Commit 5d0db96d authored by Joe Thornber's avatar Joe Thornber Committed by Alasdair G Kergon
Browse files

dm thin: open dev read only when possible 



If a thin pool is created in read-only-metadata mode then only open the
metadata device read-only.

Previously it was always opened with FMODE_READ | FMODE_WRITE.

(Note that dm_get_device() still allows read-only dm devices to be used
read-write at the moment: If I create a read-only linear device for the
metadata, via dmsetup load --readonly, then I can still create a rw pool
out of it.)

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent b17446df

drivers/md/dm-thin.c

+14 −11
Original line number Diff line number Diff line
@@ -1945,6 +1945,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv) 
	unsigned long block_size;

	dm_block_t low_water_blocks;

	struct dm_dev *metadata_dev;

	fmode_t metadata_mode;



	/*

	 * FIXME Remove validation from scope of lock.
@@ -1956,10 +1957,22 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv) 
		r = -EINVAL;

		goto out_unlock;

	}



	as.argc = argc;

	as.argv = argv;



	r = dm_get_device(ti, argv[0], FMODE_READ | FMODE_WRITE, &metadata_dev);

	/*

	 * Set default pool features.

	 */

	pool_features_init(&pf);



	dm_consume_args(&as, 4);

	r = parse_pool_features(&as, &pf, ti);

	if (r)

		goto out_unlock;



	metadata_mode = FMODE_READ | ((pf.mode == PM_READ_ONLY) ? 0 : FMODE_WRITE);

	r = dm_get_device(ti, argv[0], metadata_mode, &metadata_dev);

	if (r) {

		ti->error = "Error opening metadata block device";

		goto out_unlock;
@@ -1992,16 +2005,6 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv) 
		goto out;

	}



	/*

	 * Set default pool features.

	 */

	pool_features_init(&pf);



	dm_consume_args(&as, 4);

	r = parse_pool_features(&as, &pf, ti);

	if (r)

		goto out;



	pt = kzalloc(sizeof(*pt), GFP_KERNEL);

	if (!pt) {

		r = -ENOMEM;

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