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ext4: fix overflow when counting used blocks on 32-bit architectures 

The arithmetics adding delalloc blocks to the number of used blocks in
ext4_getattr() can easily overflow on 32-bit archs as we first multiply
number of blocks by blocksize and then divide back by 512. Make the
arithmetics more clever and also use proper type (unsigned long long
instead of unsigned long).

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Jan Kara 2013-05-31 19:39:56 -04:00 committed by Theodore Ts'o
parent a60697f411
commit 8af8eecc13
1 changed files with 2 additions and 2 deletions
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4
fs/ext4/inode.c
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@ -4702,7 +4702,7 @@ int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
struct kstat *stat)
{
struct inode *inode;
unsigned long delalloc_blocks;
unsigned long long delalloc_blocks;
inode = dentry->d_inode;
generic_fillattr(inode, stat);
@ -4720,7 +4720,7 @@ int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
delalloc_blocks = EXT4_C2B(EXT4_SB(inode->i_sb),
EXT4_I(inode)->i_reserved_data_blocks);
stat->blocks += (delalloc_blocks << inode->i_sb->s_blocksize_bits)>>9;
stat->blocks += delalloc_blocks << (inode->i_sb->s_blocksize_bits-9);
return 0;
}