Add support for creating filesystems using uninit block group

Signed-off-by: Jose R. Santos <jrs@us.ibm.com>
Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in
index 14c3ca5..a32c34a 100644 (file)
--- a/misc/mke2fs.8.in
+++ b/misc/mke2fs.8.in
@@ -427,6 +427,13 @@ Store file type information in directory entries.
 .TP
 .B has_journal
 Create an ext3 journal (as if using the
+.TP
+.B uninit_groups
+Create a filesystem without initializing all of the groups.  This speeds
+up filesystem creation time noticably, and can also reduce
+.BR e2fsck time
+dramatically.  This feature causes the filesystem to be read-only in
+older kernels is not supported in most Linux kernels, use with caution.
 .B \-j
 option).
 @JDEV@.TP

diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 461448f..857d345 100644 (file)
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -433,6 +433,8 @@ static void write_inode_tables(ext2_filsys fs)
                                        num, blk, error_message(retval));
                                exit(1);
                        }
+                       /* The kernel doesn't need to zero the itable blocks */
+                       fs->group_desc[i].bg_flags |= EXT2_BG_INODE_ZEROED;
                }
                if (sync_kludge) {
                        if (sync_kludge == 1)
@@ -448,34 +450,49 @@ static void write_inode_tables(ext2_filsys fs)
 static void setup_lazy_bg(ext2_filsys fs)
 {
        dgrp_t i;
-       int blks;
+       int blks, csum_flag;
        struct ext2_super_block *sb = fs->super;
        struct ext2_group_desc *bg = fs->group_desc;
 
-       if (EXT2_HAS_COMPAT_FEATURE(fs->super, 
-                                   EXT2_FEATURE_COMPAT_LAZY_BG)) {
+       csum_flag = EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+                                              EXT4_FEATURE_RO_COMPAT_GDT_CSUM);
+       if (EXT2_HAS_COMPAT_FEATURE(fs->super, EXT2_FEATURE_COMPAT_LAZY_BG) ||
+           csum_flag) {
                for (i = 0; i < fs->group_desc_count; i++, bg++) {
                        if ((i == 0) ||
-                           (i == fs->group_desc_count-1))
+                           (i == fs->group_desc_count - 1 && !csum_flag))
                                continue;
                        if (bg->bg_free_inodes_count ==
                            sb->s_inodes_per_group) {
-                               bg->bg_free_inodes_count = 0;
                                bg->bg_flags |= EXT2_BG_INODE_UNINIT;
-                               sb->s_free_inodes_count -= 
-                                       sb->s_inodes_per_group;
+                               if (!csum_flag) {
+                                       bg->bg_free_inodes_count = 0;
+                                       sb->s_free_inodes_count -=
+                                               sb->s_inodes_per_group;
+                               }
                        }
+
+                       /* Skip groups with GDT backups because the resize
+                        * inode has blocks allocated in them, and the last
+                        * group because it needs block bitmap padding. */
+                       if ((ext2fs_bg_has_super(fs, i) &&
+                            sb->s_reserved_gdt_blocks) ||
+                           i == fs->group_desc_count - 1)
+                               continue;
+
                        blks = ext2fs_super_and_bgd_loc(fs, i, 0, 0, 0, 0);
-                       if (bg->bg_free_blocks_count == blks) {
-                               bg->bg_free_blocks_count = 0;
+                       if (bg->bg_free_blocks_count == blks &&
+                           bg->bg_flags & EXT2_BG_INODE_UNINIT) {
                                bg->bg_flags |= EXT2_BG_BLOCK_UNINIT;
-                               sb->s_free_blocks_count -= blks;
+                               if (!csum_flag) {
+                                       bg->bg_free_blocks_count = 0;
+                                       sb->s_free_blocks_count -= blks;
+                               }
                        }
                }
        }
 }
 
-
 static void create_root_dir(ext2_filsys fs)
 {
        errcode_t               retval;
@@ -912,7 +929,8 @@ static __u32 ok_features[3] = {
                EXT4_FEATURE_INCOMPAT_FLEX_BG,
        /* R/O compat */
        EXT2_FEATURE_RO_COMPAT_LARGE_FILE|
-               EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER
+               EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER|
+               EXT4_FEATURE_RO_COMPAT_GDT_CSUM
 };
 
 
@@ -1774,6 +1792,8 @@ int main (int argc, char *argv[])
        }
 no_journal:
 
+       if (!super_only)
+               ext2fs_set_gdt_csum(fs);
        if (!quiet)
                printf(_("Writing superblocks and "
                       "filesystem accounting information: "));