ext4: Add support for 48 bit inode i_blocks.

Use the __le16 l_i_reserved1 field of the linux2 struct of ext4_inode
to represet the higher 16 bits for i_blocks. With this change max_file
size becomes (2**48 -1 )* 512 bytes.

We add a RO_COMPAT feature to the super block to indicate that inode
have i_blocks represented as a split 48 bits. Super block with this
feature set cannot be mounted read write on a kernel with CONFIG_LSF
disabled.

Super block flag EXT4_FEATURE_RO_COMPAT_HUGE_FILE

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h
index a8f3faea8eff..be25eca9c040 100644
--- a/include/linux/ext4_fs.h
+++ b/include/linux/ext4_fs.h
@@ -282,7 +282,7 @@ struct ext4_inode {
         __le32  i_dtime;        /* Deletion Time */
         __le16  i_gid;          /* Low 16 bits of Group Id */
         __le16  i_links_count;  /* Links count */
-        __le32  i_blocks;       /* Blocks count */
+        __le32  i_blocks_lo;    /* Blocks count */
         __le32  i_flags;        /* File flags */
         union {
                 struct {
@@ -302,7 +302,7 @@ struct ext4_inode {
         __le32  i_obso_faddr;   /* Obsoleted fragment address */
         union {
                 struct {
-                        __le16  l_i_reserved1;  /* Obsoleted fragment number/size which are removed in ext4 */
+                        __le16  l_i_blocks_high; /* were l_i_reserved1 */
                         __le16  l_i_file_acl_high;
                         __le16  l_i_uid_high;   /* these 2 fields */
                         __le16  l_i_gid_high;   /* were reserved2[0] */
@@ -404,6 +404,7 @@ do {									       \
 #if defined(__KERNEL__) || defined(__linux__)
 #define i_reserved1     osd1.linux1.l_i_reserved1
 #define i_file_acl_high osd2.linux2.l_i_file_acl_high
+#define i_blocks_high   osd2.linux2.l_i_blocks_high
 #define i_uid_low       i_uid
 #define i_gid_low       i_gid
 #define i_uid_high      osd2.linux2.l_i_uid_high
@@ -670,6 +671,7 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
 #define EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER     0x0001
 #define EXT4_FEATURE_RO_COMPAT_LARGE_FILE       0x0002
 #define EXT4_FEATURE_RO_COMPAT_BTREE_DIR        0x0004
+#define EXT4_FEATURE_RO_COMPAT_HUGE_FILE        0x0008
 #define EXT4_FEATURE_RO_COMPAT_GDT_CSUM         0x0010
 #define EXT4_FEATURE_RO_COMPAT_DIR_NLINK        0x0020
 #define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE      0x0040
@@ -681,6 +683,7 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
 #define EXT4_FEATURE_INCOMPAT_META_BG           0x0010
 #define EXT4_FEATURE_INCOMPAT_EXTENTS           0x0040 /* extents support */
 #define EXT4_FEATURE_INCOMPAT_64BIT             0x0080
+#define EXT4_FEATURE_INCOMPAT_MMP               0x0100
 #define EXT4_FEATURE_INCOMPAT_FLEX_BG           0x0200
 
 #define EXT4_FEATURE_COMPAT_SUPP        EXT2_FEATURE_COMPAT_EXT_ATTR
@@ -695,7 +698,8 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
                                          EXT4_FEATURE_RO_COMPAT_GDT_CSUM| \
                                          EXT4_FEATURE_RO_COMPAT_DIR_NLINK | \
                                          EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE | \
-                                         EXT4_FEATURE_RO_COMPAT_BTREE_DIR)
+                                         EXT4_FEATURE_RO_COMPAT_BTREE_DIR |\
+                                         EXT4_FEATURE_RO_COMPAT_HUGE_FILE)
 
 /*
  * Default values for user and/or group using reserved blocks