cachefiles: set default tag name if it's unspecified

fscache_acquire_cache() requires a non-empty name, while 'tag <name>'
command is optional for cachefilesd.

Thus set default tag name if it's unspecified to avoid the regression of
cachefilesd. The logic is the same with that before rewritten.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/164251399914.3435901.4761991152407411408.stgit@warthog.procyon.org.uk/

diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index 40a7924..7ac04ee 100644 (file)
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -703,6 +703,17 @@ static int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
                return -EBUSY;
        }
 
+       /* Make sure we have copies of the tag string */
+       if (!cache->tag) {
+               /*
+                * The tag string is released by the fops->release()
+                * function, so we don't release it on error here
+                */
+               cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
+               if (!cache->tag)
+                       return -ENOMEM;
+       }
+
        return cachefiles_add_cache(cache);
 }