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ext4: Add support for 48 bit inode i_blocks.

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Use the __le16 l_i_reserved1 field of the linux2 struct of ext4_inode
to represet the higher 16 bits for i_blocks. With this change max_file
size becomes (2**48 -1 )* 512 bytes.

We add a RO_COMPAT feature to the super block to indicate that inode
have i_blocks represented as a split 48 bits. Super block with this
feature set cannot be mounted read write on a kernel with CONFIG_LSF
disabled.

Super block flag EXT4_FEATURE_RO_COMPAT_HUGE_FILE

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
This commit is contained in:
Aneesh Kumar K.V
2008-01-28 23:58:26 -05:00
committed by Theodore Ts'o
parent a48380f769
commit 0fc1b45147
3 changed files with 119 additions and 11 deletions
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62
fs/ext4/super.c
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@@ -1603,17 +1603,50 @@ static void ext4_orphan_cleanup (struct super_block * sb,
/*
* Maximal file size. There is a direct, and {,double-,triple-}indirect
* block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
* We need to be 1 filesystem block less than the 2^32 sector limit.
* block limit, and also a limit of (2^48 - 1) 512-byte sectors in i_blocks.
* We need to be 1 filesystem block less than the 2^48 sector limit.
*/
static loff_t ext4_max_size(int bits)
{
loff_t res = EXT4_NDIR_BLOCKS;
/* This constant is calculated to be the largest file size for a
* dense, 4k-blocksize file such that the total number of
int meta_blocks;
loff_t upper_limit;
/* This is calculated to be the largest file size for a
* dense, file such that the total number of
* sectors in the file, including data and all indirect blocks,
* does not exceed 2^32. */
const loff_t upper_limit = 0x1ff7fffd000LL;
* does not exceed 2^48 -1
* __u32 i_blocks_lo and _u16 i_blocks_high representing the
* total number of 512 bytes blocks of the file
*/
if (sizeof(blkcnt_t) < sizeof(u64)) {
/*
* CONFIG_LSF is not enabled implies the inode
* i_block represent total blocks in 512 bytes
* 32 == size of vfs inode i_blocks * 8
*/
upper_limit = (1LL << 32) - 1;
/* total blocks in file system block size */
upper_limit >>= (bits - 9);
} else {
/* We use 48 bit ext4_inode i_blocks */
upper_limit = (1LL << 48) - 1;
/* total blocks in file system block size */
upper_limit >>= (bits - 9);
}
/* indirect blocks */
meta_blocks = 1;
/* double indirect blocks */
meta_blocks += 1 + (1LL << (bits-2));
/* tripple indirect blocks */
meta_blocks += 1 + (1LL << (bits-2)) + (1LL << (2*(bits-2)));
upper_limit -= meta_blocks;
upper_limit <<= bits;
res += 1LL << (bits-2);
res += 1LL << (2*(bits-2));
@@ -1621,6 +1654,10 @@ static loff_t ext4_max_size(int bits)
res <<= bits;
if (res > upper_limit)
res = upper_limit;
if (res > MAX_LFS_FILESIZE)
res = MAX_LFS_FILESIZE;
return res;
}
@@ -1789,6 +1826,19 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
sb->s_id, le32_to_cpu(features));
goto failed_mount;
}
if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_HUGE_FILE)) {
/*
* Large file size enabled file system can only be
* mount if kernel is build with CONFIG_LSF
*/
if (sizeof(root->i_blocks) < sizeof(u64) &&
!(sb->s_flags & MS_RDONLY)) {
printk(KERN_ERR "EXT4-fs: %s: Filesystem with huge "
"files cannot be mounted read-write "
"without CONFIG_LSF.\n", sb->s_id);
goto failed_mount;
}
}
blocksize = BLOCK_SIZE << le32_to_cpu(es->s_log_block_size);
if (blocksize < EXT4_MIN_BLOCK_SIZE ||