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dax: dax_layout_busy_page() warn on !exceptional

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Inodes using DAX should only ever have exceptional entries in their page
caches.  Make this clear by warning if the iteration in
dax_layout_busy_page() ever sees a non-exceptional entry, and by adding a
comment for the pagevec_release() call which only deals with struct page
pointers.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Ross Zwisler 2018-07-29 16:59:16 -04:00 committed by Theodore Ts'o
parent 0694f8c39f
commit cdbf8897cb
1 changed files with 9 additions and 1 deletions
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10
fs/dax.c
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@ -566,7 +566,8 @@ struct page *dax_layout_busy_page(struct address_space *mapping)
if (index >= end)
break;
if (!radix_tree_exceptional_entry(pvec_ent))
if (WARN_ON_ONCE(
!radix_tree_exceptional_entry(pvec_ent)))
continue;
xa_lock_irq(&mapping->i_pages);
@ -578,6 +579,13 @@ struct page *dax_layout_busy_page(struct address_space *mapping)
if (page)
break;
}
/*
* We don't expect normal struct page entries to exist in our
* tree, but we keep these pagevec calls so that this code is
* consistent with the common pattern for handling pagevecs
* throughout the kernel.
*/
pagevec_remove_exceptionals(&pvec);
pagevec_release(&pvec);
index++;