在 2025/7/9 05:50, Darrick J. Wong 写道:
[...]
Well, I'd also say just go for own fs_holder_ops if it was not for the
awkward "get super from bdev" step. As Christian wrote we've encapsulated
that in fs/super.c and bdev_super_lock() in particular but the calling
conventions for the fs_holder_ops are not very nice (holding
bdev_holder_lock, need to release it before grabbing practically anything
else) so I'd have much greater peace of mind if this didn't spread too
much. Once you call bdev_super_lock() and hold on to sb with s_umount held,
things are much more conventional for the fs land so I'd like if this
step happened before any fs hook got called. So I prefer something like
Qu's proposal of separate sb op for device removal over exporting
bdev_super_lock(). Like:
static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise)
{
struct super_block *sb;
sb = bdev_super_lock(bdev, false);
if (!sb)
return;
if (sb->s_op->remove_bdev) {
sb->s_op->remove_bdev(sb, bdev, surprise);
The only concern here is, remove_bdev() will handle two different things:
- Mark the target devices as missing and continue working
Of course that's when the fs can handle it.
- Shutdown
If the fs can not handle it.
And if the fs has to shutdown, we're missing all the shrinks in the
shutdown path.
Thus I'd prefer the remove_bdev() to have a return value, so that we can
fallback to shutdown path if the remove_bdev() failed.
This also aligns more towards Brauner's idea that we may want to expose
if the fs can handle the removal.
Thanks,
Qu
return;
}
It feels odd but I could live with this, particularly since that's the
direction that brauner is laying down. :)
Do we still need to super_unlock_shared here?
--D
if (!surprise)
sync_filesystem(sb);
shrink_dcache_sb(sb);
evict_inodes(sb);
if (sb->s_op->shutdown)
sb->s_op->shutdown(sb);
super_unlock_shared(sb);
}
As an aside:
'twould be nice if we could lift the *FS_IOC_SHUTDOWN dispatch out of
everyone's ioctl functions into the VFS, and then move the "I am dead"
state into super_block so that you could actually shut down any
filesystem, not just the seven that currently implement it.
Yes, I should find time to revive that patch series... It was not *that*
hard to do.
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
