diff mbox series

[v20,16/71] ceph: decode alternate_name in lease info

Message ID 20230613052424.254540-17-xiubli@redhat.com
State New
Headers show
Series ceph+fscrypt: full support | expand

Commit Message

Xiubo Li June 13, 2023, 5:23 a.m. UTC 
From: Jeff Layton <jlayton@kernel.org>

Ceph is a bit different from local filesystems, in that we don't want
to store filenames as raw binary data, since we may also be dealing
with clients that don't support fscrypt.

We could just base64-encode the encrypted filenames, but that could
leave us with filenames longer than NAME_MAX. It turns out that the
MDS doesn't care much about filename length, but the clients do.

To manage this, we've added a new "alternate name" field that can be
optionally added to any dentry that we'll use to store the binary
crypttext of the filename if its base64-encoded value will be longer
than NAME_MAX. When a dentry has one of these names attached, the MDS
will send it along in the lease info, which we can then store for
later usage.

Tested-by: Luís Henriques <lhenriques@suse.de>
Tested-by: Venky Shankar <vshankar@redhat.com>
Reviewed-by: Luís Henriques <lhenriques@suse.de>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Xiubo Li <xiubli@redhat.com>
---
 fs/ceph/mds_client.c | 43 +++++++++++++++++++++++++++++++++----------
 fs/ceph/mds_client.h |  5 +++++
 2 files changed, 38 insertions(+), 10 deletions(-)
diff mbox series

Patch

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index d9752f2d7a72..84ca9ae8fa6a 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -308,27 +308,47 @@  static int parse_reply_info_dir(void **p, void *end,
 
 static int parse_reply_info_lease(void **p, void *end,
 				  struct ceph_mds_reply_lease **lease,
-				  u64 features)
+				  u64 features, u32 *altname_len, u8 **altname)
 {
+	u8 struct_v;
+	u32 struct_len;
+	void *lend;
+
 	if (features == (u64)-1) {
-		u8 struct_v, struct_compat;
-		u32 struct_len;
+		u8 struct_compat;
+
 		ceph_decode_8_safe(p, end, struct_v, bad);
 		ceph_decode_8_safe(p, end, struct_compat, bad);
+
 		/* struct_v is expected to be >= 1. we only understand
 		 * encoding whose struct_compat == 1. */
 		if (!struct_v || struct_compat != 1)
 			goto bad;
+
 		ceph_decode_32_safe(p, end, struct_len, bad);
-		ceph_decode_need(p, end, struct_len, bad);
-		end = *p + struct_len;
+	} else {
+		struct_len = sizeof(**lease);
+		*altname_len = 0;
+		*altname = NULL;
 	}
 
-	ceph_decode_need(p, end, sizeof(**lease), bad);
+	lend = *p + struct_len;
+	ceph_decode_need(p, end, struct_len, bad);
 	*lease = *p;
 	*p += sizeof(**lease);
-	if (features == (u64)-1)
-		*p = end;
+
+	if (features == (u64)-1) {
+		if (struct_v >= 2) {
+			ceph_decode_32_safe(p, end, *altname_len, bad);
+			ceph_decode_need(p, end, *altname_len, bad);
+			*altname = *p;
+			*p += *altname_len;
+		} else {
+			*altname = NULL;
+			*altname_len = 0;
+		}
+	}
+	*p = lend;
 	return 0;
 bad:
 	return -EIO;
@@ -358,7 +378,8 @@  static int parse_reply_info_trace(void **p, void *end,
 		info->dname = *p;
 		*p += info->dname_len;
 
-		err = parse_reply_info_lease(p, end, &info->dlease, features);
+		err = parse_reply_info_lease(p, end, &info->dlease, features,
+					     &info->altname_len, &info->altname);
 		if (err < 0)
 			goto out_bad;
 	}
@@ -425,9 +446,11 @@  static int parse_reply_info_readdir(void **p, void *end,
 		dout("parsed dir dname '%.*s'\n", rde->name_len, rde->name);
 
 		/* dentry lease */
-		err = parse_reply_info_lease(p, end, &rde->lease, features);
+		err = parse_reply_info_lease(p, end, &rde->lease, features,
+					     &rde->altname_len, &rde->altname);
 		if (err)
 			goto out_bad;
+
 		/* inode */
 		err = parse_reply_info_in(p, end, &rde->inode, features);
 		if (err < 0)
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index ee64d5709f2b..5b338e591c46 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -44,6 +44,7 @@  enum ceph_feature_type {
 	CEPHFS_FEATURE_MULTI_RECONNECT,		\
 	CEPHFS_FEATURE_DELEG_INO,		\
 	CEPHFS_FEATURE_METRIC_COLLECT,		\
+	CEPHFS_FEATURE_ALTERNATE_NAME,		\
 	CEPHFS_FEATURE_NOTIFY_SESSION_STATE,	\
 	CEPHFS_FEATURE_OP_GETVXATTR,		\
 }
@@ -96,7 +97,9 @@  struct ceph_mds_reply_info_in {
 
 struct ceph_mds_reply_dir_entry {
 	char                          *name;
+	u8			      *altname;
 	u32                           name_len;
+	u32			      altname_len;
 	struct ceph_mds_reply_lease   *lease;
 	struct ceph_mds_reply_info_in inode;
 	loff_t			      offset;
@@ -120,7 +123,9 @@  struct ceph_mds_reply_info_parsed {
 	struct ceph_mds_reply_info_in diri, targeti;
 	struct ceph_mds_reply_dirfrag *dirfrag;
 	char                          *dname;
+	u8			      *altname;
 	u32                           dname_len;
+	u32                           altname_len;
 	struct ceph_mds_reply_lease   *dlease;
 	struct ceph_mds_reply_xattr   xattr_info;