cachefiles: Explain checks in a comment

Add a comment to explain the checks that cachefiles is making of the
backing filesystem[1].

Suggested-by: Jeff Layton <jlayton@kernel.org>
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/568749bd7cc02908ecf6f3d6a611b6f9cf5c4afd.camel@kernel.org/ [1]
Link: https://lore.kernel.org/r/164251405621.3435901.771439791811515914.stgit@warthog.procyon.org.uk/ # v1
This commit is contained in:
David Howells 2022-01-07 10:51:13 +00:00
parent b64a331498
commit 14b9d0902d

View File

@ -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 ||