Add a comment to explain the checks that cachefiles is making of the backing filesystem[1]. Suggested-by: Jeff Layton <jlayton@xxxxxxxxxx> Signed-off-by: David Howells <dhowells@xxxxxxxxxx> Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx> cc: linux-cachefs@xxxxxxxxxx Link: https://lore.kernel.org/r/568749bd7cc02908ecf6f3d6a611b6f9cf5c4afd.camel@xxxxxxxxxx/ [1] --- fs/cachefiles/cache.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/cachefiles/cache.c b/fs/cachefiles/cache.c index 1e9c71666c6a..2b2879c5d1d2 100644 --- a/fs/cachefiles/cache.c +++ b/fs/cachefiles/cache.c @@ -49,7 +49,13 @@ int cachefiles_add_cache(struct cachefiles_cache *cache) goto error_unsupported; } - /* check parameters */ + /* Check features of the backing filesystem: + * - Directories must support looking up and directory creation + * - We use xattrs to store metadata + * - We need to be able to query the amount of space available + * - We want to be able to sync the filesystem when stopping the cache + * - We use DIO to/from pages, so the blocksize mustn't be too big. + */ ret = -EOPNOTSUPP; if (d_is_negative(root) || !d_backing_inode(root)->i_op->lookup ||
