[PATCH 02/24] cachefiles: Fix non-taking of sb_writers around set/removexattr
From: David Howells <dhowells@redhat.com>
Date: 2024-07-29 16:20:41
Also in:
ceph-devel, linux-cifs, linux-fsdevel, linux-mm, linux-nfs, lkml, netfs, v9fs
Subsystem:
cachefiles: fs-cache backend for caching on mounted filesystems, filesystems (vfs and infrastructure), the rest · Maintainers:
David Howells, Alexander Viro, Christian Brauner, Linus Torvalds
Unlike other vfs_xxxx() calls, vfs_setxattr() and vfs_removexattr() don't
take the sb_writers lock, so the caller should do it for them.
Fix cachefiles to do this.
Fixes: 9ae326a69004 ("CacheFiles: A cache that backs onto a mounted filesystem")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Christian Brauner <brauner@kernel.org>
cc: Gao Xiang <xiang@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-erofs@lists.ozlabs.org
cc: linux-fsdevel@vger.kernel.org
---
fs/cachefiles/xattr.c | 34 ++++++++++++++++++++++++++--------
1 file changed, 26 insertions(+), 8 deletions(-)
diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c
index 4dd8a993c60a..7c6f260a3be5 100644
--- a/fs/cachefiles/xattr.c
+++ b/fs/cachefiles/xattr.c@@ -64,9 +64,15 @@ int cachefiles_set_object_xattr(struct cachefiles_object *object) memcpy(buf->data, fscache_get_aux(object->cookie), len); ret = cachefiles_inject_write_error(); - if (ret == 0) - ret = vfs_setxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, - buf, sizeof(struct cachefiles_xattr) + len, 0); + if (ret == 0) { + ret = mnt_want_write_file(file); + if (ret == 0) { + ret = vfs_setxattr(&nop_mnt_idmap, dentry, + cachefiles_xattr_cache, buf, + sizeof(struct cachefiles_xattr) + len, 0); + mnt_drop_write_file(file); + } + } if (ret < 0) { trace_cachefiles_vfs_error(object, file_inode(file), ret, cachefiles_trace_setxattr_error);
@@ -151,8 +157,14 @@ int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, int ret; ret = cachefiles_inject_remove_error(); - if (ret == 0) - ret = vfs_removexattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache); + if (ret == 0) { + ret = mnt_want_write(cache->mnt); + if (ret == 0) { + ret = vfs_removexattr(&nop_mnt_idmap, dentry, + cachefiles_xattr_cache); + mnt_drop_write(cache->mnt); + } + } if (ret < 0) { trace_cachefiles_vfs_error(object, d_inode(dentry), ret, cachefiles_trace_remxattr_error);
@@ -208,9 +220,15 @@ bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume) memcpy(buf->data, p, volume->vcookie->coherency_len); ret = cachefiles_inject_write_error(); - if (ret == 0) - ret = vfs_setxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, - buf, len, 0); + if (ret == 0) { + ret = mnt_want_write(volume->cache->mnt); + if (ret == 0) { + ret = vfs_setxattr(&nop_mnt_idmap, dentry, + cachefiles_xattr_cache, + buf, len, 0); + mnt_drop_write(volume->cache->mnt); + } + } if (ret < 0) { trace_cachefiles_vfs_error(NULL, d_inode(dentry), ret, cachefiles_trace_setxattr_error);