From b473bc2dcd5ad7c487f252d9d2b74ace70308b1f Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Fri, 6 Sep 2019 11:02:38 +0100 Subject: [PATCH] gfs2: Improve mmap write vs. truncate consistency On filesystems with a block size smaller than PAGE_SIZE, page_mkwrite is called for each memory-mapped page before that page can be written to. When such a memory-mapped file is truncated down to size x which is not a multiple of the page size and then back to a larger size, the page straddling size x can end up with a partial block mapping. In that case, make sure to mark that page read-only so that page_mkwrite will be called before the page can be written to the next time. (There is no point in marking the page straddling size x read-only when truncating down as writing to memory beyond the end of the file will result in SIGBUS instead of growing the file.) Fixes xfstests generic/029, generic/030 on filesystems with a block size smaller than PAGE_SIZE. Signed-off-by: Andreas Gruenbacher --- fs/gfs2/bmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c index 2043a72..9ef543d 100644 --- a/fs/gfs2/bmap.c +++ b/fs/gfs2/bmap.c @@ -2139,7 +2139,7 @@ static int do_grow(struct inode *inode, u64 size) if (error) goto do_end_trans; - i_size_write(inode, size); + truncate_setsize(inode, size); ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode); gfs2_trans_add_meta(ip->i_gl, dibh); gfs2_dinode_out(ip, dibh->b_data); -- 2.7.4