Reserve feature flags and fields needed for the Next3 snapshot feature

The documentation is not (as of this writing) fully complete, but
there is some documentation here:

http://sourceforge.net/apps/mediawiki/next3/index.php?title=Code_documentation
http://sourceforge.net/apps/mediawiki/next3/index.php?title=On-disk_format
http://sourceforge.net/projects/next3/files/Next3_Snapshots.pdf/download

... which will hopefully be updated soon to be fully up to date with
these assignments and more details about how things work.

For now, the assignments should avoid collisions with other new work
that people might want to do on ext3/4.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
index cb21318..8735105 100644 (file)
--- a/lib/ext2fs/ext2_fs.h
+++ b/lib/ext2fs/ext2_fs.h
@@ -50,6 +50,7 @@
 #define EXT2_UNDEL_DIR_INO      6      /* Undelete directory inode */
 #define EXT2_RESIZE_INO                 7      /* Reserved group descriptors inode */
 #define EXT2_JOURNAL_INO        8      /* Journal inode */
+#define EXT2_EXCLUDE_INO        9      /* The "exclude" inode, for snapshots */
 
 /* First non-reserved inode for old ext2 filesystems */
 #define EXT2_GOOD_OLD_FIRST_INO        11
@@ -275,6 +276,9 @@ struct ext2_dx_countlimit {
 #define EXT4_EXTENTS_FL                0x00080000 /* Inode uses extents */
 #define EXT4_EA_INODE_FL               0x00200000 /* Inode used for large EA */
 #define EXT4_EOFBLOCKS_FL              0x00400000 /* Blocks allocated beyond EOF */
+#define EXT4_SNAPFILE_FL               0x01000000  /* Inode is a snapshot */
+#define EXT4_SNAPFILE_DELETED_FL       0x04000000  /* Snapshot is being deleted */
+#define EXT4_SNAPFILE_SHRUNK_FL                0x08000000  /* Snapshot shrink has completed */
 #define EXT2_RESERVED_FL               0x80000000 /* reserved for ext2 lib */
 
 #define EXT2_FL_USER_VISIBLE           0x004BDFFF /* User visible flags */
@@ -463,6 +467,9 @@ struct ext2_inode_large {
 #define EXT2_FLAGS_SIGNED_HASH         0x0001  /* Signed dirhash in use */
 #define EXT2_FLAGS_UNSIGNED_HASH       0x0002  /* Unsigned dirhash in use */
 #define EXT2_FLAGS_TEST_FILESYS                0x0004  /* OK for use on development code */
+#define EXT2_FLAGS_IS_SNAPSHOT         0x0010  /* This is a snapshot image */
+#define EXT2_FLAGS_FIX_SNAPSHOT                0x0020  /* Snapshot inodes corrupted */
+#define EXT2_FLAGS_FIX_EXCLUDE         0x0040  /* Exclude bitmaps corrupted */
 
 /*
  * Mount flags
@@ -582,7 +589,12 @@ struct ext2_super_block {
        __u8    s_reserved_char_pad;
        __u16   s_reserved_pad;         /* Padding to next 32bits */
        __u64   s_kbytes_written;       /* nr of lifetime kilobytes written */
-       __u32   s_reserved[160];        /* Padding to the end of the block */
+       __u32   s_snapshot_inum;        /* Inode number of active snapshot */
+       __u32   s_snapshot_id;          /* sequential ID of active snapshot */
+       __u64   s_snapshot_r_blocks_count; /* reserved blocks for active
+                                             snapshot's future use */
+       __u32   s_snapshot_list;        /* inode number of the head of the on-disk snapshot list */
+       __u32   s_reserved[155];        /* Padding to the end of the block */
 };
 
 /*
@@ -628,6 +640,7 @@ struct ext2_super_block {
 #define EXT2_FEATURE_COMPAT_RESIZE_INODE       0x0010
 #define EXT2_FEATURE_COMPAT_DIR_INDEX          0x0020
 #define EXT2_FEATURE_COMPAT_LAZY_BG            0x0040
+#define EXT2_FEATURE_COMPAT_EXCLUDE_INODE      0x0080
 
 #define EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER    0x0001
 #define EXT2_FEATURE_RO_COMPAT_LARGE_FILE      0x0002
@@ -636,6 +649,7 @@ struct ext2_super_block {
 #define EXT4_FEATURE_RO_COMPAT_GDT_CSUM                0x0010
 #define EXT4_FEATURE_RO_COMPAT_DIR_NLINK       0x0020
 #define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE     0x0040
+#define EXT4_FEATURE_RO_COMPAT_HAS_SNAPSHOT    0x0080
 
 #define EXT2_FEATURE_INCOMPAT_COMPRESSION      0x0001
 #define EXT2_FEATURE_INCOMPAT_FILETYPE         0x0002