From: Pavel Tikhomirov ptikhomirov@virtuozzo.com Subject: mm: cleancache: fix corruption on missed inode invalidation

If all pages are deleted from the mapping by memory reclaim and also moved to the cleancache:

__delete_from_page_cache (no shadow case) unaccount_page_cache_page cleancache_put_page page_cache_delete mapping->nrpages -= nr (nrpages becomes 0)

We don't clean the cleancache for an inode after final file truncation (removal).

truncate_inode_pages_final check (nrpages || nrexceptional) is false no truncate_inode_pages no cleancache_invalidate_inode(mapping)

These way when reading the new file created with same inode we may get these trash leftover pages from cleancache and see wrong data instead of the contents of the new file.

Fix it by always doing truncate_inode_pages which is already ready for nrpages == 0 && nrexceptional == 0 case and just invalidates inode.

[akpm@linux-foundation.org: add comment, per Jan] Link: http://lkml.kernel.org/r/20181112095734.17979-1-ptikhomirov@virtuozzo.com Fixes: commit 91b0abe36a7b ("mm + fs: store shadow entries in page cache") Signed-off-by: Pavel Tikhomirov ptikhomirov@virtuozzo.com Reviewed-by: Vasily Averin vvs@virtuozzo.com Reviewed-by: Andrey Ryabinin aryabinin@virtuozzo.com Reviewed-by: Jan Kara jack@suse.cz Cc: Johannes Weiner hannes@cmpxchg.org Cc: Mel Gorman mgorman@techsingularity.net Cc: Matthew Wilcox willy@infradead.org Cc: Andi Kleen ak@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/truncate.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/mm/truncate.c~mm-cleancache-fix-corruption-on-missed-inode-invalidation +++ a/mm/truncate.c @@ -517,9 +517,13 @@ void truncate_inode_pages_final(struct a */ xa_lock_irq(&mapping->i_pages); xa_unlock_irq(&mapping->i_pages); - - truncate_inode_pages(mapping, 0); } + + /* + * Cleancache needs notification even if there are no pages or shadow + * entries. + */ + truncate_inode_pages(mapping, 0); } EXPORT_SYMBOL(truncate_inode_pages_final);

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