Commit fc6c2da1 authored Jan 27, 2017 by Jan Kara Committed by Greg Kroah-Hartman Mar 12, 2017

ext4: trim allocation requests to group size



commit cd648b8a8fd5071d232242d5ee7ee3c0815776af upstream.

If filesystem groups are artifically small (using parameter -g to
mkfs.ext4), ext4_mb_normalize_request() can result in a request that is
larger than a block group. Trim the request size to not confuse
allocation code.

Reported-by: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent e0b53d67

fs/ext4/mballoc.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -3123,6 +3123,13 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
		if (ar->pright && start + size - 1 >= ar->lright)
		size -= start + size - ar->lright;

		/*
		* Trim allocation request for filesystems with artificially small
		* groups.
		*/
		if (size > EXT4_BLOCKS_PER_GROUP(ac->ac_sb))
		size = EXT4_BLOCKS_PER_GROUP(ac->ac_sb);

		end = start + size;

		/* check we don't cross already preallocated blocks */