mke2fs: New bitmap and inode table allocation for FLEX_BG

Change the way we allocate bitmaps and inode tables if the FLEX_BG
feature is used at mke2fs time.  It places calculates a new offset for
bitmaps and inode table base on the number of groups that the user
wishes to pack together using the new "-G" option.  Creating a
filesystem with 64 block groups in a flex group can be done by:

mke2fs -j -I 256 -O flex_bg -G 32 /dev/sdX

Signed-off-by: Jose R. Santos <jrs@us.ibm.com>
Signed-off-by: Valerie Clement <valerie.clement@bull.net>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/lib/ext2fs/alloc_tables.c b/lib/ext2fs/alloc_tables.c
index 9b4f0e5..d87585b 100644 (file)
--- a/lib/ext2fs/alloc_tables.c
+++ b/lib/ext2fs/alloc_tables.c
@@ -27,18 +27,80 @@
 #include "ext2_fs.h"
 #include "ext2fs.h"
 
+/*
+ * This routine searches for free blocks that can allocate a full
+ * group of bitmaps or inode tables for a flexbg group.  Returns the
+ * block number with a correct offset were the bitmaps and inode
+ * tables can be allocated continously and in order.
+ */
+static blk_t flexbg_offset(ext2_filsys fs, dgrp_t group, blk_t start_blk,
+                          ext2fs_block_bitmap bmap, int offset, int size)
+{
+       int             flexbg, flexbg_size, elem_size;
+       blk_t           last_blk, first_free = 0;
+       dgrp_t          last_grp;
+
+       flexbg_size = 1 << fs->super->s_log_groups_per_flex;
+       flexbg = group / flexbg_size;
+
+       if (size > fs->super->s_blocks_per_group / 8)
+               size = fs->super->s_blocks_per_group / 8;
+
+       /*
+        * Dont do a long search if the previous block
+        * search is still valid.
+        */
+       if (start_blk && group % flexbg_size) {
+               if (size > flexbg_size)
+                       elem_size = fs->inode_blocks_per_group;
+               else
+                       elem_size = 1;
+               if (ext2fs_test_block_bitmap_range(bmap, start_blk + elem_size,
+                                                  size))
+                       return start_blk + elem_size;
+       }
+
+       start_blk = ext2fs_group_first_block(fs, flexbg_size * flexbg);
+       last_grp = group | (flexbg_size - 1);
+       if (last_grp > fs->group_desc_count)
+               last_grp = fs->group_desc_count;
+       last_blk = ext2fs_group_last_block(fs, last_grp);
+
+       /* Find the first available block */
+       if (ext2fs_get_free_blocks(fs, start_blk, last_blk, 1, bmap,
+                                  &first_free))
+               return first_free;
+
+       if (ext2fs_get_free_blocks(fs, first_free + offset, last_blk, size,
+                                  bmap, &first_free))
+               return first_free;
+
+       return first_free;
+}
+
 errcode_t ext2fs_allocate_group_table(ext2_filsys fs, dgrp_t group,
                                      ext2fs_block_bitmap bmap)
 {
        errcode_t       retval;
        blk_t           group_blk, start_blk, last_blk, new_blk, blk;
-       int             j;
+       dgrp_t          last_grp;
+       int             j, rem_grps, flexbg_size = 0;
 
        group_blk = ext2fs_group_first_block(fs, group);
        last_blk = ext2fs_group_last_block(fs, group);
 
        if (!bmap)
                bmap = fs->block_map;
+
+       if (EXT2_HAS_INCOMPAT_FEATURE(fs->super,
+                                     EXT4_FEATURE_INCOMPAT_FLEX_BG) &&
+           fs->super->s_log_groups_per_flex) {
+               flexbg_size = 1 << fs->super->s_log_groups_per_flex;
+               last_grp = group | (flexbg_size - 1);
+               rem_grps = last_grp - group;
+               if (last_grp > fs->group_desc_count)
+                       last_grp = fs->group_desc_count;
+       }
        
