diff options
author | David Howells <dhowells@redhat.com> | 2021-11-18 08:58:08 +0000 |
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committer | David Howells <dhowells@redhat.com> | 2022-01-07 13:41:32 +0000 |
commit | 1bd9c4e4f0494915b2391f373d25096579f835ff (patch) | |
tree | 270de5e2b24d809bffe697572c4410e6f05641b9 /fs/cachefiles | |
parent | 80f94f29f677d32a1edabc055acfe91c00803592 (diff) | |
download | linux-1bd9c4e4f0494915b2391f373d25096579f835ff.tar.bz2 |
vfs, cachefiles: Mark a backing file in use with an inode flag
Use an inode flag, S_KERNEL_FILE, to mark that a backing file is in use by
the kernel to prevent cachefiles or other kernel services from interfering
with that file.
Alter rmdir to reject attempts to remove a directory marked with this flag.
This is used by cachefiles to prevent cachefilesd from removing them.
Using S_SWAPFILE instead isn't really viable as that has other effects in
the I/O paths.
Changes
=======
ver #3:
- Check for the object pointer being NULL in the tracepoints rather than
the caller.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819630256.215744.4815885535039369574.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906931596.143852.8642051223094013028.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967141000.1823006.12920680657559677789.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021541207.640689.564689725898537127.stgit@warthog.procyon.org.uk/ # v4
Diffstat (limited to 'fs/cachefiles')
-rw-r--r-- | fs/cachefiles/Makefile | 1 | ||||
-rw-r--r-- | fs/cachefiles/namei.c | 43 |
2 files changed, 44 insertions, 0 deletions
diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile index 463e3d608b75..e0b092ca077f 100644 --- a/fs/cachefiles/Makefile +++ b/fs/cachefiles/Makefile @@ -7,6 +7,7 @@ cachefiles-y := \ cache.o \ daemon.o \ main.o \ + namei.o \ security.o cachefiles-$(CONFIG_CACHEFILES_ERROR_INJECTION) += error_inject.o diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c new file mode 100644 index 000000000000..913f83f1c900 --- /dev/null +++ b/fs/cachefiles/namei.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* CacheFiles path walking and related routines + * + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include <linux/fs.h> +#include "internal.h" + +/* + * Mark the backing file as being a cache file if it's not already in use. The + * mark tells the culling request command that it's not allowed to cull the + * file or directory. The caller must hold the inode lock. + */ +static bool __cachefiles_mark_inode_in_use(struct cachefiles_object *object, + struct dentry *dentry) +{ + struct inode *inode = d_backing_inode(dentry); + bool can_use = false; + + if (!(inode->i_flags & S_KERNEL_FILE)) { + inode->i_flags |= S_KERNEL_FILE; + trace_cachefiles_mark_active(object, inode); + can_use = true; + } else { + pr_notice("cachefiles: Inode already in use: %pd\n", dentry); + } + + return can_use; +} + +/* + * Unmark a backing inode. The caller must hold the inode lock. + */ +static void __cachefiles_unmark_inode_in_use(struct cachefiles_object *object, + struct dentry *dentry) +{ + struct inode *inode = d_backing_inode(dentry); + + inode->i_flags &= ~S_KERNEL_FILE; + trace_cachefiles_mark_inactive(object, inode); +} |