Re: [PATCH v3] repair: handle reading superblock from image on larger sector size filesystem

Zorro Lang
2017-04-11T03:25:43Z

On Mon, Apr 10, 2017 at 12:16:41PM -0500, Eric Sandeen wrote:
> On 4/6/17 7:05 AM, Zorro Lang wrote:
> > Due to xfs_repair uses direct IO, sometimes it can't read superblock
> > from an image file has smaller sector size than host filesystem.
> > Especially that superblock doesn't align with host filesystem's
> > sector size.
> >
> > Fortunately, xfsprogs already has code to do isa_file and geometry
> > check in xfs_repair.c, it turns off O_DIRECT after phase1() if the
> > sector size is less than the host filesystem's geometry. So move
> > the isa_file auto detection over up the phase1(), and try to do
> > once geometry check before phase1() if get_sb() return OK.
>
> Zorro, can you do a quick test for me - does a filesystem which fails
> repair without this patch also fail xfs_copy if the source and/or
> destination of the copy is on this same filesystem/device as the image
> file in your xfs_repair test?

Sure, the xfs_copy has similar problem. I'm writting a xfstests case to
do xfs_repair and xfs_copy a file image likes this. Do you have any other
related suggestions which I can write them together?

About the xfs_copy, the test result likes below:
[root@ibm-x3850x5-03 test]# xfs_info .
meta-data=/dev/sdb isize=512 agcount=4, agsize=960000 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=1 finobt=1 spinodes=0 rmapbt=0
= reflink=0
data = bsize=4096 blocks=3840000, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal bsize=4096 blocks=2560, version=2
= sectsz=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@ibm-x3850x5-03 test]# mount -oloop 078.fs /mnt/tmp
[root@ibm-x3850x5-03 test]# xfs_info 078.fs
meta-data=/dev/sdb isize=512 agcount=4, agsize=960000 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=1 finobt=1 spinodes=0 rmapbt=0
= reflink=0
data = bsize=4096 blocks=3840000, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal bsize=4096 blocks=2560, version=2
= sectsz=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@ibm-x3850x5-03 test]# umount /mnt/tmp
[root@ibm-x3850x5-03 test]# xfs_repair -f 078.fs
Phase 1 - find and verify superblock...
superblock read failed, offset 43014144, size 131072, ag 1, rval -1

fatal error -- Invalid argument
[root@ibm-x3850x5-03 test]# xfs_copy 078.fs 078.fs.bk
xfs_copy: read failed: Invalid argument
xfs_copy: read failed: Invalid argument
[root@ibm-x3850x5-03 test]# xfs_copy 078.fs /tmp
xfs_copy: read failed: Invalid argument
xfs_copy: read failed: Invalid argument
[root@ibm-x3850x5-03 test]# strace xfs_copy 078.fs 078.fs.img
...
...
open("078.fs", O_RDONLY|O_DIRECT) = 5
fstat(5, {st_mode=S_IFREG|0600, st_size=688231424, ...}) = 0
fstat(5, {st_mode=S_IFREG|0600, st_size=688231424, ...}) = 0
ioctl(5, _IOC(_IOC_READ, 0x58, 0x1e, 0x0c), 0x7ffd28252c80) = 0
chdir("/mnt/test") = 0
pread64(5, "XFSB\0\0\4\0\0\0\0\0\0\nA`\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 32768, 0) = 32768
pread64(5, 0x74c000, 512, 0) = -1 EINVAL (Invalid argument)
write(2, "xfs_copy: read failed: Invalid a"..., 40xfs_copy: read failed: Invalid argument
) = 40
pread64(5, 0x74d000, 512, 688225792) = -1 EINVAL (Invalid argument)
write(2, "xfs_copy: read failed: Invalid a"..., 40xfs_copy: read failed: Invalid argument
) = 40
exit_group(1) = ?
+++ exited with 1 +++

