[2.06 RELEASE PATCH v3 3/4] fs/xfs: Add bigtime incompat feature support

[Javier Martinez Canillas]

From: Carlos Maiolino <cmaiolino@redhat.com>

The XFS filesystem supports a bigtime feature to overcome y2038 problem.
This patch makes the GRUB able to support the XFS filesystems with this
feature enabled.

The XFS counter for the bigtime enabled timestamps starts on 0, which
translates to GRUB_INT32_MIN (Dec 31 20:45:52 UTC 1901) in the legacy
timestamps. The conversion to unix timestamps is made before passing the
value to other GRUB functions.

For this to work properly, GRUB requires to access flags2 field in the
XFS ondisk inode. So, the grub_xfs_inode structure has been updated to
cover full ondisk inode.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---

Changes in v3:
- Fix commit message in patch #3 (dkiper).
- Drop unrelated cleanups in patch #3 (dkiper).
- Fix issues pointed out in v1 that were missed on v2 (dkiper).

Changes in v2:
- Improve the commit message of patch #3 (dkiper).
- Drop Reviewed-by tag from patch #3 (dkiper).
_ Drop unrelated changes in patch #3 (dkiper).

 grub-core/fs/xfs.c  | 55 +++++++++++++++++++++++++++++++++++++--------
 include/grub/time.h |  2 ++
 2 files changed, 48 insertions(+), 9 deletions(-)

diff --git a/grub-core/fs/xfs.c b/grub-core/fs/xfs.c
index 43023e03fb3..2e6a24d034a 100644
--- a/grub-core/fs/xfs.c
+++ b/grub-core/fs/xfs.c
@@ -23,6 +23,7 @@
 #include <grub/misc.h>
 #include <grub/disk.h>
 #include <grub/dl.h>
+#include <grub/time.h>
 #include <grub/types.h>
 #include <grub/fshelp.h>
 #include <grub/safemath.h>
@@ -75,10 +76,15 @@ GRUB_MOD_LICENSE ("GPLv3+");
         XFS_SB_VERSION2_PROJID32BIT | \
         XFS_SB_VERSION2_FTYPE)
 
+/* Inode flags2 flags */
+#define XFS_DIFLAG2_BIGTIME_BIT        3
+#define XFS_DIFLAG2_BIGTIME            (1 << XFS_DIFLAG2_BIGTIME_BIT)
+
 /* incompat feature flags */
 #define XFS_SB_FEAT_INCOMPAT_FTYPE      (1 << 0)        /* filetype in dirent 
*/
 #define XFS_SB_FEAT_INCOMPAT_SPINODES   (1 << 1)        /* sparse inode chunks 
*/
 #define XFS_SB_FEAT_INCOMPAT_META_UUID  (1 << 2)        /* metadata UUID */
+#define XFS_SB_FEAT_INCOMPAT_BIGTIME    (1 << 3)        /* large timestamps */
 
 /*
  * Directory entries with ftype are explicitly handled by GRUB code.
@@ -92,7 +98,8 @@ GRUB_MOD_LICENSE ("GPLv3+");
 #define XFS_SB_FEAT_INCOMPAT_SUPPORTED \
        (XFS_SB_FEAT_INCOMPAT_FTYPE | \
         XFS_SB_FEAT_INCOMPAT_SPINODES | \
-        XFS_SB_FEAT_INCOMPAT_META_UUID)
+        XFS_SB_FEAT_INCOMPAT_META_UUID | \
+        XFS_SB_FEAT_INCOMPAT_BIGTIME)
 
 struct grub_xfs_sblock
 {
@@ -177,7 +184,7 @@ struct grub_xfs_btree_root
   grub_uint64_t keys[1];
 } GRUB_PACKED;
 
-struct grub_xfs_time
+struct grub_xfs_time_legacy
 {
   grub_uint32_t sec;
   grub_uint32_t nanosec;
@@ -190,20 +197,23 @@ struct grub_xfs_inode
   grub_uint8_t version;
   grub_uint8_t format;
   grub_uint8_t unused2[26];
-  struct grub_xfs_time atime;
-  struct grub_xfs_time mtime;
-  struct grub_xfs_time ctime;
+  grub_uint64_t atime;
+  grub_uint64_t mtime;
+  grub_uint64_t ctime;
   grub_uint64_t size;
   grub_uint64_t nblocks;
   grub_uint32_t extsize;
   grub_uint32_t nextents;
   grub_uint16_t unused3;
   grub_uint8_t fork_offset;
-  grub_uint8_t unused4[17];
+  grub_uint8_t unused4[37];
+  grub_uint64_t flags2;
+  grub_uint8_t unused5[48];
 } GRUB_PACKED;
 
-#define XFS_V2_INODE_SIZE sizeof(struct grub_xfs_inode)
-#define XFS_V3_INODE_SIZE (XFS_V2_INODE_SIZE + 76)
+#define XFS_V3_INODE_SIZE sizeof(struct grub_xfs_inode)
+/* Size of struct grub_xfs_inode until fork_offset (included)*/
+#define XFS_V2_INODE_SIZE (XFS_V3_INODE_SIZE - 92)
 
 struct grub_xfs_dirblock_tail
 {
@@ -958,6 +968,33 @@ struct grub_xfs_dir_ctx
   void *hook_data;
 };
 
+/* Bigtime inodes helpers */
+#define XFS_BIGTIME_EPOCH_OFFSET (-(grub_int64_t) GRUB_INT32_MIN)
+
+static int grub_xfs_inode_has_bigtime(const struct grub_xfs_inode *inode)
+{
+  return inode->version >= 3 &&
+       (inode->flags2 & grub_cpu_to_be64_compile_time (XFS_DIFLAG2_BIGTIME));
+}
+
+static grub_int64_t
+grub_xfs_bigtime_to_unix (grub_uint64_t time)
+{
+  return grub_divmod64 (time, NSEC_PER_SEC, NULL) - XFS_BIGTIME_EPOCH_OFFSET;
+}
+
+static grub_int64_t
+grub_xfs_get_inode_time (struct grub_xfs_inode *inode)
+{
+  struct grub_xfs_time_legacy *lts;
+
+  if (grub_xfs_inode_has_bigtime (inode))
+    return grub_xfs_bigtime_to_unix (grub_be_to_cpu64 (inode->mtime));
+
+  lts = (struct grub_xfs_time_legacy *) &inode->mtime;
+  return grub_be_to_cpu32 (lts->sec);
+}
+
 /* Helper for grub_xfs_dir.  */
 static int
 grub_xfs_dir_iter (const char *filename, enum grub_fshelp_filetype filetype,
@@ -970,7 +1007,7 @@ grub_xfs_dir_iter (const char *filename, enum 
grub_fshelp_filetype filetype,
   if (node->inode_read)
     {
       info.mtimeset = 1;
-      info.mtime = grub_be_to_cpu32 (node->inode.mtime.sec);
+      info.mtime = grub_xfs_get_inode_time (&node->inode);
     }
   info.dir = ((filetype & GRUB_FSHELP_TYPE_MASK) == GRUB_FSHELP_DIR);
   grub_free (node);
diff --git a/include/grub/time.h b/include/grub/time.h
index c919c1f0b8f..32f0afaf809 100644
--- a/include/grub/time.h
+++ b/include/grub/time.h
@@ -30,6 +30,8 @@ grub_cpu_idle(void)
 }
 #endif
 
+#define NSEC_PER_SEC ((grub_int64_t) 1000000000)
+
 void EXPORT_FUNC(grub_millisleep) (grub_uint32_t ms);
 grub_uint64_t EXPORT_FUNC(grub_get_time_ms) (void);
 
-- 
2.31.1