On Mon, Jul 31, 2023 at 03:57:57PM +0200, Christian Brauner wrote: > On Mon, Jul 31, 2023 at 03:53:25PM +0200, Christoph Hellwig wrote: > > On Mon, Jul 31, 2023 at 03:22:28PM +0200, Christian Brauner wrote: > > > Uh, no. I vasty underestimated how sensitive that change would be. Plus > > > arguably ->kill_sb() really should be callable once the sb is visible. > > > > > > Are you looking into this or do you want me to, Christoph? > > > > I'm planning to look into it, but I won't get to it before tomorrow. > > Ok, let me go through the callsites and make sure that all callers are > safe. I think we should just continue calling deactivate_locked_super() > exactly the way we do right now but remove shenanigans like the one we > have in erofs_kill_sb().
The only filesystem that did implicitly rely on fill_super() having been called was indeed - sorry to single it out - erofs. Everyone else doesn't have that sort of dependency afaict. fs/erofs/super.c: return get_tree_bdev(fc, erofs_fc_fill_super); => ->kill_sb() has requirement that ->fill_super() has been called. So I went and looked at all users of (1) get_tree_bdev() -> new mount api (2) mount_bdev -> old mount api which are the two functions that were changed in Jan's and Christoph's patch. I'm listing the results below. One thing to note is that only 40% (10 out of the 26 I looked at) of block based filesystems reliant on higher-level fs/super.c helpers directly (e.g., that excludes btrfs) have converted to the new mount api. In any case, Gao, can you remove that dependency of erofs_kill_sb() on erofs_fill_super(), please? Once that hits upstream the syzbot report will go away. fs/exfat/super.c: return get_tree_bdev(fc, exfat_fill_super); fs/ntfs3/super.c: return get_tree_bdev(fc, ntfs_fill_super); fs/squashfs/super.c: return get_tree_bdev(fc, squashfs_fill_super); fs/ext4/super.c: return get_tree_bdev(fc, ext4_fill_super); fs/xfs/xfs_super.c: return get_tree_bdev(fc, xfs_fs_fill_super); fs/adfs/super.c: return mount_bdev(fs_type, flags, dev_name, data, adfs_fill_super); fs/befs/linuxvfs.c: return mount_bdev(fs_type, flags, dev_name, data, befs_fill_super); fs/bfs/inode.c: return mount_bdev(fs_type, flags, dev_name, data, bfs_fill_super); fs/ext2/super.c: return mount_bdev(fs_type, flags, dev_name, data, ext2_fill_super); fs/fat/namei_msdos.c: return mount_bdev(fs_type, flags, dev_name, data, msdos_fill_super); fs/fat/namei_vfat.c: return mount_bdev(fs_type, flags, dev_name, data, vfat_fill_super); fs/freevxfs/vxfs_super.c: return mount_bdev(fs_type, flags, dev_name, data, vxfs_fill_super); fs/hfs/super.c: return mount_bdev(fs_type, flags, dev_name, data, hfs_fill_super); fs/hfsplus/super.c: return mount_bdev(fs_type, flags, dev_name, data, hfsplus_fill_super); fs/hpfs/super.c: return mount_bdev(fs_type, flags, dev_name, data, hpfs_fill_super); fs/isofs/inode.c: return mount_bdev(fs_type, flags, dev_name, data, isofs_fill_super); fs/jfs/super.c: return mount_bdev(fs_type, flags, dev_name, data, jfs_fill_super); fs/minix/inode.c: return mount_bdev(fs_type, flags, dev_name, data, minix_fill_super); fs/ntfs/super.c: return mount_bdev(fs_type, flags, dev_name, data, ntfs_fill_super); fs/ocfs2/super.c: return mount_bdev(fs_type, flags, dev_name, data, ocfs2_fill_super); fs/omfs/inode.c: return mount_bdev(fs_type, flags, dev_name, data, omfs_fill_super); fs/qnx6/inode.c: return mount_bdev(fs_type, flags, dev_name, data, qnx6_fill_super); fs/sysv/super.c: return mount_bdev(fs_type, flags, dev_name, data, sysv_fill_super); fs/udf/super.c: return mount_bdev(fs_type, flags, dev_name, data, udf_fill_super); fs/ufs/super.c: return mount_bdev(fs_type, flags, dev_name, data, ufs_fill_super); => no custom ->kill_sb() method. fs/cramfs/inode.c: ret = get_tree_bdev(fc, cramfs_blkdev_fill_super); fs/fuse/inode.c: err = get_tree_bdev(fsc, fuse_fill_super); fs/gfs2/ops_fstype.c: error = get_tree_bdev(fc, gfs2_fill_super); fs/romfs/super.c: ret = get_tree_bdev(fc, romfs_fill_super); fs/affs/super.c: return mount_bdev(fs_type, flags, dev_name, data, affs_fill_super); fs/efs/super.c: return mount_bdev(fs_type, flags, dev_name, data, efs_fill_super); fs/f2fs/super.c: return mount_bdev(fs_type, flags, dev_name, data, f2fs_fill_super); fs/qnx4/inode.c: return mount_bdev(fs_type, flags, dev_name, data, qnx4_fill_super); fs/reiserfs/super.c: return mount_bdev(fs_type, flags, dev_name, data, reiserfs_fill_super); fs/zonefs/super.c: return mount_bdev(fs_type, flags, dev_name, data, zonefs_fill_super); => ->kill_sb() has no requirement that ->fill_super() has been called.
