user/sven/linux.git/init/do_mounts.c, branch v5.15.2

init: don't panic if mount_nodev_root failed

2021-09-20T02:24:52Z

Attempt to mount 9p file system as root gives the following kernel panic: 9pnet_virtio: no channels available for device root Kernel panic - not syncing: VFS: Unable to mount root "root" (9p), err=-2 CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.15.0-rc1+ #127 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack_lvl+0x45/0x59 panic+0x1e2/0x44b ? __warn_printk+0xf3/0xf3 ? free_unref_page+0x2d4/0x4a0 ? trace_hardirqs_on+0x32/0x120 ? free_unref_page+0x2d4/0x4a0 mount_root+0x189/0x1e0 prepare_namespace+0x136/0x165 kernel_init_freeable+0x3b8/0x3cb ? rest_init+0x2e0/0x2e0 kernel_init+0x19/0x130 ret_from_fork+0x1f/0x30 Kernel Offset: disabled ---[ end Kernel panic - not syncing: VFS: Unable to mount root "root" (9p), err=-2 ]--- QEMU command line: "qemu-system-x86_64 -append root=/dev/root rw rootfstype=9p rootflags=trans=virtio ..." This error is because root_device_name is truncated in prepare_namespace() from being "/dev/root" to be "root" prior to call to mount_nodev_root(). As a solution, don't treat errors in mount_nodev_root() as errors that require panics and allow failback to the mount flow that existed before patch citied in Fixes tag. Fixes: f9259be6a9e7 ("init: allow mounting arbitrary non-blockdevice filesystems as root") Signed-off-by: Leon Romanovsky Reviewed-by: Christoph Hellwig Signed-off-by: Al Viro

init/do_mounts.c: Harden split_fs_names() against buffer overflow

2021-09-20T02:24:49Z

split_fs_names() currently takes comma separate list of filesystems and converts it into individual filesystem strings. Pleaces these strings in the input buffer passed by caller and returns number of strings. If caller manages to pass input string bigger than buffer, then we can write beyond the buffer. Or if string just fits buffer, we will still write beyond the buffer as we append a '\0' byte at the end. Pass size of input buffer to split_fs_names() and put enough checks in place so such buffer overrun possibilities do not occur. This patch does few things. - Add a parameter "size" to split_fs_names(). This specifies size of input buffer. - Use strlcpy() (instead of strcpy()) so that we can't go beyond buffer size. If input string "names" is larger than passed in buffer, input string will be truncated to fit in buffer. - Stop appending extra '\0' character at the end and avoid one possibility of going beyond the input buffer size. - Do not use extra loop to count number of strings. - Previously if one passed "rootfstype=foo,,bar", split_fs_names() will return only 1 string "foo" (and "bar" will be truncated due to extra ,). After this patch, now split_fs_names() will return 3 strings ("foo", zero-sized-string, and "bar"). Callers of split_fs_names() have been modified to check for zero sized string and skip to next one. Reported-by: xu xin Signed-off-by: Vivek Goyal Reviewed-by: Jan Kara Signed-off-by: Al Viro

Merge branch 'work.init' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2021-09-09T19:38:18Z

Pull root filesystem type handling updates from Al Viro: "Teach init/do_mounts.c to handle non-block filesystems, hopefully preventing even more special-cased kludges (such as root=/dev/nfs, etc)" * 'work.init' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: fs: simplify get_filesystem_list / get_all_fs_names init: allow mounting arbitrary non-blockdevice filesystems as root init: split get_fs_names

block: remove CONFIG_DEBUG_BLOCK_EXT_DEVT

2021-08-24T12:42:40Z

This might have been a neat debug aid when the extended dev_t was added, but that time is long gone. Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20210824075216.1179406-3-hch@lst.de Signed-off-by: Jens Axboe

fs: simplify get_filesystem_list / get_all_fs_names

2021-08-23T05:25:40Z

Just output the '\0' separate list of supported file systems for block devices directly rather than going through a pointless round of string manipulation. Based on an earlier patch from Al Viro . Vivek: Modified list_bdev_fs_names() and split_fs_names() to return number of null terminted strings to caller. Callers now use that information to loop through all the strings instead of relying on one extra null char being present at the end. Signed-off-by: Christoph Hellwig Signed-off-by: Vivek Goyal Signed-off-by: Al Viro

init: allow mounting arbitrary non-blockdevice filesystems as root

2021-08-23T05:25:40Z

Currently the only non-blockdevice filesystems that can be used as the initial root filesystem are NFS and CIFS, which use the magic "root=/dev/nfs" and "root=/dev/cifs" syntax that requires the root device file system details to come from filesystem specific kernel command line options. Add a little bit of new code that allows to just pass arbitrary string mount options to any non-blockdevice filesystems so that it can be mounted as the root file system. For example a virtiofs root file system can be mounted using the following syntax: "root=myfs rootfstype=virtiofs rw" Based on an earlier patch from Vivek Goyal . Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro

init: split get_fs_names

2021-08-23T05:25:40Z

Split get_fs_names into one function that splits up the command line argument, and one that gets the list of all registered file systems. Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro

block: factor out a part_devt helper

2021-06-01T13:45:49Z

Add a helper to find the dev_t for a disk + partno tuple. Signed-off-by: Christoph Hellwig Reviewed-by: Ming Lei Link: https://lore.kernel.org/r/20210525061301.2242282-8-hch@lst.de Signed-off-by: Jens Axboe

block: merge struct block_device and struct hd_struct

2020-12-01T21:53:40Z

Instead of having two structures that represent each block device with different life time rules, merge them into a single one. This also greatly simplifies the reference counting rules, as we can use the inode reference count as the main reference count for the new struct block_device, with the device model reference front ending it for device model interaction. Signed-off-by: Christoph Hellwig Reviewed-by: Jan Kara Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe

block: remove the partno field from struct hd_struct

2020-12-01T21:53:40Z

Just use the bd_partno field in struct block_device everywhere. Signed-off-by: Christoph Hellwig Reviewed-by: Jan Kara Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe