Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux

[firefly-linux-kernel-4.4.55.git] / fs / xfs / xfs_attr_remote.h

diff --git a/fs/xfs/xfs_attr_remote.h b/fs/xfs/xfs_attr_remote.h
index c7cca60a062a1ab1a45eb7f08632773e54d0a734..92a8fd7977cc2b48649ed3e5c22344fe83fcd8c1 100644 (file)
--- a/fs/xfs/xfs_attr_remote.h
+++ b/fs/xfs/xfs_attr_remote.h
@@ -20,6 +20,14 @@
 
 #define XFS_ATTR3_RMT_MAGIC    0x5841524d      /* XARM */
 
+/*
+ * There is one of these headers per filesystem block in a remote attribute.
+ * This is done to ensure there is a 1:1 mapping between the attribute value
+ * length and the number of blocks needed to store the attribute. This makes the
+ * verification of a buffer a little more complex, but greatly simplifies the
+ * allocation, reading and writing of these attributes as we don't have to guess
+ * the number of blocks needed to store the attribute data.
+ */
 struct xfs_attr3_rmt_hdr {
        __be32  rm_magic;
        __be32  rm_offset;
@@ -39,6 +47,8 @@ struct xfs_attr3_rmt_hdr {
 
 extern const struct xfs_buf_ops xfs_attr3_rmt_buf_ops;
 
+int xfs_attr3_rmt_blocks(struct xfs_mount *mp, int attrlen);
+
 int xfs_attr_rmtval_get(struct xfs_da_args *args);
 int xfs_attr_rmtval_set(struct xfs_da_args *args);
 int xfs_attr_rmtval_remove(struct xfs_da_args *args);