ceph: implement hidden per-field ceph.*.layout.* vxattrs

Allow individual fields of the layout to be fetched via getxattr.
The ceph.dir.layout.* vxattr with "disappear" if the exists_cb
indicates there no dir layout set.

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Sam Lang <sam.lang@inktank.com>

1 files changed, 59 insertions, 0 deletions

diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c
index f3c4fe7202c7..2135817e708d 100644
--- a/fs/ceph/xattr.c
+++ b/fs/ceph/xattr.c
@@ -77,6 +77,46 @@ static size_t ceph_vxattrcb_layout(struct ceph_inode_info *ci, char *val,
         return ret;
 }
 
+static size_t ceph_vxattrcb_layout_stripe_unit(struct ceph_inode_info *ci,
+                                               char *val, size_t size)
+{
+        return snprintf(val, size, "%lld",
+                        (unsigned long long)ceph_file_layout_su(ci->i_layout));
+}
+
+static size_t ceph_vxattrcb_layout_stripe_count(struct ceph_inode_info *ci,
+                                                char *val, size_t size)
+{
+        return snprintf(val, size, "%lld",
+               (unsigned long long)ceph_file_layout_stripe_count(ci->i_layout));
+}
+
+static size_t ceph_vxattrcb_layout_object_size(struct ceph_inode_info *ci,
+                                               char *val, size_t size)
+{
+        return snprintf(val, size, "%lld",
+               (unsigned long long)ceph_file_layout_object_size(ci->i_layout));
+}
+
+static size_t ceph_vxattrcb_layout_pool(struct ceph_inode_info *ci,
+                                        char *val, size_t size)
+{
+        int ret;
+        struct ceph_fs_client *fsc = ceph_sb_to_client(ci->vfs_inode.i_sb);
+        struct ceph_osd_client *osdc = &fsc->client->osdc;
+        s64 pool = ceph_file_layout_pg_pool(ci->i_layout);
+        const char *pool_name;
+
+        down_read(&osdc->map_sem);
+        pool_name = ceph_pg_pool_name_by_id(osdc->osdmap, pool);
+        if (pool_name)
+                ret = snprintf(val, size, "%s", pool_name);
+        else
+                ret = snprintf(val, size, "%lld", (unsigned long long)pool);
+        up_read(&osdc->map_sem);
+        return ret;
+}
+
 /* directories */
 
 static size_t ceph_vxattrcb_dir_entries(struct ceph_inode_info *ci, char *val,
@@ -130,6 +170,8 @@ static size_t ceph_vxattrcb_dir_rctime(struct ceph_inode_info *ci, char *val,
 
 
 #define CEPH_XATTR_NAME(_type, _name)   XATTR_CEPH_PREFIX #_type "." #_name
+#define CEPH_XATTR_NAME2(_type, _name, _name2)  \
+        XATTR_CEPH_PREFIX #_type "." #_name "." #_name2
 
 #define XATTR_NAME_CEPH(_type, _name)                                   \
         {                                                               \
@@ -140,6 +182,15 @@ static size_t ceph_vxattrcb_dir_rctime(struct ceph_inode_info *ci, char *val,
                 .hidden = false,                                \
                 .exists_cb = NULL,                      \
         }
+#define XATTR_LAYOUT_FIELD(_type, _name, _field)                        \
+        {                                                               \
+                .name = CEPH_XATTR_NAME2(_type, _name, _field), \
+                .name_size = sizeof (CEPH_XATTR_NAME2(_type, _name, _field)), \
+                .getxattr_cb = ceph_vxattrcb_ ## _name ## _ ## _field, \
+                .readonly = false,                              \
+                .hidden = true,                 \
+                .exists_cb = ceph_vxattrcb_layout_exists,       \
+        }
 
 static struct ceph_vxattr ceph_dir_vxattrs[] = {
         {
@@ -150,6 +201,10 @@ static struct ceph_vxattr ceph_dir_vxattrs[] = {
                 .hidden = false,
                 .exists_cb = ceph_vxattrcb_layout_exists,
         },
+        XATTR_LAYOUT_FIELD(dir, layout, stripe_unit),
+        XATTR_LAYOUT_FIELD(dir, layout, stripe_count),
+        XATTR_LAYOUT_FIELD(dir, layout, object_size),
+        XATTR_LAYOUT_FIELD(dir, layout, pool),
         XATTR_NAME_CEPH(dir, entries),
         XATTR_NAME_CEPH(dir, files),
         XATTR_NAME_CEPH(dir, subdirs),
@@ -173,6 +228,10 @@ static struct ceph_vxattr ceph_file_vxattrs[] = {
                 .hidden = false,
                 .exists_cb = ceph_vxattrcb_layout_exists,
         },
+        XATTR_LAYOUT_FIELD(file, layout, stripe_unit),
+        XATTR_LAYOUT_FIELD(file, layout, stripe_count),
+        XATTR_LAYOUT_FIELD(file, layout, object_size),
+        XATTR_LAYOUT_FIELD(file, layout, pool),
         { 0 }   /* Required table terminator */
 };
 static size_t ceph_file_vxattrs_name_size;      /* total size of all names */