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Subject[PATCH AUTOSEL 4.18 093/131] dm cache: only allow a single io_mode cache feature to be requested
Date
From: John Pittman <jpittman@redhat.com>

[ Upstream commit af9313c32c0fa2a0ac3b113669273833d60cc9de ]

More than one io_mode feature can be requested when creating a dm cache
device (as is: last one wins). The io_mode selections are incompatible
with one another, we should force them to be selected exclusively. Add
a counter to check for more than one io_mode selection.

Fixes: 629d0a8a1a10 ("dm cache metadata: add "metadata2" feature")
Signed-off-by: John Pittman <jpittman@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/md/dm-cache-target.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index ce14a3d1f609..44df244807e5 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -2250,7 +2250,7 @@ static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
{0, 2, "Invalid number of cache feature arguments"},
};

- int r;
+ int r, mode_ctr = 0;
unsigned argc;
const char *arg;
struct cache_features *cf = &ca->features;
@@ -2264,14 +2264,20 @@ static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
while (argc--) {
arg = dm_shift_arg(as);

- if (!strcasecmp(arg, "writeback"))
+ if (!strcasecmp(arg, "writeback")) {
cf->io_mode = CM_IO_WRITEBACK;
+ mode_ctr++;
+ }

- else if (!strcasecmp(arg, "writethrough"))
+ else if (!strcasecmp(arg, "writethrough")) {
cf->io_mode = CM_IO_WRITETHROUGH;
+ mode_ctr++;
+ }

- else if (!strcasecmp(arg, "passthrough"))
+ else if (!strcasecmp(arg, "passthrough")) {
cf->io_mode = CM_IO_PASSTHROUGH;
+ mode_ctr++;
+ }

else if (!strcasecmp(arg, "metadata2"))
cf->metadata_version = 2;
@@ -2282,6 +2288,11 @@ static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
}
}

+ if (mode_ctr > 1) {
+ *error = "Duplicate cache io_mode features requested";
+ return -EINVAL;
+ }
+
return 0;
}

--
2.17.1
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