mke2fs: allow metadata blocks to be at the beginning of the file system

Add the extended options packed_meta_blocks and journal_location_front
which causes mke2fs to place the metadata blocks at the beginning of
the file system.

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

diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in
index 30f7839..9c38e20 100644 (file)
--- a/misc/mke2fs.8.in
+++ b/misc/mke2fs.8.in
@@ -280,6 +280,16 @@ If the
 file system feature is enabled this option controls whether there will
 be 0, 1, or 2 backup superblocks created in the file system.
 .TP
+.B packed_meta_blocks\fR[\fB= \fI<0 to disable, 1 to enable>\fR]
+Place the allocation bitmaps and the inode table at the beginning of the
+disk.  This option requires that the flex_bg file system feature to be
+enabled in order for it to have effect, and will also create the journal
+at the beginning of the file system.  This option is useful for flash
+devices that use SLC flash at the beginning of the disk.
+It also maximizes the range of contiguous data blocks, which
+can be useful for certain specialized use cases, such as supported
+Shingled Drives.
+.TP
 .BI root_owner [=uid:gid]
 Specify the numeric user and group ID of the root directory.  If no UID:GID
 is specified, use the user and group ID of the user running \fBmke2fs\fR.

diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 9e6169d..c3783ba 100644 (file)
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -94,6 +94,7 @@ static gid_t  root_gid;
 int    journal_size;
 int    journal_flags;
 static int     lazy_itable_init;
+static int     packed_meta_blocks;
 static char    *bad_blocks_filename = NULL;
 static __u32   fs_stride;
 static int     quotatype = -1;  /* Initialize both user and group quotas by default */
@@ -311,6 +312,40 @@ _("Warning: the backup superblock/group descriptors at block %u contain\n"
        ext2fs_badblocks_list_iterate_end(bb_iter);
 }
 
+static errcode_t packed_allocate_tables(ext2_filsys fs)
+{
+       errcode_t       retval;
+       dgrp_t          i;
+       blk64_t         goal = 0;
+
+       for (i = 0; i < fs->group_desc_count; i++) {
+               retval = ext2fs_new_block2(fs, goal, NULL, &goal);
+               if (retval)
+                       return retval;
+               ext2fs_block_alloc_stats2(fs, goal, +1);
+               ext2fs_block_bitmap_loc_set(fs, i, goal);
+       }
+       for (i = 0; i < fs->group_desc_count; i++) {
+               retval = ext2fs_new_block2(fs, goal, NULL, &goal);
+               if (retval)
+                       return retval;
+               ext2fs_block_alloc_stats2(fs, goal, +1);
+               ext2fs_inode_bitmap_loc_set(fs, i, goal);
+       }
+       for (i = 0; i < fs->group_desc_count; i++) {
+               blk64_t end = ext2fs_blocks_count(fs->super) - 1;
+               retval = ext2fs_get_free_blocks2(fs, goal, end,
+                                                fs->inode_blocks_per_group,
+                                                fs->block_map, &goal);
+               if (retval)
+                       return retval;
+               ext2fs_block_alloc_stats_range(fs, goal,
+                                              fs->inode_blocks_per_group, +1);
+               ext2fs_inode_table_loc_set(fs, i, goal);
+       }
+       return 0;
+}
+
 static void write_inode_tables(ext2_filsys fs, int lazy_flag, int itable_zeroed)
 {
        errcode_t       retval;
@@ -755,6 +790,13 @@ static void parse_extended_opts(struct ext2_super_block *param,
                                r_usage++;
                                continue;
                        }
+               } else if (strcmp(token, "packed_meta_blocks") == 0) {
+                       if (arg)
+                               packed_meta_blocks = strtoul(arg, &p, 0);
+                       else
+                               packed_meta_blocks = 1;
+                       if (packed_meta_blocks)
+                               journal_location = 0;
                } else if (strcmp(token, "stride") == 0) {
                        if (!arg) {
                                r_usage++;
@@ -916,6 +958,7 @@ static void parse_extended_opts(struct ext2_super_block *param,
                        "\tstripe-width=<RAID stride * data disks in blocks>\n"
                        "\toffset=<offset to create the file system>\n"
                        "\tresize=<resize maximum size in blocks>\n"
+                       "\tpacked_meta_blocks=<0 to disable, 1 to enable>\n"
                        "\tlazy_itable_init=<0 to disable, 1 to enable>\n"
                        "\tlazy_journal_init=<0 to disable, 1 to enable>\n"
                        "\troot_uid=<uid of root directory>\n"
@@ -2040,6 +2083,11 @@ profile_error:
                                                fs_param.s_log_block_size);
        free(journal_location_string);
 
+       packed_meta_blocks = get_bool_from_profile(fs_types,
+                                                  "packed_meta_blocks", 0);
+       if (packed_meta_blocks)
+               journal_location = 0;
+
        /* Get options from profile */
        for (cpp = fs_types; *cpp; cpp++) {
                tmp = NULL;
@@ -2635,7 +2683,11 @@ int main (int argc, char *argv[])
        fs->stride = fs_stride = fs->super->s_raid_stride;
        if (!quiet)
                printf("%s", _("Allocating group tables: "));
-       retval = ext2fs_allocate_tables(fs);
+       if ((fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_FLEX_BG) &&
+           packed_meta_blocks)
+               retval = packed_allocate_tables(fs);
+       else
+               retval = ext2fs_allocate_tables(fs);
        if (retval) {
                com_err(program_name, retval, "%s",
                        _("while trying to allocate filesystem tables"));

diff --git a/misc/mke2fs.conf.5.in b/misc/mke2fs.conf.5.in
index 894805a..f29e854 100644 (file)
--- a/misc/mke2fs.conf.5.in
+++ b/misc/mke2fs.conf.5.in
@@ -365,6 +365,10 @@ This relation indicates whether file systems with the
 .B sparse_super2
 feature enabled should be created with 0, 1, or 2 backup superblocks.
 .TP
+.I packed_meta_blocks
+This boolean relation specifes whether the allocation bitmaps, inode
+table, and journal should be located at the beginning of the file system.
+.TP
 .I inode_ratio
 This relation specifies the default inode ratio if the user does not
 specify one on the command line.