        /*
         * Allocate the block and inode bitmaps, if necessary
@@ -56,6 +118,15 @@ errcode_t ext2fs_allocate_group_table(ext2_filsys fs, dgrp_t group,
        } else
                start_blk = group_blk;
 
+       if (flexbg_size) {
+               int prev_block = 0;
+               if (group && fs->group_desc[group-1].bg_block_bitmap)
+                       prev_block = fs->group_desc[group-1].bg_block_bitmap;
+               start_blk = flexbg_offset(fs, group, prev_block, bmap,
+                                                0, rem_grps);
+               last_blk = ext2fs_group_last_block(fs, last_grp);
+       }
+
        if (!fs->group_desc[group].bg_block_bitmap) {
                retval = ext2fs_get_free_blocks(fs, start_blk, last_blk,
                                                1, bmap, &new_blk);
@@ -66,6 +137,22 @@ errcode_t ext2fs_allocate_group_table(ext2_filsys fs, dgrp_t group,
                        return retval;
                ext2fs_mark_block_bitmap(bmap, new_blk);
                fs->group_desc[group].bg_block_bitmap = new_blk;
+               if (flexbg_size) {
+                       dgrp_t gr = ext2fs_group_of_blk(fs, new_blk);
+                       fs->group_desc[gr].bg_free_blocks_count--;
+                       fs->super->s_free_blocks_count--;
+                       fs->group_desc[gr].bg_flags &= ~EXT2_BG_BLOCK_UNINIT;
+                       ext2fs_group_desc_csum_set(fs, gr);
+               }
+       }
+
+       if (flexbg_size) {
+               int prev_block = 0;
+               if (group && fs->group_desc[group-1].bg_inode_bitmap)
+                       prev_block = fs->group_desc[group-1].bg_inode_bitmap;
+               start_blk = flexbg_offset(fs, group, prev_block, bmap,
+                                                flexbg_size, rem_grps);
+               last_blk = ext2fs_group_last_block(fs, last_grp);
        }
 
        if (!fs->group_desc[group].bg_inode_bitmap) {
@@ -78,11 +165,29 @@ errcode_t ext2fs_allocate_group_table(ext2_filsys fs, dgrp_t group,
                        return retval;
                ext2fs_mark_block_bitmap(bmap, new_blk);
                fs->group_desc[group].bg_inode_bitmap = new_blk;
+               if (flexbg_size) {
+                       dgrp_t gr = ext2fs_group_of_blk(fs, new_blk);
+                       fs->group_desc[gr].bg_free_blocks_count--;
+                       fs->super->s_free_blocks_count--;
+                       fs->group_desc[gr].bg_flags &= ~EXT2_BG_BLOCK_UNINIT;
+                       ext2fs_group_desc_csum_set(fs, gr);
+               }
        }
 
        /*
         * Allocate the inode table
         */
+       if (flexbg_size) {
+               int prev_block = 0;
+               if (group && fs->group_desc[group-1].bg_inode_table)
+                       prev_block = fs->group_desc[group-1].bg_inode_table;
+               group_blk = flexbg_offset(fs, group, prev_block, bmap,
+                                                flexbg_size * 2,
+                                                fs->inode_blocks_per_group *
+                                                rem_grps);
+               last_blk = ext2fs_group_last_block(fs, last_grp);
+       }
+
        if (!fs->group_desc[group].bg_inode_table) {
                retval = ext2fs_get_free_blocks(fs, group_blk, last_blk,
                                                fs->inode_blocks_per_group,
@@ -91,12 +196,19 @@ errcode_t ext2fs_allocate_group_table(ext2_filsys fs, dgrp_t group,
                        return retval;
                for (j=0, blk = new_blk;
                     j < fs->inode_blocks_per_group;
-                    j++, blk++)
+                    j++, blk++) {
                        ext2fs_mark_block_bitmap(bmap, blk);
+                       if (flexbg_size) {
+                               dgrp_t gr = ext2fs_group_of_blk(fs, blk);
+                               fs->group_desc[gr].bg_free_blocks_count--;
+                               fs->super->s_free_blocks_count--;
+                               fs->group_desc[gr].bg_flags &= ~EXT2_BG_BLOCK_UNINIT;
+                               ext2fs_group_desc_csum_set(fs, gr);
+                       }
+               }
                fs->group_desc[group].bg_inode_table = new_blk;
        }
        ext2fs_group_desc_csum_set(fs, group);
-
        return 0;
 }
 

