On Wed, May 24, 2023 at 07:48:00AM -0700, Darrick J. Wong wrote:
> On Wed, May 24, 2023 at 08:10:41PM +0800, Long Li wrote:
> > I found a corruption during growfs:
> >
> > XFS (loop0): Internal error agbno >= mp->m_sb.sb_agblocks at line 3661 of
> > file fs/xfs/libxfs/xfs_alloc.c. Caller __xfs_free_extent+0x28e/0x3c0
> > CPU: 0 PID: 573 Comm: xfs_growfs Not tainted 6.3.0-rc7-next-20230420-00001-gda8c95746257
> > Call Trace:
> > <TASK>
> > dump_stack_lvl+0x50/0x70
> > xfs_corruption_error+0x134/0x150
> > __xfs_free_extent+0x2c1/0x3c0
> > xfs_ag_extend_space+0x291/0x3e0
> > xfs_growfs_data+0xd72/0xe90
> > xfs_file_ioctl+0x5f9/0x14a0
> > __x64_sys_ioctl+0x13e/0x1c0
> > do_syscall_64+0x39/0x80
> > entry_SYSCALL_64_after_hwframe+0x63/0xcd
> > XFS (loop0): Corruption detected. Unmount and run xfs_repair
> > XFS (loop0): Internal error xfs_trans_cancel at line 1097 of file
> > fs/xfs/xfs_trans.c. Caller xfs_growfs_data+0x691/0xe90
> > CPU: 0 PID: 573 Comm: xfs_growfs Not tainted 6.3.0-rc7-next-20230420-00001-gda8c95746257
> > Call Trace:
> > <TASK>
> > dump_stack_lvl+0x50/0x70
> > xfs_error_report+0x93/0xc0
> > xfs_trans_cancel+0x2c0/0x350
> > xfs_growfs_data+0x691/0xe90
> > xfs_file_ioctl+0x5f9/0x14a0
> > __x64_sys_ioctl+0x13e/0x1c0
> > do_syscall_64+0x39/0x80
> > entry_SYSCALL_64_after_hwframe+0x63/0xcd
> > RIP: 0033:0x7f2d86706577
> >
> > The bug can be reproduced with the following sequence:
> >
> > # truncate -s 1073741824 xfs_test.img
> > # mkfs.xfs -f -b size=1024 -d agcount=4 xfs_test.img
> > # truncate -s 2305843009213693952 xfs_test.img
> > # mount -o loop xfs_test.img /mnt/test
> > # xfs_growfs -D 1125899907891200 /mnt/test
> >
> > The root cause is that during growfs, user space passed in a large value
> > of newblcoks to xfs_growfs_data_private(), due to current sb_agblocks is
> > too small, new AG count will exceed UINT_MAX. Because of AG number type
> > is unsigned int and it would overflow, that caused nagcount much smaller
> > than the actual value. During AG extent space, delta blocks in
> > xfs_resizefs_init_new_ags() will much larger than the actual value due to
> > incorrect nagcount, even exceed UINT_MAX. This will cause corruption and
> > be detected in __xfs_free_extent. Fix it by growing the filesystem to up
> > to the maximally allowed AGs when new AG count overflow.
> >
> > Signed-off-by: Long Li <leo.lilong@xxxxxxxxxx>
> > ---
> > v3:
> > - Ensure that the performance is consisent before and after the modification
> > when nagcount just overflows and 0 < nb_mod < XFS_MIN_AG_BLOCKS.
> > - Based on Darrick's advice, growing the filesystem to up to the maximally
> > allowed AGs when new AG count overflow.
> >
> > fs/xfs/libxfs/xfs_fs.h | 3 +++
> > fs/xfs/xfs_fsops.c | 13 +++++++++----
> > 2 files changed, 12 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
> > index 1cfd5bc6520a..36ec2b1f7e68 100644
> > --- a/fs/xfs/libxfs/xfs_fs.h
> > +++ b/fs/xfs/libxfs/xfs_fs.h
> > @@ -248,6 +248,9 @@ typedef struct xfs_fsop_resblks {
> > #define XFS_MAX_LOG_BLOCKS (1024 * 1024ULL)
> > #define XFS_MIN_LOG_BYTES (10 * 1024 * 1024ULL)
> >
> > +/* Maximum number of AGs */
> > +#define XFS_AGNUMBER_MAX ((xfs_agnumber_t)(-1U))
>
> My apologies, I led you astray. This should be:
>
> #define XFS_MAX_AGNUMBER ((xfs_agnumber_t)(NULLAGNUMBER - 1))
>
OK, it is undoubtedly better to follow the definition in xfsprogs, which will
be modified in the next version.
> since it already exists in multidisk.h from xfsprogs.
> xfs_validate_sb_common probably ought to validate that
> sb_agcount <= XFS_MAX_AGNUMBER as well.
>
In my understanding the range of sb_agcount should be [1, 0xFFFFFFFF], it
should validate that sb_agcount <= (XFS_MAX_AGNUMBER + 1) , so it's not necessary
to check the upper limit of the sb_agcount.
> > +
> > /*
> > * Limits on sb_agblocks/sb_agblklog -- mkfs won't format AGs smaller than
> > * 16MB or larger than 1TB.
> > diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
> > index 13851c0d640b..2b37d3e61bdf 100644
> > --- a/fs/xfs/xfs_fsops.c
> > +++ b/fs/xfs/xfs_fsops.c
> > @@ -115,11 +115,16 @@ xfs_growfs_data_private(
> >
> > nb_div = nb;
> > nb_mod = do_div(nb_div, mp->m_sb.sb_agblocks);
> > - nagcount = nb_div + (nb_mod != 0);
> > - if (nb_mod && nb_mod < XFS_MIN_AG_BLOCKS) {
> > - nagcount--;
> > - nb = (xfs_rfsblock_t)nagcount * mp->m_sb.sb_agblocks;
> > + if (nb_mod && nb_mod >= XFS_MIN_AG_BLOCKS)
> > + nb_div++;
> > + else if (nb_mod)
> > + nb = nb_div * mp->m_sb.sb_agblocks;
> > +
> > + if (nb_div > XFS_AGNUMBER_MAX) {
> > + nb_div = XFS_AGNUMBER_MAX;
> > + nb = nb_div * mp->m_sb.sb_agblocks;
> > }
> > + nagcount = nb_div;
> > delta = nb - mp->m_sb.sb_dblocks;
> > /*
> > * Reject filesystems with a single AG because they are not
> > --
> > 2.31.1
> >
