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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: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Joe Thornber 2013-05-10 14:37:19 +01:00 committed by Alasdair G Kergon
parent b17446df2e
commit 5d0db96d13
1 changed files with 14 additions and 11 deletions
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25
drivers/md/dm-thin.c
View File

@ -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;