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xfs: growfs: don't read garbage for new secondary superblocks

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When updating new secondary superblocks in a growfs operation, the
superblock buffer is read from the newly grown region of the
underlying device. This is not guaranteed to be zero, so violates
the underlying assumption that the unused parts of superblocks are
zero filled. Get a new buffer for these secondary superblocks to
ensure that the unused regions are zero filled correctly.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
This commit is contained in:
Dave Chinner 2012-10-09 14:50:52 +11:00 committed by Ben Myers
parent e04426b920
commit 1375cb65e8
1 changed files with 19 additions and 2 deletions
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19
fs/xfs/xfs_fsops.c
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@ -399,9 +399,26 @@ xfs_growfs_data_private(
/* update secondary superblocks. */
for (agno = 1; agno < nagcount; agno++) {
error = 0;
/*
* new secondary superblocks need to be zeroed, not read from
* disk as the contents of the new area we are growing into is
* completely unknown.
*/
if (agno < oagcount) {
error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp,
XFS_AGB_TO_DADDR(mp, agno, XFS_SB_BLOCK(mp)),
XFS_FSS_TO_BB(mp, 1), 0, &bp);
} else {
bp = xfs_trans_get_buf(NULL, mp->m_ddev_targp,
XFS_AGB_TO_DADDR(mp, agno, XFS_SB_BLOCK(mp)),
XFS_FSS_TO_BB(mp, 1), 0);
if (bp)
xfs_buf_zero(bp, 0, BBTOB(bp->b_length));
else
error = ENOMEM;
}
if (error) {
xfs_warn(mp,
"error %d reading secondary superblock for ag %d",
@ -423,7 +440,7 @@ xfs_growfs_data_private(
break; /* no point in continuing */
}
}
return 0;
return error;
error0:
xfs_trans_cancel(tp, XFS_TRANS_ABORT);