From 23fffa925ea2c9a2bcb1a4453e2c542635aa3545 Mon Sep 17 00:00:00 2001 From: Lukas Czerner Date: Sat, 12 Apr 2014 09:56:41 -0400 Subject: fs: move falloc collapse range check into the filesystem methods Currently in do_fallocate in collapse range case we're checking whether offset + len is not bigger than i_size. However there is nothing which would prevent i_size from changing so the check is pointless. It should be done in the file system itself and the file system needs to make sure that i_size is not going to change. The i_size check for the other fallocate modes are also done in the filesystems. As it is now we can easily crash the kernel by having two processes doing truncate and fallocate collapse range at the same time. This can be reproduced on ext4 and it is theoretically possible on xfs even though I was not able to trigger it with this simple test. This commit removes the check from do_fallocate and adds it to the file system. Signed-off-by: Lukas Czerner Signed-off-by: "Theodore Ts'o" Acked-by: Dave Chinner Reviewed-by: Christoph Hellwig --- fs/open.c | 8 -------- 1 file changed, 8 deletions(-) (limited to 'fs/open.c') diff --git a/fs/open.c b/fs/open.c index 3a83253d3373..adf34202213a 100644 --- a/fs/open.c +++ b/fs/open.c @@ -284,14 +284,6 @@ int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len) if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0)) return -EFBIG; - /* - * There is no need to overlap collapse range with EOF, in which case - * it is effectively a truncate operation - */ - if ((mode & FALLOC_FL_COLLAPSE_RANGE) && - (offset + len >= i_size_read(inode))) - return -EINVAL; - if (!file->f_op->fallocate) return -EOPNOTSUPP; -- cgit