success(struct afs_operation *op)
{
_enter("op=%08x", op->debug_id);
afs_check_dir_conflict(op, &op->file[0]);
afs_vnode_commit_status(op, &op->file[0]);
}
@@ -69,6 +70,11 @@ static int afs_do_silly_rename(struct afs_vnode *dvnode, struct afs_vnode *vnode
return PTR_ERR(op);
afs_op_set_vnode(op, 0, dvnode);
afs_op_set_vnode(op, 1, dvnode);
op->file[0].dv_delta = 1;
op->file[1].dv_delta = 1;
op->file[0].update_ctime = true;
op->file[1].update_ctime = true;
op->dentry = old;
op->dentry_2 = new;
@@ -129,6 +135,7 @@ int afs_sillyrename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
switch (ret) {
case 0:
/* The rename succeeded. */
set_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags);
d_move(dentry, sdentry);
break;
case -ERESTARTSYS:
@@ -148,18 +155,11 @@ out:
static void afs_silly_unlink_success(struct afs_operation *op)
{
struct afs_vnode *vnode = op->file[1].vnode;
_enter("op=%08x", op->debug_id);
afs_check_dir_conflict(op, &op->file[0]);
afs_vnode_commit_status(op, &op->file[0]);
afs_vnode_commit_status(op, &op->file[1]);
afs_update_dentry_version(op, &op->file[0], op->dentry);
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);
}
}
static void afs_silly_unlink_edit_dir(struct afs_operation *op)
@@ -200,12 +200,30 @@ static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode
afs_op_set_vnode(op, 0, dvnode);
afs_op_set_vnode(op, 1, vnode);
op->file[0].dv_delta = 1;
op->file[0].update_ctime = true;
op->file[1].op_unlinked = true;
op->file[1].update_ctime = true;
op->dentry = dentry;
op->ops = &afs_silly_unlink_operation;
trace_afs_silly_rename(vnode, true);
return afs_do_sync_operation(op);
afs_begin_vnode_operation(op);
afs_wait_for_operation(op);
/* If there was a conflict with a third party, check the status of the
* unlinked vnode.
*/
if (op->error == 0 && (op->flags & AFS_OPERATION_DIR_CONFLICT)) {
op->file[1].update_ctime = false;
op->fetch_status.which = 1;
op->ops = &afs_fetch_status_operation;
afs_begin_vnode_operation(op);
afs_wait_for_operation(op);
}
return afs_put_operation(op);
}
/*