>
> Thanks,
> -Eric
>
> > Signed-off-by: Zorro Lang <zlang@redhat.com>
> > ---
> >
> > Hi,
> >
> > V2 did a stupid change, it tried to check superblock before get_sb(). So
> > V3 fix this problem by below changes:
> >
> > 1) move the "if (!isa_file)" auto detection over up the phase1().
> > 2) try to get_sb() before phase1, and check the sector size. Turn
> > off the O_DIRECT if the sector size is smaller than the underlying
> > filesystem.
> > 3) The step#2 maybe fail, due to can't get a valid primary superblock.
> > So keep the similar steps after phase1(), I didn't remove it.
> >
> > Thanks,
> > Zorro
> >
> > repair/xfs_repair.c | 96 ++++++++++++++++++++++++++++++-----------------------
> > 1 file changed, 54 insertions(+), 42 deletions(-)
> >
> > diff --git a/repair/xfs_repair.c b/repair/xfs_repair.c
> > index b07567b..9df5719 100644
> > --- a/repair/xfs_repair.c
> > +++ b/repair/xfs_repair.c
> > @@ -627,6 +627,42 @@ is_multidisk_filesystem(
> > return true;
> > }
> >
> > +/*
> > + * if the sector size of the filesystem we are trying to repair is
> > + * smaller than that of the underlying filesystem (i.e. we are repairing
> > + * an image), the we have to turn off direct IO because we cannot do IO
> > + * smaller than the host filesystem's sector size.
> > + */
> > +static void
> > +check_geometry_sectsize(
> > + struct xfs_sb *sb)
> > +{
> > + int fd;
> > + long old_flags;
> > + struct xfs_fsop_geom_v1 geom = { 0 };
> > +
> > + if (isa_file) {
> > + fd = libxfs_device_to_fd(x.ddev);
> > +
> > + if (ioctl(fd, XFS_IOC_FSGEOMETRY_V1, &geom) < 0) {
> > + do_log(_("Cannot get host filesystem geometry.\n"
> > + "Repair may fail if there is a sector size mismatch between\n"
> > + "the image and the host filesystem.\n"));
> > + geom.sectsize = BBSIZE;
> > + }
> > +
> > + if (sb->sb_sectsize < geom.sectsize) {
> > + old_flags = fcntl(fd, F_GETFL, 0);
> > + if (fcntl(fd, F_SETFL, old_flags & ~O_DIRECT) < 0) {
> > + do_warn(_(
> > + "Sector size on host filesystem larger than image sector size.\n"
> > + "Cannot turn off direct IO, so exiting.\n"));
> > + exit(1);
> > + }
> > + }
> > + }
> > +}
> > +
> > int
> > main(int argc, char **argv)
> > {
> > @@ -657,6 +693,23 @@ main(int argc, char **argv)
> > timestamp(PHASE_START, 0, NULL);
> > timestamp(PHASE_END, 0, NULL);
> >
> > + /* -f forces this, but let's be nice and autodetect it, as well. */
> > + if (!isa_file) {
> > + int fd = libxfs_device_to_fd(x.ddev);
> > + struct stat statbuf;
> > +
> > + if (fstat(fd, &statbuf) < 0)
> > + do_warn(_("%s: couldn't stat \"%s\"\n"),
> > + progname, fs_name);
> > + else if (S_ISREG(statbuf.st_mode))
> > + isa_file = 1;
> > + }
> > +
> > + rval = get_sb(&psb, 0, XFS_MAX_SECTORSIZE, 0);
> > + if (rval == XR_OK) {
> > + check_geometry_sectsize(&psb);
> > + }
> > +
> > /* do phase1 to make sure we have a superblock */
> > phase1(temp_mp);
> > timestamp(PHASE_END, 1, NULL);
> > @@ -674,48 +727,7 @@ main(int argc, char **argv)
> > "Exiting now.\n"));
> > exit(1);
> > }
> > -
> > - /* -f forces this, but let's be nice and autodetect it, as well. */
> > - if (!isa_file) {
> > - int fd = libxfs_device_to_fd(x.ddev);
> > - struct stat statbuf;
> > -
> > - if (fstat(fd, &statbuf) < 0)
> > - do_warn(_("%s: couldn't stat \"%s\"\n"),
> > - progname, fs_name);
> > - else if (S_ISREG(statbuf.st_mode))
> > - isa_file = 1;
> > - }
> > -
> > - /*
> > - * if the sector size of the filesystem we are trying to repair is
> > - * smaller than that of the underlying filesystem (i.e. we are repairing
> > - * an image), the we have to turn off direct IO because we cannot do IO
> > - * smaller than the host filesystem's sector size.
> > - */
> > - if (isa_file) {
> > - int fd = libxfs_device_to_fd(x.ddev);
> > - struct xfs_fsop_geom_v1 geom = { 0 };
> > -
> > - if (ioctl(fd, XFS_IOC_FSGEOMETRY_V1, &geom) < 0) {
> > - do_log(_("Cannot get host filesystem geometry.\n"
> > - "Repair may fail if there is a sector size mismatch between\n"
> > - "the image and the host filesystem.\n"));
> > - geom.sectsize = BBSIZE;
> > - }
> > -
> > - if (psb.sb_sectsize < geom.sectsize) {
> > - long old_flags;
> > -
> > - old_flags = fcntl(fd, F_GETFL, 0);
> > - if (fcntl(fd, F_SETFL, old_flags & ~O_DIRECT) < 0) {
> > - do_warn(_(
> > - "Sector size on host filesystem larger than image sector size.\n"
> > - "Cannot turn off direct IO, so exiting.\n"));
> > - exit(1);
> > - }
> > - }
> > - }
> > + check_geometry_sectsize(&psb);
> >
> > /*
> > * Prepare the mount structure. Point the log reference to our local
> >
> --
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