diff options
| author | Hugh Dickins <hughd@google.com> | 2016-07-10 16:46:32 -0700 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2016-08-22 22:38:27 +0100 |
| commit | 193cd538c09810024bb295380d84208f85e98bba (patch) | |
| tree | 905d6617e18aa6a8616b0bdc1e9b352cf4dcbf50 | |
| parent | d9ce899cd99c1b22fb991a5942a1e0e504f6f498 (diff) | |
tmpfs: fix regression hang in fallocate undo
commit 7f556567036cb7f89aabe2f0954b08566b4efb53 upstream.
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")
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: use PAGE_CACHE_SHIFT instead of PAGE_SHIFT]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -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 c4dc08ae240f..a2b87affdc23 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1865,9 +1865,11 @@ 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; } |