diff --git a/lib/ext2fs/initialize.c b/lib/ext2fs/initialize.c
index 8fc1b01..011656f 100644 (file)
--- a/lib/ext2fs/initialize.c
+++ b/lib/ext2fs/initialize.c
@@ -159,6 +159,7 @@ errcode_t ext2fs_initialize(const char *name, int flags,
        set_field(s_first_meta_bg, 0);
        set_field(s_raid_stride, 0);            /* default stride size: 0 */
        set_field(s_raid_stripe_width, 0);      /* default stripe width: 0 */
+       set_field(s_log_groups_per_flex, 0);
        set_field(s_flags, 0);
        if (super->s_feature_incompat & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
                retval = EXT2_ET_UNSUPP_FEATURE;
@@ -377,6 +378,10 @@ ipg_retry:
         * Note that although the block bitmap, inode bitmap, and
         * inode table have not been allocated (and in fact won't be
         * by this routine), they are accounted for nevertheless.
+        *
+        * If FLEX_BG meta-data grouping is used, only account for the
+        * superblock and group descriptors (the inode tables and
+        * bitmaps will be accounted for when allocated).
         */
        super->s_free_blocks_count = 0;
        csum_flag = EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
@@ -397,6 +402,8 @@ ipg_retry:
                        fs->group_desc[i].bg_itable_unused = numblocks;
                }
                numblocks = ext2fs_reserve_super_and_bgd(fs, i, fs->block_map);
+               if (fs->super->s_log_groups_per_flex)
+                       numblocks += 2 + fs->inode_blocks_per_group;
 
                super->s_free_blocks_count += numblocks;
                fs->group_desc[i].bg_free_blocks_count = numblocks;

diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in
index 1e9a203..aa068b3 100644 (file)
--- a/misc/mke2fs.8.in
+++ b/misc/mke2fs.8.in
@@ -26,6 +26,10 @@ mke2fs \- create an ext2/ext3 filesystem
 .I blocks-per-group
 ]
 [
+.B \-G
+.I number-of-groups
+]
+[
 .B \-i
 .I bytes-per-inode
 ]
@@ -245,6 +249,13 @@ option rather than manipulating the number of blocks per group.)
 This option is generally used by developers who
 are developing test cases.  
 .TP
+.BI \-G " number-of-groups"
+Specify the number of block goups that will be packed together to
+create one large virtual block group on an ext4 filesystem.  This
+improves meta-data locality and performance on meta-data heavy
+workloads.  The number of goups must be a power of 2 and may only be
+specified if the flex_bg filesystem feature is enabled.
+.TP
 .BI \-i " bytes-per-inode"
 Specify the bytes/inode ratio. 
 .B mke2fs
@@ -445,6 +456,11 @@ Use hashed b-trees to speed up lookups in large directories.
 .B filetype
 Store file type information in directory entries.
 .TP
+.B flex_bg
+Allow bitmaps and inode tables for a block group to be placed anywhere
+on the storage media (use with -G option to group meta-data in order
+to create a large virtual block group).
+.TP
 .B has_journal
 Create an ext3 journal (as if using the
 .B \-j

diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 11dffb7..460452d 100644 (file)
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -98,8 +98,9 @@ static void usage(void)
        fprintf(stderr, _("Usage: %s [-c|-l filename] [-b block-size] "
        "[-f fragment-size]\n\t[-i bytes-per-inode] [-I inode-size] "
        "[-J journal-options]\n"
-       "\t[-N number-of-inodes] [-m reserved-blocks-percentage] "
-       "[-o creator-os]\n\t[-g blocks-per-group] [-L volume-label] "
+       "\t[-G meta group size] [-N number-of-inodes]\n"
+       "\t[-m reserved-blocks-percentage] [-o creator-os]\n"
+       "\t[-g blocks-per-group] [-L volume-label] "
        "[-M last-mounted-directory]\n\t[-O feature[,...]] "
        "[-r fs-revision] [-E extended-option[,...]]\n"
        "\t[-T fs-type] [-jnqvFSV] device [blocks-count]\n"),
@@ -1105,6 +1106,7 @@ static void PRS(int argc, char *argv[])
        int             blocksize = 0;
        int             inode_ratio = 0;
        int             inode_size = 0;
+       unsigned long   flex_bg_size = 0;
        double          reserved_ratio = 5.0;
        int             sector_size = 0;
        int             show_version_only = 0;
@@ -1189,7 +1191,7 @@ static void PRS(int argc, char *argv[])
        }
 
        while ((c = getopt (argc, argv,
-                   "b:cf:g:i:jl:m:no:qr:s:t:vE:FI:J:L:M:N:O:R:ST:V")) != EOF) {
+                   "b:cf:g:G:i:jl:m:no:qr:s:t:vE:FI:J:L:M:N:O:R:ST:V")) != EOF) {
                switch (c) {
                case 'b':
                        blocksize = strtol(optarg, &tmp, 0);
@@ -1239,6 +1241,20 @@ static void PRS(int argc, char *argv[])
                                exit(1);
                        }
                        break;
+               case 'G':
+                       flex_bg_size = strtoul(optarg, &tmp, 0);
+                       if (*tmp) {
+                               com_err(program_name, 0,
+                                       _("Illegal number for flex_bg size"));
+                               exit(1);
+                       }
+                       if (flex_bg_size < 2 ||
+                           (flex_bg_size & (flex_bg_size-1)) != 0) {
+                               com_err(program_name, 0,
+                                       _("flex_bg size must be a power of 2"));
+                               exit(1);
+                       }
+                       break;
                case 'i':
                        inode_ratio = strtoul(optarg, &tmp, 0);
                        if (inode_ratio < EXT2_MIN_BLOCK_SIZE ||
@@ -1647,6 +1663,20 @@ static void PRS(int argc, char *argv[])
 
        if (inode_size == 0)
                inode_size = get_int_from_profile(fs_types, "inode_size", 0);
+       if (!flex_bg_size && (fs_param.s_feature_incompat &
+                             EXT4_FEATURE_INCOMPAT_FLEX_BG))
+               flex_bg_size = get_int_from_profile(fs_types,
+                                                   "flex_bg_size", 16);
+       if (flex_bg_size) {
+               if (!(fs_param.s_feature_incompat &
+                     EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
+                       com_err(program_name, 0,
+                               _("Flex_bg feature not enabled, so "
+                                 "flex_bg size may not be specified"));
+                       exit(1);
+               }
+               fs_param.s_log_groups_per_flex = int_log2(flex_bg_size);
+       }
 
        if (inode_size && fs_param.s_rev_level >= EXT2_DYNAMIC_REV) {
                if (inode_size < EXT2_GOOD_OLD_INODE_SIZE ||

diff --git a/misc/mke2fs.conf.5.in b/misc/mke2fs.conf.5.in
index 6734bf3..5dd92d8 100644 (file)
--- a/misc/mke2fs.conf.5.in
+++ b/misc/mke2fs.conf.5.in
@@ -301,6 +301,13 @@ specify one on the command line.
 .I inode_size
 This relation specifies the default inode size if the user does not
 specify one on the command line.
+.TP
+.I flex_bg_size
+This relation specifies the number of block goups that will be packed
+together to create one large virtual block group on an ext4 filesystem.
+This improves meta-data locality and performance on meta-data heavy
+workloads.  The number of goups must be a power of 2 and may only be
+specified if the flex_bg filesystem feature is enabled.
 .SH FILES
 .TP
 .I /etc/mke2fs.conf