From: Valerie Clement <valerie.clement@xxxxxxxx>
This patch adds a new option -D <descriptor-size> to mkfs to allow creating
ext4 filesystems with larger group descriptor size.
By default, the group descriptor size is 32 bytes.
To support 64-bit physical block numbers and thus to be able to use filesystems
> 16TB, the group descriptor size must be increased to 64 bytes.
Use mkfs -t ext4 -D 64 to create an ext4 filesystem with 64-byte group
descriptor size. This set the EXT4_FEATURE_INCOMPAT_64BIT flag on device.
The descriptor size is limited to a power-of-two value and to the block size.
Signed-off-by: Valerie Clement <valerie.clement@xxxxxxxx>
---
lib/ext2fs/ext2_fs.h | 7 +++++++
lib/ext2fs/initialize.c | 1 +
misc/mke2fs.c | 33 +++++++++++++++++++++++++++++++--
3 files changed, 39 insertions(+), 2 deletions(-)
diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
index a316665..f6e8b36 100644
--- a/lib/ext2fs/ext2_fs.h
+++ b/lib/ext2fs/ext2_fs.h
@@ -217,6 +217,13 @@ struct ext2_dx_countlimit {
/*
* Macro-instructions used to manage group descriptors
*/
+#define EXT2_MIN_DESC_SIZE 32
+#define EXT2_MIN_DESC_SIZE_64BIT 64
+#define EXT2_MAX_DESC_SIZE EXT2_MIN_BLOCK_SIZE
+#define EXT2_DESC_SIZE(s) \
+ ((EXT2_SB(s)->s_feature_incompat & EXT4_FEATURE_INCOMPAT_64BIT) ? \
+ (s)->s_desc_size : EXT2_MIN_DESC_SIZE)
+
#define EXT2_BLOCKS_PER_GROUP(s) (EXT2_SB(s)->s_blocks_per_group)
#define EXT2_INODES_PER_GROUP(s) (EXT2_SB(s)->s_inodes_per_group)
#define EXT2_INODES_PER_BLOCK(s) (EXT2_BLOCK_SIZE(s)/EXT2_INODE_SIZE(s))
diff --git a/lib/ext2fs/initialize.c b/lib/ext2fs/initialize.c
index 16e9eaa..ee7af93 100644
--- a/lib/ext2fs/initialize.c
+++ b/lib/ext2fs/initialize.c
@@ -149,6 +149,7 @@ errcode_t ext2fs_initialize(const char *name, int flags,
set_field(s_log_block_size, 0); /* default blocksize: 1024 bytes */
set_field(s_log_frag_size, 0); /* default fragsize: 1024 bytes */
+ set_field(s_desc_size, 0);
set_field(s_first_data_block, super->s_log_block_size ? 0 : 1);
set_field(s_max_mnt_count, EXT2_DFL_MAX_MNT_COUNT);
set_field(s_errors, EXT2_ERRORS_DEFAULT);
diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 4a6cace..115eef9 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -96,7 +96,7 @@ static void usage(void)
{
fprintf(stderr, _("Usage: %s [-c|-t|-l filename] [-b block-size] "
"[-f fragment-size]\n\t[-i bytes-per-inode] [-I inode-size] "
- "[-j] [-J journal-options]\n"
+ "[-D descriptor-size] [-j] [-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] "
"[-M last-mounted-directory]\n\t[-O feature[,...]] "
@@ -911,6 +911,7 @@ static void PRS(int argc, char *argv[])
int blocksize = 0;
int inode_ratio = 0;
int inode_size = 0;
+ int desc_size = 0;
double reserved_ratio = 5.0;
int sector_size = 0;
int show_version_only = 0;
@@ -993,7 +994,7 @@ static void PRS(int argc, char *argv[])
}
while ((c = getopt (argc, argv,
- "b:cf:g:i:jl:m:no:qr:s:tvE:FI:J:L:M:N:O:R:ST:V")) != EOF) {
+ "b:cf:g:i:jl:m:no:qr:s:tvD:E:FI:J:L:M:N:O:R:ST:V")) != EOF) {
switch (c) {
case 'b':
blocksize = strtol(optarg, &tmp, 0);
@@ -1110,6 +1111,14 @@ static void PRS(int argc, char *argv[])
exit(1);
}
break;
+ case 'D':
+ desc_size = strtoul(optarg, &tmp, 0);
+ if (*tmp) {
+ com_err(program_name, 0,
+ _("invalid descriptor size - %s"), optarg);
+ exit(1);
+ }
+ break;
case 'v':
verbose = 1;
break;
@@ -1439,6 +1448,26 @@ static void PRS(int argc, char *argv[])
}
}
+ if (desc_size) {
+ if (desc_size < EXT2_MIN_DESC_SIZE ||
+ desc_size > EXT2_BLOCK_SIZE(&fs_param) ||
+ desc_size & (desc_size -1)) {
+ com_err(program_name, 0,
+ _("invalid descriptor size %d (min %d/max %d)"),
+ desc_size, EXT2_MIN_DESC_SIZE,
+ blocksize);
+ exit(1);
+ }
+ if (desc_size != EXT2_MIN_DESC_SIZE)
+ fprintf(stderr, _("Warning: %d-byte descriptors not "
+ "usable on older systems\n"),
+ desc_size);
+ fs_param.s_desc_size = desc_size;
+ if (desc_size > EXT2_MIN_DESC_SIZE)
+ fs_param.s_feature_incompat |= EXT4_FEATURE_INCOMPAT_64BIT;
+ }
+
+
if (!force && fs_param.s_blocks_count >= ((unsigned) 1 << 31)) {
com_err(program_name, 0,
_("Filesystem too large. No more than 2**31-1 blocks\n"
-
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