[v2] ceph: support getting ceph.dir.rsnaps vxattr

[Yanhu Cao <gmayyyha@gmail.com>]

It's easy to know how many snapshots have been created.

Link: https://tracker.ceph.com/issues/47168
Signed-off-by: Yanhu Cao <gmayyyha@gmail.com>
---
 fs/ceph/inode.c      | 1 +
 fs/ceph/mds_client.c | 9 ++++++++-
 fs/ceph/mds_client.h | 1 +
 fs/ceph/super.h      | 2 +-
 fs/ceph/xattr.c      | 7 +++++++
 5 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 357c937699d5..650cad4b3ecb 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -891,6 +891,7 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page,
 			ci->i_rfiles = le64_to_cpu(info->rfiles);
 			ci->i_rsubdirs = le64_to_cpu(info->rsubdirs);
 			ci->i_dir_pin = iinfo->dir_pin;
+			ci->i_rsnaps = iinfo->rsnaps;
 			ceph_decode_timespec64(&ci->i_rctime, &info->rctime);
 		}
 	}
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 4a26862d7667..3466845c0179 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -176,6 +176,13 @@ static int parse_reply_info_in(void **p, void *end,
 			memset(&info->snap_btime, 0, sizeof(info->snap_btime));
 		}
 
+		/* snapshot count, remains zero for v<=3 */
+		if (struct_v >= 4) {
+			ceph_decode_64_safe(p, end, info->rsnaps, bad);
+		} else {
+			info->rsnaps = 0;
+		}
+
 		*p = end;
 	} else {
 		if (features & CEPH_FEATURE_MDS_INLINE_DATA) {
@@ -214,7 +221,7 @@ static int parse_reply_info_in(void **p, void *end,
 		}
 
 		info->dir_pin = -ENODATA;
-		/* info->snap_btime remains zero */
+		/* info->snap_btime and info->rsnaps remain zero */
 	}
 	return 0;
 bad:
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index bc9e95937d7c..76f2ed1a7cbf 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -88,6 +88,7 @@ struct ceph_mds_reply_info_in {
 	s32 dir_pin;
 	struct ceph_timespec btime;
 	struct ceph_timespec snap_btime;
+	u64 rsnaps;
 	u64 change_attr;
 };
 
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 4c3c964b1c54..eb108b69da71 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -332,7 +332,7 @@ struct ceph_inode_info {
 
 	/* for dirs */
 	struct timespec64 i_rctime;
-	u64 i_rbytes, i_rfiles, i_rsubdirs;
+	u64 i_rbytes, i_rfiles, i_rsubdirs, i_rsnaps;
 	u64 i_files, i_subdirs;
 
 	/* quotas */
diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c
index 3a733ac33d9b..c7d8ecc3d04b 100644
--- a/fs/ceph/xattr.c
+++ b/fs/ceph/xattr.c
@@ -231,6 +231,12 @@ static ssize_t ceph_vxattrcb_dir_rsubdirs(struct ceph_inode_info *ci, char *val,
 	return ceph_fmt_xattr(val, size, "%lld", ci->i_rsubdirs);
 }
 
+static ssize_t ceph_vxattrcb_dir_rsnaps(struct ceph_inode_info *ci, char *val,
+					  size_t size)
+{
+	return ceph_fmt_xattr(val, size, "%lld", ci->i_rsnaps);
+}
+
 static ssize_t ceph_vxattrcb_dir_rbytes(struct ceph_inode_info *ci, char *val,
 					size_t size)
 {
@@ -352,6 +358,7 @@ static struct ceph_vxattr ceph_dir_vxattrs[] = {
 	XATTR_RSTAT_FIELD(dir, rentries),
 	XATTR_RSTAT_FIELD(dir, rfiles),
 	XATTR_RSTAT_FIELD(dir, rsubdirs),
+	XATTR_RSTAT_FIELD(dir, rsnaps),
 	XATTR_RSTAT_FIELD(dir, rbytes),
 	XATTR_RSTAT_FIELD(dir, rctime),
 	{
-- 
2.24.3 (Apple Git-128)