tmpfs: fix mounts when size is less than the page size
When tmpfs is mounted with a size less than one page, the number of blocks
is set to 0 which makes the tmpfs mount unlimited. This can lead to a
quick and surprising death if someone typos a tmpfs mount command and
writes too much.
tmpfs can still be mounted as unlimited if size or nr_blocks is exactly 0,
as Documentation/filesystems/tmpfs.txt says.
Hugh: do this by rounding size up instead of down in all cases: which
slightly expands other odd-sized tmpfs mounts, but in a consistent way.
Signed-off-by: Michael Marineau <mike@marineau.org>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/shmem.c b/mm/shmem.c
index ce64b66..7be9434 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2012,7 +2012,7 @@
}
if (*rest)
goto bad_val;
- *blocks = size >> PAGE_CACHE_SHIFT;
+ *blocks = DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
} else if (!strcmp(this_char,"nr_blocks")) {
*blocks = memparse(value,&rest);
if (*rest)