kernel.git/fs/overlayfs/super.c, branch linux-5.8.y

ovl: fix mount option checks for nfs_export with no upperdir

2020-07-15T22:11:15Z

Without upperdir mount option, there is no index dir and the dependency checks nfs_export => index for mount options parsing are incorrect. Allow the combination nfs_export=on,index=off with no upperdir and move the check for dependency redirect_dir=nofollow for non-upper mount case to mount options parsing. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: force read-only sb on failure to create index dir

2020-07-15T22:11:15Z

With index feature enabled, on failure to create index dir, overlay is being mounted read-only. However, we do not forbid user to remount overlay read-write. Fix that by setting ofs->workdir to NULL, which prevents remount read-write. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: fix regression with re-formatted lower squashfs

2020-07-15T22:10:31Z

Commit 9df085f3c9a2 ("ovl: relax requirement for non null uuid of lower fs") relaxed the requirement for non null uuid with single lower layer to allow enabling index and nfs_export features with single lower squashfs. Fabian reported a regression in a setup when overlay re-uses an existing upper layer and re-formats the lower squashfs image. Because squashfs has no uuid, the origin xattr in upper layer are decoded from the new lower layer where they may resolve to a wrong origin file and user may get an ESTALE or EIO error on lookup. To avoid the reported regression while still allowing the new features with single lower squashfs, do not allow decoding origin with lower null uuid unless user opted-in to one of the new features that require following the lower inode of non-dir upper (index, xino, metacopy). Reported-by: Fabian Link: https://lore.kernel.org/linux-unionfs/32532923.JtPX5UtSzP@fgdesktop/ Fixes: 9df085f3c9a2 ("ovl: relax requirement for non null uuid of lower fs") Cc: stable@vger.kernel.org # v4.20+ Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: fix oops in ovl_indexdir_cleanup() with nfs_export=on

2020-07-15T22:09:59Z

Mounting with nfs_export=on, xfstests overlay/031 triggers a kernel panic since v5.8-rc1 overlayfs updates. overlayfs: orphan index entry (index/00fb1..., ftype=4000, nlink=2) BUG: kernel NULL pointer dereference, address: 0000000000000030 RIP: 0010:ovl_cleanup_and_whiteout+0x28/0x220 [overlay] Bisect point at commit c21c839b8448 ("ovl: whiteout inode sharing") Minimal reproducer: -------------------------------------------------- rm -rf l u w m mkdir -p l u w m mkdir -p l/testdir touch l/testdir/testfile mount -t overlay -o lowerdir=l,upperdir=u,workdir=w,nfs_export=on overlay m echo 1 > m/testdir/testfile umount m rm -rf u/testdir mount -t overlay -o lowerdir=l,upperdir=u,workdir=w,nfs_export=on overlay m umount m -------------------------------------------------- When mount with nfs_export=on, and fail to verify an orphan index, we're cleaning this index from indexdir by calling ovl_cleanup_and_whiteout(). This dereferences ofs->workdir, that was earlier set to NULL. The design was that ovl->workdir will point at ovl->indexdir, but we are assigning ofs->indexdir to ofs->workdir only after ovl_indexdir_cleanup(). There is no reason not to do it sooner, because once we get success from ofs->indexdir = ovl_workdir_create(... there is no turning back. Reported-and-tested-by: Murphy Zhou Fixes: c21c839b8448 ("ovl: whiteout inode sharing") Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: inode reference leak in ovl_is_inuse true case.

2020-07-15T22:05:40Z

When "ovl_is_inuse" true case, trap inode reference not put. plus adding the comment explaining sequence of ovl_is_inuse after ovl_setup_trap. Fixes: 0be0bfd2de9d ("ovl: fix regression caused by overlapping layers detection") Cc: # v4.19+ Reviewed-by: Amir Goldstein Signed-off-by: youngjun Signed-off-by: Miklos Szeredi

ovl: remove unnecessary lock check

2020-06-08T07:57:19Z

Directory is always locked until "out_unlock" label. So lock check is not needed. Signed-off-by: youngjun Signed-off-by: Miklos Szeredi

ovl: make private mounts longterm

2020-06-04T08:48:19Z

Overlayfs is using clone_private_mount() to create internal mounts for underlying layers. These are used for operations requiring a path, such as dentry_open(). Since these private mounts are not in any namespace they are treated as short term, "detached" mounts and mntput() involves taking the global mount_lock, which can result in serious cacheline pingpong. Make these private mounts longterm instead, which trade the penalty on mntput() for a slightly longer shutdown time due to an added RCU grace period when putting these mounts. Introduce a new helper kern_unmount_many() that can take care of multiple longterm mounts with a single RCU grace period. Cc: Al Viro Signed-off-by: Miklos Szeredi

ovl: get rid of redundant members in struct ovl_fs

2020-06-04T08:48:19Z

ofs->upper_mnt is copied to ->layers[0].mnt and ->layers[0].trap could be used instead of a separate ->upperdir_trap. Split the lowerdir option early to get the number of layers, then allocate the ->layers array, and finally fill the upper and lower layers, as before. Get rid of path_put_init() in ovl_lower_dir(), since the only caller will take care of that. [Colin Ian King] Fix null pointer dereference on null stack pointer on error return found by Coverity. Signed-off-by: Miklos Szeredi

ovl: add accessor for ofs->upper_mnt

2020-06-04T08:48:19Z

Next patch will remove ofs->upper_mnt, so add an accessor function for this field. Signed-off-by: Miklos Szeredi

ovl: sync dirty data when remounting to ro mode

2020-05-13T09:11:24Z

sync_filesystem() does not sync dirty data for readonly filesystem during umount, so before changing to readonly filesystem we should sync dirty data for data integrity. Signed-off-by: Chengguang Xu Signed-off-by: Miklos Szeredi