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dax: Check page->mapping isn't NULL

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If we race with inode destroy, it's possible for page->mapping to be
NULL before we even enter this routine, as well as after having slept
waiting for the dax entry to become unlocked.

Fixes: c2a7d2a115 ("filesystem-dax: Introduce dax_lock_mapping_entry()")
Cc: <stable@vger.kernel.org>
Reported-by: Jan Kara <jack@suse.cz>
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Matthew Wilcox 2018-11-27 13:16:33 -08:00 committed by Dan Williams
parent 2e6e902d18
commit c93db7bb6e
1 changed files with 1 additions and 1 deletions
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2
fs/dax.c
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@ -365,7 +365,7 @@ bool dax_lock_mapping_entry(struct page *page)
struct address_space *mapping = READ_ONCE(page->mapping);
locked = false;
if (!dax_mapping(mapping))
if (!mapping || !dax_mapping(mapping))
break;
/*