xfs: take m_growlock when running growfsrt

Take the grow lock when we're expanding the realtime volume, like we do
for the other growfs calls.

Reviewed-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Darrick J. Wong <[e-mail]>
Signed-off-by: Chandan Babu R <[e-mail]>

fs/xfs/xfs_rtalloc.c

···
 	/* Needs to have been mounted with an rt device. */
 	if (!XFS_IS_REALTIME_MOUNT(mp))
 		return -EINVAL;
+
+	if (!mutex_trylock(&mp->m_growlock))
+		return -EWOULDBLOCK;
 	/*
 	 * Mount should fail if the rt bitmap/summary files don't load, but
 	 * we'll check anyway.
 	 */
+	error = -EINVAL;
 	if (!mp->m_rbmip || !mp->m_rsumip)
-		return -EINVAL;
+		goto out_unlock;
 
 	/* Shrink not supported. */
 	if (in->newblocks <= sbp->sb_rblocks)
-		return -EINVAL;
+		goto out_unlock;
 
 	/* Can only change rt extent size when adding rt volume. */
 	if (sbp->sb_rblocks > 0 && in->extsize != sbp->sb_rextsize)
-		return -EINVAL;
+		goto out_unlock;
 
 	/* Range check the extent size. */
 	if (XFS_FSB_TO_B(mp, in->extsize) > XFS_MAX_RTEXTSIZE ||
 	    XFS_FSB_TO_B(mp, in->extsize) < XFS_MIN_RTEXTSIZE)
-		return -EINVAL;
+		goto out_unlock;
 
 	/* Unsupported realtime features. */
+	error = -EOPNOTSUPP;
 	if (xfs_has_rmapbt(mp) || xfs_has_reflink(mp) || xfs_has_quota(mp))
-		return -EOPNOTSUPP;
+		goto out_unlock;
 
 	nrblocks = in->newblocks;
 	error = xfs_sb_validate_fsb_count(sbp, nrblocks);
 	if (error)
-		return error;
+		goto out_unlock;
 	/*
 	 * Read in the last block of the device, make sure it exists.
 	 */
···
 				XFS_FSB_TO_BB(mp, nrblocks - 1),
 				XFS_FSB_TO_BB(mp, 1), 0, &bp, NULL);
 	if (error)
-		return error;
+		goto out_unlock;
 	xfs_buf_relse(bp);
 
 	/*
···
 	 */
 	nrextents = nrblocks;
 	do_div(nrextents, in->extsize);
-	if (!xfs_validate_rtextents(nrextents))
-		return -EINVAL;
+	if (!xfs_validate_rtextents(nrextents)) {
+		error = -EINVAL;
+		goto out_unlock;
+	}
 	nrbmblocks = xfs_rtbitmap_blockcount(mp, nrextents);
 	nrextslog = xfs_compute_rextslog(nrextents);
 	nrsumlevels = nrextslog + 1;
···
 	 * the log.  This prevents us from getting a log overflow,
 	 * since we'll log basically the whole summary file at once.
 	 */
-	if (nrsumblocks > (mp->m_sb.sb_logblocks >> 1))
-		return -EINVAL;
+	if (nrsumblocks > (mp->m_sb.sb_logblocks >> 1)) {
+		error = -EINVAL;
+		goto out_unlock;
+	}
+
 	/*
 	 * Get the old block counts for bitmap and summary inodes.
 	 * These can't change since other growfs callers are locked out.
···
 	 */
 	error = xfs_growfs_rt_alloc(mp, rbmblocks, nrbmblocks, mp->m_rbmip);
 	if (error)
-		return error;
+		goto out_unlock;
 	error = xfs_growfs_rt_alloc(mp, rsumblocks, nrsumblocks, mp->m_rsumip);
 	if (error)
-		return error;
+		goto out_unlock;
 
 	rsum_cache = mp->m_rsum_cache;
 	if (nrbmblocks != sbp->sb_rbmblocks)
···
 		}
 	}
 
+out_unlock:
+	mutex_unlock(&mp->m_growlock);
 	return error;
 }