On 3/30/12 10:01 AM, Eric Sandeen wrote:
> In some cases the target file may have a non-local attribute,
> but the temp file gets assigned a local attribute on creation,
> due to selinux, for example.
>
> In this case, the large-ish selinux attr will create a forkoff
> in the temp file smaller than the forkoff in the target file,
> because the FMT_EXTENTS attr takes up less space. There is
> no mechanism to grow the forkoff to match, so we can end up
> failing to swap these 2 inodes if the result is not enough
> data space in the temp inode as a result.
>
> After testing the target file for a non-local extent, and
> checking to see if the forkoff needs to be grown on the first
> pass, we can add a large attr to knock all attributes of the
> temp file out of local format, and grow the fork offset.
>
> This passes xfstest 227, and also resolves issues seen on
> a metadata image provided by Gabriel.
>
> Reported-by: Gabriel VLASIU <gabriel@xxxxxxxxxx>
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
Ping #2? This was a real bug once, IIRC. Probably still is...
Patch 1/2 helped identify the problem, so ping on that too I guess.
-Eric
> diff --git a/fsr/xfs_fsr.c b/fsr/xfs_fsr.c
> index d83bdc9..e8ab028 100644
> --- a/fsr/xfs_fsr.c
> +++ b/fsr/xfs_fsr.c
> @@ -1022,6 +1022,8 @@ fsr_setup_attr_fork(
> struct stat64 tstatbuf;
> int i;
> int diff = 0;
> + struct fsxattr fsx;
> + int target_attr_local = 0;
> int last_forkoff = 0;
> int no_change_cnt = 0;
> int ret;
> @@ -1052,6 +1054,11 @@ fsr_setup_attr_fork(
> return -1;
> }
>
> + memset(&fsx, 0, sizeof(fsx));
> + ioctl(fd, XFS_IOC_FSGETXATTR, &fsx);
> + if (fsx.fsx_nextents == 0)
> + target_attr_local = 1;
> +
> i = 0;
> do {
> xfs_bstat_t tbstat;
> @@ -1072,6 +1079,7 @@ fsr_setup_attr_fork(
> if (dflag)
> fsrprintf(_("orig forkoff %d, temp forkoff %d\n"),
> bstatp->bs_forkoff, tbstat.bs_forkoff);
> + diff = tbstat.bs_forkoff - bstatp->bs_forkoff;
>
> snprintf(name, sizeof(name), "user.%d", i);
>
> @@ -1086,6 +1094,21 @@ fsr_setup_attr_fork(
> return -1;
> }
> continue;
> + } else if (i == 0 && diff < 0 && target_attr_local == 0) {
> + /*
> + * A small attr may exist from eg selinux but, if the
> + * target is not local, write a big attr to tempfile
> + * to knock it out of local format to match target.
> + * This should actually increase the temp forkoffset.
> + */
> + char val[2048];
> + memset(val, 'X', 2048);
> + ret = fsetxattr(tfd, name, val, 2048, XATTR_CREATE);
> + if (ret) {
> + fsrprintf(_("could not set large ATTR\n"));
> + return -1;
> + }
> + continue;
> }
>
> /*
> @@ -1100,7 +1123,6 @@ fsr_setup_attr_fork(
> last_forkoff = tbstat.bs_forkoff;
>
> /* work out which way to grow the fork */
> - diff = tbstat.bs_forkoff - bstatp->bs_forkoff;
> if (abs(diff) > fsgeom.inodesize - sizeof(struct xfs_dinode)) {
> fsrprintf(_("forkoff diff %d too large!\n"), diff);
> return -1;
>
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> http://oss.sgi.com/mailman/listinfo/xfs
>
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