tmpfs: check residence in data_locked

[dougm]

Summary

tmpfs_seek_data_locked should return the offset of the first page either resident in memory or in swap, but may return an offset to a nonresident page. Check for residence to fix that.

[dougm]

Fix some sloppiness.

[markj]

sys/fs/tmpfs/tmpfs_vnops.c

2111

If we encounter an invalid page, I believe we still need to consult the swap pager before proceeding to the next pindex.

[dougm]

Try to address feedback from @markj and @alc.

[alc]

sys/fs/tmpfs/tmpfs_vnops.c

2111

if m->pindex != p, testing vm_page_any_valid(m) needn't happen at all if p_swp == p or m->pindex >= p_swp. Otherwise, we were repeating it on the same page in the first iteration of the below loop.

[dougm]

Avoid checking the same page for validity twice, at the cost of finding the next page when it might turn out not to matter.

[dougm]

Copy @alc's edit.