diff options
| author | Hugh Dickins <hughd@google.com> | 2016-07-10 16:46:32 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-07-10 20:08:44 -0700 |
| commit | 7f556567036cb7f89aabe2f0954b08566b4efb53 (patch) | |
| tree | 020fc68e31c9361c49786606a819dc5be9a2a8a6 | |
| parent | 617a8d6bc19edd075e8111c6770f79cae75be51f (diff) | |
tmpfs: fix regression hang in fallocate undo
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>
| -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 24463b67b6ef..171dee7a131f 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2225,9 +2225,11 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset, error = shmem_getpage(inode, index, &page, SGP_FALLOC); if (error) { /* Remove the !PageUptodate pages we added */ - shmem_undo_range(inode, - (loff_t)start << PAGE_SHIFT, - ((loff_t)index << PAGE_SHIFT) - 1, true); + if (index > start) { + shmem_undo_range(inode, + (loff_t)start << PAGE_SHIFT, + ((loff_t)index << PAGE_SHIFT) - 1, true); + } goto undone; } |