ext4: Add support for 48 bit inode i_blocks.
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>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7be27db..2b9dc96 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1603,17 +1603,50 @@
/*
* 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 @@
res <<= bits;
if (res > upper_limit)
res = upper_limit;
+
+ if (res > MAX_LFS_FILESIZE)
+ res = MAX_LFS_FILESIZE;
+
return res;
}
@@ -1789,6 +1826,19 @@
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 ||