From: Joe Thornber 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: Joe Thornber Signed-off-by: Alasdair G Kergon --- drivers/md/dm-thin.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) Index: linux/drivers/md/dm-thin.c =================================================================== --- linux.orig/drivers/md/dm-thin.c +++ linux/drivers/md/dm-thin.c @@ -1945,6 +1945,7 @@ static int pool_ctr(struct dm_target *ti 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 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 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;