| Message ID | 28989C0C9F1C0A428470D967B5FCED372A7E6D@BPXM22GP.gisp.nec.co.jp |
|---|---|
| State | Accepted, archived |
| Headers | show |
On Wed, Jun 11, 2014 at 08:37:22AM +0000, Akira Fujita wrote: > mke2fs -G option allows root user to set flex_bg count (power of 2). > However ext4 has bad metadata layout if we specify more than or equal to > 2^32 to mke2fs -G, because of the 32bit shift operation > in ext2fs_allocate_group_table(). > And the maximum block group count of ext4 is 2^32 -1 (ext4_group_t s_groups_count), > so diallow more than 2^32 flex_bg count. > > Steps to reproduce: > > # mke2fs -t ext4 -G 4294967296 DEV > > # dumpe2fs DEV > <snip> > Flex block group size: 1 <----- flex_bg is 1! > <snip> > Group 0: (Blocks 0-32767) > Checksum 0x4afd, unused inodes 7541 > Primary superblock at 0, Group descriptors at 1-1 > Reserved GDT blocks at 2-59 > Block bitmap at 60 (+60), Inode bitmap at 61 (+61) > Inode table at 62-533 (+62) > 32228 free blocks, 7541 free inodes, 2 directories, 7541 unused inodes > Free blocks: 540-32767 > Free inodes: 12-7552 > Group 1: (Blocks 32768-65535) [INODE_UNINIT] > Checksum 0xc890, unused inodes 7552 > Backup superblock at 32768, Group descriptors at 32769-32769 > Reserved GDT blocks at 32770-32827 > Block bitmap at 32828 (+60), Inode bitmap at 32829 (+61) > Inode table at 32830-33301 (+62) > 32234 free blocks, 7552 free inodes, 0 directories, 7552 unused inodes > Free blocks: 33302-65535 > Free inodes: 7553-15104 > <snip> > > Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com> Looks reasonable to me, you can add my Reviewed-by. --D > --- > misc/mke2fs.c | 6 ++++++ > 1 file changed, 6 insertions(+) > diff --git a/misc/mke2fs.c b/misc/mke2fs.c > index b451cc3..b9145d1 100644 > --- a/misc/mke2fs.c > +++ b/misc/mke2fs.c > @@ -1605,6 +1605,12 @@ profile_error: > _("flex_bg size must be a power of 2")); > exit(1); > } > + if (flex_bg_size > MAX_32_NUM) { > + com_err(program_name, 0, > + _("flex_bg size (%lu) must be less than" > + " or equal to 2^31"), flex_bg_size); > + exit(1); > + } > break; > case 'i': > inode_ratio = strtoul(optarg, &tmp, 0); > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/misc/mke2fs.c b/misc/mke2fs.c index b451cc3..b9145d1 100644 --- a/misc/mke2fs.c +++ b/misc/mke2fs.c @@ -1605,6 +1605,12 @@ profile_error: _("flex_bg size must be a power of 2")); exit(1); } + if (flex_bg_size > MAX_32_NUM) { + com_err(program_name, 0, + _("flex_bg size (%lu) must be less than" + " or equal to 2^31"), flex_bg_size); + exit(1); + } break; case 'i': inode_ratio = strtoul(optarg, &tmp, 0);
mke2fs -G option allows root user to set flex_bg count (power of 2). However ext4 has bad metadata layout if we specify more than or equal to 2^32 to mke2fs -G, because of the 32bit shift operation in ext2fs_allocate_group_table(). And the maximum block group count of ext4 is 2^32 -1 (ext4_group_t s_groups_count), so diallow more than 2^32 flex_bg count. Steps to reproduce: # mke2fs -t ext4 -G 4294967296 DEV # dumpe2fs DEV <snip> Flex block group size: 1 <----- flex_bg is 1! <snip> Group 0: (Blocks 0-32767) Checksum 0x4afd, unused inodes 7541 Primary superblock at 0, Group descriptors at 1-1 Reserved GDT blocks at 2-59 Block bitmap at 60 (+60), Inode bitmap at 61 (+61) Inode table at 62-533 (+62) 32228 free blocks, 7541 free inodes, 2 directories, 7541 unused inodes Free blocks: 540-32767 Free inodes: 12-7552 Group 1: (Blocks 32768-65535) [INODE_UNINIT] Checksum 0xc890, unused inodes 7552 Backup superblock at 32768, Group descriptors at 32769-32769 Reserved GDT blocks at 32770-32827 Block bitmap at 32828 (+60), Inode bitmap at 32829 (+61) Inode table at 32830-33301 (+62) 32234 free blocks, 7552 free inodes, 0 directories, 7552 unused inodes Free blocks: 33302-65535 Free inodes: 7553-15104 <snip> Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com> --- misc/mke2fs.c | 6 ++++++ 1 file changed, 6 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html