From: Yu Zhao <yuzhao@google.com>
Date: Tue, 8 Sep 2015 22:03:33 +0000 (-0700)
Subject: shmem: recalculate file inode when fstat
X-Git-Tag: omap-for-v4.3/fixes-rc1~54^2~33
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=44a30220bc0a171c010e8df63d144655abdafe61;p=pandora-kernel.git

shmem: recalculate file inode when fstat

Shmem uses shmem_recalc_inode to update i_blocks when it allocates page,
undoes range or swaps.  But mm can drop clean page without notifying
shmem.  This makes fstat sometimes return out-of-date block size.

The problem can be partially solved when we add
inode_operations->getattr which calls shmem_recalc_inode to update
i_blocks for fstat.

shmem_recalc_inode also updates counter used by statfs and
vm_committed_as.  For them the situation is not changed.  They still
suffer from the discrepancy after dropping clean page and before the
function is called by aforementioned triggers.

Signed-off-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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