diff options
| author | Hugh Dickins <hughd@google.com> | 2016-07-10 16:46:32 -0700 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2016-07-12 08:41:10 -0400 |
| commit | 116c75f642ad4a6d267f399c9f1fe8b91fb822c5 (patch) | |
| tree | 180133ef4e45a3ebb7dc2e689f4312a3ada43005 | |
| parent | b7aa372fec2c1d4a1fcf4398ae88ba94134b9522 (diff) | |
tmpfs: fix regression hang in fallocate undo
[ Upstream commit 7f556567036cb7f89aabe2f0954b08566b4efb53 ]
The well-spotted fallocate undo fix is good in most cases, but not when
fallocate failed on the very first page. index 0 then passes lend -1
to shmem_undo_range(), and that has two bad effects: (a) that it will
undo every fallocation throughout the file, unrestricted by the current
range; but more importantly (b) it can cause the undo to hang, because
lend -1 is treated as truncation, which makes it keep on retrying until
every page has gone, but those already fully instantiated will never go
away. Big thank you to xfstests generic/269 which demonstrates this.
Fixes: b9b4bb26af01 ("tmpfs: don't undo fallocate past its last page")
Cc: stable@vger.kernel.org
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
| -rw-r--r-- | mm/shmem.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 86c150bf8235..46511ad90bc5 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2137,9 +2137,11 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset, NULL); if (error) { /* Remove the !PageUptodate pages we added */ - shmem_undo_range(inode, - (loff_t)start << PAGE_CACHE_SHIFT, - ((loff_t)index << PAGE_CACHE_SHIFT) - 1, true); + if (index > start) { + shmem_undo_range(inode, + (loff_t)start << PAGE_CACHE_SHIFT, + ((loff_t)index << PAGE_CACHE_SHIFT) - 1, true); + } goto undone; } |