Commit f16bd3fa authored by ethanwu's avatar ethanwu Committed by Ilya Dryomov
Browse files

ceph: supply snapshot context in ceph_zero_partial_object() 



The ceph_zero_partial_object function was missing proper snapshot
context for its OSD write operations, which could lead to data
inconsistencies in snapshots.

Reproducer:
../src/vstart.sh --new -x --localhost --bluestore
./bin/ceph auth caps client.fs_a mds 'allow rwps fsname=a' mon 'allow r fsname=a' osd 'allow rw tag cephfs data=a'
mount -t ceph fs_a@.a=/ /mnt/mycephfs/ -o conf=./ceph.conf
dd if=/dev/urandom of=/mnt/mycephfs/foo bs=64K count=1
mkdir /mnt/mycephfs/.snap/snap1
md5sum /mnt/mycephfs/.snap/snap1/foo
fallocate -p -o 0 -l 4096 /mnt/mycephfs/foo
echo 3 > /proc/sys/vm/drop/caches
md5sum /mnt/mycephfs/.snap/snap1/foo # get different md5sum!!

Cc: stable@vger.kernel.org
Fixes: ad7a60de ("ceph: punch hole support")
Signed-off-by: default avatarethanwu <ethanwu@synology.com>
Reviewed-by: default avatarViacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Tested-by: default avatarViacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent 8356b4b1

fs/ceph/file.c

+16 −1
Original line number Diff line number Diff line
@@ -2568,6 +2568,7 @@ static int ceph_zero_partial_object(struct inode *inode, 
	struct ceph_inode_info *ci = ceph_inode(inode);

	struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);

	struct ceph_osd_request *req;

	struct ceph_snap_context *snapc;

	int ret = 0;

	loff_t zero = 0;

	int op;
@@ -2582,12 +2583,25 @@ static int ceph_zero_partial_object(struct inode *inode, 
		op = CEPH_OSD_OP_ZERO;

	}



	spin_lock(&ci->i_ceph_lock);

	if (__ceph_have_pending_cap_snap(ci)) {

		struct ceph_cap_snap *capsnap =

				list_last_entry(&ci->i_cap_snaps,

						struct ceph_cap_snap,

						ci_item);

		snapc = ceph_get_snap_context(capsnap->context);

	} else {

		BUG_ON(!ci->i_head_snapc);

		snapc = ceph_get_snap_context(ci->i_head_snapc);

	}

	spin_unlock(&ci->i_ceph_lock);



	req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,

					ceph_vino(inode),

					offset, length,

					0, 1, op,

					CEPH_OSD_FLAG_WRITE,

					NULL, 0, 0, false);

					snapc, 0, 0, false);

	if (IS_ERR(req)) {

		ret = PTR_ERR(req);

		goto out;
@@ -2601,6 +2615,7 @@ static int ceph_zero_partial_object(struct inode *inode, 
	ceph_osdc_put_request(req);



out:

	ceph_put_snap_context(snapc);

	return ret;

}