xfs: use larger in-core attr firstused field and detect overflow

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

diff --git a/fs/xfs/libxfs/xfs_da_format.h b/fs/xfs/libxfs/xfs_da_format.h
index 0a49b02863724204450fbce07f9df2806b34af76..74bcbabfa52329bda4d932daeab73ae624bde7f1 100644 (file)
--- a/fs/xfs/libxfs/xfs_da_format.h
+++ b/fs/xfs/libxfs/xfs_da_format.h
@@ -725,7 +725,13 @@ struct xfs_attr3_icleaf_hdr {
        __uint16_t      magic;
        __uint16_t      count;
        __uint16_t      usedbytes;
-       __uint16_t      firstused;
+       /*
+        * firstused is 32-bit here instead of 16-bit like the on-disk variant
+        * to support maximum fsb size of 64k without overflow issues throughout
+        * the attr code. Instead, the overflow condition is handled on
+        * conversion to/from disk.
+        */
+       __uint32_t      firstused;
        __u8            holes;
        struct {
                __uint16_t      base;
@@ -733,6 +739,12 @@ struct xfs_attr3_icleaf_hdr {
        } freemap[XFS_ATTR_LEAF_MAPSIZE];
 };
 
+/*
+ * Special value to represent fs block size in the leaf header firstused field.
+ * Only used when block size overflows the 2-bytes available on disk.
+ */
+#define XFS_ATTR3_LEAF_NULLOFF 0
+
 /*
  * Flags used in the leaf_entry[i].flags field.
  * NOTE: the INCOMPLETE bit must not collide with the flags bits specified