Messages in this thread | | | Date | Tue, 17 May 2022 22:32:38 +0000 | From | Al Viro <> | Subject | Re: [PATCH v2 2/2] FUSE: Retire superblock on force unmount |
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On Tue, May 17, 2022 at 10:20:06PM +0000, Al Viro wrote: > On Thu, May 12, 2022 at 08:29:10AM +1000, Daniil Lunev wrote: > > Force unmount of FUSE severes the connection with the user space, even > > if there are still open files. Subsequent remount tries to re-use the > > superblock held by the open files, which is meaningless in the FUSE case > > after disconnect - reused super block doesn't have userspace counterpart > > attached to it and is incapable of doing any IO. > > Why not simply have those simply rejected by fuse_test_super()? > Looks like that would be much smaller and less invasive patch... > Confused...
... because Miklos had suggested that, apparently ;-/ I disagree - that approach has more side effects. "mount will skip that sucker" is, AFAICS, the only effect of modiyfing test_super callback(s); yours, OTOH...
Note that generic_shutdown_super() is *not* called while superblock is mounted anywhere. And it doesn't get to eviction from the list while it still has live dentries. Or inodes, for that matter.
So this if (sb->s_bdi != &noop_backing_dev_info) { if (sb->s_iflags & SB_I_PERSB_BDI) bdi_unregister(sb->s_bdi); bdi_put(sb->s_bdi); sb->s_bdi = &noop_backing_dev_info; } is almost certainly not safe to be done on a live superblock.
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