From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Kleikamp Subject: Re: stat64 for over 2TB file returned invalid st_blocks Date: Thu, 01 Dec 2005 08:32:19 -0600 Message-ID: <1133447539.8557.14.camel@kleikamp.austin.ibm.com> References: <01e901c5f66e$d4551b70$4168010a@bsd.tnes.nec.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Return-path: Received: from e34.co.us.ibm.com ([32.97.110.152]:15747 "EHLO e34.co.us.ibm.com") by vger.kernel.org with ESMTP id S932249AbVLAOc0 (ORCPT ); Thu, 1 Dec 2005 09:32:26 -0500 To: Takashi Sato In-Reply-To: <01e901c5f66e$d4551b70$4168010a@bsd.tnes.nec.co.jp> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Thu, 2005-12-01 at 21:00 +0900, Takashi Sato wrote: > Hi all, >=20 > I found a problem at stat64 on 32bit architecture. >=20 > When I called stat64 for a file which is larger than 2TB, stat64 > returned an invalid number of blocks at st_blocks on 32bit > architecture, although it returned a valid number of blocks on 64bit > architecture(ia64). =46or jfs, it's a bigger problem than just stat64. When writing the in= ode to disk, jfs calculates the number of blocks from the 32-bit value: dip->di_nblocks =3D cpu_to_le64(PBLK2LBLK(ip->i_sb, ip->i_blocks)) So it won't only report the wrong number of blocks, but it will actuall= y store the wrong number. :-( > The following describes the cause of this issue: > i_blocks in inode is 4bytes on 32bit architecture. If it receives > more than 2^32 number of blocks, it would overflow and set an > invalid number to st_blocks. >=20 > Below describes a sequence of setting overflowed inode.i_blocks > to st_blocks through stat64. >=20 > 1. generic_fillattr(struct inode *inode, struct kstat *stat) > - Copy data from overflowed inode.i_blocks to kstat.blocks. >=20 > 2. vfs_getattr(struct vfsmount *mnt, struct dentry *dentry, > struct kstat *stat) > - Return invalid kstat.blocks to sys_stat64(). >=20 > 3. sys_stat64(char __user * filename, struct stat64 __user * statbuf) > - Copy data from invalid kstat.blocks to stat64.st_blocks. >=20 > I also found the following problem. >=20 > - ioctl with FIOQSIZE command returns the size of file's data which > has written to disk. The size of file's data is calculated as > follows in inode_get_bytes(). > =20 > (((loff_t)inode->i_blocks) << 9) + inode->i_bytes >=20 > On the file which is larger than 2TB, the ioctl will return an > invalid size because i_blocks can't express the right number of > blocks. >=20 > I think the following modification is essential to fix these > problems. >=20 > 1. Change the type of inode.i_blocks and kstat.blocks from unsigned > long to unsigned long long. This would be okay. > 2. Change the type of architecture dependent stat64.st_blocks in > include/asm/asm-*/stat.h from unsigned long to unsigned long long. > I tried modifying only stat64 of 32bit architecture > (include/asm-i386/stat.h). This changes the API, but the structure does suggest that the 4-byte pa= d should be used for the high-order bytes of st_blocks, so that's not really a problem. A correct fix would replace __pad4 with st_blocks_high (or something like that) and ensure that the high-order word was stored there. Your proposed fix would only be correct on little-endian hardware, as J=F6rn pointed out. > I have some tested for a file whose size is 3TB on JFS filesystem. > The following is the patch. >=20 > Signed-off-by: Takashi Sato >=20 > diff -uprN -X linux-2.6.14.org/Documentation/dontdiff linux-2.6.14.or > g/include/asm-i386/stat.h linux-2.6.14-blocks/include/asm-i386/stat.h > --- linux-2.6.14.org/include/asm-i386/stat.h 2005-10-28 09:02:08.0000= 00000 +0900 > +++ linux-2.6.14-blocks/include/asm-i386/stat.h 2005-11-18 22:42:37.0= 00000000 +0900 > @@ -58,8 +58,7 @@ struct stat64 { > long long st_size; > unsigned long st_blksize; > =20 > - unsigned long st_blocks; /* Number 512-byte blocks allocated. */ > - unsigned long __pad4; /* future possible st_blocks high bits */ > + unsigned long long st_blocks; /* Number 512-byte blocks allocated. = */ > =20 > unsigned long st_atime; > unsigned long st_atime_nsec; > diff -uprN -X linux-2.6.14.org/Documentation/dontdiff linux-2.6.14.or > g/include/linux/fs.h linux-2.6.14-blocks/include/linux/fs.h > --- linux-2.6.14.org/include/linux/fs.h 2005-10-28 09:02:08.000000000= +0900 > +++ linux-2.6.14-blocks/include/linux/fs.h 2005-11-18 17:08:03.000000= 000 +0900 > @@ -438,7 +438,7 @@ struct inode { > unsigned int i_blkbits; > unsigned long i_blksize; > unsigned long i_version; > - unsigned long i_blocks; > + unsigned long long i_blocks; > unsigned short i_bytes; > spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */ > struct semaphore i_sem; > diff -uprN -X linux-2.6.14.org/Documentation/dontdiff linux-2.6.14.or > g/include/linux/stat.h linux-2.6.14-blocks/include/linux/stat.h > --- linux-2.6.14.org/include/linux/stat.h 2005-10-28 09:02:08.0000000= 00 +0900 > +++ linux-2.6.14-blocks/include/linux/stat.h 2005-11-18 17:08:56.0000= 00000 +0900 > @@ -69,7 +69,7 @@ struct kstat { > struct timespec mtime; > struct timespec ctime; > unsigned long blksize; > - unsigned long blocks; > + unsigned long long blocks; > }; > =20 > #endif >=20 > Any feedback and comments are welcome. >=20 > Best regards, Takashi Sato --=20 David Kleikamp IBM Linux Technology Center - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html